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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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15th Nov 2018, 6:00 pm | #21 | |
Pentode
Join Date: Aug 2005
Location: Shrewsbury, Shropshire, UK.
Posts: 149
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Re: GEC BRT400 receiver.
Quote:
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18th Nov 2018, 1:59 pm | #22 |
Pentode
Join Date: Oct 2005
Location: Hebden Bridge, West Yorkshire, UK.
Posts: 199
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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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Peter G8BBZ |
18th Nov 2018, 2:34 pm | #23 |
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Re: GEC BRT400 receiver.
International radiation symbol on the RX front panel at bottom right?
David
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18th Nov 2018, 3:35 pm | #24 |
Nonode
Join Date: Jun 2010
Location: Spalding, Peterborough, Cambridgeshire, UK.
Posts: 2,851
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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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18th Nov 2018, 3:52 pm | #25 |
Pentode
Join Date: Oct 2005
Location: Hebden Bridge, West Yorkshire, UK.
Posts: 199
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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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Peter G8BBZ |
22nd Nov 2018, 7:39 am | #26 | |
Hexode
Join Date: Mar 2009
Location: Minneapolis, Minnesota, USA.
Posts: 275
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Re: GEC BRT400 receiver.
Quote:
The FRR-59A receiver and its shipboard counterpart the WRR-2A also used forced-air cooling. They were built by the National Radio Company in the 1960's. Most of the following information comes from Fed Osterman's book "Shortwave Receivers, Past and present, 1942-2013". The radio weighed 250lbs and split into two main pieces. It had 64 valves, and 24 semiconductors. it was envisioned as a replacement for the R390A. Apparently they were not particularly reliable. You can find pictures at: http://www.navy-radio.com/rcvrs/frr59.htm If you look carefully you can see the air duct connection between the upper and lower parts. A friend of mine has one which turned up a metal recycler. Quite literally the price was by the pound (weight). 73 John |
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