405 line sound receiver.

[Murphyv310]

Message received and understood David.
An interesting receiver then.

[Geordie McBoyne]

Today, the 405 line sound receiver was connected to a power supplier set to 200 volts HT and 6.3volts for the valve heaters.
Well, the big surprise the unit works but not on 41.5Mhz AP frequency. In fact it's a Birmingham receiver fixed tuned to 58.25Mhz.
Tracing the circuit reveals the demodulator is similar to radio practice. The TRF output transformer secondary is connected to one of the diodes in the 6Q7GT double-diode-triode and the other end of the coil goes to the 100K load resistor. Connect 'scope across this resistor.
However, the unit has the usual contact problems with the EF50 sockets, replacements needed, or simply replace the valves with 6AM6 miniature pentodes. Adaptor places required of course.

Geordie McBoyne.

[Murphyv310]

I've some NOS EX military bases David if you want a couple, they are larger in diameter though than the paxolin types.