TR2002 Transmitter Receiver

 This ex-RAF equipment first appeared on the government surplus market in the UK during the 1960s and was suitable for conversion for use on the 2 metre amateur band.

I recall buying one but I don't think I did much with it as it needed a pair of matched crystals to make it a self-contained transmitter and receiver, but I think I did get it going in transmit mode in conjunction with my normal 2-meter receiver.

I remember being very disappointed back in 1963 as my purchase was missing some of its valves, although I must admit that my memories are now pretty hazy. I do however remember the frequency on which it operated. This was 121.5 MHz; the international distress frequency for aircraft. Until recently the merest sniff of a signal radiated from a house on 121.5MHz would have been picked up by satellites and a helicopter might have landed unannounced in your back garden. I believe this channel was no longer monitored by satellite after 2009, but that is not to say that it would not be picked up at your local airport. I once tested a marine transmitter in our lab at Plessey using decent shielded RF equipment and was surprised to hear the local coastguard ask me to desist transmissions. I was tweaking the output on the marine distress calling channel, so powering the TR2002 in an unmodified state even with a dummy load is certainly not recommended.

In my junk box after nearly 50 years I still have the microphone transformer and the transmit crystal from my original purchase...

Here are some general views of my latest TR2002..








 You can see that the set is constructed on two separate chassis; the upper being the receiver which is marked "Type 127; 10P/13202" and the lower the transmitter and modulator including a small dynamotor which supplies the HT. The lower chassis is marked "Type 96; 10R/176".

The TR2002 was designed for use on a 24V supply and connections are relatively simple and straightforward being aerial, headphones, microphone and a send/receive switch.

It's RAF code is 10D/17997 and the manufacturer, clearly seen on the front panel label, was Burndept of Erith Kent

Brief technical details, including valve line-up are as follows:

Receiver: Fixed frequency of 121.5MHz using a 13.972MHz crystal and an IF of 9.72MHz

RF amplifier 2V1:CV850 (6AK5), Mixer 2V2 CV850 (6AK5), receiver crystal oscillator/quadrupler 2V8:CV850 (6AK5), oscillator doubler 2V9 CV850 (6AK5), first IF amplifier 2V3:CV131 (EF92), second IF amplifier 2V4:CV131 (EF91), third IF amplifier 2V5:CV131 (EF91), detector 2V6:CV140 (EB91)and audio frequency amplifier/output 2V7:CV138 (EF91)

Transmitter: Fixed frequency of 121.5MHz using a 10.125MHz crystal. Develops about 5 watts input to the output valve.

Transmit oscillator/tripler 1V5:CV416 (6F17), first frequency doubler 1V6:CV416 (6F17), second frequency doubler 1V7:CV416 (6F17), RF output 1V8:CV416 (6F17)


The microphone amplifier uses a pair of push pull amplifier valves 1V1 & 1V2: CV2135 (6BR7), fed by a microphone transformer and the output a pair of push pull valves 1V3 & 1V4: CV416 (6F17) driving a modulation transformer in the HT supply of the RF output valve. This of course gives a high-level AM transmission.

My first purchase had been disappointing as the 6F17 valves had been removed. This type was a special beam tetrode as scarce as hens teeth in Liverpool. Whether the Air Ministry had ordered the valves to be removed before disposal, or whether it was the proprietor of Super Radio I don't know? Maybe the first few that had been sold had been fired up and upset the staff at Liverpool Airport who'd complained to Mr Benson, I can't say, but I wouldn't be surprised...

This latest acquisition is perfect. All the valves are present and it's unmodified and completely original... most unusual.

See the Short Wave Magazine article from March 1970 on it's conversion to 2 metres

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