BUREAU OF ENGINEERING
|A "cost no object" relationship existed between RCA and the U.S. Navy. Maybe it was because RCA was created at the request of the Navy in November, 1919. At any rate, many of the early Navy-RCA receivers are "over-the-top" in heavy-duty construction, sheer-size and weight, circuit design and performance. The RAA receivers were the first longwave superheterodynes built for the Navy. Even though produced during the depths of the Great Depression, RCA's extravagance when designing for the Navy is evidenced by the RAA. This article is mostly a restoration log that is written as the work progresses rather than trying to remember all of the details after the project is finished. This format allows those interested in the process and problem solutions to follow along as the restoration evolves. This restoration log-web article will be updated at least once a month as the project progresses. H. Rogers - June 2017|
RAA - 1930s Navy Long Wave Superheterodyne Receiver
|RAA History -
The U.S. Navy RAA receiver was first produced in 1931. The initial
versions, RAA up to RAA-2 (1934) were built by RCA-Victor Corporation
but, by the RAA-3 (1935,) RCA
Manufacturing Company, Inc., a division of RCA that handled most of the
commercial and military contracts, was the builder. As RCA expanded
their radio-dominance in the thirties, they created several divisions
within the corporation to handle specific parts of the business.
Radiomarine Corporation of America had been created in the mid-twenties
from Wireless Specialty Apparatus Company after their acquisition by
RCA. Radiomarine Corporation was a powerful subsidiary of RCA that handled all of the commercial shipboard radio
equipment sales and service and also ran many of the coastal ship-to-shore
stations that sent RCA Radiograms to-and-from commercial ships at sea
around the world. RCA Manufacturing
Company, Inc. was created in the thirties after the 1930 anti-trust suit
settlement essentially recreated RCA into the "Radio Corporation"
that the Navy had originally envisioned in 1919. Since commercial and military
contracts were becoming a large part of the radio business, RCA
internally separated the primary business, RCA-Victor, as the entertainment
radio-phonograph-recording-broadcasting division and RCA Manufacturing Company for
commercial and military radio equipment building.
Recent History of RAA-3 SN:64 - I received an e-mail from Robert Goff W7MKA in Grants Pass, Oregon wanting to know if I'd be interested in restoring an early Navy LW receiver, the RAA. Robert wanted to donate the RAA if I would perform the much needed restoration. During to course of our e-mail exchanges, it was suggested that Bob Welch W6AQU, who is a mutual friend and who happened to live not very far from Robert, bring the RAA down to the upcoming N7RCA Minden, Nevada swap meet in June. Actually, the swap meet was several months away but that was just one of a couple of options suggested for transportation. A few days before the June 17th 2017 N7RCA swap, Robert transported the RAA to Bob's QTH and the two of them loaded it into Bob's truck. At the N7RCA swap on Saturday, I met up with Bob who had actually driven the six-hour trek Friday afternoon. After the swap meet was winding down, KØDWC and I unloaded the RAA from Bob's truck and loaded it into my Toyota FJ (with the rear seats folded down.) Later that afternoon, Chuck KØDWC came over to my QTH in Dayton and we moved the RAA from the FJ into the shop. As a thanks to Bob W6AQU for bringing the RAA over to the N7RCA swap, I gave him a restored Hallicrafters SX-28 receiver.
Robert W7MKA told me that the RAA had been up in Eugene, Oregon for years. It seemed that a retired professor from SOU had purchased a large piece of property off of the Loraine Highway in Eugene. The property had lots of old growth trees, one trailer and piles of stuff scattered around the property, including the RAA. It seems that the RAA had been wrapped up in a tarp and was stored outside. Robert obtained the RAA from the professor who only wanted a "scrap metal" price for it. How the RAA originally got to Eugene and why it was stored on the property there was unknown to Robert.
|WWII History of
RAA-3 SN:64 - When pulling the tubes to begin major
disassembly, I discovered two important clues as to the SN: 64 location
and use, at least during WWII. The RF Amplifier tube is well-protected, double shielded
with a standard aluminum tube shield and the threaded cap
shield that's on the Tuner band switch box shield. When pulling the Type
58 tube, I noticed that there was a label on the tube that read "U.S.S.
WHITNEY" with tube test data and two dates. The first date was
ink-stamped "7 OCT 1941" and the second date was in pencil " 7 / 6 / 44"
with penciled test data. There is an early label under the Whitney label
that has pencil written test data but no date. This label though must
date from before October 1941 indicating that the tube, a Sylvania 58,
is a pre-WWII installed tube.
Loose in the tube shield was another tag (very faded) that read "U.S.S. DIXIE, RADIO SHOP, Tested, Date." If there was any data written after Tested or Date it was faded beyond reading. So what do these labels indicate? All of the other tubes in the RAA-3 were WWII issue USN tubes with no labels. Only the pre-war Sylvania had a label.
The Ships - The U.S.S. Whitney and the U.S.S. Dixie were both Destroyer Tenders. Destroyer Tenders were large "repair" ships that were assigned to a flotilla of Destroyers. Since Destroyers were small ships with limited crew facilities, the Tenders not only provided most types of repairs but also provided dining facilities, electrical power when needed, refueling when needed, water desalination (showers and flushing needs,) Destroyer crew quarters when needed and many other support duties for the Destroyers in the flotilla. Both the Whitney and the Dixie had radio repair shops and stores of spare tubes and spare parts. Since both labels indicate radio repairs (or servicing) by the Whitney and the Dixie, it seems possible that RAA-3 SN:64 was used onboard a Destroyer before and during WWII.
photo above: This label is very faded but the top line is "U.S.S. DIXIE," the second line is "RADIO SHOP," the third line is "Tested" and the fourth line is "Date."
No other tubes in the receiver had tube test labels left on them (but the Power Supply does.) All of the other tubes were WWII USN tubes. The RF Amplifier tube was the only pre-war tube and its early date is actually before Pearl Harbor was attacked.
|More Tube Labels
- I started to disassemble the Power Supply on July 8, 2017. There are
three tubes used, two Type 5Z3 and one Type 874. All three tubes have
test labels and all three are from the Repair Ship AR-1 U.S.S. MEDUSA.
Two labels have easily readable dates. One 5Z3 had two labels one on top
of the other. Both labels had readable dates and both were from the
MEDUSA. The two labels are shown to the right. Note the the early label
is dated 5/2/42. The later label is dated 6-20-45, almost at the end of
WWII. The other readable label is on the 874 tube and it is dated
6-28-45, indicating that probably all of tubes were tested as part of
servicing. However, since the Power Supply doesn't have a matching
serial number to the RAA-3 SN:64, we can't be sure that this power
supply was actually used with the RAA-3 during that time period (WWII.) It's
probable that while servicing or repairing the receivers, power supplies
were interchanged since the power supply is specified for use with
either the RAA or the RAB receivers and can also be used with all
versions of either receiver. If used with the RAB-1 there's a toggle
switch inside the power supply that must be switched to the RAB-1
position. In the opposite position, the power supply works with all
versions of the RAA or the RAB, RAB-2 thru 4. Suffice it to say,
although the power supply tube labels are certainly interesting, their
direct connection to the RAA-3 SN:64 receiver cannot be confirmed.
The Ship - The U.S.S. MEDUSA was a Repair Ship. These ships were like Destroyer Tenders but a little larger and not specifically assigned to Destroyers. The Medusa would do repairs on any type of ship. The same type of repair facilities were on Repair Ships and the Radio Repair Shop was well-stocked with repairmen, tubes and parts. The Medusa was assigned to the South Pacific in 1944 and 1945. Likewise, the Whitney and the Dixie were Pacific ships. In fact, the Whitney was docked at Pearl Harbor on December 7, 1941 but came thru the attack undamaged. It seems likely that RAA-3 SN:64 was in the Pacific, probably for all of its service life and certainly just before and during WWII.
Inspection and Condition Assessment &
All of the photos in the following section are of RAA-3 SN: 64 before any restoration started. Some minor cleaning was done as part of the inspection process.
The Radio Frequency Tuner - CRV-46034-A
The RAA receiver uses a Tuner Section that employs an Antenna Input section that has selectable coupling (close or loose) to the RF amplifier stage that uses a type 58 tube. The Mixer is a type 24-A tube and the LO is a type 56 tube. The impressive tuning condenser consists of ten sections that are paired together to provide a five-gang air variable that is 27 inches long. Each of the five sections are located in its own shielded compartment. The tuning condenser is driven by a brass worm gear and a fiber wheel gear. Each coil used in the tuner is housed in a shielded compartment or is shielded with a screw-on shield can. The Tuner covers from 10kc up to 1000kc in five bands. Power to the tuner comes from the Power Supply and is routed via a cable that connects to a terminal strip located on the right side of the chassis (viewed from rear.) The IF-AF Unit is connected to the Tuner via a shielded cable that is connected to a terminal strip located in the LO section of the tuner. The output signal (at the proper IF) is routed down this cable to the IF-AF Unit where the proper (matching) band is selected by the IF-AF bandswitch to provide the correct IF section where then the Tuner IF signal is amplified, detected and audio amplified..
Since four separate IF stages are used for the five tuning ranges, the Tuner LO has to combine with the incoming tuned RF signal in the Mixer stage to output 37.8kc for bands one and three, 20kc for band two, 95.5kc for band four and 238kc for band five. The band switch uses a set of 90 degree gears to drive the multi-section band switch that has each switch-section within a shielded compartment.
The chassis, the shielded compartments, the brackets, the cabinet and most hardware is made of nickel-plated brass. The front panel is made of .25" thick aluminum that measures 27.5" wide and 20.5" tall. These non-ferrous metals were used to reduce corrosion from salt-air environments found onboard ships at sea or at shore stations.
photo above: Not many receivers have a tuning condenser that's 27" long with ten air variables set up in pairs for a five gang tuning condenser.
photo above right: The data plate of the RAA-3 is mounted on the Tuner front panel. Note the contract date of 2 Nov, 1935. Serial number is 64.
photo lower right: The tuning dial is miniscule and not illuminated. It uses the 0-100 vernier and the 0-10 course dials. The chart frame holds the tuning chart. I have the original tuning chart, a penciled chart and a "blank" chart.
photo right: Nomenclature plates for the Antenna input. Note the large studs for connecting antenna and ground. The broken shaft operates a switch for changing the Coupling from Close to Loose. I have the rest of the wooden shaft and the original knob. The control on the right is the band switch. This control operates a right-angle gear that drives the multi-section band switch that is mounted parallel to the front panel. The tuning range is shown in kilocycles for each band.
|photo left: Back view of the RAA Tuner showing the
band switch compartments towards the front panel. The shield for
the Antenna Input section is missing. The three threaded
cylindrical shields on top of the shielded compartment are for
the three tubes in the Tuner section. Nine coils are on top of the chassis
and are located under the cylindrical shields. Seven coils are under the chassis
and are located in individual compartments. The five compartments of the
shielded band switch also have coils. Power is applied to the
Tuner from the Power Unit cable harness that connects to a
terminal strip located at the front right side of the chassis
(as viewed from the rear.) There is also a shielded cable that
comes from the IF-AF Unit that connects to the terminal strip at
the LO section of the band switch compartment. The terminal
strip can been seen as an opening in the shield near the front
panel. There is a metal shielded housing that covers the
terminal strip that is missing. Fortunately, the IF-AF unit also
has the same type of metal cover so a replica can be made for the Tuner.
|The Original Tuning Chart
and Navy Radio Stations - The original tuning chart has
survived with this RAA-3 receiver and is shown to the right.
NSS was "radio central" for the U.S. Navy and was located
at Annapolis, Maryland near Washington D.C.
NPL was at Point Loma near San
NPG was at Mare Island Naval
Shipyard located in the northern part of San Francisco Bay.
was located at Truckerton Island, NJ and was mainly used as a backup
station for the North Atlantic. NBA
was located at Balboa, Canal Zone (Panama.)
was located at Pearl Harbor, Hawaii.
These Navy stations were monitored by Navy ships because many orders and other important information originated at the Navy Department in Washington D.C. where it was usually transmitted by NSS to NPL or NPG and then relayed by NPL or NPG to NPM where the orders or info were then transmitted to the Navy ships in the Pacific.
Shown to the right is the original tuning chart from RAA-3 SN:64. The number immediately after the station call is the station's frequency in kilocycles. The TUNING column shows where to set the tuning dial with the band switches set to the proper kilocycle tuning range. I haven't been able to find out what "CCT TIMES" means. Various other kilocycle frequencies versus tuning dial readouts are also provided.
To see the photo-edited replica of this chart used in the restoration go to "Finishing Front Panel Work" further down this webpage.
|Scrap Test Log
- Another interesting scrap of paper was in the same envelope with the original tuning
charts and is shown to the left. It's likely that this is a note of some
stations that were tuned in while the RAA-3 was either being tested or
repaired. Unfortunately, since it was just a scrap of paper, it
wasn't dated. However, it's possible to estimate an approximate time
period from the stations listed.
CMX from Havana was on 900kc from the late-twenties to the early forties. CMX was affiliated with NBC in the thirties. In June 1943, Cuban Socialists bought CMX and it became Radio Mil Diez using the call letters CMX for their 1010kc broadcast station. Radio Mil Diez was on the air from 1943 to 1948. Tuned on 9-48, Band 5 (approximately 990kc on tuning chart - see NOTE below)
WIBW in Topeka, KS was on 580kc (and still is.) The station ran 5000 watts in the forties. Tuned on 4-20, Band 5 (580kc on tuning chart)
KFAB was on 780kc before 1948 and was located in Lincoln, NE from the late-twenties until 1948. KFAB moved to Omaha in 1948 and changed frequency to 1110kc. Tuned on 7-30, Band 5 (approximately 790kc on tuning chart)
NOTE: KFAB is tuned in 10kc higher than assigned frequency. This is slightly more than a 1% error in the middle of the tuning range for that band. CMX 900kc tuning in at 990kc would be a 10% tracking error showing higher. For CMX to be Radio Mil Diez would have the error going lower which isn't likely. The 10% tracking error (at the top of the frequency coverage) would not be uncommon. Probably CMX tuned is the 900kc pre-June 1943 station. The stations listed date this note certainly to no later than 1948 and it's highly probable that the note actually dates from before June 1943.
The Intermediate and Audio Frequency Amplifier - CRV-50022-A
photo above: The front panel of the Intermediate and Audio Frequency Amplifier. The hole in the panel is for the Plate Voltage meter (which is missing.)
There are four separate IF
amplifiers that are selected with the band switch on the front panel.
When setting up the Tuner a particular tuning range will be selected.
The same range must be selected on the IF-AF Unit which provides the
Tuner-Mixer with the proper IF for its output frequency. Two IF
amplifier stages are employed but, since there are four separate IF sections, there are twelve IF transformers in the
Since there are four different IFs, there must be four different BFOs
also. Total of sixteen transformers that are mounted under the chassis
in individual compartments.
The Automatic Volume control is actually an audio output limiter that provides some protection from heavy static or nearby lightning discharges. The Sensitivity control adjusts the level of RF and IF amplification. The toggle switches are top, AVC - ON - OFF. The middle switch is C.W. or I.C.W., indicating continuous wave or interrupted continuous wave. I.C.W. was a mechanical way to use a "chopper" (a rotating wheel that had alternating conductive and non-conductive segments) which would break the CW at a rate that produced an audio frequency interruption. This was to allow reception of CW without a heterodyne generator at the receiving end (a BFO or an oscillating regenerative detector.) Generally, I.C.W. will have the "chop" produce a frequency shift of the carrier (usually several hundred kilocycles shift.) I.C.W. was replaced with MCW or modulated CW which essentially is a transmitted carrier wave modulated by an audio tone oscillator. MCW used a much narrower slice of the spectrum than I.C.W. did. If an AM Voice signal was to be received, then the switch was placed in the I.C.W. position which turned off the BFO. The bottom toggle switch is the Audio Filter - Broad or Sharp. This is a 1000hz audio bandpass filter that was used to limit interference by reducing the bandwidth audio frequency response specifically for CW tone. The Sharp bandwidth is about 100hz.
The RAA receivers were primarily used for CW (or ICW-MCW) reception. Although it would easily receive AM-Voice signals and was specified to do so in the manual, the typical shipboard use was for CW (nearly all Navy radio operation was CW until after WWII.) The audio output response is 200hz to 4000hz in Broad and about 950hz to 1050hz in Sharp. The audio output impedance is nominally 600Z ohms and intended for 'phones since the audio power is only about 500mW. The meter monitored the +200vdc plate voltage and also served as a power-on indicator. The circuit uses eight tubes which when combined with the three tubes in the tuner and the three tubes in the power supply brings the total tube count to 14.
photo above: The IF-AF nomenclature plates. The Automatic Volume control is actually an output limiter control. Sensitivity controls the grid bias on the RF amplifer tube and the IF amplifiers. Note the Frequency Band switch for selecting the proper IF section.
photo right: Under the IF-AF chassis showing the twelve IF transformers and the four BFO coils (rear-most coil set in each section.) Band switch is in the center of the chassis.
photo left: The top of the IF-AF chassis. The IF-BFO-DET tubes are located under the shield cans. The Audio and AVC section is at the top with four un-shielded glass tubes. Although not readily apparent in this photo, the Audio-AVC chassis can be dismounted from the chassis and the wiring harness disconnected. This may have been for ease of maintenance or construction. The shielded cable (that I'm holding) is routed to the Tuner unit through cabinet holes and connected to the terminal strip at the LO on the Tuner. The RF output (signal) at the selected Intermediate Frequency travels down this shielded cable where the proper IF must also be selected at the IF-AF unit for the signal to proceed thru the IF and onto the Detector and AF output. This cable is severely damaged and will have to be rebuilt. Surface rust is obvious on the ferrous-metal parts. The nickel-plated brass parts are in decent condition.
I've tried using a brass brush on the corrosion on the bypass capacitor can in the foreground after taking this photo shown to the left. This easily removes the corrosion and the metal is in pretty good condition afterward. The corrosion is mostly surface type and hasn't "rotted" the metal. There's a photo further down this page showing the cleaned bypass condenser.
Update 9/2018 - I've brass wire-brushed all of these parts and the chassis. I was amazed at the improvement, especially the nickel-plated chassis. I still will have to paint the cans of the bypass caps and transformers to have these components look decent but I was able to remove the majority of the rust.
The Power Unit - CRV-20016-A
The power supply uses two rectifier tubes. The power supply operates on 110vac to 120vac. In the CRV-20016-A version that was used with the RAA-3 and RAA-4 along with the RAB HF receivers the rectifier tubes are 5Z3 types. Earlier power supplies used type 80 tubes. The high plate voltage is +200vdc. An 874 cold cathode regulator tube is used on the +90vdc supply. Other voltages are +75vdc and +48vdc. Bias voltages are -1.1vdc, -1.8vdc and -3.3vdc. Power is supplied to the RAA-3 receiver via two large power cables with one cable connected to the Tuner and the other cable connected to the IF-AF section. The CRV-20016-A version has a multiple tap primary on the power transformer. The terminals are 1 for AC Line 1, 2A for 110VAC, 2B for 115VAC and 2C for 120VAC. At present the primary is set up for 115VAC operation. I'm going to utilize the 2C terminal for 120VAC input which is closer to my line voltage and will have the power transformer secondary windings operating closer to the specified voltages.
|The RAA-3 cabinet is actually two units bolted together. The Tuner
cabinet is 27.5" wide and the IF-AF cabinet is 10.25" wide.
When assembled together the cabinet measures 37.75" wide, 20.25" tall
and 21.60" deep. The cabinet
is made out of nickel-plated sheet brass to reduce corrosion from
salt-air. This probably helped to protect the wrinkle finish paint from
"lifting" due to corrosion under the paint.
The first impression is that this cabinet is made out of aluminum however that impression vanishes when one tries to move the cabinet. IT IS HEAVY!
The Tuner side has guides at each bottom corner. The IF-AF side has a centrally-mounted guide on the top and on the bottom. The edge of the IF-AF chassis slides in this guide keeping the unit in position so the thumbnuts can be tightened. There are entry holes for the power unit's cables. The entry hole for the Tuner can be seen. The entry hole for the IF-AF unit is in the upper right part of the back panel. There is also a hole thru the sides that are mounted together. This allows the shielded cable harness connection between the IF-AF unit and the Tuner LO. There are holes in the bottom that indicate that shock-mounts were probably originally bolted there.
The two cabinets will have to be "unbolted" and separated. This will allow for easier moving and more thorough cleaning, body work, surface prep and repaint.
Inspection - June 18, 2017 to June 23, 2017 - No doubt, this is a formidable
There is a lot of damage due to poor storage conditions. This damage is
both cosmetic and electronic. With a project that requires this much
work it helps to create a list of problems and observations that will help to formulate a restoration plan. Here's the obvious,...
1. Entire repaint will be required. Black wrinkle finish - I'll have to contact VHT to see if I can buy a quart and then thin to spray using the larger paint equipment I have (the type for painting cars.)
2. Cabinet straighten and repair. Whatever the mounts were, they are missing.
3. Corrosion removal. Most is surface corrosion however some erosion is noticeable on the inside of the front panels where the mounting brackets contact the aluminum. Erosion on the back of the Tuner panel is pretty serious.
4. Wiring harnesses will require rebuilding. I'll try to use as much of the original wire as possible but it's probably going to be necessary to replace a lot of wires.
5. Data plates and nomenclature plates need restoring. Fairly easy.
6. Dial doesn't rotate although tuning mechanism works. Shaft turns so dial set screws are probably loose. Dial is held by a threaded boss and nut. The nut was loose.
7. Missing Plate Voltage meter - wiring to meter cut very short. Same Plate meter that's used on the early RBA, RBB or RBC receivers. The metal housing versions of the meter.
8. Broken shaft on Coupling switch control. I have the original broken shaft and knob. The shaft is made of wood (fiber material) so a replacement is fairly easy to construct.
Here's some of the other problems,...later update notes are in italics.
1. Several IF transformers are damaged, some minor,...one major. Appears that mice running around in the compartments broke several wires from the coils to the terminals of the IF transformers. One coil on one of the 238kc IF was bitten into and about 20% of the coil is missing. This one will need to be rewound or a replacement coil from a 200kc IF trimmed to work. Too bad someone removed the bottom shields years ago.
2. Severe nut and seed storage in LO section of tuner - no apparent damage after removal. Used a shop vac (there was a lot of seed/nut debris - see photos below.) One terminal on the bandswitch is broken.
3. IF Bandswitch doesn't rotate - appears shaft is corroded in one bearing - WD-40 and slight pressure defeated the corrosion and the IF Bandswitch is now operational. After the WD-40 had time to seep into the bearing the switch operation is very easy and requires very little effort to effect band changes now. >>>
>>> 4. Phone jack in IF-AF appears to be missing insulator spacer, wiring shot to jack. This appears to be an output from the detector. It must be for testing since access to this jack would be difficult if the receiver was installed into the cabinet. No access hole in the cabinet where the jack is located. This jack is for alignment and is for installing a detector plate current meter for measuring peak current during alignment. Though the bottom shields are missing, there was a hole in the shield to allow access to this jack.
5. Severe surface corrosion on all transformers and chokes (due to steel cases.) These components will need repainting after the corrosion is removed. Most of these components are actually bypass capacitors.
6. Generally, the Tuner and Power Supply are in better condition than IF-AF unit which has the most damage and will be the most difficult to restore to functionability.
The Tentative Restoration Plan - Though a restoration can usually be accomplished without a manual or schematic, it's much easier and ultimately much more complete and accurate with a manual for reference. The first step is to get some documentation (manual found.) During disassembly, all removed parts, including hardware, will be "bagged and tagged" in individual, identified plastic bags. This will be a tremendous help during reassembly since all parts will be easy to find and easy to identify. Since the Tuner and the PS are fairly heavy they will have to be restored in the shop. The PS will be restored first since it appears to be in the best overall condition. The Tuner will be restored next since it's better than the IF-AF unit. Both of these pieces can be worked on in the Summer out in the shop. The IF-AF unit is about 75 lbs out of the cabinet and can be brought into the upstairs lab for repair. This can be done during the Winter, if necessary. Cabinet repair will be done last after the RAA is operational and the Tuner, the IF-AF unit and the PS panels have been restored. If the cabinet restoration ends up being a Winter project, painting may be postponed until it warms up. One caveat,...this plan is subject to change depending on what unforeseen problems are encountered during the restoration process (and we do expect to find many more problems than those listed so far.)
UPDATE to the Plan: December 1, 2017 - As mentioned, the above plan was tentative. I've already changed the plan after some careful thought. Rather than restore each unit, one at a time, I decided to go ahead and do all of the cosmetic restoration work first. This was mainly to be sure that as I progressed through the restoration, I would already know that the finished RAA-3 was going to "look good." This meant I had to do all of the panel repairs, the painting with black wrinkle finish of the Tuner panel, the IF-AF panel and the Power Unit panel. The Tuner panel had significant erosion damage on the back that had to be repaired. This panel is huge and having its wrinkle finish paint job turn out fantastic was a major relief. The added advantage of painting the wrinkle finish on the panels early during the restoration is that the panels can be set aside and the wrinkle paint allowed to fully cure and become the tough, hard finish it can be after a month or two (or maybe a year.) Once all the panels, the panel data plates and the panel hardware are finished and can be set aside to "cure," I'll then do the electronic restoration. Power Unit first because I'll probably need the power supply to restore, test and troubleshoot the Tuner and the IF-AF Unit. Once I have the complete receiver chassis together and operational, then I'll restore the cabinet. The cabinet is extremely heavy and will need to be sand blasted, so this type of operation is probably best done in the summer. Of course, plans always are subject to change and hopefully the changes make sense and will help in the ultimate completion of this restoration.
RAA-3 Disassembly Problems and Some Preliminary Testing
One of the first discoveries was the "Unexpected Cache" shown below. Although disheartening, clean-up, luckily, revealed no problems but many more unpleasant discoveries awaited.
Panel Dismounting -
July 1, 2017 - The first step in disassembly
is to dismount the front panels. This will allow easier moving
of the chassis of both the Tuner and IF-AF unit. Also, further
disassembly can then proceed with the panels off. But first, we
have to deal with stuck screws.
Stuck Screws - Even though the chassis and shields are brass and the screws are brass, both still oxidize. I'm finding that some of the screws will break the heads off rather than unscrew. I find that I have to soak the screws in penetrating oil overnight before trying to remove screws. If the screw is still stuck then I apply heat and more penetrating oil. The heat is applied with a soldering iron tip directly to the screw head. The heat-expansion "breaks" the corrosion and helps the oil penetrate which usually allows the screw to be removed without damage. After the screw is removed the threaded hole is "chased" with the proper size tap to clean out any remaining corrosion.
Knob Set Screws - The knob set screws are 8-32 spline socket set screws. None of my spline wrenches fit this spline socket correctly. I had to make a special tool that fit into the spline socket tightly to allow set screw removal. Again, corrosion of the steel set screw in the brass hub of the knob seems to be encountered in every knob and each knob has two set screws. Soaking in penetrating oil overnight is the first step. Then apply heat with a soldering iron tip directly to the set screw. I use a small soldering iron tip that will fit down the barrel to contact the set screw directly without touching the sides of the knob barrel. It helps to alternate between heating and then cooling with more penetrating oil followed by more heat. This procedure was successful for removing the set screws in all but two knobs. These knobs had set screws that defied all the normal removal techniques. Alternating heat and oil over a period of two days with special tools such as a reverse-twist drill and a screw extractor proved useless.
|Front Panel Removal
- July 5, 2017 - What was necessary to remove the final
two knobs may seem unthinkable but the two knobs had to be
destroyed in order to remove them from their shafts and allow
dismounting of the front panels. I had original replacements for
the knobs, so we weren't dealing with irreplaceable parts. I
used a Dremel tool and a "cut off" disk to first slice the
bakelite off of the brass hub. Once the bakelite was removed,
then I used the "cut off" disk to cut away just the set screws.
Once most of the set screw itself (two in each knob hub) was cut
away, the pressure is released and the hub just slides off the
shaft. If done carefully, no damage will happen to the shaft.
With the knobs removed, the next step was to remove the remaining panel screws. Four of the panel screws on the Tuner had been broken sometime in the past. I applied penetrating oil for about two days before trying to remove the remaining screws. I used a blade screw driver that was a very tight fit into the screw slot. Once the blade was in place, I gave the screw driver a couple of hits on the handle to transfer the shock thru the screw. All of the remaining panel screws were removed successfully using this method.
The Tuner panel has some serious erosion on the back where the vertical mounting brackets were attached. In order for the vertical mounting brackets to be fully "flush" against the back of the panel, the erosion will have to be filled. Since the panel is going to be reconditioned to remove oxidation and prepared for painting, it should be relatively easy to use real metal body filler to fill-in the eroded areas. This can then be sanded flat. How it matches the undamaged aluminum remains to be seen when we actually go thru this process.
The IF-AF Unit panel was in good condition although dirty and a bit of surface oxidation. All removed hardware, knobs, tags, handles, tubes, etc. were "bagged and tagged" in plastic bags for easy identification for the reassembly process.
|photo left: Tuner with front panel removed. Note the
decade tuning dial gear that is driven by the tuning shaft. Note
how clean some of the coil boxes are. These were inaccessible to
mice and contaminates.
photo right: The IF-AF unit with front panel removed. Although this looks pretty bad, the rust is mostly surface corrosion. Note the foremost bypass condenser has been cleaned just using a brass brush.
Supply Panel Removal - July 9, 2017 - Overall
there is much less corrosion on the Power Supply. The cabinet
and panel had fully screened ventilation holes that prevented
any entry of mice or other damaging pests. Inside the chassis
is fairly clean and the components appear in good condition with
little or no rust anywhere. Underneath the chassis is about the
I applied penetrating oil on all panel mounting screws and nuts the day before I attempted unscrewing any hardware. This helped a great deal as nearly all screws were easily removed. Only the cable clamp screws proved somewhat difficult but eventually they were removed undamaged.
The photo to the right shows the power supply with the front panel removed. The rust spot on one of the filter capacitors appears to have been caused by moisture trapped by the cloth woven cover of the wiring harness.
Continuity Tests and ACV Tests -
July 13, 2017 - The first step
to determine if the power supply is going to function is a continuity
test of the iron,...that would be the power transformer and the two
chokes. Next would be to test the oil-paper filter capacitors for shorts
and value. Since we have the rectifier tubes removed, we can actually
apply AC voltage to the primary of the power transformer to test its
functionability. Since no DC high voltage can be developed, we are only
checking the primary, the filament voltage windings, the high voltage
winding and the AVC AC voltage winding. If these tests show the
transformer produces the correct AC voltages, then it will be left
powered for about 15 minutes to see if any heat develops. Without a
load, the transformer should stay cool.
Test Results - All iron checked good for continuity. Capacitors checked as "not shorted." There are three vitreous enamel coated, 100W tapped resistors. All three resistors have open sections and therefore have to be rebuilt. These resistors makeup the voltage dividers that provide the proper B+ and negative bias voltages. The AC power cable has to be replaced. This was a shielded cable originally but the cable inside the shield is rotted. The AC power switch tested okay. Someone installed 20A fuses, should be 5A. The AC power switch and fuse block assembly needs partial rewiring that is mainly due to rotting of the AC power cable within the assembly. Replacing the AC power cable will correct the majority of the problems. I haven't tested the coils and capacitors within the AC Line Filter unit yet.
|What Needs Rework on the
Power Unit - The three vitreous enamel coated resistors
need rebuilding. New AC power cable. Rebuild output wiring harness.
July 15, 2017 - Cleaned and reconditioned the AC power switch, fuse board, power cable input and output box. Removed shield from old cable which is soldered to a metal tube that projects out the side of the unit and side of the box. Original wire appears to be 14 or 16 awg 2 conductor with black rubber jacket with shield sleeved over the cable.
July 16, 2017 - Clip-lead connected 120vac to thru the AC line filter to the power transformer. HV winding was over 400-0-400vac. Tube heater winding was 3.0vac. AVC voltage winding was 3.0vac. Rectifier heater was 5.9vac. Voltages were somewhat high because the AC line voltage was 120vac and also there was no load on the windings. Let AC voltage remain on power transformer for about 5 minutes with no changes in voltages and no heat build-up.
July 17, 2017 - I found it was difficult to locate any "new" 14-2 power cable at local stores. However, Home Depot in Carson City did have the correct type cable in stock. Lowe's and True Value don't carry 14-2 anymore and it is difficult to find online except by the 250' roll. I think two-conductor power cable is not going to be an in-stock item much longer.
|July 19, 2017 -
Miscellaneous Mechanical Work - Removed all broken 10-24 screws
that had been used to mount the front panel of the Tuner to the chassis.
There were six screw ends that needed to be removed. I had been putting
penetrating oil on the screw ends for a few days. The first screw end
was long enough that it could be grasped with vice grips and unscrewed.
One other screw was just barely long enough to grasp and remove. The
next screw had to be drilled and a screw extractor used to remove it.
The remaining three were drilled and threaded themselves thru and out as
the drill bit grabbed while cutting. When all broken screw ends were
removed, I used a 10-24 tap to chase the threads to remove any
corrosion. The IF-AF unit didn't have any broken screws but the threaded
holes were chased to clean-up the threads and remove any corrosion.
Power Supply - Soldered the original RCA spade lugs to the new AC power cable. This cable connects to the fuse board terminal strip using these two spade lugs. The fuse board also has to output lugs that have to be soldered to the AC Line Filter input wires. I'm going to install new shielding over the new AC power cable. The original was copper braided shield that looked exactly like the shield used on RG-8 coaxial cable, so that's what I'm going to use. The original power cable was about three feet long. Probably when onboard ship the receiver/power supply was connected directly into a wiring box and didn't use a "plug" and the cable was probably just long enough for the connection. I'm going to have a six foot power cable with the braided shield (from RG-8) over it. The original shield was soldered to the AC input metal barrel for the AC cable input to secure that end. The plug-end had the shield secured using a tightly wrapped length of TC that was soldered. This kept the shield in place if the power cable was moved. I'll secure the shield in the same manner but it will have an early-style, heavy-duty two-wire 115vac plug for connecting the power. I'm considering running the PS using a 1:1 isolation transformer with separate ground for the RAA chassis. This would replicate the "floating" AC that was used onboard ships. Another advantage of the isolation transformer can be adjustment of the actual AC voltage (using a Variac) applied to the receiver since our house line runs over 120vac.
|Stripping - July 21, 2017
- I had to do some methylene-chloride* stripping on another
project, so I though I'd subject the IF-AF Amplifier panel to the
stripper and see what happened. The remaining paint on this panel was so
oxidized, it just about fell off when the methylene-chloride hit it.
With the paint off, I can see the pitting and corrosion that has
occurred on this panel. It's not bad and will clean up with just a
little scrapping and application of abrasives.
Missing Hardware - While trying the stripper, I also removed and "bagged and tagged" all of the knurled thumbscrews on all three panels. I noticed that the Power Unit and the IF-AF Amplifier panels were complete with all of their thumbscrews but the Tuner was missing three long thumbscrews and one short thumbscrew. I'll have these replicated, probably by one of my machinist friends. They are black finished brass and use a C-clip to retain the thumbscrew to the panel. Size and threads are 12-24. (Actually, later close examination showed that the "short" thumb screws had the ends broken off. All thumb screws should be the same length.)
Also removed the screens from the Power Unit front panel in preparation for stripping and painting. Since the Power Unit is in good condition, I'll paint this panel now to allow the Black Wrinkle Finish plenty of time to harden. It usually takes minimum two or three days for wrinkle finish to get hard enough to remount parts. Waiting a week is better. Maximum hardness of the wrinkle finish usually takes about 30 days to cure.
July 22, 2017 - Stripped the Power Unit panel. It turned out very nice. Had to do a light sanding with 220 grit to remove the very minor oxidation pits. Once the panel is wrinkle finish painted none of these minor defects will show. See photo below upper photo.
Tried NaOH (Easy Off Oven Cleaner) to remove the green oxidation on the side of the Tuner chassis. This worked fairly well. Required two applications to remove about 80%. Probably one more application will remove the 20% remaining. As far as dirt, oil, grease or any other contaminate, these were gone with the first application.
*Methylene-chloride stripper is very hazardous and must be used OUTSIDE only. Do not use this type of stripper in an enclosed, non-ventilated area. All types of commonly found gloves DO NOT protect your hands. You must use PVA gloves that are layered with Nitrile gloves.
|July 23, 2017 - Power
Unit - Moved AC input from 115vac tap to 120vac tap. Rechecked
the voltages at the power transformer. HV was 415-0-415vac, HTR was
2.9vac, RECT FIL was 5.5vac, AVC FIL was 2.8vac. Again, this is with no
load. The circuit normally has a 1144 ohm 100 watt resistor that is a
constant, "dead" load on the
B+, so I'm sure once everything is up an running the voltages will be
much lower and probably in spec.
Calculated all wire wound resistor dissipations and designed replacements for the three open WW 100W resistors. These replacements will "plug in" to the mounting clips as the original resistors did. Unfortunately, it's impossible to repair the original resistors and the only acceptable method is to design and build replicas that fit into the original clips and provide the same resistance and dissipation. The replicas will have terminals for mounting individual WW resistors and will be built on a strip of high-temp delrin. Though they won't look like the originals, they will fit exactly and operate correctly. The original WW resistors will be saved for future reference.
IF-AF Amplifier - Panel oxidation was cleaned up using 220 grit sand paper. Some of the oxidation/corrosion areas are pretty rough and may require further treatment and perhaps minor metal filling. The oxidation/erosion of the metal may be due to dissimilar-metals with salt residue and moisture acting as an electrolyte. The erosion is only where there was contact of the aluminum with nickel-plated brass parts such as the chassis vertical brackets used in the Tuner or the contact of the aluminum panels and the nickel-brass cabinets.
Had to drill out two broken 4-40 screws on the IF-AF panel. Chased all 4-40 threaded holes with a tap to clean threads of any oxidation. IF-AF Panel photo lower right.
|Tuner Panel Backside - The
photo to the right shows the severe erosion that is located on the back
of the Tuner panel at the upper left part of the panel. As can be seen
by referencing the straight-edge, the erosion in some areas is almost
halfway thru the panel thickness. As mentioned above, this erosion is
not everywhere. It is only where the nickel-plated brass made contact.
Some areas are very minor and clean up with 220 grit sand paper. The
area shown in the photo is the most serious. Some of the residue found
when dismounting the front panels appeared very similar to "baking soda"
which makes me think that maybe it's salt residue from "salt-air" of the sea
that was "trapped" over the years and then had time to react with the
moisture of the storage environment. Salt water can be very corrosive. Well, regardless of what caused it,
the question is how to repair the damage?
After a thorough cleaning, I'm going to try using USC All Metal Aluminum body filler. It is a catalyst-activated paste filler used in autobody repairwork. It should be strong enough and if the area is ultra-clean, it should adhere quite well. When it sets up, it can be sanded to be flat with the non-damaged surface. Since the non-damaged aluminum will also be sanded and the all metal filler is also aluminum silver in color, hopefully the repairs won't be too conspicuous.
As mentioned somewhere further up this page, the back of the Tuner panel has to be fairly flat so the mounting against the two vertical support brackets aren't distorted or bent when the mounting screws and nuts are tightened.
|July 27, 2017 - Tuner
Panel Work - Three broken screws had to be drilled out. 4-40 tap used
to chase threads afterward. On all three panels, all broken screws have
been removed and all threaded holes are now open with the correct
threads. Stripped Tuner Panel of all remaining paint using methylene-chloride. Wet sanded panel
back and front to assess condition. Front of panel is very good with
only a few corrosion spots that aren't serious. Rear of the panel is in good
condition except the upper left area (viewed from rear of panel.) Wire
brushed corroded area and it cleans up but will require a heavy-duty
rotating steel wire brush to remove all corrosion and residue. I'm going
to use USC All Metal Aluminum Body Filler to "level" the rear side of
the Tuner panel.
Power Unit - Replica Wire Wound Resistors - Checked Mouser and all resistors required are in stock. Order soon. Checked measurements of 1" copper pipe end caps to use for end caps on replica resistors. These are virtually the same diameter and will work perfectly. Bought six caps to build the three WW resistors needed. Test fit into mounting clips and the fit is perfect.
|July 29, 2017 - Ground post was causing some interference with thorough cleaning of the Tuner Panel. This post was a "press-fit" with serrations to prevent it turning. On the back side, a 10-24 screw and internal-tooth lock washer also secured this ground post to the panel. Used a large socket to act as an anvil with a clearance hole for the ground post. With a 10-24 threaded into the post, I tapped the post out of the panel with a small hammer hitting the top of the screw. No damage to either the ground post or the panel. Ground post and screw were put into the "Antenna and Ground Post" plastic bag and the bag placed in the box with the other bagged Tuner parts.|
Front Panel Body Work
The erosion damage on the back of the Tuner panel was something I've never encountered before. The repair using USC All-Metal Body Filler was also a first.
|Aug 3, 2017 -
Made it to Sparks, Nevada and to Summit Racing to purchase a quart of
USC All-Metal Body Filler, which they had in-stock. Also, purchased
three cans of VHT Black Wrinkle Finish for painting the Power Unit panel
and the AF/IF panel. Tuner panel will be painted after the body filler
has successfully repaired backside of that panel.
Delay - A major delay in our restoration work is due to re-laying out the shop to have more shelving for storage and moving an eight-foot work bench to a better location that allows more work space and an "in shop" test and repair bench with full lab equipment. A couple of weeks delay will end up with a much easier environment to work in.
Aug 25, 2017 - Shop layout is done.
September 1, 2017 - Started to clean up the erosion damage on the Tuner panel. I used a rotary wire brush powered by a handheld electric drill. This dug-thru the loose powder and eroded metal to show bright aluminum underneath. The photo to the right shows the worst area of the Tuner panel backside (the upper left corner as viewed from the rear.) With the metal bright, the damage becomes very apparent and visible. Note in the photo that further into the panel area that there is no damage and the metal is nice and flat.
September 5, 2017 - Hal Layer KK6HY generously sent me an original RAA manual. Thanks Hal! The new B&W header photo is from this manual.
Oct 6, 2017 - I thoroughly went over the entire eroded area with a new conical wire brush to get into every corner of the damage. Afterwards, I cleaned the entire area with denatured alcohol. USC Body Filler tomorrow.
Oct 7, 2017 - Applying the USC All-Metal Body
Filler - All other projects were out of the way and today was
going to be a warm day, so I had planned ahead to do the aluminum body
filler (ABF) on the rear panels.
The ABF is a thick aluminum-filled paste to which an amber liquid catalyst is mixed to activate curing. Instructions indicate that about a "golf ball" size amount of ABF takes about 12 to 15 drops of catalyst. Working time is less than 10 minutes. I spread the mix with a disposable plastic putty knife. In the upper left corner the erosion had attacked and thinned the edge. I made a masking tape "dam" to keep the ABF from running over the edge. The erosion damage was so deep that four coats of ABF were needed to get the entire area somewhat level. However, minor erosion "blemishes" could be covered with just one thin coat. The ABF does set-up fairly fast but doesn't "cure" to its full hardness for several hours. I let it set overnight which was long enough for full curing. Both the Tuner panel and the IF-AF panel had ABF applied to erosion damaged areas.
|Oct 8, 2017 -
I checked the ABF after letting it cure overnight. It was H-A-R-D! In
fact, I tried 220 grit sandpaper by hand - just as a test. It hardly did
anything - just scuffed the ABF and didn't remove anything significant. Later in the day, I decided to try again. This time with 60
grit on a hand sander (that's what the ABF instructions recommend.) What a difference. This removed the excess ABF
very easily. The seemingly rough removal was accomplished on the Tuner panel in
about 15 minutes. The surface was very flat feeling but still had some
appearance of not being level. The next sanding will be with 120 grit but,
the next sanding session will be outside. What a
mess! Aluminum powder everywhere in the shop. I thought it was just
going on the floor, which I kept sweeping up every few minutes. The fine
powder seemed to travel about six to eight feet in all directions. Since it's
I had to do a thorough clean up.
After this initial sanding, the back of the Tuner panel looks very good. After more sanding I might have to apply a minor "touch up" fill for small spots that I missed. Also, some of the holes in the panels were filled in with the ABF. I'll have to drill out the clearance holes and drill and re-tap the threaded holes. In all, I should have the Tuner panel and the IF-AF panel done in a few more days.
Applying Black Wrinkle Finish Paint
"Acres of Wrinkle Finish." That's what I thought about when painting these enormous panels. The system I use for successful wrinkle finish application is one that I developed over years of "trial and error" and crummy-looking paint jobs. The wrinkle finish painting procedure described here is one that "works every time." Without a doubt, the RAA-3 Tuner Panel is the largest panel I've ever painted with wrinkle finish and I was extremely relieved when all three panels turned out perfect.
|Oct 9, 2017 (cont.) - After the
panel repair work is finished, I'll be going on to the wrinkle finishing
even though it's Fall and the weather is getting cooler. In preparation
of the painting phase of this project, I'm going to have to rebuild my
wrinkle finish heat applicator. I used to use 100W incandescent lamps in
aluminum bell-reflector clip lamps. Two or three of these would provide
enough heat to activate the wrinkling process. Most of my incandescent
light bulbs are bad and 100W replacements are getting difficult to find. I
decided to go with "brood lamps" instead. These are "heat lamps" that
are rated at 250W. Since heat is the objective, they are incandescent
filament-type lamps and will provide the heat necessary for wrinkle
finishing. I purchased the brood lamps at Tractor Supply. Also, when
I actually will be doing the wrinkle finish heat application I will be standing by with a
handheld heatgun to help activate wrinkling in problem areas like
corners or edges. Although the lamps might get all of the panels to
fully wrinkle, having the heatgun ready can speed along the process and
assures a full wrinkle on the entire panel.
Oct. 17, 2017 - Another delay. This short delay came in the form of a very nice RBA-1 receiver that needed restoration. This project will probably "eat up" about three or four weeks but the RBA-1 is all original and complete so it is well-worth the time involved. Turned out very nice.
Nov 19, 2017 - Built the heat lamp station today. Has a 24" x 36" piece of 3/4" plywood mounted to the top of a roll cart. There are two articulated desk lamps mounted in opposite corners of the wooden top. The lamps are 250W brood lamps. Just about any combination of desk lamp movements produce a good heat pattern for various shapes of panels. I'll have to test on a scrap piece first and, if all is okay, I'll proceed to paint the RAA panels after they are prep'd.
Nov 20-21, 2017 - Drilled out ABF where it had filled some of the panel holes. Where the holes were threaded a tap was run thru the hole to "chase" the threads. The most difficult part to clean of excess ABF were the recessed 0.5" diameter relief holes for the retaining clips for the panel thumb screws. I looked in several sources for a .25" diameter bit with a 0.5" cutting shoulder but nothing could be found anywhere. Finally, I decided to just use the .375" diameter AL/OX cylinder grinding tip and a Dremel tool to remove the excess ABF from the recessed holes. This actually worked pretty well. Final clean up of the recessed holes was done using a 0.5" diameter end-mill - by hand - followed by cleaning the area with a brass wire brush.
Nov 22, 2017 - Panels were cleaned up in preparation for painting. Consisted of light sanding followed by lacquer thinner wash. Since there was virtually no wind today, I applied the paint outside then brought the panel into the shop and put the panel under the heat lamps. Most of the problems with painting wrinkle finish are due to not enough paint applied over the entire surface. This results in uneven wrinkling or "stripes" in the wrinkle pattern. The other problem is not enough heat to induce the wrinkle process. This results in uneven wrinkling or lack of wrinkling in some areas. I always apply four "double" coats. Each part of each double coat is applied first in one direction and then in the opposite direction. Each of the complete double coats are applied in different directions with about a one minute wait between double coats. This reduces the possibility of stripes or uneven wrinkling. You have to be careful to not apply so much paint that it runs or sags. I usually shoot the paint with the panel lying flat. After the fourth double coat, the panel is taken into the shop and put under the heat lamps. I adjust the lamps so they are about 12" to 15" above the painted panel. I also have a hand-held heatgun that I use to continuously apply heat to the entire panel. I evenly go over the entire panel but I especially watch the edges and corners since these have a tendency to not wrinkle. The wrinkle process takes about 7 or 8 minutes to start on a large panel like the RAA panels. Once the wrinkling starts, I continue with the heat gun and sometimes I'll move the lamp positions to apply heat where wrinkling hasn't started yet. It takes another 5 or 6 minutes for the entire panel to wrinkle. I then turn off the heat lamps but continue to "wave" the heatgun for another minute making sure that edges and corners have all wrinkled. Do not hold the heatgun in one spot, too much heat will "gloss" the paint and ruin the wrinkle. Keep the heatgun moving all the time. With the heat removed, I let the panel cool down. I don't even move it for at least 30 minutes. I successfully wrinkle finished the IF-AF Unit panel and the Power Unit panel today.
Nov 23, 2017 - It's appropriate that I painted the Tuner panel on Thanksgiving morning. I had really been concerned about the wrinkle finish on the Tuner panel because it's huge - "acres" of wrinkle finish. I modified the heat lamp station by adding two more lamps. These were equipped with 100W incandescent lamps. The paint would be heated with two 250W brood lamps and two 100W incandescent lamps plus the hand-held heatgun. I applied four double coats of black wrinkle to the Tuner panel outside then moved the panel to the heat station. It took about 6 minutes of heat to get the wrinkle started. Full wrinkle in about another five minutes. The wrinkle on all three panels was thick and even with lots of texture.
However, even after a day of curing, the wrinkle will still be somewhat soft so I won't be mounting anything to these panels for quite a while. I usually wait at least a week to allow the wrinkle to fully harden. A month is better. Who knows how long it will be before these panels are once again mounted to their chassis? How about one year?
Photos of the wrinkle finished RAA panels below.
|photo left: IF-AF panel after painting with VHT Black Wrinkle
Finish. By comparing this photo to earlier photos of this panel without
paint it becomes obvious how many defects and surface problems the
wrinkle finish texture hides.
photo right: Tuner panel after painting with VHT Black Wrinkle Finish. The panel is still setting on the heat table (lamps are off, of course.) Note the lamps. The two dark color bells have the 250W brood lamps. The two aluminum bells have 100W incandescent lamps installed. Besides the four lamps, a hand-held heatgun is used to induce the wrinkle. The "key" to successful wrinkle finish painting is plenty of paint and lots of heat.
|photo left: The Power Unit panel after painting with VHT Black Wrinkle Finish. Not only does the wrinkle finish texture hide minor defects in the metal surface but, as the paint cures, it becomes much "tougher" and has the ability to resist some types of abuse. The VHT paint seems to attain its full cure in about one month. One can carefully handle the painted panel within about 30 minutes after the wrinkle has appeared. This is about how long it takes for the paint to "cool down" from the heat applied to induce wrinkling. After one day of curing, the paint is easy to handle but it's still relatively soft. If anything is mounted to the panel, the paint will compress and sometimes "squeeze" out from under a screw head or a mounting flange. I usually wait a minimum of a week before mounting any parts. A month is better. This panel set around for a year - nice and hard now.|
Restoring the Data Plates
Although this section seems rather long, the data and control nomenclature plates are just as important as the wrinkle finish paint. The data plates might seem small and probably not too difficult to do but just the opposite is true. Proper restoration is tedious work but the end result is worth the effort.
|Nov 29, 2017 - All of the data plates and the
control nomenclature plates were in pretty poor condition. Lots of wear
is apparent on the band switch plates. Close inspection of these plates
revealed that the rear of each plate is nickel-plated. It also appears
that the fronts might have been nickel-plated. This would result in the
data and control plates being black background with silver lettering.
Maybe a thorough cleaning might reveal some remaining nickel. If not, I'll be stripping off the remaining paint on the plates and hopefully
there will be nickel under the paint and that would confirm that the
plates were originally black background with silver letters. I do have
all of the materials to nickel-plate these pieces, if that's original.
NOTE: Earlier versions of the
RAA receiver used silver background with black letters on the ID plates
and black background on the control plates. You can see this in the B&W
photo from the manual (header photo) and on the photo of the RAA-2 on
the U.S.S. Texas. Also, note on the Texas RAA-2 that the Meter (Plate
Voltage) tag and
the Tuning tag appear to be silver lettering.
Nov 30, 2017 - Brass brushed the IF-AF data plate. It's nickel-plated back and front. The band switch plate from the IF-AF unit looked brass but the back was nickel-plated. I used NaOH to clean corrosion but leave any plating unharmed. Most of the brass color disappeared and the plate looked more nickel color. I'm pretty sure I'll have to re-nickel plate all of the tags so they will end up consistent in their nickel color. First I'll strip any paint left so the tags. At that point, I should be able to tell actual condition of the tags.
Dec 1, 2017 - Stripped all of the data plates of remaining paint. Used methylene-cholride and stripped outside, with proper gloves. All paint was easily removed. Some plates needed a little bit of brass wire brush application to remove all paint. Washed with water followed by drying and then washing with lacquer thinner.
|Data Plate Photos - Photo upper-right shows some of the data plates front and back. Nickel plating is obvious. Photo below-left shows the data plates with all of the paint stripped. Again, it's apparent that the data plates were nickel-plated front and back. The photo below-right is a close-up of the Power Unit data plate. Although the lettering looks brass, note the upper right mounting hole showing nickel. Since the lettering was always exposed, the nickel probably oxidizes to this brass color. When cleaned with NaOH, the nickel color begins to show through the oxidation (see June 17, 2018 for notes on further cleaning.)|
|Dec 13, 2017 -
It's been very cold with morning temps of 10F or lower. Shop temp is
about 32F unless I turn on the Reznor heater. Too cold for much
restoration work. However, I did locate my Nickel Sulfate solution and
my pure Nickel anodes for doing the electroplating of the data plates.
The plating process runs a small electrical current through the Nickel Sulfate solution from the anode to the piece to be plated. The current flow removes molecules of the anode and deposits them on the the piece that is being plated. It doesn't take very much voltage (1 to 3 volts) to have enough current flow. Proper voltage polarity has to be observed so that the current flow is from the nickel anode (+) to the plated piece (-.) Too much current (voltage too high) will "bubble" excessively or even "foam." This will turn the plated piece black. The bubbles from the current flow should be about like the bubbles in a glass of champagne. Not enough current (no bubbles) and the piece will take a very long time to plate or will plate unevenly or not at all. The bubbles are of course a gas and that gas is released during electroplating. The sulfate gas will cause headaches with a mild exposure. With more severe exposure nausea can result. All nickel plating should be done outside (brrrr.)
The plated piece has to be very clean. Anything showing on the surface will also show through the plating. I don't want to "polish" the data plates because the original lettering was matte nickel finish. The cleaning can be done chemically with either NaOH or with Sparex cleaner. >>>
>>> The actual plating only takes a few seconds to see the nickel color on the plated piece. However, this is a very thin coating. To achieve a good thick plating will require several minutes for small pieces like the data plates. Maybe five minutes for the larger data plates. The solution, the anode and the plated piece should all be at least 70F,...warmer is better and plates faster.
Buying Nickel Plating Supplies - I bought everything at an old jewelry hobby shop in Reno many years ago (late-eighties.) At that time, the solution was sold by the quart. Anodes were mounted on stainless steel tangs. I've recently looked and there are several sources on the Internet that sell all of the nickel plating supplies. If you want something local, try to find a shop that sells supplies for making your own jewelry. Otherwise, go with the Internet.
Winter Diversion - March 10, 2018 - A friend gave me an old Zenith tube caddy that was supposed to have a good selection of metal tubes for the BC-344/342 family of receivers. When I got home and inspected the caddy's contents I was surprised to find a meter in with the tubes. The meter looked promising in that it had a metal case. It looked even more promising when I turned it over and I saw the scale was 0 to +250vdc. The face of the meter was full glass with the zero mechanism mounted in the glass. The meter was exactly like the Weston 506 Navy meter needed for the RAA-3. Well,...maybe not exactly. The scale face is white and the meter is made by Simpson. But, other than those two minor points, it is exactly like the missing meter for the RAA. It actually is a later replacement meter for the Weston 506, so the fit is perfect and it's already scaled for 0 to +250vdc. This means it can be connected up directly to the RAA IF/AF unit harness. This was the last major part that I was missing. Of course, if the original type Weston/Navy 506 meter turns up, that would be great. But, for now, we have a meter that will function correctly and is a correct "replacement part."
June 17, 2018 - Finally, back
at it (it was a cold Spring this year.) I started cleaning all of
the data plates in preparation for nickel plating. The only thing that
seemed to cut the corrosion was to just go ahead and "brass brush" the
data plates. The tags will need a chemical cleaning before nickel
plating. Also, "brass brushed" the handles in preparation for painting.
Although I had thought about using "off the shelf" paint, I decided to
go ahead and use my black nitrocellulose lacquer which was probably what
was used originally for the handles and the chart frame. The knurled
thumb screws are going to be given a "black patina" treatment. This is a
chemical oxidation process that turns brass black. It's probably close
to what was originally done to treat these screws.
Nickel Plating Data Plates
July 4, 2018 - Got everything set-up to nickel plate. The first tag turned out splotchy and gray. I tried another tag with just about the same results. Turns out I had the polarity backwards. Hmmm. The good thing is I didn't "electro-strip" the tag material because I had the current so low. I'll try again tomorrow using the correct polarity. It had been many years since I nickel plated anything but you'd think I'd remember how to connect up everything.
July 5, 2018 - Plated six of the ten tags. Minor problem with the shallow plastic container I'm using for the Nickel Sulfate solution. The tag being plated has to be horizontal to be fully immersed in the solution. This puts the center of the tag furthest from the anodes. The centers on two of the larger tags are pretty thin on the plating. For the remaining tags I'll use the 4000ml beaker which will allow for vertical placement of the tags while plating. This should then allow the center of the tags to plate better.
July 6. 2018 - The nickel plating set up is shown in the photo to the right. Pretty simple. Adjustable power supply, Pyrex beaker, two nickel anodes and the nickel sulfate solution. The actual plating has to be done outside. I waited until afternoon so I would have a good breeze to keep lots of fresh air supplied. On the average I used about +3 to +4vdc and 400mA but that depended on the size of the tag. Larger tags can take more current. The small "TUNING" and "PLATE VOLTAGE" tags only take about 250mA at about +3vdc.
|July 6, 2018 (cont.) - The
4000ml beaker really made the difference. I was able to keep the tags
vertical and that allowed for an even plating. I went ahead and
re-nickel plated all of the tags I had done the day before. This was to
have all ten tags have basically the same finish. The AVC tag on the IF
Unit was too large for placement in the beaker so I had to plate
that tag in the shallow plastic container. I oriented the anodes to
equalize the plating. I also had to position the tag to have it as close
to vertical as possible. I could only keep about half of the tag in the
solution. I had to keep moving the tag to make sure the plating was
even. The end result was fine as can be seen in the photo to the left.
One has to remember that most of the nickel
surface is going to be painted over. Only the raised nomenclature and
scales will show silver through the black paint. There were two reasons
for the nickel plating. First was to have a corrosion resistant surface
that allowed the background paint to adhere well and second to have
"silver on black" nomenclature and scales for the best visibility.
Fill on Data Plates
July 26, 2018 - This is one of those processes that has to be experimented with to develop a method and tools that work. First, the original process for manufacturing these data plates can't be duplicated because the background paint was originally applied between the etching process and the photo-mask removal. That meant that the lettering was protected and removal of the photo-mask didn't affect the background paint. This resulted in the lettering showing perfectly in the nickel-plated silver color. Since these data plates don't have the benefit of the photo-mask when they are painted, that paint goes directly onto the lettering as well as the background. The process that has to be developed is how to successfully remove the paint from the lettering surface without damaging the nickel plating and without damaging the paint-filled background.
Now, the things that don't work,...any type of squeegy, whether metal or rubber will not successfully remove the paint from just the lettering surfaces. Since the tool edge is dragged along the "high points" of the data plate, the removed paint residue tends to "roll" under the edge and ends up ruining the background paint surface. Next,...using lacquer thinner and a flat pad surface to chemically remove paint from the "high points." This "almost" works. Usually though enough removed paint is mixed with the thinner and somehow contacts the background paint. Sometimes excessive pressure when rubbing the data plate across the thinner pad will deform the plate and allow the background to contact the thinner pad removing the paint there. Any abrasive such as 400 grit AlOx paper will scratch the nickel plated surface. Any steel tools will also scratch the nickel.
This doesn't leave too many methods of removal that aren't super-labor intensive. I've come to the conclusion after trying many different methods now (and also reviewing what I've done in the past when restoring etched metal tags) that the only safe method is the use home-made copper tools to "scratch off" the paint from the "high points" of the data plate. Copper tools will not scratch the nickel plated no matter how hard you press. The tool must present a sharp, bend-resistant edge to maintain good control of the paint removal process and limit any collateral damage to the paint background. Any minor defects afflicted on the paint background can usually be touched up afterwards.
|July 29, 2018 - Making the Copper
Tool - The copper tool is made with the shape of a very shallow
"S" curve which allows holding the tool like a pencil but having the
tool edge at a good angle for scraping. The copper material is .190"
thick and the working edge is sharpened. Both ends are sharpened with
the long end having the .190" thickness but the other end is reduced
thickness to .060" for lines and scales. Since the copper is very soft
compared to the nickel plating, it won't scratch the nickel at all.
However, because of the soft nature of the copper, the tool must be
sharpened often (every few letters.) I use a small flat file to sharpen
the working edge. See photo below showing tool with two completed tags.
July 31, 2018 - Success on Background Paint Removal - This is tedious work but it seems to be the only method that ends up with the data plate looking perfect. The background paint is black nitrocellulose lacquer. I use the Preval spray system that has replaceable sprayers. A glass jar holds the mixed lacquer (Preval sprayers are available from Home Depot.) I sprayed two data plates at first to develop a removal system that would work. The copper tool allows accurate paint removal from each individual letter or number comprising all of the nomenclature on the data plate. I had to use a head-mounted magnifier to actually see "close-up" what I was doing. This is slow and exacting work. There are no short-cuts. On average, it took about one and a half hours to finish an identification tag while the control nomenclature plates took about half an hour. The ID plates are very dense with lettering and numbers, so that's why the time required was longer than the control nomenclature plates. Only ten minute paint removal sessions are recommended since eye fatigue seems to result in minor mistakes.
While removing the paint, you have to continuously brush off the paint residue. Also, the copper tool MUST be very sharp. Usually about three or four letters can be finished before the tool needs to be resharpened. Just a couple of file strokes is all that's necessary for sharpening the tool's cutting edge. When paint removal is completed then the data plate is wiped with a piece of soft flannel cloth. Any touchup necessary for minor scratching of the background paint can be accomplished with either a black Pilot pen or, if it's a deep scratch, then thinned lacquer can be applied using a toothpick. Be sure to only apply the lacquer in the scratch, not around it.
Aug 10, 2018 - To sum it up - All ten data plates finished on August 10th. I absolutely hate that this part of the data plate restoration process turned out to be so tedious, so crude and that the time involved was so excessively long. I thought there might be an elegant, simple way to remove the paint but this scraping process is the only method that I've found that results in an excellent appearing data plate. BUT, the copper tool is the key to success in this primitive but effective process.
Finishing the Front Panel(s) Work
Panel Hardware - The hardware consists of the grab
handles, the tuning chart frame, the various panel mounting screws, the
data plate screws and the knurled thumb screws.
August 15, 2018 - Tuning Chart Frame was given a black lacquer paint job. I'm using the Preval sprayer system so I can spray my own mix of nitrolac+thinner. Paint has to be thin in order to spray as a mist. Too little thinner and the spray will have droplets that result in orange peel or lumps. Usually a proportion of 1:1 works okay. Two parts thinner to one part paint is pretty thin but can work okay in hot weather. 1.5 thinner to 1 paint seems best for the Preval type sprayer. Tuning Chart Frame mounted with six 4-40 round head brass machine screws .250" long. The screws are nickel-plated (as original.)
|September 23, 2018 - It
took quite a while to decide what color the grab handles were. Inside
the shop, the handles looked dark bronze color. Outside in sunlight, the
handles looked black. Close examination seemed to indicate that the
handles were bronze color (maybe the original color from the parts supplier) but did have black
paint on them that had mostly worn off. I went ahead and painted the handles
black nitrolac along with the mounting screw heads. After the paint had set
for a while, the handles were mounted to the panels.
All of the data plates were mounted with 4-40 x .250" round head brass machine screws that were nickel plated. These were either NOS or excellent used screws. These screws were .062" longer that the originals. I had to use the longer screws because of the better condition of the threads further into the panel. Other than the length, the NOS screws are exactly like the originals. On the IF/AF Amplifier panel four 4-40 holes were worn or enlarged enough that the screws couldn't be tightened. On these four holes, I peened the hole rim with a center punch to reduce the diameter and allow the 4-40 screws to tighten.
September 23, 2018 - Tuning Dial - This is a dual dial system that has a 0-10 dial on the main shaft and a 0-100 dial that is gear driven from the main shaft. The 0-100 dial rotates on a fixed shaft attached to the Tuner chassis. The 0-10 dial was slipping and loose when I took the RAA apart. This problem was caused by a missing Woodruff key that keeps the 0-10 dial "locked" to the main shaft. Since the key was missing, eventually the 0-10 dial loosened and began to slip. I think the key was originally a small tab that fit into the key notch and locked the dial to the main shaft. It appears that the small tab was broken off and that's when the dial began to slip. I needed to make another key which can be just like a Woodruff key and not necessarily attached to the 0-10 dial. I just made a .030" square metal piece about .090" long to act as the key. To synchronize the two dials I had to set the tuning condenser to full mesh. Then the 0-100 dial was set to 0 and the 0-100 drive gear installed onto the main shaft. The key was installed to "lock" the gear to the main shaft and then the 0-10 dial was installed with it set to 0 and the locking nut tightened. The main shaft has to be held with vise grips to keep it from tuning while the locking nut is tightened. Once mounting was complete, then the drive gear and the 0-100 dial gear were given a light coat of grease. With a test knob installed, tuning was smooth and effortless. Synchronization was good.
September 24, 2018 - Ground Terminal - This fitting needs to be press-fit back into the panel. The base has serrations to assure a good electrical connection to the panel. The base/standoff needs a patina finish and also needs to have the threads "chased" since the thumb screw doesn't thread in all the way. Patina-oxide treatment for correct finish. Patina is a chemical that darkens brass to blackish-brown color. The piece is cleaned with a wire brush and then soaked in the patina. Color happens very rapidly. I had to use a vise to apply enough pressure to press-fit the Ground terminal into the panel. The vise jaws had brass covers and the panel rested on a wooden block to assure that no damage happened while pressing the base/standoff into place.
September 24, 2018 - Antenna Terminal - This also requires the patina-oxide treatment. The Antenna Terminal is insulated with a .250" thick fiber board about 2" square. The terminal is mounted to the fiber board and two screws and lock washers mount the fiber board to the panel. The original screws and lock washer were used. These were cleaned and then the screw heads were painted black.
September 24, 2018 - Panel Mounting Screws
- All of the panels mounting screws were either in very poor condition
or were actually broken or missing. The screws should be 10-24 round
head brass machine screws. Excellent condition used screws were used.
These had to be cleaned and painted black before installation. Each
panel screw has to also mount with a #10 internal tooth locking washer. I used stainless steel lock washers because nickel content in
stainless gives it the correct "nickel" color.
September 28, 2018 - COUPLING Control Shaft Repair - This was the control that had the broken shaft. It was "frozen" in place, probably by corrosion. I had been putting WD-40 on the shaft bearing without any luck (where the metal coupler went thru the bearing.) I finally used the penetrating oil and that got the shaft coupler free. The next step was to repair the broken shaft. The shaft was made out of fiber rod that is 5/16" diameter and then turned down to 1/4" where the knob mounts. The break was where the shaft diameter changed. The easiest fix was to clean the break so its surface was flat. Then drill and tap a threaded hole for a 4-40 threaded rod. The broken off part of the shaft (1/4" section which was still mounted in the knob) was also cleaned to a flat surface and it was drilled and tapped for 4-40 threads. Each threaded hole was about 3/8" deep. Also, the broken off part of the shaft had to have the threaded hole counter-bored about 1/8" deep to provide a pocket for the excess epoxy and to also allow some movement of the shaft to achieve a straight alignment of the shaft before the epoxy cured. A 4-40 brass threaded rod 1/2" long was dipped in epoxy and threaded into the 5/16" shaft end. Then the 1/4" fiber end was threaded onto the stud. The shaft end was aligned for straightness. Excess epoxy was cleaned off. When the epoxy set-up the repair was quite strong. Also, the COUPLING control is very easy to operate now that the oxidation has been removed. This shaft repair won't be stressed by operation of the switch.
|September 29, 2018 - IF/AF Amplifier - Almost
all of the surface rust was removed using a brass wire brush.
Alternate cleanings using WD-40 and brass wire brushing removed most of
the corrosion. The harness connections were cleaned as were the terminal
strips. The AVC pot and the Sensitivity pot are both beyond repair.
Excessive corrosion destroyed the internal arm rivet mounting on both
pots. The pots are a 20K pot
with a special taper (1K change in first quarter rotation, similar to an
"audio taper" control) for the AVC control and a 25K pot for the
Sensitivity control. Both controls are wire-wound types. Vintage
replacements will have to be utilized. However, all three toggle
switches responded well to the "DeOxit down the barrel" trick
(also down the gaps around the terminals) and now are functional
switches. Mounted the
Simpson B+ meter.
Another Unpleasant Discovery on the IF/AF Chassis - The interconnect signal cable from the Tuner to the IF/AF Amplifier has a metal cover over the terminal strip. This cover was difficult to dismount. Three of the four screw heads were twisted off (sometime in the past.) I worked a bit with the last screw but its head also twisted off. I tried to pry the cover off but it was not moving at all. I decided to drill out the screw shanks. Since they were brass this was pretty easy except the cast metal cover apparently was softer material. The drill bit wanted to "crawl" off of the brass screw shank and drill into the cover metal. Once all four screw shanks were drilled out the cover was then somewhat moveable and with some persuading was finally dismounted. Piles of corrosion streamed out from under the cover and buried the terminal strip. It looked like a combination of sand and rust. The underside of the cover was "lumpy" it was so corroded. See photo below.
|The photo to the
left shows the Tuner interconnecting terminal block right after I got
the cover off. It looks like salt-moisture probably wicked into the
terminal area from the Tuner cable and collected there, unable to
evaporate, causing the corrosion to the inside of the cast metal cover.
Looking at the debris, it looked like it would vacuum up so the shop vac was used to remove the loose corrosion. I also used a brass bristle brush to clean the terminals. The shielded inter-connect cable was already going to be replaced. The wires that are routed under the chassis look like they can be repaired since the damage is minor and limited to the insulation. The cover exterior is in good condition and the interior can be cleaned of the corrosion (it had been roughly scraped out in the photo right.) Also, the photo right shows the area after vacuuming.
2018 - Thumb Screws
- These had a lot of surface oxidation that had mostly come from the
aluminum panel and probably salt air. The deposits were white or
sometimes green. The actual thumb screw being brass was in good
condition once the surface contamination was removed. I used NaOH
(Sodium Hydroxide is conveniently available as Easy Off Oven Cleaner) to
rapidly and thoroughly remove any of the oxidation. A small plastic cup
held the thumb screw while the EOOC was
sprayed on. I let it soak for about three
minutes and then rinsed the thumb screw in cold water. Once the surface was clean, I used
a brass bristle brush to remove any remaining contamination that was in the
threads or the knurls. I then submerged the thumb screw into dark brown
patina and let it soak for several minutes. Upon removal from the patina
the thumb screw was dried and then inserted through the panel hole and
the retaining stainless steel "C" clip installed. This oxide
treatment looks great and is authentic.
- All of the original knobs are moderately discolored from years of outdoor
exposure. They all need cleaning first. Then some method is needed to
return the black color to the knobs. I'm going to try black "colored car
wax" as this shouldn't be too aggressive and probably will result in a
subtle improvement. Two knobs needed to be replaced
since they had to be "cut off" in order to dismount the front panel. The
replacements are good condition used knobs that are duplicates of the
original type although they were removed from a "parts set" RAL-7
receiver. More on the RAL-7 parts follows,...
October 3, 2018 - Transformer Tests and other Tests on the IF/AF Amplifier - Continuity tests show that the audio output transformer is good. The second AF interstage transformer tests good. The first AF interstage secondary tests good but I couldn't easily test the primary since it's capacitive-coupled in the grid circuit. The Audio AVC transformer has a good primary but the balanced secondary has one side open. This AVC circuit, while similar to the AVC circuit used in the RAL-7, uses a balanced output where the RAL-7 is single-ended. Luckily, the AVC circuit is similar enough that the same type AVC and Sensitivity (Volume) pots are used at the same values. If the original AVC transformer can't be repaired then it appears that a push-pull audio output transformer might be substituted (mounted in the original can, of course.)
Inspection of the wiring harness that runs from the power input terminals to the IF/AF circuitry showed that this harness is repairable. The last section that contains the wires to the AVC and Sensitivity pots, the three toggle switches, the Band Pass Filter and the Low Pass Filter will have to be rebuilt. The connections to the B+ meter will need to be repaired. Although the wiring chart shows single wires to each meter post, in actuality, two wires each go to each post. Two are grounds (-) and one wire goes to the B+ terminal on the input terminal strip (+) and the other wire (+) connects that B+ input to the rest of the IF/AF B+ requirements. The remaining parts of this harness appear to be in good usable condition.
|October 7-9, 2018
- Mounted Tuner and IF/AF Amp Panels - It requires fourteen
10-24 x 1/2" roundhead brass machine screws with raven finish and
stainless steel #10 internal tooth locking washers to mount the Tuner
panel. It takes the six of the same type of screws and washers to mount
the IF/AF panel. I mounted the Tuner panel first and raised the chassis
up about 2" using 2x4s to make sure the panel bottom was above the table
top. Once the panel was mounted, I installed the knobs. The Tuning knob
and the Band Switch knob are replacements that came from the parts set
RAL-7. The IF/AF Amp panel was mounted and 2x4s as chassis spacers so
the panels would be the same height off the table. The knobs on the
IF/AF Amp have been cleaned but they haven't been "black waxed" yet.
They still show the brownish discoloration from long term exposure. The B+ meter was installed. Except for the thumb
screws for securing the receiver into the cabinet, this is how the RAA-3
is going to look from the exterior. The get an idea of the immense size
of the RAA-3, note how the Hewlett Packard 606A signal generator behind
is dwarfed by the RAA-3. The width of the receiver is over three feet, 38 inches
The next phase of work will be the electronic rebuilding of the power supply. Although I still have a lot of electronic work to do on the receiver, much of the testing will require the power supply to be functional. Also, the harnesses will need rebuilding to be able to apply power to the receiver.
Photo to the left shows how RAA-3 SN: 64 looks so far.
Building Wire Wound Resistors
|November 23, 2018
- After some thought and talking to WA6OPE about the difficulty of
building wire wound resistors, he mentioned the option of using 100 watt
Ohmite vitreous enamel wire wound voltage dividers as replacements. I
then checked eBay for the various values available and was able to find
very close values to what I needed for the Power Supply. For the "dead
load" on the B+, the original value was 1140 ohms at 100 watts. I was
able to find a 1250 ohm at 100 watts,...within 10% which should be close
enough. For the 15,500 ohm 100 watt B+ divider resistor I found a 15,000
ohm 100 watt Ohmite divider type resistor,...within 5%. Each of the
values necessary can be achieved by sliding taps. I'll have to find some
extras since only one comes with the resistor. For the bias resistor,
which was a 405 ohms at 100 watts, I found a 500 ohm 100 watt divider
type resistor. Again, I'll have to find some extra sliders since only
one comes with the resistor. Since the total resistance is about 20%
high I can use an extra slider to trim the value to 405 ohms.
As to how to fit these types of resistors into the power supply, I bought 1" copper pipe end caps that fix exactly into the resistor mounting clips. By attaching the resistor end terminals to these copper end caps a "plug-in" resistor can be created. As far as the connections to the various taps, the original resistors were connected into the circuit from the power supply chassis wiring harness through wires that were soldered to each tap. I should be able to achieve the same type of connections using the sliding taps and their solder connections.
More details when the parts arrive,...
To be continued,...restoration updates every few weeks (or so.)
1. Model RAA Radio Receiving Equipment - Manual, RCA Victor Company - June 30, 1931 - The manual provides detailed information on design, construction and operation. Schematic, wiring diagrams, parts list, alignment instructions.
1. www.navy-radio.com - Nick England's incredible website provides a wealth of information on all aspects of Navy Radio. Photos of the RAA-2 onboard the USS Texas and the 1941 USS North Carolina Radio Room No. 2 were provided courtesy of Nick England. Many, many vintage photos. An excellent resource for those interested in Navy Radio gear, stations and history.
2. Training Film from Navy Department - Radioman Training, 1943 - This 10 minute film covers how Navy orders that originated in Washington D.C. were transmitted by NSS and then relayed to NPG and then to NPM where it was then relayed to ships in the Pacific. Lots of WWII radio gear shown in the film.
3. Wikipedia and other online sources - Info on Destroyer Tenders USS Whitney and USS Dixie. Repair Ship USS Medusa.
Thanks to: Bob Welch W6AQU, Robert Goff W7MKA, Chuck Cusick KØDWC, Joe Conner, Steve Rosenfeld, Rob Flory and Nick England for their help and information. Thanks to Hal Layer KK6HY for the original manual.
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