The Racal 1792 listening only the signal generator

[ErrorFinn]

I bought Racal 1792 radio from Army surplus store, and when i first tried it, i got to hear a morse code for a while, but after that, only powerful BC stations, then there was a little "Holy Smoke" i turn the device off at once. and after that, now my device don´t smoke but it listening only the Signal generator. i check the powersupply and it is working perfectly and the frequency synthesis too. i did test it with the scope..I think all those different modes and bandwidths settings working well too. Do i must change some capacitors (tantalum) or where i best to start to search a reason for my problem.i check A4 board but i cant find any reason for that smoke. My radio´s displays are non backlighted type...
73de Oh1cl/ Errorfinn

[Sparky67]

Hi Errorfinn,

Yes, smoke is often a sign of a tantalum capacitor failing on the RA1792. It is a common fault. Have a close look for a tantalum with a hole in it, or a darker colour.

If you can not see a damaged capacitor check all the volts from the power supply. If one voltage is low unplug all the boards and check again. Then plug each board in, one at a time, and check the volts each time. That will help you locate the board(s) with the damaged capacitor - if there is one....!

Hope this helps.

Martin
G4NCE

[ErrorFinn]

Hi!

Under one of the circuit boards was a detached coil that looked like a resistor after i
Reinstall it. the radio is now responding to the antenna, louder noise 😀. After that i notice the first rf amplifier was skipped. But still nothing reasonable from speaker. The capacitors looks all very nice..

[Radio Wrangler]

The RA1792 is very much a cost-cut receiver, there is no preselector and minimal input filtering. They are easily overloaded by out-of-band large signals. So don't expect too much from it. The performance they deliver is not up to the standard suggested by their appearance and prices.

David