The Racal RA17 was the first production communications radio receiver to use the Wadley Loop. When it was launched in 1955, it almost eliminated frequency drift - a major issue on receivers of the time. With single sideband being more widely used, the level of drift was a key issue. The RA17 was a huge beast - it weighed in at 67lbs, but it had some nice features. The tuning mechanism meant that it effectively had a tuning dial 145 feet long, although it was relatively easy to get from one end of the spectrum to the other. It had a line-up of 23 valves / tubes. Some have said it was the best receiver of its time - I am biassed as I worked for Racal (not back then) but the company went on to produce many more goof HF communications receivers. Find out more about the RA17 receiver, its specification, how it worked, and the story of how it came about: https://www.electronics-notes.com/articles/history/radio-receivers/racal-ra17.php
Having operated the RA17 in my professional service life, as a Royal Navy W/T operator and having owned one for about 8 years, as my primary SWL receiver.. I can confirm that it was the best receiver I ever used. I would love to have one now, but having moved home several times, and at one time lived on a Narrow Boat on the U.K. Canal system for a few years, it had to go... Present receivers, which I consider to be "good" are Kenwood R5000 ( running of a 13.5 regulated power supply, as the internal mains unit runs the receiver hot... )... and an excellent condition Yaesu FRG 8800 with the VHF converter fitted. Antenna`s in use... are a 20 metre broomstick, a 40 metre broomstick and a 67foot long wire at about 20 feet agl...
Having worked a lot with HF Communications receivers, both professionally and as a radio amateur, I would say that the RA17 was good, but not spectacular. It still had the common ailments of 50's receivers of too much gain before the main selectivity. Racal however understood this, and provided for a tunable RF preselector and a step attenuator at the antenna input. The frequency stability was good, but anyway not sufficient for unattended SSB operation without AFC and a pilot carrier. Such demands had to be handled by a separate stabilised oscillator such as the MA150 and the MA121 ISB adapter. If there was a "prize" for best mid-50's HF receiver, it would in my opinion go to the Rohde&Schwarz EK11-10, which used a low-gain, high-selectivity front end, and an early decade frequency synthesiser as its first LO. It had a setting accuracy of +/- 10 Hz and a long-term stability of about the same. 73/ Karl-Arne SM0AOM
We used Racal receivers at FCC monitoring stations back in the early 70s. Great receivers. We used an external frequency standard for absolute stability. Tom WA4ILH
The "stock" RA17, even with an external 1 MHz reference, was not stabilised in the sense of SSB/ISB requirements (drift rate better than 0.5 ppm/day). VFO and BFO frequencies were not derived from any reference sources, which is necessary for the level of stability required for channelised working in these modes. You had to use external synthesised sources such as the MA150 decade oscillator and an ISB/SSB converter behind. 73/ Karl-Arne SM0AOM
When I arrived at National Radio in 1963 they were already studying the RA-17 they bought which became the SS Wadley Loop HRO-500 a few years later. The general consensus was that it was a good altho overly complicated radio that had competition such as the 51J4, 50S1, R-390A to contend with, was not easily maintainable, and was obsolete by then. As with most equipment designed in the 50's it did not have a product detector. I happen to own a pair of Racals, a UK late production RA-17L with EU tubes and power cable, and the more civilized US version the RA-17C-3/AN/URR-501 with US tubes and power connector. The latter has been fully overhauled (what a chore, a R-390A is childs play in comparison) and is primarily used on the HAM AM frequencies where the IF bandwidth selections are excellent. The 17L is untouched. This is mandatory reading for anyone wishing to tackle these beasts. http://www.radiomuseum.co.uk/racal.html The dial accuracy is nowhere as accurate as a Collins, later Drake's, some Heathkit, and the HRO-500. The selectivity filters shape factor is poor by later standards but far better than the single crystal and 2-3 IF stages in most other boatanchors. So far my filmstrip readout is OK but replacements are very scarce considering the 10K or so built. Audio output in the C-3 has been upped to 1W from 50mw in the 17L. Not enough to drive any of my old 10-15" speakers but I prefer quality headphones anyway when on the air. I have plenty of other radios with PP outputs when wanted. The R-390A drives an old PP 5881 hi fi amp from the diode load and rattles the windows. Carl
It was probably "a sign of the times" that both Point-to-Point services, civilian and military, here almost invariably used Collins and Rohde&Schwarz receivers in quantity. The Racals were used in naval coast stations, and onboard larger vessels, notably later submarines and ice-breakers. SIGINT also used quite a few RA-117's. My own RA-17 and RA-117's all have SIGINT provencance, and they represented a "stop-gap" measure between the Hammarlund Super-Pro generation and the early solid-state receivers such as the Plessey PR-155. When the solid-state SRT CR300 family became available in quantity during 1973/74, both the PR-155 and RA-117's were rapidly phased out for maintenance reasons. Civilian users of the RA-17 and RA-117 were very scarce, the Swedish Telecom radiomonitoring stations used SP-400-X and SP-600's in a very large extent, and coast stations preferred the Eddystone 830/5 and Collins 51S-1 for MF/HF operations until the CR300 generation took over. The crews at both the coast stations and the radiomonitoring people actually preferred the SP-600's above other receivers, and they protested quite loudly when they were replaced with the PR-155 and WJ-8718. The State ice-breakers were among the RA-17/117 users that kept on for the longest time, most due to the very good LF converter that formed a part of the RA-17/117 system. For decades, an RA-17 with the very scarce RA-66 panoramic adapter (similar to the one below) was on display at the now decommisioned transmitter site for weather-fax. Hopefully, it did not end up in the scrap-heap. 73/ Karl-Arne SM0AOM
Fascinating reading about people's experiences with the RA17 and how it compares with the competition. The RA17 success enabled Racal as a company was able to get off the ground properly and become the force it was in later years. Obviously no receiver is perfect, so it is interesting to see the comments. Thanks
Big Racal tube fan since the 1980‘s as the RA 17 came here in Holland in hughe quantities available in the surplus shops. Most of them were ex Royal Navy. Nice receivers, difficult to maintain. Don‘t touch the filters ! Now most suffer from leaking capacitors and resistors out of tolerance. But remember.. these receivers are more than 50 years old ! Compared with an RA 63 or RA 98 SSB adapter they still performing nice. Also own a Racal KL 3011, a special made RA 17- C 16 version for the dutch military. 73’s from the Netherlands, Tjerk Polee PE1IOC ( visit my call at qrz.com )
You are right Carl ( hé, german name, hört sich ja gut an ), but the flood of available Racals like RA 17 and even RA 117 did dry up at the mid 90’s here in the Netherlands. To find a nice looking receiver , well aligned.. you must have luck. To find an SSB adapter like RA 63 or RA 98, the preselector/ protector or longwave converters like RA 37 or even better RA 137.. you must be very lucky, very rare and seldom seen here in the low countries ! So.. what you can get , grab it and store it away for the days you will have REAL time for this wunderfull hobby ! Tjerk
