Radio Boulevard
Western Historic Radio Museum
 

RACAL
British High-Performance Receivers

 

RACAL Company History, RA-17 and the Wadley Loop, RA-17C-12, RA-17 Versions
 RA-117, RA-6117, RA-117 Versions, Set-up and Operation Hints
 RA-6217 Solid-State Receiver, Operating the RA-237-B Low Frequency Converter

 


photo right: The BBC Control and Receiving Room at Crowsley Park - 1968.
Obviously, the BBC liked RACAL receivers, after all, they had merged with RACAL in the sixties. There are sixteen RA-17s in the photo.   from: bbceng.info  

 

RACAL


Raymond Brown of Racal

Racal Ltd. was a British company that was founded by Raymond F. Brown and George "Jock" Calder Cunningham in 1950. The company name was derived from their names, RAy Brown and Geo. CALder Cunningham. In 1950, both Brown and Cunningham had quit their jobs at Plessey Company, a large British electronics firm, to start their own electronics business. Both men put up about £ 50 to get their business started. Initially located in Isleworth, West London, within a year the company became Racal Engineering Ltd. When Racal business was slow, as it often was at first, they would build things other than electronics, such as golf clubs or shelving units. In 1954, Racal moved to their commonly known location, Bracknell, Berkshire, which is south of London.

Things changed for Racal in 1953 when the British Royal Navy became interested in having Racal build a couple hundred Collins 51J receivers for Royal Navy use. If Racal was going to build copies of Collins' 51J, they would have to be licensed by Collins to do so. Naturally, Racal wanted to use mostly British parts but Collins Radio Company insisted that only parts from the USA could be used and only assembly could be performed by Racal. Ultimately, the proposal ended up with a group from Collins doing an inspection of the (then) small Racal manufacturing facility. Apparently, Collins wasn't impressed and simply refused to license the manufacture of the 51J by Racal. The only option left was for Racal to design their own receiver for the Royal Navy contract. Racal contacted Dr. Trevor Wadley to help with the project.


Geo. "Jock" Calder Cunningham of Racal

RA-17

Dr. Trevor Wadley, the Wadley Loop and the RA-17 - Dr. Trevor Wadley was a well-known, South African electronics inventor and engineer. He had a near-eidetic memory and rarely took any written notes. During WWII, Wadley had worked on British Radar systems. His well-known inventions were the Ionosonde, which measured characteristics of the Earth's ionosphere. The Wadley Loop, that is mostly widely known for its first use in the Racal receivers but was also later used in the Barlow-Wadley XCR-30 receiver. Wadley's generally best known invention was the Tellurometer, a portable device that precisely measured land distances by timing a microwave signal propagation delay. Until lasers became commonly-used surveying tools, the Tellurometer was the most accurate land-distance measuring device.


For the Racal receiver project, Wadley proposed using a circuit that he had developed in the 1940s for test equipment (and that Dr. Wadley was planning on incorporating into a receiver design of his own,) as the basis for the new receiver. The "Wadley Loop" became the "heart" of the new Racal receiver design because it radically transformed the then typical receiver's inability to successfully and accurately copy RTTY (called RATT in UK) signals and other data transmissions that required virtually "no drift" in the receiver's frequency control circuits. The Wadley Loop allowed the new Racal receiver perform like a Collins 51J but doing so with an entirely original design.
 

The Wadley Loop virtually eliminated frequency drift by using a combination of a variable frequency oscillator, a 1.0mc crystal oscillator and three mixer circuits. Note the block diagram shown below right. In the upper series of blocks, the ANT-RF input signal is routed through a RF AMP and a 30mc LP filter to Mixer 1 where it is combined with the output from VFO-1(MC/VFO) which tunes from 40.5mc to 69.5mc. The output of Mixer 1 will vary from 40.65mc to 39.35mc going into Mixer 2 where it combines with a 37.5mc signal resulting in a 2mc to 3mc signal that is combined with the KC/VFO which tunes 2.1mc to 3.1mc resulting in a 100kc output going to the 100kc IF. The 37.5mc signal originates from a 1.0mc crystal oscillator that feeds a harmonic generator that produces strong multiple 1mc harmonics that are used to create thirty selectable 1mc wide tuning ranges. This "comb" of harmonics are fed into Mixer 4 and combined with the output from the MC/VFO which tunes 40.5mc to 69.5mc. The combination of the MC/VFO and the selected harmonic results in the specific one megacycle tuning range as selected by the MC dial which also results in a 37.5mc output from Mixer 4. The output of Mixer 4 is routed through a 37.5mc Amplifier, a bandpass filter and a second 37.5mc Amplifier before it inputs to Mixer 2. If a frequency drift happens in the MC/VFO that drift shows up in both Mixer 1 and in Mixer 4. Since the output of Mixer 2 is the difference of the two inputs from Mixer 1 and Mixer 4 any drift in the MC/VFO is cancelled on the output of Mixer 2.


photo above: Dr. Trevor Wadley test-listening to a RACAL RA-17 receiver.  
          photo from: www.samilitaryhistory.org

Rinus Jansen gives the best explanation of the Wadley Loop function in this excerpt from his "The Racal Handbook" which is quoted next.
 

"Let's assume we want to receive a signal of 12Mhz.

This 12Mhz goes through the two low-pass filters and the RF amplifier and arrives at Mixer 1. The Mhz VFO (VFO-1) is tuned to 12Mhz thus resulting in an output of 52.5Mhz.

The output to the 1st IF is 52.5 - 12Mhz = 40.5Mhz; this signal can pas through the 40Mhz filter which is , as previously said, 650khz wide.

First we take a look at what happens at the 37.5Mhz side:

The Mhz VFO signal of 52.5Mhz arrives at Mixer 4 together with the 15th harmonic of the 1Mhz oscillator. These signals are mixed and we get 52.5 - 15 = 37.5Mhz.

The received 12Mhz signal (which has been translated to 40.5Mhz in the meantime) is mixed with the 37.5Mhz signal at Mixer 2 and becomes 3Mhz. The khz VFO (VFO-2) is tuned to 0, giving an output of 3.1Mhz. These two signals are mixed in Mixer 3, resulting in the final IF of 100kHz.

Signal Path Block Diagram from the RA17 Manual

What happens if the Mhz VFO drifts 100khz?

The signal at the aerial is still 12Mhz. The Mhz VFO has drifted up in frequency by 100khz (0.1Mhz) and now gives an output of 52.6Mhz. The resultant frequency from Mixer 1 is 52.6 - 12 = 40.6Mhz.

Now the 37.5Mhz side again:

Mixer 4 is presented with the 15th harmonic of the 1Mhz crystal oscillator, resulting in an output of 52.6 - 15 = 37.6Mhz.

This signal is mixed in Mixer 2 and results in (yes!) 40.6 - 37.6 = 3Mhz!

This technique ensures that any drift in the Mhz VFO is cancelled out, due to the way in which its signal has been fed into the system twice."

 
Although the Wadley Loop might be the "heart" of the Racal receiver, by this time designated as the RA-17, it was the elaborate Antenna-RF preselector circuit that allowed the receiver's performance to be maximized for any frequency or antenna used. The preselector had a very Hi-Q and had six tuning ranges plus a variable tuning control. This allowed exact tuning of the RF amplifier grid input which resulted in the absolute best transfer of antenna energy to the receiver's front end. A four-step attenuator could be selected if unusually strong signals are encountered. The receiver was triple conversion with a tunable 39.35-40.65mc first IF, then a 2-3mc second IF and finally a fixed 100kc third IF. Six IF bandwidths from 8kc down to 100hz were available on the first versions (13kc to 100hz on later versions.) The BFO was calibrated and had a range of +/-8kc. The meter could measure RF level and AF level (later, a S-meter function was added.) External, low power 600Z outputs were available at the rear of the chassis and the built-in speaker was provided for convenient monitoring. Later versions had a 3Z ohm 1 watt audio output for a high-quality external loudspeaker. The tuning dial was a 35mm film strip that moved behind a fixed (but adjustable) reference index. The film strip had dual 1000kc scales graduated in 1kc increments. The black scale was for HF and the inverse red scale was for LF. A 100kc calibration oscillator could be used for adjusting the position of the moveable index to allow accurate frequency indication. Most RA-17 receivers used 23 tubes but the ones built specifically for North American used 22 tubes since the British GZ-34 rectifier tube was replaced with a solid-state rectifier.

Racal's new receiver, the RA-17, was the first successful receiver to employ the "Wadley Loop" system for oscillator and conversion stability. The first British Royal Navy RA-17 receivers supposedly cost 300 each, an equivalent cost then of about $1500. The RA-17 prototypes were built in 1956 and production started around 1957 and ran up to around 1973. The RA-17 design effort wasn't cheap however. Before it was in production, Racal had over-spent by 40,000 on the design and had almost bankrupt the company. A contract with the British Army helped Racal recoup their losses and assured their continued future. The RA-17 was upgraded several times but also many special versions were produced. The RA-17 "C series" was built for North American or NATO use and has mostly US-compatible parts.  >>>

>>>   As the Racal receivers became more and more popular with world-wide commercial and military users, a manufacturing facility was opened in the USA (one of many around the world) called Racal Communications, Inc., located in Silver Spring, Maryland (moved to Rockville, MD in 1972.) All of the receivers produced in the USA (or produced in the UK for North America) will have either an "A," a "C" or "6" (or combinations) added to the standard model number thus the RA-6117 was the "made in the USA" version of the RA-117 receiver (the RA-117 was a somewhat different version of the RA-17 that, for the most part, was produced concurrently with the various types of RA-17 receivers.)  

Production of the RA-17 and RA-117 ran up to about the mid-1970s at which time the RA-1217/RA-6217 solid state receiver was also in production having been introduced around 1967. Racal also produced many different types of accessory equipment for the RA-17, e.g., VLF/LF/MF converters, digital frequency readouts using Nixie tube displays, panoramic adapters, SSB adapters, diversity equipment, RTTY equipment, complete receiver setups for diversity reception, for RTTY reception, for frequency measurements not to mention complete transmitters sets and many other devices. Eventually, with more and more mergers and purchases, Racal produced a multitude of different types of electronic equipment.


Ernest Harrison of Racal

The merger with the BBC probably accounts for all of the Racal receivers at Crowsley Park. At one time, Racal employed 30,000 workers building many different types of electronics (not just radio equipment.) It was the third largest electronics firm in Britain and had facilities in 110 different countries. Jock Cunningham died in 1958 and, in 1966, Ray Brown accepted a political position in British government in the Ministry of Defense, retiring from the company. After 1966, Ernest Harrison, a very early and longtime employee (photo left,) was in charge of Racal. The company also owned Decca, Chubb and Vodafone to name a few of their holdings. Several reorganizations and division sales occurred in the 1990s and, in 2000, Thomson-CSF (aka Thalen Group) purchased the bulk of Racal Electronics.

The Many Names of RACAL

1950-1960 Names: Racal Ltd., Racal Engineering Ltd. 

1960 to 1990 Names: Racal Communications Ltd (UK), Racal Electronics Ltd (UK), Racal Communications, Inc. (USA)

post-1990 Names: Racal Radio Ltd , Racal - The Electronics Group, Racal Radio Group Ltd.

 

 

RA-17 C-Series    

The RA-17 Series receivers comprise many slightly different versions, in fact, over 40 different versions. The version differences depending upon the end-user's specific requirements. Almost all RA-17 receivers will have a suffix that further identifies what particular version the receiver is built to. The "C- Series" were the North American versions of the RA-17 built in England but specifically for export. There were over 20 different versions of the C-Series of RA-17 receivers. Most of the different versions were for specific uses, such as Broadcast monitoring where the BFO circuit was eliminated and different IF bandwidths used or changes to allow operation with specific models of Racal accessories. Some USA C-12 versions, if supplied to the military, were also identified as AN/URR-501A using the US Army-Navy designation. Most C-Series hardware is UNF for USA compatibility. All of the tubes are USA types but two were eliminated, the GZ-34 rectifier tube and V-24 were replaced with solid-state substitutes (V-24 appears to have been changed to SS very early in all of the RA-17 production.)

Other minor C-Series changes were to the 3.0Z ohm audio output that was increased to 1 watt. Also, a 10K 10W load was added to the B+ when the receiver was placed in Stand By and standard UHF and BNC connectors were used for rear-chassis connection auxiliary inputs or outputs (for accessory devices.) The Antenna-RF preselector (panel ID: ANT TUNE) is actually an elaborate antenna tuning network that essentially provides a precisely tuned, Hi-Q output that feeds the RF amplifier grid. The preselector has six tuning ranges and a variable frequency "tuner." This tuned RF input can be bypassed in the "wideband" position which is then an untuned "wideband" fixed 75Z ohm input. The Antenna Tuning provides an increase in sensitivity by way of much better signal transfer to the RF amplifier grid and also the Hi-Q allows for better selectivity for the incoming signal which helps with reducing interference from strong, near-frequency, near-field signals.


RA-17C-12    SN: N 4144  from 1960

A four-step attenuator can be inserted into the signal path to reduce the input level to the RF amplifier if intensely strong signals are encountered. The RF amplifier is a standard pentode tube in RA-17 receivers but the C-Series used a cascaded dual-triode tube 6ES8 (the RA-17 L also had this change although the tube used was an ECC189.)

The kilocycle tuning dial is a filmstrip type that is six feet long and spans 1000kc with a resolution of 1kc. When tuning the receiver, the dial index remains stationary while the numerical dial scale moves behind the index in a linear fashion. The megacycle dial is circular and is read thru the lower window of the dial escutcheon. To readout the tuned frequency one has to add the megacycle dial setting to the kilocycle dial reading. If the megacycle dial is set to 11 and the kilocycle dial reads 854 then the tuned frequency is 11.854mc (as shown in the RA-17C-12 photo above.) The black kilocycle scale is used while tuning from 1-30mc while the red kilocycle scale is used when operating with the optional MW-LF-VLF converter (10kc to 980kc.) The tuning system is super-smooth and very light feeling. The film strip is easy to read to at least 1kc accuracy. A 100kc Calibration oscillator is provided to assure frequency readout accuracy. The RA-17 used 23 tubes but since the GZ-34 rectifier tube was replaced in the C-series receivers with a solid-state rectifier the RA-17C-12 uses 22 tubes. The RA-17 Series tunes from 1.0mc up to 30mc in 29, one megacycle wide tuning ranges. Tuning from .5mc to 1.0mc is possible but with noticeably diminishing performance as the frequency is tuned lower within that range.

The use of triple-conversion and the drift reduction Wadley Loop provided solid stability. The normal C-Series bandwidth was selectable from 13kc down to 100hz in six positions. Last IF operates at 100kc with rear chassis outputs available. Selectable fast and slow AVC and a Noise Limiter were provided. A standard diode detector was used but the BFO injection is sufficient to allow easy demodulation of SSB signals. Several types of audio outputs are available at the rear connector terminals. BNC connectors provide IF output, 1MC output and RF input (for the LF converter and other compatible accessories.) UK versions only had a two-position meter function (toggle) switch. The "C" versions had a three-position switch allowing RF level, S-meter and AF level functions.
 

Top of the Chassis RA-17C-12 - Top left are the Selectivity filters and in front of those two modules is the IF section of the receiver. Top center is the 1mc oscillator (note the 1mc crystal on chassis.) The left module with the yellow tape is the KC-VFO and conversion mixers and the module to the right is the MC-VFO and conversion mixers. Front center is the film strip dial drive, speaker to the left and meter to the right. The power transformer and power supply components are located upper right in the photo. Audio transformer is in front of the power transformer. NOTE: The cast aluminum chassis of the early Racal receivers usually will have the rough appearance that this receiver's chassis has.


photo above
: This profile shot shows how the top of the RA-17 receiver shows how the top and side panels slope toward the rear (like the Collins 51J receivers.) Also, note the louvers on the top cover. Front panel nomenclature is silk-screened which increases the difficulty of a front panel restoration.
Most of the RA-17 side panels have a slope beginning about halfway back and the top cover also slopes at the rear half of the receiver (see photo lower-left.) The front panel is steel and is the standard 10.5" x 19.0" but the receiver depth is 20.5" which is considerably deeper than any USA-made receivers. The panels on the RA-17 receiver were originally supposed to be British Admiralty Gray (or battleship gray) but most encountered seem to be a light greenish color.

Many RA-17 receivers panels were equipped with panel "scuff protectors" that mounted behind the Kilocycle and Megacycle tuning knobs. These were normally made from clear plexiglass and protected the panel from "fat finger" syndrome that usually left the paint worn off in a "ring" around the knobs. The RA-17C-12 shown above and right has opaque black "scuff protectors" installed. Apparently, this type could be installed if the panel already had "wear-rings" since they hid any damage and prevented any further damage. Since these type of protectors aren't transparent the covered nomenclature is engraved into the black-on-white plastic material.

The MC and KC tuning knobs along with the five "non-winged" smaller knobs have a collet-type of grip on the shaft. Knob removal requires using a hex wrench to loosen the chrome nut at the center of each knob. These collets shouldn't be over-tightened when reinstalling these knobs.

Bottom of the Chassis RA-17C-12 - Underneath of the chassis shows the cast-aluminum construction and how that then provided for several "cast-in" shielded compartments. At the top of the chassis, as shown in the photo to the right, is the IF section of the receiver. Note how the Selectivity control uses right-angle gears to actuate the switches in the two filter modules located on the top of the chassis. The shielded section contains the Wadley loop circuitry. At the bottom left is the power supply and the small shielded compartment is the attenuator.

 

RA-17 Versions

RA-17 - First version was only built for one year.  It had different selectivity positions, different antenna-preselection coils, pentode RF amplifier tube, different meter. Sometimes unofficially referred to as the Mark I

RA-17 Mark II - Improvements to 100kc filtering, other minor improvements to appearance

RA-17 L - New selectivity positions, double tuned antenna coils, dual triode RF amplifier tube, usually also referred to as the Mark III version. There are at least twelve different types of "L" versions.

RA-17 C Series - Primarily for North American market with US-type tubes, hardware and connectors. Over 20 different numbered versions. C-12 was very popular, became AN/URR-501A. C-16 went to Netherlands.

The following is a detailed list of the many versions of the RA-17 that were produced. This list is from: "Keith's Vintage RACAL Enthusiast's Site" www.recelectronics.co.uk

RA-17B ~ Only four selectable bandwidths on this version of the RA-17
RA-17C ~ General designation for the versions built for North America-USA
RA-17C-2 ~ Canadian Army Model has modified BFO and MC drive, otherwise like RA-17C-3
RA-17C-3 ~ Standard North American-USA version with solid-state rectifiers and 75Z ohm wideband termination
RA-17C-5 ~ Similar to C-3 except +/- 6kc BFO range
RA-17C-6 ~ Similar to C-3 except with double-tuned circuits and AVC in the RF amplifier stage
RA-17C-7 ~ Similar to C-6 except partially changed over to UNF screw threads
RA-17C-8 ~ Similar to C-3 except with time delay compensation IF circuits
RA-17C-9 ~ Similar to C-3 but changed for use with RA78B
RA-17C-10 ~ Special build? - no details available
RA-17C-11 ~ Special Order only RA-17C-3 with time delay compensated IF, Bandwidths 1.2, 3, 8kc and additional IF output with 5kc bandwidth
RA-17C-12 ~ Standard North American-USA version RA-17 Mark 3, UNF screw threads throughout, 1 watt AF output (3Z ohm) US Military designation AN/URR-501A
RA-17C-13 ~ Special Order only C-12 but with pentode RF amplifier and dial brake on the MC control
RA-17C-14 ~ Special Order only "Broadcast Version" of the C-12 with bandwidths of 1.2, 3, 5, 7, 9 and 13 kc
RA-17C-15 ~ Special Order only C-12 modified for use with MA78B
RA-17C-16 ~ C-12 modified for Dutch Army but no other details
RA-17C-16/1 ~ Special version for the Netherlands but no other details
RA-17C-17 ~ C-12 modified for use with MA257
RA-17C-18 ~ C-12 with time delay compensated IF, bandwidths of 1.2, 3, 6.5 and 13kc, additional IF output with 5-8kc bandwidth
RA-17C-19 ~ C-12 modified for use with RA78D and RA66
RA-17C- 26 ~ C-12 modified for use with RA66
RA-17D ~ Early version for North America-USA with 13kc bandwidth replacing 3kc bandwidth
RA-17E ~ RA-17 with 13kc bandwidth replacing 3kc bandwidth
RA-17F/G ~ RA-17 Mark II with 6BA6 compensated IF section
RA-17H ~ RA-17 with time compensated delay IF circuits
RA-17J ~ RA-17 with double tuning in AVC and RF stages
RA-17K ~ RA-17 Mark II modified for use with RA78
RA-17L ~ The standard British version of RA-17 Mark III
RA-17L-2 ~ RA-17L with UG-style Antenna receptacle
RA-17L-3 ~ RA-17L with Thorn Pigmy connector
RA-17L-4 ~ RA-17L modified for use with MA1350A
RA-17L-5 ~ RA-17L modified for use with MA1350A and RA66  (aka RA-17C-25)
RA-17L-6 ~ RA-17L modified for use with RA66 with addition of MA251
RA-17N ~ Special version with 1.6mc IF stage and coupling facilities for use with MA143
RA-17P ~ RA-17L Broadcast version with special bandwidths of 1.2, 3, 5, 7, 9 and 13kc
RA-17R ~ RA-17L modified for use in RA78
RA-17R-1 ~ RA-17R modified for use with RA66B by addition of MA251 supplementary to mods to operate in MA78
RA-17T ~ RA-17L with modified IF bandwidths of .2, .5, 1.2, 2, 4 and 13kc also with IF/RF Gain control disabled when AVC is switched on (Special Mod.)
RA-17U ~ RA-17L modified for use with MA257
RA-17W ~ Same as RA-17T

Notes: RA-78 was a frequency measuring receiver with nixie tube digital frequency readout and other auxiliary gear - all equipment mounted in relay rack
           RA-66 was a panadaptor that needed the MA251 buffer module to be installed into the RA-17 for interfacing between the two units
           MA-143 was a six-channel crystal-controlled oscillator, worked with RA-117 but could be used with RA-17N - provided six crystal-controlled frequency selections
           MA-257 was a MC stepper unit for selecting ten scanning MC ranges, the ten ranges ran in sequence.
           MA-1350 was a Decade Frequency Oscillator synthesized frequency lock for RA-17 tuning - worked with the RA-17 tuned frequency and MA-1350 switch settings

Other data from Rinus Jansen's "The Racal Handbook"

 

  RA-117 Series,  RA-6117


 RA-6117  SN: 193  - built in Silver Spring, Maryland, USA, ca: 1966

The RA-117 was introduced somewhat later than the RA-17 but for the most part was built along side that receiver. It's a slightly different receiver than the RA-17 and was developed to allow more of a variety of auxiliary equipment to be interconnected and operate with the receiver (such as the MA-79G exciter.) The RA-6117 is a version of RA-117 built in Silver Spring, Maryland, USA by Racal Communications, Inc. It's almost identical to the RA-117 but using all standard USA manufactured tubes. All of the hardware is also standard US threads and sizes. USA-made components used. USA-style knobs are used on the RA-6117.
 

The RA-117 antenna preselector circuit was slightly changed to provide a "wide band" selection that was an untuned hi-Z input or to "wide band 75" selection that was an untuned 75Z ohms input. The USA-built RA-6117 eliminated the 75Z ohm wide band position. The six-step frequency ranges was unchanged and still allowed tuning for maximum response for the particular frequency and antenna in use. There was also the step-attenuator provided for coping with very strong signals but still being able to retain the tuned selectivity that the R.F. TUNE (was ANT TUNE on the RA-17) provides. The RF amplifier used a cascaded dual triode tube (6ES8.) The major changes in the RA-117 were to the conversion frequencies and building in more capabilities of the receiver to interface with other types of RACAL equipment. 
 

The Wadley Loop front-end was basically unchanged but the RA-117 did add an extra conversion-IF amplifier stage after the 2-3mc IF bringing the total conversions to four. The four conversions consisted of a tunable 40.65-39.35mc, a tunable 2-3mc, a fixed 1.6mc and a fixed 100kc. The additional conversion used a slightly different type KC-VFO (tuned 3.6mc to 4.6mc rather than the 2.1mc to 3.1mc VFO of the RA-17.)

The KC-VFO/Mixer operated into a fixed 1.6kc IF which was then converted (crystal oscillator/mixer) to a fixed 100kc IF. The 3.6-4.6mc KC-VFO also featured an external input and an external output to allow the RA-117 tuning to control (or be controlled) by other devices. The Racal RA-79G exciter when used with the RA-117 could be set up to allow the RA-117 KC-VFO to control the exciter's tuned frequency, allowing a "transceive" operation. VFO selector switch is on the RA-117 front panel next to the Kilocycle tuning knob.

IF bandwidths from 13kc to 100hz, Fast and Slow AVC, three position switch allows the meter to act as an RF signal level, AF level or S-meter, standard envelop detector - no product detector are the features provided and all were basically the same as the RA-17C. Several BNC inputs/outputs are provided for External VFO, various Oscillator Outputs, 100kc IF Output along with terminals for several 600Z ohm outputs and a 1W 3.0Z ohm output. There were some versions produced that had modifications to the AVC usually consisting of longer delay times to allow better copy of RTTY signals (British - RATT signals.)

A separate audio output (600Z ohm) with an Audio Level control on the front panel that has its own output transformer and operates separate from the standard receiver audio output. This output was for driving a data device, an audio input RTTY converter, for example. The small built-in speaker can be switched off if a larger speaker is desired (connecting to the 1W 3.0Z ohm output works best.) RA-117 receivers use 25 tubes. RA-117 Series tunes 1-30mc in 30 bands. Also, .5-1mc tuning with noticeably diminished performance as one tunes lower in frequency within this range.

The RA-117 front panel color is usually cream color with black nomenclature. Scuff protectors aren't usually found on RA-117 receivers as the EXT/INT VFO switch interferes with their proper positioning. Although the RA-17 and RA-117 panels are standard 10.5" x 19.0" the receiver's chassis is quite deep at 20.5" which, of course, won't fit into any standard American cabinets. There were cabinets available that were specifically for the RA-17/RA-117 and only increase the overall receiver foot-print an inch or two. Even at that, the RA-17 and RA-117 are huge receivers that demand a lot of bench space. Other after-market general purpose cabinets that have the necessary depth are usually very large and really increase the overall receiver size substantially. However, most receivers usually will have their dust covers and, like the R-390A, look quite nice setting on a table "sans cabinet" and in that configuration don't seem to take up all that much bench space.

RA-6117 Top of Chassis - Much of the component layout is very similar to the RA-17 receiver. Note the extra module located next to the Selectivity filters. This is the Crystal Oscillator and Mixer module for the 1.6mc to 100kc conversion used only in the RA-117 or RA-6117 receivers. Note in the MC-VFO that two of the tubes have been oriented to the horizontal position. Many more coaxial cables in the RA-117 to allow for the INT-EXT VFO connections and output connections for the dual 100kc IF outputs. Note how the side panels and the rear panel comprise an almost complete enclosure. The top cover is flat with small perforations for venting heat.

 

RA-117 Versions

RA-117A-1 ~ RA-117A modified to North American version with US-style plugs and US-type tubes
RA-117A-2 ~ RA-117A modified for use with MA282/RA66B
RA-117B ~ not used
RA-117C ~ Broadcast version with crystal filter bandwidths removed (.1 and .3kc)
RA-117C-1 ~ RA-117 modified for use with RA220B
RA-117C-2 ~ RA-117 modified for use with RA133A
RA-117D ~ Special for RA167. Replaced RA273
RA-117E ~ Royal Navy Version for RA220
RA-117F ~ Swedish Version of RA-117A
RA-117Q ~ Double tuned RF input with 60kc IF bandwidth. North American version
RA-117Q-2 ~ British version of RA-117Q
RA-117R ~ RA-117Q but with 100kc IF centered on 100kc
RA-117S ~ Special for GCHQ Tewkesbury ref TX
RA-6117 ~ RA-117 Version built in Silver Spring, MD, USA, built with US components
RA-6117A ~ Same as RA-6117, built in Silver Spring, MD
RA-6117A-1 ~ RA-6117 with 100kc to 25kc IF conversion module mounted on rear panel of receiver

Notes: MA282 was a frequency changing coupler so the RA66 panadaptor would work with the RA-117
           RA220B was a Marine Receiving Terminal
           RA133A Dual Diversity Receiver

         
From "Keith's Vintage RACAL Enthusiast's Site"  www.recelectronics.co.uk    and other data from Rinus Jansen's "The RACAL Handbook"

 
RACAL Ham Receiver? - Racal Communications, Inc., the USA-based company located in Silver Spring, Maryland (from 1965 to '71,...Rockville, MD '72 to '97) built and offered a "ham receiver" version of the RA-17,...the RA-71. The receiver was based on the RA-17 and constructed in a similar fashion, Wadley Loop, cast aluminum chassis, film-strip dial,...all of the familiar Racal features. Tuning was from 500kc up to 30mc and used the same MC Tuning and KC Tuning of the RA-17. Slight changes were made by adding a Product Detector in the SSB/CW position and a tunable Notch Filter. Also, the dial escutcheon was changed to a rectangular set-up and the built-in monitoring speaker eliminated. Audio output impedance or power is not specified but does indicate a 6AK6 AF Output tube. The knobs used were slightly different from the standard RA-17 style. The RA-71 was built from 1965 thru 1966.

So,...why don't we see very many RA-71 receivers come up for sale nowadays? The original advertised selling price was $1200!
 

photo right: RACAL RA-71

 
 

 RA-17 and RA-117 Setup and Operation

Setting the Power Transformer Primary Voltage - Most RA-17 receivers found in the USA will have had the primary taps set to some voltage between 110vac up to 125vac. Most of the C-Series were set to 115vac from the factory, which was standard line voltage in the USA during 1960s. Today, most line voltages are somewhat higher, usually running  between 120vac and 125vac. Changing the power transformer primary voltage input requires moving one or two wires to other terminals. These are solder connections. BUT, try to find which terminal is which from the manual. It's not shown anywhere in the RA-17 UK manual or the RA-17C-12 UK-USA manual. The terminals are numbered on the transformer but those numbers aren't shown on the schematic. I'm not sure how the writers of the RA-17 manuals expected the users to set the primary voltage other than measuring the DC resistance of the windings and figuring out what went where.

Fortunately, the RA-6117 manual has a power transformer drawing and the numbers are shown on the RA-6117 schematic. The RA-117 was built along with the RA-17 receivers and they generally shared the same Hammond power transformer. The USA-built RA-6117 receivers did have a slightly different power transformer (BTC Co.) but luckily both are shown in the drawings. The terminal drawing, schematic and listing are shown below.

My line voltage runs 122vac so I've set my receivers and accessories to the 120vac setting. This requires soldering one wire to 125vac and soldering the other wire to -5vac resulting in 120vac input. With the terminals provided it's possible to set the primary voltage from a low of 100vac (110vac minus 10vac) up to 125vac (125vac minus 0vac) or 200vac (210 - 10) to 250vac (250 - 0.)



RA-17 uses a Hammond power transformer identified as NATO 5950-21-862-1369/TF4TX03LA with terminals as shown in the drawing on the left.

RA-6117 uses a BTC CO. power transformer identified as TF1RX03YY/BX-3944 with terminals as shown in the drawing on the right

The only schematic showing the terminal numbers as referenced to the actual windings of the transformer is in the RA-6117 manual. Shown above is a portion of the schematic showing the terminal numbers. The terminal number to transformer winding connections are the same for both types of transformers.

 

Terminals Connections to Windings on T1


Terminal 14 - HV
Terminal 15 - HV

Terminal 20 - 0vac Primary Adjust - subtracts 0 from other Pri Term selected
Terminal 21 - minus 5vac Primary Adjust - subtracts 5vac from other PT selected
Terminal 22 - minus 10vac Primary Adjust - subtracts 10vac from other PT selected

Terminal 23 - 6.3vac - connected to T1 shield (Terminal 31) and to chassis
Terminal 24 - 6.3vac

Terminal 26 - 110vac Primary
Terminal 27 - 125vac Primary
Terminal 28 - 210vac Primary
Terminal 29 - 230vac Primary
Terminal 30 - 250vac Primary
Terminal 31 - Shield-Chassis

Terminal connections are the same for either TF4TX03LA or TF1RX03YY, only the physical location of the terminals on either transformer are different.

 
Meter Notes for the RA-17 and RA-(6)117 - Earlier RA-17 receivers were equipped with a 200uA fs meter with dual scales to indicate RF and AF levels. AF level consisted of a 10mw red line indication on the 200uA scale. North American versions added a three-position rotary "meter" switch and an S-meter function-scale (in green) to a meter that was generally supplied by Stark. The S-meter position provides a relative indication of signal strength but the readings will depend on several factors including antenna type, the setting of the RF Attenuator or the tuning of the preselector. The adjustment pot behind the cinch-plug (just below the meter) is for the S-meter function only. See photo right.

The AF meter indication works only on the 600Z ohm 3mw line which has its own individual output transformer and is controlled by the Audio Level control located next to the AF Gain control on the front panel. If you have the Audio Level control set to minimum you will not see any indication on the meter. If you want to see an audio level then it probably would be a good idea to install a 680 ohm 1/2W load resistor to the audio line terminals on the rear of the chassis. The other unused audio outputs should also probably have similar load resistors installed. 

With the meter switch in the RF Level position, if the BFO is turned on, it will show a constant level on the meter. RF Level only shows signal carrier levels in the AM mode.


photo right: Stark meter on RA-17C-12

 
Performance RA-17 and RA-(6)117 - With either the RA-17 or the RA-(6)117, sensitivity is first rate as these receivers can "hear" just about anything that's being transmitted, depending on the listener's location and receiving conditions. Best reception results will require a good, resonant frequency or "tuned" antenna system and very careful tuning of the RF antenna preselector. This circuit is very Hi-Q and the tuned "peak" is very sharp. The signal gain with precise grid input tuning to the RF amplifier is impressive. "Wideband" can be used with strong, near-field signals, like AM BC stations. The Attenuator can be used to reduce strong signals while still keeping the preselector tuned. The filmstrip dial is easy to read and is accurate "to the kilocycle" if the CAL oscillator is used. IF Bandwidth selections will usually be 3kc or 6kc for normal listening. SWBC stations sound fine on 6kc and if they are particularly strong and transmitting something interesting the 13kc bandwidth provides excellent reproduction. The 13kc can be used on AMBC in the 1000kc to 1700kc part of the band. Performance below 1000kc is okay for about 100kc or so, then it begins to degrade. The bandwidths of 1.2kc, 500kc and 100kc can be used for CW signals. For reducing adjacent frequency SSB signals while in the AM mode, "off frequency tuning" is the easiest and most effective defense. Speaking of SSB, the BFO coupling is via a 10pf capacitor but that provides sufficient injection for excellent SSB demodulation. In some cases, the RF/IF Gain might have to be reduced to clear up distortion on particularly strong SSB signals but most average strength SSB signals demodulate fine with the IF/RF Gain fully advanced and the AVC on. Upper and lower sideband can be selected by using the +/- BFO setting (which is like the R-390A.) Use + BFO settings for LSB and - BFO settings for USB. For the best audio reproduction use a good quality external speaker connected to the 3.0Z ohm output. Shortwave BC stations and AMBC stations that are transmitting quality programming will sound incredible.
 

photo right: This beautiful example of a RA-17L receiver belongs to WØHRO. The receiver is mounted in the correct, original RACAL table cabinet that was available for the RA-17. Note that the meter switch is a two position toggle switch which is correct for "L" versions.    Photo from WØHRO

 
Reworking Overview - The RA-17 or RA-117 are not particularly easy receivers to work on. The modular construction allows removing individual circuits from the chassis but most modules are a combination of hard-wiring interconnections (usually power connections, but not always) and coaxial cable-BNC connections. Module removal will sometimes require some receiver disassembly and almost always some wire unsoldering. With good documentation, the process isn't too difficult but be prepared - none of the modules just "plug-in." Luckily, most manuals are available online. The RA-17 and RA-117 are comparable to the R-390A for level of circuit complexity and difficulty in repairs. The components are top-quality British units in the receivers built in the UK. USA-built receivers will have top-quality US manufactured components installed. There is an old adage about "Racal solder joints" that does seem to be a sort of common problem. These are "cold solder joints" (Brits call them "dry solder joints") that just need to have the solder "re-flowed" to correct. My RA-6117 had a cold solder joint in the 1.6mc Mixer/Oscillator module that caused intermittent operation. As with any "half century old" electronics gear, you will find problems - even on functional units. Mechanical wear, cosmetic problems, corrosion are to be expected. After all, most of these receivers were used by either the military or commercial users, so end-user abuse is fairly common. Another source of instabilities and birdies is poor contact on the shielding under the chassis. There are seven smaller shields that fit into place providing shielding of the Wadley Loop circuitry. These must be present and must be making good contact with the chassis to prevent feedback and oscillations from occurring. Alignments need to follow the instructions in the manual as sometimes special equipment is needed. Some of the filters in the MC-VFO Mixer and the 1mc Harmonic Generator need to be sweep aligned. Check the instructions before "diving in." Alignment adjustments are located almost everywhere on the chassis. Expect to have to receiver on its side for much of the alignment, however the IF bandwidth crystal filter adjustments are accessed on the side of the receiver, requiring the receiver to be "rightside-up." Like any complex receiver, the first one worked on is your learning experience and any that follow become more familiar and easier to get through. If you've successfully reworked R-390A or 51J receivers, then you'll know what to expect in a RA-17 or RA-117 receiver.

  

Adding the Optional Remote Standby (RA-6117) - The receiver muting, aka remote standby, was a option that wasn't installed on my RA-6117 receiver (sn: 193.) There isn't any actual specific data on the standby circuit in the RA-6117 manual other than a basic block drawing that is part of the block diagram circuit flow drawing. The block drawing shows that the B+ going to the Stand By position on the function switch is disconnected at the filter choke and routed to a relay that disconnects B+ and alternately connects a 10K 10W load resistor to the B+ when the remote standby relay is actuated. The voltage for the relay coil isn't specified on the drawing or the receiver schematic but does show that the relay coil is connected directly to the "Receiver Mute" terminals. However, in the British RA-117 manual, the standby relay is shown on the schematic. That receiver used a 24vdc coil relay connected to the "Receiver Mute" terminals. Since I didn't want to have to supply a separate voltage to "mute" the receiver, I chose to use a very small Potter-Brumfield sealed relay that was 4PDT and had a 115vac coil that only needed 10mA to actuate the relay. I tied all of the four NC, NO and ARM contacts together for maximum current carrying capability. I made a small bracket to mount the relay at the top-rear of the chassis near the terminal strip (making use of existing holes.) The wires from the relay were routed thru an existing chassis hole (that was located directly under the relay) to the receiver power supply section. I desoldered the wire (B+) connected to pin 2 on L80, the choke. I added an extension wire and this was connected to the NC contact of the relay. A wire from the ARM of the relay was then soldered to pin 2 of L80. Then a wire from the NO contact was connected to the junction of the 10K 10W load resistor and white-yellow wire from S5 (standby position.) One Mute terminal was connected to one relay coil terminal. The other relay coil terminal was wired to 120vac at the downstream side of the fuse. The second Mute terminal was wired to the 120vac neutral at the power transformer terminal. Shorting the two Mute terminals completes the 120vac circuit and turns on the relay which disconnects B+ and connects it to the 10K 10W load resistor which puts the receiver in standby. The manual selection of "Standby" with the function switch is not affected by this addition. This remote standby actuation is somewhat different than the standard NC-receive/NO-transmit action with a NC action on the Mute terminals required during transmit. This is somewhat like the R-390A "Break-in" function which also requires NC on transmit. Most T-R relays provide contacts for both NC or NO on transmit functions so no problems should arise with this remote standby addition. The Remote Standby addition makes the RA-6117 an "easy to use" station receiver that provides excellent signal reception along with an impressive bench presence.
 

Shown to the left is my RA-6117 sn:193 paired with the W6MIT homebrew AM100, otherwise known as the "1625 Rig" - a transmitter built in 1997 by John Svboda W6MIT. It uses an Exciter from a 1950s military T-368 transmitter to drive a pair of 1625 tubes connected in parallel for the PA. Another pair of 1625 tubes connected in push-pull are the modulators. The "1625 Rig" runs 100W output CW and 70W output AM on 160M, 80M, 40M and 20M. For a complete write-up on the W6MIT "1625 Rig" go to "Post-WWII Ham Gear" - use "Home/Index" at the bottom of this page for navigation.
 

This small "foot-print" station is stuck into a corner of the ham shack and provides great performance from both the transmitter and the receiver. Conveniently, the "1625 Rig" has its own "roll around" stand that eliminates the need for "space on the operating bench" for the station (so much for "impressive bench presence.")

 

RA-1217, RA-6217 Receivers

By the late-sixties, the RA-17 and RA-117 were competing with many solid-state communication receivers built by other companies. In 1967, the all solid-state RA1217 (UK) and RA-6217 (North America) were introduced. The same concept of using triple conversion with a Wadley Loop became the basis for these new receivers. Mechanical digital readout and a tuned preselector, along with a very small, light-weight package were the main features of the RA-1217 and the RA-6217. These receivers were comprised of several plug-in modules fitted to a main frame chassis. As with earlier receivers, many Racal accessories were available for these receivers and there are many inputs and outputs on the rear panel to accommodate all of the optional equipment. The receiver operated on 115vac to a power supply module that then supplied the -16vdc to operate the circuits. At only three and a half inches in height, several receivers could be operated within a very small rack space. The RA-1217 and RA-6217 were produced up into the late-seventies.

photo left: A US Army SSA Radio Operator using two RACAL RA-6217E receivers and the matching panadaptor, the RA-366B - Vietnam War Era. Note that there is another RA-6217A dual receiver and panadaptor setup behind the foremost operator. This US Army photo is from their website, army.mil. The caption reads "The Army Signal Security Agency provided direct support Signal Intelligence detachments to tactical units throughout South Vietnam."

RA-6217E Receivers in Storage Unit?
- I found three of these receivers at an estate sale in Moundhouse, Nevada in October 2019. To say they were "bargain priced" would be an understatement ($10 each.) All three receivers were jammed into a shelving unit at the rear of an extremely "packed" storage unit that had more slot machine parts and junk test equipment than radios. One RA-6217E receiver was almost a complete unit, lacking only the top cover and the shield over the RF input section. The second receiver was about 75% complete having nearly all of its modules but missing the important IF module, the tuning knobs and the top cover. The last receiver was about 40% there, missing several modules, the meter, all the knobs, the front panel and both top cover and small bottom access cover.

Getting one RA-6217E Working - On the test bench, I checked over the mostly complete RA-6217E and, other than being filled with sand and tree leaves, it looked like it was in pretty good shape. A careful power-up had the receiver working,...sort of. Contact cleaning and manipulation of the controls got the receiver working fairly well, at least on AM, USB and CW. LSB and the tuned BFO were non-functional. The RF meter was pinned to the negative but worked in the Audio mode (these problems ended up being corrected with adjustments that were on the IF module and the meter driver board.) The audio was taken off of the Phone jack (600Z) and used to operate an eight inch 600Z loudspeaker. Audio was impressive.   >>>

 

photo right: The completed RA-6217E. Note that these RACAL receivers feature "right-hand" operated kHz tuning. The RA-6217 version "E" was optimized for use with a panadaptor.

>>>   Luckily, the 75% complete, "parts set" receiver had the RF module shield so that was removed and installed on the RF module of the operational receiver. The mechanical digital readout on the working receiver was in really rough condition but the two "parts sets" had excellent digital readouts. Replacing the mechanical digital readout is no easy task but I removed the readout set from the 75% receiver to formulate a removal procedure. It requires moderate disassembly of the receiver's front-end along with maintaining a mechanical alignment during the readout swap. Before starting, tune the receiver to 00-000 and slowly tune further negative in MC and KC until the mechanical stops are contacted. In my case, the MC stopped at -00 and the KC stopped at -938. When removing the readouts, the MC readout is one unit and the KC is another unit. They are removed individually. To access the MC/KC readout requires front panel removal. Then dismount the meter, the meter switch, both dial lamp mounts, the fine tuning pot, the VFO switch and the harness clamp. The MC rotary switch has to be dismounted and the cover removed off of the VFO. Access to and removal of the MC readout is now very easy. Not so though for the KC readout. The KC readout is mounted with four screws, two screws are easy to access but the other two require a low profile, offset blade screwdriver to remove. Once these two difficult to remove screws are out then the KC readout can be removed. Installation of the good condition readout set was essentially the reverse of the removal procedure. The mechanical alignment of the various gears has to be checked during reassembly because it is possible to have the mesh too tight resulting in difficult tuning. When the mechanics are correct the tuning is very light. If accurate mechanical settings were maintained during reassembly then the receiver should power-up and receive signals at the proper frequency readout (,...and it did.)

Two problems remain,...LSB still doesn't function (I'm suspecting the "soldered-in-place" crystal) but I can use the variable BFO to receive LSB, so not a crucial problem. Then there's the missing top cover. I have to make the top cover which is .060 aluminum with no venting of any type. Once the aluminum piece is cut the mounting holes can be measured, marked and drilled. Then the aluminum can be sprayed with Easy Off Oven Cleaner, which is NaOH (Sodium Hydroxide.) NaOH will produce a matte finish on the aluminum surface. Just spray on, let it set for a few minutes and then rinse with cold water. Don't rub, let it air dry or use a heat gun to dry. The finish will be flat or matte aluminum which is like the original. There's no need to coat the finish with any sort of "clear coat spray." The cover can be mounted as soon as it's dry.

The 1 watt 15Z ohm audio output is accessed from the rear multi-pin connector/socket. Also, remote standby is on the same connector. I will have to make individual pin connections using push-on terminals. Pin outs for the RA-1217 (docs I have) don't match the RA-6217 (docs I don't have.)  

Other Early Solid-State RACAL Receivers - The RA-217 was an all solid-state version of the RA-117. It featured a mechanical digital readout for KC tuning, Wadley Loop, product detector and crystal controlled, fixed USB and LSB BFOs. The RA-329B was a militarized RA-217 paired with a MA-323 FSK unit in one square packaged military case. The RA-1218 was essentially the RA-1217 with a Nixie-tube digital display built-in. The RA-1219 was the same as the RA-1218 but with a Wadley Loop control of the KC VFO.
 

Using the Racal RA-237-B  L.F. Converter

with the RA-17C-12 Receiver on MW, LF & VLF

The RA-237-B is a later version of the RA-37 and the RA-137 LF Converters. The RA-237 was designed to work with the RA-117 receivers but it will also work fine with the RA-17. The "B" indicates that this version was built in England for use in North America and is equipped with USA-type tubes, hardware and connectors. A 2mc bandpass filter was added to the RA-237-B input circuit which isn't in the earlier versions. The RA-237-B uses a six-tube circuit. The use of the converter allows the RA-17 tuning range to be extended down to 10kc, giving the combination a total frequency coverage of 10kc up to 30mc continuous.     >>>

>>>  The RA-237-B up-converts the incoming RF signal into the 2-3mc range by mixing the 1mc Xtal Oscillator from the RA-17 with the incoming LF RF signal from the RA-237-B. The RF input is routed through a low pass filter system and the 1mc Xtal Oscillator is routed through a harmonic generator and a band pass filter. Both signals combine in the Mixer stage. The RA-237-B Mixer output is connected a cathode follower buffer and then to the RA-17's 2nd IF input (2-3mc.) From there the remaining RA-17 circuitry functions can be utilized. The RA-237-B provides a tuning range of 10kc up to 980kc. The RA-237-B has its own antenna and RF input preselector tuning system that is similar to the RA-17's. Wideband and Wideband with a 500kc low pass filter can be selected which bypasses the preselector. Using the preselector allows precise tuning of the incoming RF signal before its routed to the RF amplifier grid. The attenuator allows signal reduction if extremely strong adjacent frequency signals are present, such as on the AM BC band. The ANT. TUNING control tunes the RF signal input within each selected range and the approximate resonant frequency is readout on the illuminated slide rule dial. The drum dial rotates with each range selected and displays "band in use." The POWER ON toggle turns the tube filaments and dial lamps on only. The OPERATION toggle selects whether the LF converter controls RA-17 tuning or bypasses the converter allowing HF operation of the RA-17. >>>

There are two coaxial cable interconnections to the RA-17, RF and 1mc and then three wire connections, HT1, HT2 and AVC. HT1 and HT2 provide the +250vdc B+ voltage supplied from the RA-17 and is controlled with the OPERATION switch. AVC allows the RA-17 AVC to control the RA-237-B RF gain or manual gain can be selected if desired. The LF antenna input is via a SO-239 connector.

The converter has shielding to the various modules but full shielding of the chassis was not provided. Racal indicated that a special cabinet could be provided to house both a RA-17 and a RA-237-B (14" x 19" opening.) 

RA-237-B Servicing - This RA-237-B was in very good condition but it did need a little adjustment for good performance. Of the six tubes, four had to be replaced. Replaced both dial lamps. Only one was open but I replaced both with #40 lamps, threaded base 6-8v 150mA. The ANT. TUNING readout was mechanically off by about 30%. This required loosening the set screws on the fiber tuning condenser drive gear, setting the condenser to full mesh and then adjusting the readout to slightly below the low end of the scale. This really isn't "calibrating" or alignment, it just mechanically has the dial readout agree with the mechanical position of the tuning condenser. I also changed the AC input voltage primary on the power transformer from 115vac to 120vac since our line voltage here runs around 122vac. A few sheet metal dents and bends required minor body work. Minor cleaning, mostly dust.
 

 


photo left: RA-237-B chassis top.

Testing - I made up a three-wire harness for the HT1, HT2 and AVC connections and found a couple of RG-58 test cables with BNC connectors for the 1mc and RF connections. With the RA-17 and the RA-237 powered, I first set the RA-17 to 530kc reading the "red scale" on the dial. I then selected 500kc-980kc ANT RANGE on the RA-237-B and tuned the ANT TUNING for maximum background noise. The "nvroads" station was heard quite well (public service type of BC.) I then tuned both units to 350kc and peaked the RA-237-B. I heard the Canadian NDB NY 350kc in British Columbia coming in and this was at about 3:30PM - the sun was still up! I tuned WWVB 60kc and it was about 40db over S-9. USN VLF MSK stations NLK 24.8kc and NAA 24.0kc were also received easily. The operation is very easy with just tuning in signals on the RA-17, reading the "red scale" using the Kilocycle tuner. The Megacycle tuner is non-operational when the LF Converter is being used so its setting isn't important. Peaking the RA-237-B for best signal response will be necessary every few kilocycles if weak signals are being searched for. For really weak signals, the AVC should be turned off and the RF gain reduced along with increasing the AF Gain. This will prevent the AVC from acting on the noise and reducing the signal gain.

Operation - With the RA-17 turned on and the RA-237-B power on, select "10kc to 980kc" with the OPERATION toggle switch. Using the Kilocycle tuning and observing the red scale on the RA-17 dial select a frequency, e.g. 350kc. On the RA-237-B, using the ANT RANGE switch, select 210kc to 500kc range. Using the RA-237-B ANT TUNING, adjust the dial to read approximately 350kc. As you near 350kc, the background noise in the RA-17 will increase and will peak somewhere near 350kc as read on the RA-237-B dial. As you search for a NDB station with the RA-17, peak the RA-237-B every 5kc or so. The converter's preselector circuit has a very high Q and the tuning is very sharp. The frequency is read directly on the red scale of the RA-17 and the approximate antenna peaking frequency is read on the RA-237-B dial. With very weak signals, switch off the AVC and control the front end gain manually. This will prevent the noise level from controlling the AVC and reducing the front end gain. Manual control also is necessary during very noisy conditions. The Hi-Q ANT TUNING is narrow enough to reduce a lot of the LF reception noise in most cases and AVC can be used during good conditions and moderate signal levels. If you want to return to HF just switch the OPERATE toggle switch to 980kc to 30mc position and the RA-17 front end takes over and allows HF reception. Below are reception logs for the RA-17/RA-237-B combo from Nov 10 to Dec 12, 2019.

 

Reception Log for November 10, 2019  -  2150-2215hrs PST  -  Ant 135' "T"

1. YTL 328kc - Big Trout Lake, ON, CAN
2. VT 332kc - Buffalo Narrows, SK, CAN
3. DB 341kc - Burwash Landing, YK, CAN
4. RYN 338kc - Tuscon, AZ
5. YZH 343kc - Slave Lake, AB, CAN
6. POY 344kc - Powell, WY
7. SBX 347kc - Shelby, MT
8. YXL 346kc - Sioux Lookout, ON, CAN
9. NY 350kc - Enderby, BC, CAN
10. IN 353kc - International Falls, MN
11. YWP 355kc - Webequie, ON, CAN
12. ZF 356kc - Yellowknife, NWT, CAN
13. YQZ 359kc - Quesnel, BC, CAN
14. RPX 362kc - Roundup, MT
15. YMW 366kc - Maniwaki, QC, CAN
16. ZP 368kc - Sandspit, Queen Charlotte Islands, BC, CAN
17. EX 374kc - Kelowna, BC, CAN
18. CNP 383kc - Chappell, NE
19. YWB 389kc - West Bank, BC, CAN
20. PNA 392kc - Pinedale, WY
21. YL 395kc - Lynn Lake, MB, CAN
22. ULS 395kc - Ulysses, KS
23. ZSS 397kc - Yellowhead-Saskatoon, SK, CAN
24. FN 400kc - Ft. Collins, CO
25. QQ 400kc - COMOX Vancouver Is., BC, CAN

 

 

 

 

 

 

Reception Log for November 11, 2019  -  1920-1950hrs PST   -   Ant 135' "T"

1. UAB 200kc - Anahim Lake, BC, CAN
2. LU 213kc - Abbottsford, BC, CAN
3. EL 242kc - El Paso, TX
4. XC 242kc - Cranbrook, BC, CAN
5. QL 248kc - Lethbridge, AB, CAN
6. YCD 251kc - Nanaimo, BC, CAN
7. LW 257kc - Kelowna, BC, CAN
8. VR 266kc - Vancouver, BC, CAN
9. XS 272kc - Prince George, BC, CAN
10. YYF 290kc - Penticton, BC, CAN
11. TOR 293kc - Torrington, WY
12. DC 326kc - Princeton, BC, CAN
13. MA 326kc - Midland, TX
14. RYN 338kc - Tuscon, AZ

Reception Log for November 13, 2019  -  2220-2235hrs PST  Ant 135' "T"

1. LYI 414kc - Libby, MT
2. FQ 420kc - Foremost, MN
3. ATS 414kc - Artesia, NM - 25W
4. ZQ 410kc - Sir Wilfred Laurier, Canada Coast Guard Ship, BC, CAN
5. Z7 408kc - Claresholm, AB, CAN
6. MW 408kc - Moses Lake, WA
7. YLJ 405kc - Meadow Lake, SK, CAN
8. AZC 403kc - Colorado City, AZ
9. L4 402kc - Nipawin, SK, CAN - 200W  < newly heard station #345


 

Reception Log for Nov. 20, 2019 from 2150-2220 PST netted 36 stations logged about 30 minutes, tuning from 326kc up to 410kc. Listed here are only the newly heard stations for the RACAL set up. Other stations heard in this session are listed in the other logs.

1. YPO 401kc - Peawanuck, ON, CAN
2. JDM 408kc - Colby, KS  25W
3. YJQ 325kc - Bella Bella, BC, CAN
4. X2 328kc - Athabasca, AB, CAN
5. YY 340kc - Mont Joli, QC, CAN
6. XX 344kc - Abbotsford, BC, CAN
7. PA 347kc - Prince Albert, SK, CAN
8. LLD 353kc - Lenai City, Hawaii
9. AL 353kc - Trina, WA
10. ODX 355kc - Ord, NE  25W
11. YAZ 359kc - Tofino, Van Is, BC, CAN
12. SX 367kc - Cranbrook, BC, CAN
13. DPY 365kc - Deer Park, WA  25W
14. AA 365kc - Fargo, ND

NOTES:

11-10-2019 - Cndx very good with fairly low noise
11-11-2019 - Cndx noisy probably due to the time I was listening
11-13-2019 - Cndx very good with fairly low noise
11-20-2019 - Cndx very good with low noise

Total NDBs logged with wire antenna - 61

Antenna for these four sessions was the 135' "T" which is an 80 meter Inv Vee fed with 99' of ladder line with the ladder line wires tied together and connected to the center conductor of the Antenna Input of the RA-237-B.

 

NOTE: I've checked 630M (472kc to 479kc) several times and have only heard JT9 signals, no CW signals,...yet. On December 12, 2019 some very, very, very slow CW was copied (not QRSS but probably 2 or 3 wpm - might be a ham beacon - 474kc.)

UPDATE Nov 30, 2019 - I've started using a Pixel Technologies Shielded-Magnetic Loop antenna with the Racal LF combo. So far, the performance of the loop has allowed receiving NDBs east out to Quebec and west to Hawaii. More details shown in the reception logs below.

UPDATE Dec 6, 2019 - Below are reception logs using the RACAL RA17/RA237B with the Pixel Loop. The loop was indoors (second floor) and pointed NE. Conditions were great. 28 NDBs logged in a 25 minute session on Dec 5 and 27 NDBs logged on Dec 8. One newly heard station, YFM 332kc LaGrande, Quebec, #347 on the 5th of December.

I also logged another newly heard station with the Pixel Loop/RACAL setup a few days earlier, PMV 329kc Plattsmouth, NE, #346.

Reception Log for Dec 5, 2019, 1905hrs-1930hrs PST using Pixel Loop (*indicates not listed in previous logs)

Reception Log for Dec 9, 2019, 1910hrs-1940hrs PST using Pixel Loop - 27 stations received (only stations not listed in previous logs are shown)

1. YWB 389kc - West Bank, BC,CAN
2. PNA 392kc - Pinedale, WY
3. TW 389kc - Twin Falls, ID *
4. JW 388kc - Pigeon Lake, AB, CAN *
5. HAU 386kc - Helena, MT *
6. QV 385kc - Yorkton, SK, CAN *
7. PI 383kc - Tyhee, ID *
8. MR 385kc - Monterey, CA *
9. GC 380kc - Gillette, WY *
10. YE 382kc - Fort Nelson, BC, CAN *
11. EX 374kc - Kelowna, BC, CAN
12. YBV 370kc - Berens River AP, MB, CAN *
13. AA 365kc - Fargo, ND
14. SX 367kc - Cranbrook, BC, CAN
15. ZP 368kc - Sandspit, Queen Charlott Is., BC, CAN
16. DPY 365kc - Deer Park, WA
17. RPX 362kc - Roundup, MT
18. YQZ 359kc - Quesnel, BC, CAN
19. ODX 355kc - Ord, NE
20. IN 353kc - International Falls, MN
21. PG 353kc - Portage, MB, CAN *
22. NY 350kc - Enderby, BC, CAN
23. YXL 346kc - Sioux Lookout, ON, CAN
24. YZH 343kc - Slave Lake, AB, CAN
25. YY 340kc - Mont Joli, QC, CAN
26. RYN 338kc - Tuscon, AZ
27. ZU 338kc - Whitecourt, BC, CAN *
28. YFM 332kc - La Grande 4, QC, CAN * < newly heard station #347
1. ZZD 308kc - Edmonton IAP, AB, CAN
2. YIV 300kc - Island Lake, MB, CAN
3. Z1 305kc - Three Hills, AB, CAN 25W < newly heard station #348
4. UNT 312kc - Penticton, BC, CAN
5. YQF 320kc - Red Deer, AB, CAN
6. LGD 296kc - LaGrande, OR 25W
7. YER 334kc - Fort Severn, ON, CAN 195W < newly heard station #349
8. YLD 335kc - Chapleau, ON, CAN
9. MEF 356kc - Medford, OR

Reception Log for Dec 10, 2019, 1905hrs-1935hrs PST using Pixel Loop - 22 stations received  (only stations not listed in previous logs are shown)

Reception Log for Dec 12, 2019, 2015hrs-2045hrs PST using Pixel Loop - 38 stations received (only stations not listed in previous logs are shown)

1. YNE 207kc - Norway House, MB, CAN 1KW < newly heard station #350
2. IB 209kc - Atikokan, ON, CAN
3. RL 218kc - Red Lake, ON, CAN
4. YKA 223kc - Kamloops, BC, CAN
5. CG 227kc - Castlegar, BC, CAN
6. BR 233kc - Brandon, MB, CAN
7. XE 257kc - Saskatoon, SK, CAN
8. ZSJ 258kc - Sandy Lake, ON, CAN
9. GEY 275 - Greybull, WY
10. NM 278kc - Matagami, QC, CAN
11. CEP 278kc - Ruidoso, NM
12. QR 290kc - Regina IAP, SK, CAN
1. VC 317kc - La Ronge, SK, CAN
2. YEK 329kc - Arviat, NU, CAN 500W < newly heard station #351
3. ZXE 356kc - Saskatoon, SK, CAN
4. HQG 365kc - Hugoton, KS 25W
5. YPL 382kc - Pickle Lake, ON, CAN
6. MM 388kc - Fort McMurray, AB, CAN
7. ML 392kc - Charlevoix, QC, CAN
8. DQ 394kc - Dawson Creek, BC, CAN

 

Total NDBs logged with RACAL setup - 102 (from Nov 10 to Dec 12)

Medium Wave Performance - The RA-17 and RA-237-B combination works amazing well for MW/LF reception. The first four reception logs (shown above) list the NDB stations received with a wire antenna which usually presents a fairly high noise level. However, the very Hi-Q of the preselector in the RA-237-B helps to reduce noise as does the double conversion scheme. The last four logs are results using a Pixel Technologies Shielded-Magnetic Loop antenna located indoors (2nd floor.) These last four logs show that there is an definite advantage to using a loop antenna on MW, even in a quite, rural area. None of the listening sessions were longer than 30 minutes and the total number of NDB stations tuned in was 102 NDBs, six of which were newly heard stations. The manual specs the sensitivity for the combo at 1uv for A1 and 3uv for A2 which is certainly believable, although noise levels in the MW, LF and VLF regions usually don't allow reception of signals at that level of sensitivity. Noise levels are lowest at night during the winter hours. That is one consideration when looking at these logs,...all reception was performed during the peak "low noise" time and best DX propagation time of the "longwave season" which is between October and February with the "peak time" being December and January.

UPDATE: Dec 11, 2019 - After using the RA-17 and RA-237-B combination for a little over one month and logging over 100 NDBs (with six newly heard stations,) I'd have to rate this setup as one of the best performers for MW and LF reception. Overall, the MW/LF reception is relatively quiet, even when using an large wire antenna. Since the received noise is low, very weak NDBs are easy to copy. The tuning dial is amazingly accurate, one of the best, usually holding 1kc accuracy (taking into account the BFO offset.) When the shielded-magnetic loop was added to the combo even better weak station copy was the result. The RA-17/RA-237-B's ability to extract very weak MCW signals out of a normally noisy reception environment is comparable to the Hammarlund SP-600VLF-31's ability. But, the low noise and dial accuracy advantages goes to the RACAL.  

 

Bond Bonus

RACAL Receivers in 1962 Bond Movie "Dr. No"
 

RACAL receivers at MI-6 - This is the famous scene (for radio enthusiasts) near the beginning of the 1962 James Bond movie "Dr. No" depicting MI-6 Communications with a dozen RA-17C receivers in an impressive console.

Although all of the receivers dial lamps appear off, it's probably that the studio lighting is so bright the dials appear to not be illuminated

RA-17C receivers?...note the meter switch isn't a toggle but a rotary switch as used on the C version receivers.

Several versions of this movie scene can be found many places on the Internet.

More RACALs in Classic 1964 Bond Movie "Goldfinger"

 

RACAL Equipment in Goldfinger's Industrial Laser Control Room - The shot is from the famous "No, Mr. Bond. I expect you to die!" Laser-cutting scene. The room behind Goldfinger (Gert Frobe) is loaded with RACAL gear being used as props depicting the control gear for the Industrial Laser that figures prominently in the scene.

In the photo to the left, the RACAL RA-17 receivers are well-shown. The upper-most setup is the RA-129 RTTY Receiver with the RA-17 receiver and above it the RA-70 and the Plessey PV78B. The lower setup is the RA-81 Panoramic Receiver using the RA-66 Panadaptor and the RA-17 Receiver. There is another RA-17 setup to the left (with the actor/op in front of it) that is shown in other parts of the entire scene.

Interesting trivia - Gert Frobe had a very limited ability to speak his lines in English. Goldfinger's voice was expertly dubbed by actor Michael Collins


I clipped this shot from the "Laser Scene" video available from many sources on the Internet
 
Conclusion - The RACAL RA-17 and RA-117 receivers were built for world-wide commercial and military users. This meant the receivers were much more expensive than the typical ham receiver would have been at the time. It also means that these receivers had many more features that aren't found on most ham receivers. Specifications and tolerances were much better and performance was at the zenith of tube technology from the time period.

Today, a well-cared-for RACAL receiver will out-perform almost any of its contemporary competition. After all, they were originally designed to have the same performance capabilities as the Collins 51J receivers. The fact that the RACAL receivers are not seen very often in the USA probably accounts for the scant general knowledge of how these receivers worked and how well they received just about anything on the air.

But,...there were the ergonomics,...granted the left-handed operation of the kilocycle tuning takes some getting used to (if you're right-handed, that is,) but the tuning is so easy to operate and the film-strip dial is so easy to read (not to mention just ultra-cool) all is forgiven - once you've become the owner of a RACAL. Sure,...the overall front panel appearance pays homage to the Collins 51J, but without that initial Royal Navy interest, perhaps the RA-17 would have never come about. We're lucky that Collins Radio Company refused to license RACAL to build 51Js and forced the small British company to seek another avenue to supply the Royal Navy with a competitive design that achieved top performance with drift-free reception in a totally original method. The RACAL RA-17 and the RA-117 were the results.

Built from 1957 up well-into the 1970s, many of these high performance British receivers are still around doing their jobs, mostly in ham stations, serious SWL stations or enthusiasts' collections around the world. These "half-century +" old receivers are either well-cared-for originals that are meticulously and diligently maintained or they are the less-fortunate examples that have required a complete rebuild in order to attain their legendary performance. In either case, RACALs are still being used and appreciated world-wide.   

 
References - Hardcopy:

1. "The RACAL Handbook" by Rinus Jansen - A review of Racal Communication Equipment, 1956-1975 - This book has most of the classic RACAL gear with lots of artwork-type pictures and good descriptions. Jansen has the best description of how the Wadley Loop "self-corrects" for frequency drift and he shows it mathematically. First published in 1990 by Radio Bygones (Dorset, England,) many subsequent printings, up to 2000. Rinus Jansen/Kent Electronics first copyright 1990 in the Netherlands.

2. Manuals for the RA-17/UK, RA-17C-12/UK-USA, RA-117/UK, RA-6117/USA, RA-6217A/USA  -  most manuals are available online.

3. RA-71 information and photo from "Shortwave Receivers Past & Present" by Fred Osterman - Four editions with the fourth edition being a huge book with just about every receiver ever made listed in detail.

References - Online:

1. Keith's Vintage RACAL Enthusiast's Site - lots of information and photos of many of the RACAL receivers and accessories. Excellent source of detailed information. www.recelectronics.co.uk

2. G3YNH hosts several RACAL websites (or has links to them.) www.g3ynh.info/Racal/ra17.html  

3. Wikipedia has information on the various mergers and other companies that Racal owned.

4. Keith's Vintage RACAL Enthusiast's Site has a photo in the "Brief Company History" section showing the demolition of one of RACAL's Bracknell buildings after the Thalen purchase. 

Photo Credits:

1. Photo of Raymond Brown from Getty Images. It's difficult to find many photos of Raymond Brown. Getty Images has the only two I could find.

2. Photo of Geo. "Jock" Calder Cunningham from the Imperial War Museum - iwm.org.uk. Interestingly there are three photos of Cunningham and they are all titled "Jock of Racal."

3. Photo of Dr. Trevor Wadley from South Africa Military History site - www.samilitaryhistory.org   Go to "miscellaneous" section and "Wadley Ionosonde" - Wikipedia also has some information on Dr. Wadley

4. Photo of Ernest Harrison from picclick.fr - There are many photos of Ernest Harrison on the Internet.

5. Photo of Crowsley Park from bbc.eng.info - This site has three good photos of the BBC-Crowsley Park Control Room with lots of RACAL receivers in each photo.

 
 

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