23 December 2013

A tiny glimpse into South Africa's rich radio history


I recently received an interesting email from OM Jan ZS6BMN. Jan related a few pieces of the radio history of South Africa, which I found very interesting. Jan kindly gave me permission to record these valuable pieces of history on this blog. Perhaps someday someone will take on the challenge of making an in-depth study of the rich history of radio in South Africa.

Jan did sound a warning that the accuracy of some of the information may have "suffered as a result of the passage of time." All information is posted here in good faith and in a positive spirit. No offense is ever intended.

With kind permission from Jan ZS6BMN

On the Barlow Wadley and Racal RA17 Radios. (slightly edited)
Great to learn that you own one of those very FB RA-17 receivers! Trevor Wadley designed the loop and it was first used by Racal. It was news to me to learn very recently that he had been contracted by National Co. as consultant way back then and was involved with the HRO-500 project! He designed the portable (Barlow) Wadley as a low-cost unit, but ran into legal problems with Racal. They were initially built by Barlows at their New Germany plant in Natal (KZN now), but due to the ongoing legal battle the manufacturing was moved to Taiwan. I have owned a number of these through the years and now have one of the latest (Taiwanese) versions. The first units came with a chromium-plate front panel, then came the grey ones and finally those from Taiwan were sporting military green panels. Performance wise I found the last ones to be the best, but all were good performers. The block diagram shows that the BW XCR-30 is in concept virtually identical to the RA17. 

At the start of my career in electronics I did my practical part of training at Derdepoort Radio Station in 1965/1966. I have finished school in 1963. Went to college in 1964, turned 18 and could at long last write the Amateur Radio Examination in November 1964. Those days one could not apply for a Ham licence in South Africa before the age of 18! At Derdepoort we had a pair of RA-17s with a Plessey diversity FSK unit on a trolley and this system was used for monitoring and as the receiving setup when running minor pres or diplomatic news services. At that time I still had my listener's call sign: ZS6-237 and was trying to get to grips with CW - nothing much has changed :-) I have also volunteered for night-shift (19:00 to 07:00) and then when everybody went to sleep used the Racals on the trolley and turned the Collins log-p to the States to decode RTTY. The log-p was part of the Bapsfontein USA system and was used with the latest Collins phase-lock loop receivers. These were easy to tune, but sometimes only locked on the correct frequency after numerous loop resets. On Amateur Radio side only ZS6UR was a regular on RTTY in South Africa so it was still a very rare mode. I still have all those printouts! I have really enjoyed the time at Derdepoort a lot! As the only trainee interested in Ham Radio I had privileges like access to the library (CQ, QST and all of that) and the laboratories and was permitted to use all of the test equipment too! Great training that was!

Those masts/towers in the Derdepoort photo were 110 feet high and were all over the place supporting rhombic antennas in groups of three pointed at London, NY, Sydney, Leopoldville. The three rhombics in a group were a mile apart. The large receivers, made by STC, were triple diversity units (used on London and Tangiers) while most of the others, Marconi, Philips and Mullard were double diversity. The Marconis were for FSK only, while the others were all independent sideband units for voice and high-speed telegraphy. The London service carried 16 telegraphy channels on the one sideband and 2 voice channels on on the other and operated in duplex for the overseas telephone communications. Some of the telegraphy high-speed telegraph units used one sideband for traffic and the other for quarter speed repeats. They were operating also in the TOR mode in full duplex. Pity that everything got demolished and this is the only photo I could get of the station in an old magazine. No photos of the inside exist as everything was wrapped in security. Even in the history write-up only a single small paragraph mentions the Derdepoort receiving and Olifantsfontein transmitting stations. I believe a similar fate hit the AT&T radio stations in the USA, but hopefully some there were preserved.... In an article that I read on the fate of some of the well-known USA stations I got the impression that real estate there too has triumphed over sentimentality as stations were demolished to make place for expansion. That is called progress in the Western World!

Dr Trevor Wadley
Dr Trevor Wadley was a research scientist at the CSIR and developed the original Wadley-loop prototype receiver in 1948. One of these as well as the much later prototype of the BW portable is currently on display at the SAIEE museum in Johannesburg.

One of my practical tasks in ‘65 was to re-assemble and align the RA17 that was previously taken apart to serve as example when some of the Hams at Derdepoort Radio have embarked on an optimistic project to construct a number of these receivers. My 'Elmer', Gijs, ZS6AKO (SK), was a master die-maker and made the die and mold for the chassis and faceplate bezel. The end-result was a number of FB clones that possibly ran circles around the standard unit on SSB as they have added a product detector and a few other smaller refinements. The S-meters were calibrated in microvolts – rare for that time! He went one step further in having all of the controls on his receiver labeled in Afrikaans! Gijs has also constructed a matching exciter and a legal-limit linear amplifier using three TT21 tubes. His antenna was a cubical quad. I have spent many many hours at the QTH of OM Gijs just to monitor him working DX! My own station at the time consisted of his old transmitter and an old HRO-MX. When he passed away in 2008 I did not want to ask about the whereabouts of his FB station and only much later heard there were no takers and that receiver was sold for R 600.00 - a crying shame and I still feel very upset that I have missed out on the opportunity of owning that specific set. Great mentor and good friend OM Gijs was to me...... In later years he concentrated on his other hobby - building model steam locomotives.
BTW: When the undersea cable was commissioned in the late sixties followed by the commercial satellite service the demise of point-to-point radio stations was almost certain. Derdepoort Radio was closed down and all the radio equipment destroyed for security reasons. What a waste! The buildings were used as laboratories for a short while, but together with the large property surrounding the station (a game reserve in the old days) everything was eventually sold to property developers. The building was demolished and now there are a number of townhouse complexes. The location of the station was between Sinoville, Wonderboom Airport and the Kameeldrift agricultural holdings.

Photo credits
1. Derdepoort Radio Station: Suid-Afrikaanse Panorama, 1964
2. Wadley prototype: SAIEE Museum Webpages.
3. Barlow Wadley prototype: ‘AWA Newsletter’, 12/2013, taken at the SAIEE Museum.
4. The other photos came from the private collection of ZS6BMN.

Compiled b ZS6RSH (2013-12-12)

Edited by ZS6BMN (2013-12-13)

Wadley Prototypes 1948

BW XCR-30 block diagram
BW XCR-30 inside
HRO-MX inside bottom
HRO-MX inside top
Ham RTTY 1965 at Deerdepoort

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