Radio Boulevard

Western Historic Radio Museum

 

Building an Authentic 1937 Ham Station

using the

Utah Radio Products
 
UAT-1  80W  Transmitter

 

by: Henry Rogers WA7YBS/WHRM

 


   photo: Utah UAT-1 with RCA ACR-175 - ca 1938 - station call unknown

I first wrote this article in 2006, but as time progressed, so did the 1930s station. As with all of my articles, this one was always being updated. You will note that sometimes I am writing about the Utah UAT-1 in the context of a new project and then there will be an addition at the end of each section if anything new has happened. I have generally sorted this as a year by year change. I hope the fact that this article does change periodically will provide continuing interest and entertainment. Additionally, we have re-edited this article to appear like our other web-articles. Also, when we closed the museum in 2012, the 1937 Station moved (along with us) to Dayton, Nevada. There is a section about how we are currently operating the 1937 station at the new QTH.  H. Rogers Dec. 2013

 

Building an Authentic 1937 Ham Station

For sometime I have wanted to put together an operational, late-1930s Ham Station with the capabilities of operating both CW and AM on the high frequency ham bands. What were only random thoughts became a real possibility when a 1937 Utah UAT-1 transmitter was obtained. The transmitter was going to require a complete restoration due to an old incomplete modification/update that unfortunately compromised much of the UAT-1's originality. Additionally, a thirties-type Antenna Coupler would be required along with a correct vintage Speech Amplifier-Modulator. The receiver should represent the best of the late thirties designs that were within the economic capabilities of a ham who would have purchased and built the UAT-1. The antenna to be used would be our already in-use 135 foot inverted vee fed with open line. Here is a detailed look at the equipment and how this authentic late-thirties station was actually put "on-the-air."

The 1937 Utah UAT-1 Transmitter

Utah Radio Products Company had been in business since the twenties mainly offering transformers and speakers for other manufacturers to use in their equipment. In January 1937, Utah announced the "Add-a-Unit" Kits. These were five different kits that were based around Kit #1, an eighty-watt, CW transmitter. The other kits included an Antenna Coupler, a Speech Amplifier/Low Power Modulator, a High Power Modulator and a High Power RF Amplifier. All five kits provided the builder with a complete 500W CW/450W AM transmitter for a little over $200.00. Each kit sold for about $50, except the Antenna Coupler which sold for $13.95. Each cabinet was designed to be bolted on top (or below) another cabinet resulting in a rather tall transmitter that was "loaded" with Utah "iron."

The circuit of the UAT-1 is a standard crystal controlled oscillator using a metal 6L6 tube. The oscillator output is coupled via plug-in coils to the RF Power Amplifier, consisting of two metal 6L6 tubes in parallel. The PA output is link coupled via a large, 2.25" diameter, plug-in coil. A total of three plug-in coils are required for each amateur band used. The UAT-1 is capable of about 80 watts input on CW depending on the antenna and coupling used. The transmitter section is built on a steel chassis that mounts in the upper tray of the cabinet. The power supply chassis mounts in the lower tray of the cabinet and provides 600 vdc to the PA and 400 vdc to the Oscillator along with 6.3 vac for the 6L6 heaters. Choke input is used and the filtering is adequate for a good quality CW signal.

The advertisement above appeared in January 1937 issue of QST

Far Left: Utah Catalog Cover   Above: Inside page of catalog

 

The UAT-1 Restoration

 I obtained the Utah UAT-1 in a trade with NU6AM. Jim not only had the transmitter but also its original assembly manual, original catalog and two original letters from Utah's Amateur Division Engineer, Oliver Read, to the transmitter's first owner, Franklin Schaefer, of Oakland, California. The Utah transmitter cabinet and front panel were in very good physical condition but internally the UAT-1 had been modified extensively. A former owner had wanted to increase the power output by converting the PA to 807s. Fortunately, the transmitter chassis was almost unaltered - physically - as only original holes had been used to mount the newer components. The transmitter chassis was missing most of the original parts but the original variable condensers and a few of the original sockets were still present.

The power supply was completely modified and many newer parts were now mounted on its chassis resulting in several non-original holes having been cut. Though many newer parts were installed on the PS chassis, the original power transformer and both original filter chokes were still present and functional. The best way to repair the damage was to remove all of the components and install one large "butch plate" to cover all of the holes. This was painted to match the chassis. New holes were then cut to allow mounting the original type parts in their correct location. In fact, both chassis were "stripped" of all parts so assembly could be performed "per the manual" with original type components.  >>>

>>>   The Utah UAT-1 assembly manual was invaluable as it provided information on exactly what parts were originally used and how Utah expected the transmitter to perform. However, like many early ham documents, the manual is vague in many of the details. This was because so much depended on the skill and experience of the builder. The Utah manual did provide assembly drawings showing suggested mounting locations for the various components but a wiring layout was not provided. The builder was supposed to know good transmitter construction techniques and follow those rules in completing the transmitter. I used vintage parts in restoring the UAT-1 with the exception of capacitors and the 25 watt wire wound resistors (the originals were missing anyway.) All new filter capacitors were mounted inside duplicate of original electrolytic capacitor cans that had bakelite screw bases for mounting to the power supply chassis. The one paper wax capacitor was built up by installing a new cap inside an old shell and then re-waxing. All wiring was sleeved in original type black varnished "spaghetti". The goal was to have the UAT-1 look and perform as if it was built by an experienced technician in 1937.

Before restoration photos. Above Left: front shot showing that overall the UAT-1 was in good condition. Above Center: Inside is a different story, note 807s in the transmitter chassis.
Above Right: Showing the highly modified power supply with extra transformers and regulator tubes.

 

Coils and Crystals - Details

Coils - The UAT-1 did not have any correct plug-in coils when obtained. We had to wind new coils on the proper "old style" forms. Several manufacturers of the day offered these plug-in forms molded from either bakelite or R-39 material. Utah specified Hammarlund forms, although Bud, Insuline and others offered almost identical forms. The Oscillator Plate coil and the PA Grid coil are wound on a four pin Hammarlund form that is 1.5" in diameter. The PA Plate coil is wound on a five pin form that is 2.25" in diameter. All coils are wound with 16 gauge wire. Although the original specifications call for DSC (double silk covered) wire, this is difficult (if not impossible) to find in any quantity. I had to use modern, high temperature enamel coated copper wire for winding the coils. The UAT-1 manual gives all of the coil data for 160M, 80M, 40M and 20M. Additionally, I had the two letters from Utah Radio Products Co. to the original owner, one of which gave coil data for 10M. 

Crystals and Grinding Crystals to Usable Frequencies - The UAT-1 uses crystals mounted in HC-3 type holders. These are the large, round crystal holders that fit a standard five-pin tube socket. The major supplier of the day was Bliley, although Valpey, Hi-Power and J-K (James Knight) were also popular crystal manufacturers. Luckily, I was able to scrounge around my "junk boxes" and find 21 of the proper type crystals - most of them in their original boxes. Unfortunately, most of the crystals were for odd frequencies within (and some outside) the ham bands of today. Out of the 21 crystals, I found only one 40M crystal and two 80M crystals that were inside the currently popular CW section of the bands. I decided that some experimenting was necessary if the larger portion of these crystals were going to be useable. Early crystals (and FT-243 holders) can be easily disassembled and the crystal removed from the holder. Since the frequency is determined mainly by the thickness of the crystal, grinding the crystal was the usual method to alter the frequency. Since grinding removes material, this process will raise the crystal frequency. Generally, the maximum amount of frequency change is limited to around 100kc though it depends on if the crystal is going to be used at a fundamental or at an overtone. 100kc on an 80 meter or 40 meter fundamental crystal is about the limit.

I found several military FT-243 type crystals in the 6MC region that I disassembled to remove the crystal. Using 320 and 400 grit oxide paper and water, these crystals were ground up to the CW portion of 40M. Grinding can be done with the oxide paper placed on a flat surface and water used as a lubricant. Precision grinding can be performed on a sheet of glass using fine carborundum grit and water, though experience seems to show this is unnecessary. When grinding, rotate the crystal in a "figure-8" pattern to keep the removal of material even. Also, grinding both sides of the crystal will help keep the removal of material somewhat even. Don't grind the crystal the same way endlessly. You have to rotate the crystal and change orientation and also grind the reverse side in the same manner. This comes from optical grinding where a very accurate surface is required. The grinding errors are "spread around" and never become a problem when the crystal orientation is frequently changed. This will result in a very flat, symmetrical grind.

Testing Crystal Frequency by "Ringing" - The test jig was an HP-606 Signal Generator with a digital frequency counter and a Tektronix oscilloscope. The procedure is to "ring" the crystal. Connect the signal generator to one pin of the crystal. Connect the 'scope input to the other crystal pin. Connect a common between the 'scope and the generator. You'll see a waveform on the 'scope. Sweep the signal generator frequency through the expected crystal frequency while watching the 'scope. At the crystal's operating frequency the waveform on the 'scope will increase dramatically. Look at the frequency counter for an accurate measurement of the crystal activity frequency.

After a few minutes of grinding, the crystal will have to be reassembled into the intended crystal holder then test for its active frequency. Disassemble if more grinding is required. Each time the crystal is tested, you have to reassemble the crystal in its intended holder to perform the test accurately. Be sure to watch the amplitude of the waveform at the frequency of operational activity. You'll probably see this change somewhat with grinding. If the amplitude is reduced during a check it usually means the grind is changing the surface flatness. The next grind should be carefully done in a straight "back and forth" pattern with changes in the orientation of the crystal. Then check the activity. Be sure the crystal surfaces are very clean. You should see the activity level increase. Usually, careful grinding with frequent changes in orientation will allow the grind to be flat and symmetrical.

When the crystal frequency was within about 10 KC of the desired frequency, the grit was changed to 600. The output (activity) of the crystal depends on how fine (and symmetrical and flat) the finished grind is, (too rough and the output will be very low and the active frequency erratic.) I used the fine grit to grind the crystal to the desired frequency. When you are within 2kc of the intended frequency it would be a good idea to try the crystal in the transmitter. The oscillator circuit and the capacitance of the holder (C load,) the socket and the wiring (along with oscillator current) will all slightly affect the frequency of operation. Usually the frequency is within 1kc of where the crystal "rings." However, the transmitter test lets you know for sure how the crystal is going to operate. You might have to do a little more grinding but I usually stop if I'm within 1kc of the intended frequency. The type of holder and the length and width of the crystal don't affect the operation. The thickness, the fineness of the finished grind and cleanliness of the surfaces are what is important in this process. Ultimately, I ended up with several usable crystals with correct vintage holders for both 40M and 20M CW and 80M phone.

Left: The coil set for 40M wound on Hammarlund forms.

 

Right: Various HC-3 type crystals with original boxes.

 

Initial Testing of the UAT-1

Initial set-up of the UAT-1 requires that the 100 watt adjustable divider resistor in the power supply be set for 400 vdc to the 6L6 Oscillator with 600 vdc applied to the PA 6L6s. After this, a quick dip of the Oscillator current using the OSCILLATOR TANK control will have the oscillator running at the crystal frequency. The resonance curve will not be symmetrical. Choose the side of the curve that is wider and set the oscillator current for about 20mA.  Next, close the sending key and quickly dip the PA Plate current (right-side meter) using the P.A. PLATE TANK control. The plate current will be low at resonance, ~75mA. This is followed by increasing the PA Grid current using the P.A. GRID TANK control. This also requires switching the left-side meter by moving the phone plug cable from the CRYSTAL OSC. GRID current jack to POWER AMP. GRID current jack in order to read PA grid current. Resonate the PA grid condenser for the peak reading of PA grid current. This should be at about 5mA on the meter. Re-dip the PA PLATE TANK and the transmitter is then tuned to resonance for the particular coils and crystal installed. The PA TANK current will be between 100mA and 125mA. This reading depends on the coupling between the PA TANK coil and the antenna output link. The tighter the coupling the more output but you only want between 100mA and 125mA with the OSC and PA GRID at resonance and the PA TANK dipped.

With the initial tune up it is necessary to neutralize the PA. This is a rather easy procedure using a "dummy" plug to remove the plate and screen B+ and then tuning the plate through resonance while watching the PA grid current. The neutralizing condenser is insulated and mounted to the rear chassis of the transmitter. >>>

>>>  Originally, the condenser was a shaft adjustment but since the original condenser was missing, I used a recessed, screw driver adjustable shaft condenser of the correct value when rebuilding the UAT-1. Add just enough capacitance to stop any movement in the PA grid current while tuning through resonance and the PA will be neutralized.

With link coupling, the loading on the PA Plate depends on the coupling to the antenna or load. Generally, the greater the coupling the more plate current at resonance and the greater the power output. The Utah letters to the original owner, Franklin Schaefer, imply that he was having difficulty loading the UAT-1 with just two turns on the link. Oliver Read,  the Amateur Radio Division Engineer at Utah, suggested in one letter to increase the link to three or four turns to increase loading current. Read also mentions that the antenna coupler should have three to four turns on its link. I wound the 40M and 20M PA Plate coils with a three-turn link spaced below the PA tank coil and found that I had ample coupling available. However, on 80M more coupling was necessary for proper loading. I used a plastic coil form that just fit over the PA tank coil winding and then wound a three-turn link on that. I used flexible wires for the link connection to the pins on the coil form. This arrangement gave the necessary coupling for full output on 80M and resulted in good AM phone modulation.

For CW operation, the design of the UAT-1 has the Oscillator running all the time and just the PA is keyed. This results in some "back wave" but it is not radiated any great distance. Although one can directly couple from the output link to an antenna cut for a specific frequency, an Antenna Coupler would provide greater versatility along with additional harmonic suppression. We decided to build an authentic Antenna Coupler similar to the one that Utah sold as Kit #3.

The finished Utah UAT-1 - 80 Watt, CW transmitter.

A rear view of the restored Utah UAT-1 with 40M coils installed

 

 

The Antenna Coupler

The Utah Antenna Coupler was a fixed-link, series-parallel type tuner with individual condensers, RF watt meter and a switch for selecting series or parallel tuning. Since the link in the transmitter is also fixed, the operator would have to experiment with the number of turns on each link for best loading of the transmitter. This would be acceptable if only one band were going to be used but I wanted the UAT-1 to operate on 80M, 40M and 20M. I decided to build a swinging-link that would allow for some adjustability of the loading. Also, in keeping with the typical late-thirties Ham station construction, clips were used for both turns selection on the inductance and for series/parallel switching. Finding a suitable housing was not difficult as it was discovered an old BC-348 cabinet has almost identical width and depth dimensions. By using the BC-348 cabinet's back as the front an "open-in-the-rear" cabinet results. I used a masonite front panel (black wrinkle finished) for the proper look and to cover the old holes in the metal cabinet. I found a matched pair of 25pf to 125pf transmitting variable condensers in my junk box. These were mounted directly to the masonite after rectangular openings were cut in the aluminum. This allowed the condensers to be insulated from chassis or ground.  >>>

>>>   The junk box also turned up a large diameter tuning inductance that I mounted using wooden dowels. The swinging link was another junk box item that was modified to mount to the cabinet. The RF amp meter has a 0 to 1 RF Amp range. The meter is connected through one of the feed lines and provides an indicator that RF is getting to the antenna. The actual reading is not important as variables like antenna impedance or SWR will affect the RF current. The RF Amp Meter is only for a maximum output indicator. When operating the coupler in parallel the RF Amp meter will read very little current since this arrangement is low current at the feed point. In series, the current is usually about .6 Amps at full output. The completed cabinet was given a black wrinkle finish and bolted to the top of the UAT-1 using the original mounting holes provided. The link connection between the UAT-1 and the coupler is via period twisted feed line. The antenna feed line connects to porcelain insulators mounted on top of the coupler. I used National Type O dials to provide the nickel-plated scales along with knobs that were identical to those on the UAT-1. A vintage metal  "ID plate" (ANTENNA CURRENT) similar to those used on the Utah transmitter was mounted below the RF Amp Meter. This resulted in an antenna coupler that was a good physical match to the UAT-1. The coupler provides versatility to the UAT-1, allowing it to operate on 80M, 40M and 20M with a good match to the 135' center-fed dipole antenna used.

 The UAT-1 and Antenna Coupler - 2006 to 2007

 

UPDATES:   For 2007, I wanted to eliminate the need of separate antennas for receive and transmit. I decided to add an antenna relay and receiver stand-by relay inside the coupler for easier operation when going from receive to transmit along with better receiver performance. I used old Potter-Brumfield external contact, open frame relays for appearance and ease of connecting the twisted feed lines. The receiver's twisted feed line is connected to bakelite ANT-GND terminals mounted on the side of the coupler. The relays are controlled by a separate, vintage (homebrew) 24vdc power supply that is mounted in front of the operating position and has a "Transmit-Receive" switch on the panel. I used more of the vintage ID tags on this device for the appropriate matching appearance. The advantage of using the "transmitting antenna" as the receiving antenna was the primary reason for adding this function to the coupler. Several tests revealed that no matter what matching devices were used between the receiver and the old original end-fed wire receiving antenna, nothing performed as well as using the transmitter antenna coupler with the 135' center fed dipole for the receiver antenna.

For 2008, I added a ceramic switch to the Antenna Coupler for the "Series-Parallel" function and a dual-deck ceramic switch for a five position adjustment on the various taps on the antenna coil. This has resulted in much faster and easier adjustment of the transmitter and coupler together. I installed small black pointer knobs on the switch shafts. I didn't have any metal tags that had numerals or "Series-Parallel" so I used color-coded dots to indicate coil taps - positions 1-5 are brown,red,orange,yellow and green dots - and the position of the series-parallel switch - white=P and gray=S.  I also replaced the RF Amp meter with an older meter that was the same type used in the original Utah coupler. Though the new coupler still doesn't look much like a Utah unit, it does adjust much easier now.

For 2013, with a different antenna here in Dayton, I've found that the coupler matches 80M in Series and I show about 0.8Amps of RF Antenna Current. On 40M, I also use Series and show about 0.6Amps of RF Antenna Current

 Rear view of the UAT-1 for 2008

 

 

The Speech Amplifier and Modulator

The "Add-a-Unit" Speech Amplifier-Modulator #2 Kit used push-pull 6L6s run in Class A-B rated at 60 watts. The various inputs allowed for crystal microphone, phonograph input and a 200 ohm input. Meters monitored the P-P 6L6 plate current and screen current. The modulator chassis was mounted in the upper tray of the cabinet and the power supply was in the lower tray. Just how many of these #2 Kits Utah sold is unknown but certainly very few survive. I decided rather than spend an eternity looking for the Utah modulator, I would build a correct vintage unit. I had the remains of an old homebrew rig that had a suitable UTC CVA-1 Vari-match Modulation transformer rated conservatively at 30 watts. This homebrew unit furnished the chassis, front panel, current meter, filter choke and the modulation transformer. All the remaining parts were scrounged out of my "junk boxes."

I used a circuit that combined the 1939 ARRL HB 50W Modulator and the 1946 ARRL HB 40W Modulator. The two circuits are virtually identical except 6J5s are used in 1946 instead of 6C5s and the bias for the 6L6s is supplied by a 22.5 vdc battery in 1946 instead of an external negative power supply. The early version modulator has no shaping of the audio so no doubt the bandwidth of the AM signal would have been very wide.  >>>

 >>>  The 1946 version has some low frequency roll off but nothing for the higher frequencies that affect bandwidth. I just added a couple of capacitors in the second audio amplifier to bring the high frequencies into a 3db roll off around 3KC to 4KC. The circuit layout had to be rearranged from the original homebrew modulator layout to provide ample separation between the low-level audio and the power supply. Ample shielding was also used in the construction to assure that no hum got into the low-level amplifier stages. I used a matching knob for the audio gain control and also added several of the vintage metal ID tags for a nice matching appearance. The completed modulator looks like it is from the late thirties era and, most important, it has the "late-thirties AM sound." 

To run "phone" on the UAT-1 it is necessary to remove the telegraph key plug from the "KEY" jack and insert the plate meter cable and plug. Then insert the plug and cable from the modulator into the POWER AMP. PLATE current jack. This connects the modulation transformer between the UAT-1's 600 vdc B+ and the RF Choke/PA Tank Coil/PA Plates. Connecting the meter cable to "KEY" allows the plate meter to read total cathode current.

Above: The modulator's front panel appearance 2006 - 2007.     Right: View of the chassis 2006 - 2007.

 

UPDATES:   For 2008, I decided to rebuild the modulator into another BC-348 cabinet so the entire transmitter could be "stacked" as was the custom in the 1930s. I had an old BC-348 cabinet that was in really bad shape with lots of extra holes drilled in it, so I didn't feel too bad about using it for this project. I used a piece of masonite for the front panel and painted it black wrinkle finish. The panel was mounted to the back of the BC-348 cabinet which then became the front of the modulator cabinet. I did the same thing when building the antenna coupler. It was lucky that the original chassis that I had used for the first modulator fit into the BC-348 cabinet. I did have to lower the rectifier socket below the chassis so there would be clearance for the 83 rectifier tube. >>> >>>  Also, some of the minor layout problems were corrected. During the rebuild, a couple of non-soldered joints were found - hmmm, how'd that happen? Well, good crimp joints work fine for a while, I guess. I used the same ID tags. Circuit-wise, I changed the audio shaping by moving it to the next stage in the audio chain so it would not be installed on a grid circuit. The battery shown in the old photo was bad. The photo below shows the new battery made from 15 AA batteries connected in series for -22.5 vdc bias. Other than that, the modulator was still the same as before. The new appearance is much better and more authentic looking.
Left: Modulator Front Panel 2008

 

 

 

 

Right: Rear View of Modulator

 

The Completed 1930s Ham Station at WHRM 2006 to 2012

The complete 1937 Ham Station is set up in the Vintage Ham Shack of the Western Historic Radio Museum. We are cramped for space but we did manage to fit everything necessary into an area approximately 48" wide and about 40" tall. Each year we have been setting up different receivers with the station. For 2009, we have gone back to the fabulous National HRO from 1935 for the station receiver. It has incredible sensitivity and pleasant audio. Also, it seems to better fit the look of the typical thirties ham station and while the Hammarlund SP-100X was a great receiver, it did look mis-matched with a kit transmitter. The Hammarlund Comet-Pro was simply "over-kill." The telegraph keys are a Les Logan Speed-X Model 321 hand key and an old Vibroplex Original bug. The microphone is a 1937-style Astatic D-104 (with large case and large ID tag) mounted atop a nickel plated stand. The stand-by receiver is a 1930 National SW-5. The QSL cards are 1930s vintage.

The station feed line had to cross the ceiling of the Vintage Ham Shack to connect to a knife-switch arrangement that allowed selecting either the 1940-50s station or the 1930s Station to feed the 135 ft dipole transmitting antenna. I had built the antenna and the feed line so it is unique in that it has 5" spacing and the spacers are made from plastic coat hangers. >>>

>>>  To cross the ceiling without sagging I used two supports that were made from 1" x 2" wooden bases for two ceramic cone standoff insulators. The feed line must make a 90 degree rotation to accomplish the transition from vertical at the knife switch to horizontal at the antenna coupler. This gives the station a real vintage look since the feed line is so large.

Operating the station is a lot of fun and gives one an appreciation of what hams of the thirties endured for a normal QSO. If you enjoy constant "tweaking" and "tuning" - this station provides ample opportunities for both. However, it is a real thrill when an answer to a CW CQ is received and the signal report comes back from an "out of state" station - "RST 589." CW operation is usually on 40M around 7085KC or 7049KC. AM operation is normally on the West Coast Saturday Morning AM NET on 3870KC. As all AM operators already know, you are never satisfied with the AM quality of your own signal and this station was no exception. When we first got the station "on-the-air" in 2006, we actually were getting reports of "weak modulation" or "audio challenged." Although monitoring the signal by listening through a receiver and earphones indicated that the audio sounded okay, actual "on-the-air" reports were a different matter. When an oscilloscope was used to monitor the signal it became very apparent that the modulator was "clipping" and only allowing about 30% modulation. A check of the 6L6 modulator tubes' grid bias under operating conditions showed that the -22.5 vdc bias battery must have had a high internal resistance as the grid voltage was following the audio drive voltage rather than keeping the grids at a fixed bias. Installing a new -22.5 vdc battery (made from 15 AA batteries in series) cured the problem and allowed for full modulation. Current audio reports are now positive and complimentary. 

Initially, I used a 1937 RME-69/DB-20 receiver with the UAT-1. Later, I switched receivers to the 1935 HRO. Then for awhile I used a Hammarlund SP-100 Super Pro. From 2009 to 2012, I returned to using the 1935 HRO receiver. The following write-up was just after I made the change back to the HRO. The 2009 photo shows the 1937 station at what I think was its best appearance while in the Western Historic Radio Museum. H. Rogers  Dec.2013

The 1937 Station at WHRM - The power supply for the HRO is the old style 5897AB that I rebuilt into a triple-filtered unit. The T-R relay power supply just to the left of the bug. I added a National SW-5 as the stand-by receiver. The bakelite cathedral clock is a late-twenties Hammond that still works (donated by K6QY.) The framed photograph is of a 1934 ham meet that took place in Yosemite Park. The book on the HRO power supply is a 1936 ARRL Radio Amateur's Handbook. The tube boxes are from the 1930s and 1940s. The QSL cards are mostly thirties vintage.

I put a finish on the table. It had looked really un-finished, maybe because it was. Anyway, I used Minwax Polyshades Antique Walnut for the finish. This is a tinted, polyurethane finish that worked really well on new wood. Took about 4 coats to get the color I wanted. The table has an inset piece of 1/8" masonite on top.

I changed the D-104 microphone stand. With a close examination, I found that someone had added the "tilt-back" fitting to what was a standard mike stand. I just removed that fitting and now the D-104 looks stock. This is a pre-1937 Astatic D-104 with the thick case and large ID tag that has "Astatic Microphone Laboratories" on it. The telegraph keys are a vintage Speed-X hand key and an Original Vibroplex with a black wrinkle finish base.

Another small change is the routing of the feed line to the Utah transmitter. It bothered me that the stranded wire seemed to sag before it connected to the stand-off insulators of the transmitter. I shortened the feed line just enough to have the routing be very straight and appear somewhat angular.

 


 

 

The 1937 Station in Dayton, Nevada - 2013

The 1937 Station remained in a state of disassembly for just over one year after our move from Virginia City to Dayton. By the end of 2013, I had to get the Utah back on the air. I bought a nice desk at a second hand store in Carson City to get some place to set up the station.

The next step was to check out the UAT-1. This went together with no problems. Routing the feedline to the transmitter did, however, present a problem. Although for the initial test, the feedline was directly routed to the UAT-1, this would be a real hassle when switching between the other upstairs stations that operate from the Johnson Matchbox and the UAT-1 that has its own balanced coupler. I used a knife-switch in the museum but it was too large for the 450 Z ohm line I was now using. I looked through the junk boxes and found a smaller really nice condition vintage knife-switch. After wall-mounting the knife-switch and connecting the feedlines, it was now easy to switch from the Johnson Matchbox to the UAT-1 coupler.

The antenna in Dayton loads quite differently than the old antenna in Virginia City did. I actually now show antenna current - about 0.8 Amps - on the coupler's RF current meter on 75M. The Dayton antenna is a 135' center-fed Inverted Vee with 98' of 450 Z ohm ladder line. The apex of the antenna is at about 30' which produces a fairly high launch angle that is good for communications on 75M out to about 300 miles radius. Since the actual antenna Z is unknown, it's not really possible to calculate the power into the antenna but tuning for maximum RF current is usually a good thing. The normal Sat. morning 75M AM net comment is "Good Signal - not as strong as you usually are - but 100% copy." 

I've set up the station to use the 1940 National HRO Senior receiver. I totally rebuilt this HRO several years ago and I'm lucky to have eight coil sets that provide coverage from 100kc up to 30mc. It's performance using the 697 power supply and the HRO speaker is superb. >>>

 >>>   Note that the station setup now has the transmitter on the right and the receiver on the left. This was primarily to keep the feed lines from the knife switch to the Matchbox and to the UAT-1 coupler about the same length. Generally, I prefer to have the receiver on the left anyway (must be from doing a lot of CW.)  On the wall are numerous QSL cards. Some are my QSLs and some are vintage cards that go back to the 1930s. The desk-top riser that holds the HRO and coils is homemade and was built to be able to hold an HRO receiver with the five coil set box and all of the other HRO and UAT-1 accessories. Note to the far right is part of D-65, a first production run HRO from 1935. If you have "sharp eyes" you might notice the W6UF QSL card from Bill Eitel, the "EI" in Eimac. Bill lived down the road (2.5 miles) from our present QTH. (W6UF QSL is far right, top row, second card to the left.)
 

The Historic "Utah to Utah" Sked

On February 25, 2007, K7RLD and I engaged in a historical QSO. Possibly the first, two-way, "Utah UAT-1 to Utah UAT-1" QSO in more than fifty years. K7RLD is John Morris of Bellevue, Washington. We had been in e-mail contact since John found a complete Utah UAT-1 with the Utah Antenna Coupler. This transmitter was listed on the Seattle Craig's List and though it needed some work, it was essentially a complete restorable UAT-1. John contacted me about a few miscellaneous details of my UAT-1 restoration and from that we were in somewhat regular e-mail contact. John's UAT-1 didn't have the original Utah power transformer but a later style Hammond transformer had been installed. The high voltage and current capabilities of the Hammond transformer were insufficient to drive both the UAT-1 oscillator and PA. John's solution was to separate the B+ requirements and run the oscillator on a separate power supply. At this point, we decided to have a real test of our two UAT-1 transmitters - a two way CW QSO that would have to last longer than just an exchange of calls.

Our first attempt was on Sunday morning, February 25, 2007 at 10:00 AM local time on 7050 kc on the 40M CW band. Though I could hear John calling me, I was not being heard. My repeated return calls were not acknowledged. Fellow AM operator, KJ6CA, Bob Rhodes from Sacramento, California called in and was able to work John. I had told Bob earlier about the upcoming sked. In the meantime, I discovered that my UAT-1 oscillator had drifted out of adjustment due to a "touchy" 7049 kc crystal. By the time I got everything adjusted again, John was gone. Conditions had deteriorated to the point where I could no longer copy Washington. I had a short CW chat with KJ6CA, who again tried to call John but was unsuccessful. Our first attempt at a two way "Utah to Utah" QSO was a bust.

I immediately e-mailed John to let him know that the failure was on my side due to the misadjusted oscillator on my UAT-1. We rescheduled our "sked" for the same frequency but at 4:00 PM local time. At 3:55 PM, I heard John testing his Utah so I broke in and our QSO began. John's UAT-1 was being received on my 1935 HRO at a good RST 569. QRM was very light and conditions were much better than they had been in the morning. Our QSO went through several exchanges and lasted 30 minutes - a superior test for both of our transmitters. John's Utah transmitter sounds very good with a solid stable note with just a hint of slow rise time giving his signal the true vintage sound. He is keying both the oscillator and the PA. In my UAT-1, I let the oscillator free run and just key the PA. John's transmitting antenna is a double extended Zepp and he uses a separate vertical antenna for his Collins R-388 receiver.

Our historical "Utah to Utah" QSO was copied by several hams both in Washington and Nevada. Thanks to all who e-mailed and sent reports. Maybe a "Utah to Utah" sked for AM phone will be next.

Visit K7RLD's website for a recording of the "Utah to Utah" sked, plus more info on his UAT-1 and other vintage ham gear.    K7RLD's Website

K7RLD's Utah UAT-1 with the Utah Antenna Coupler

 

Miscellaneous Info on the Utah UAT-1

Here is an interesting vintage photo that turned up on eBay. It shows a circa 1938 or so ham station set up in the corner of a room. The receiver is an RCA ACR-175 from 1936 and the transmitter is a Utah UAT-1 with the matching Antenna Coupler. The station is CW only and the bug can be seen in front of the receiver. Most of the QSL cards are from "7-land" indicating that the station was located in the Pacific Northwest. Prior to 1946, Nevada, Utah and Arizona were in "6-land."

 

Copyright Henry Rogers WA7YBS, Western Historic Radio Museum - APR 2006, updated DEC 2006, FEB 2007, MAR 2008, JUL 2008, NOV 2009

Re-edited and new photos added: DEC 2013

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