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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 15th Nov 2018, 6:00 pm   #21
GW4FRX
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Default Re: GEC BRT400 receiver.

Quote:
Originally Posted by John KC0G View Post
Sadly the papers from the 1963 Convention are very hard to find. I know of only three copies in libraries in the U.K., and the British library does not appear to have one. The convention was organised by the Electronics Division of the I.E.E, and they published the papers as E.D. 4 (as shown on the spine), and not as a set of I.E.E conference proceedings which had recently been started. This was the first I.E.E convention on H.F. Communication since the Radiocommunication Convention in 1947 (J. I.E.E. Vol 94, 1947,part IIIA, Nos 11-16)
I have a copy of the E.D.4 convention papers if you need any references. Being interested in HF receiver design at the time I saved it when BBC Schedule Unit had a clear-out in about 1978.
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Old 18th Nov 2018, 1:59 pm   #22
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Default Re: GEC BRT400 receiver.

Hi All,
The receiver referred to by Hawker is the Royal Navy Outfit CJA/CJC.
More info at:
http://www.commsmuseum.co.uk/receive...%20CJA/cja.htm
The receiver in the attached photo belongs to Don ZL4GX and shows the receiver with its associated Frequency Synthesiser.
Outfit CJC was a single receiver in a desktop cabinet without a synthesiser. Outfit CJA was a dual receiver installation with each receiver having an associated synthesiser in a floor mount cabinet and weighing nearly half a ton! The receiver alone weighs more than 150lbs. and is the only receiver I know which need air cooling - the cabinets have forced air circulation and there is an air intake port on the receiver to duct air to the IF amplifiers.
The synthesiser is not a true synthesiser in the modern sense. It compares a sample of the receiver local oscillator with an internally generated signal derived from an external 100kHz source to derive an error voltage. This is the fed back to the receiver to a reactance modulator on the local oscillator to correct any frequency error.
The Outfit CJA was intended primarily for the un-attended reception of RTTY broadcasdt traffic, and replaced Outfit CJK (Racal RA117E etc.) which had been introduced as a stop-gap due to the late delivery of CJA.
The extreme front end performance referenced by Hawker is achieved using selected ECC82 cascode RF amplifiers and 6 tuned circuits at signal frequency, housed in a massive turret.
Few of these receivers (and none of the synthesisers) seem to have survived in the UK, possibly because of the silver-plated chassis making the valuable as scrap.
If anybody has a synthesiser they don't want please let me know!
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Old 18th Nov 2018, 2:34 pm   #23
Radio Wrangler
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Default Re: GEC BRT400 receiver.

International radiation symbol on the RX front panel at bottom right?

David
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Old 18th Nov 2018, 3:35 pm   #24
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Default Re: GEC BRT400 receiver.

Another one on bottom left. I wonder if it is the gas reference or stabiliser tubes?
Rob
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Old 18th Nov 2018, 3:52 pm   #25
G8BBZ
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Default Re: GEC BRT400 receiver.

The receiver pictured is ex New Zealand Navy. My ex Royal Navy receiver doesn't have the radiation warning symbols. I think Robin may be right as there is nothing inside the receiver with any warning labels attached.
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