Federal A10 mystery
 

I found this Federal A10, 5-tube in great shape at Kutztown and gave it a try tonight. A little cleaning of the sockets and a repair to a socket surround that cracked. Cable ties come in handy. Xfmrs replaced above the chassis.

Using a ARBE-III and the power wiring from the website I got it up with my local AM xmtr and a Peerless speaker. No headphone jack on this one. But it took a while.

It seems the radio is only working from the detector thru the 2 AF amps to the speaker. Only the final dial tunes. I have a three tube radio of modest quality but detuning a bit helps the fidelity. Nothing special on the Peerless. The 1st and 2nd RF sections do nothing. I can pull the tubes and it still works and I have all the right voltages there.

There is a working rheostat for the final section and a volume control for the RF section which does nothing but I can see it working on a meter.

I have not been under it yet so there is more to come. The question is, how can this thing work as a one-dial if the RF was bypassed somehow? It's in Riders #1.

Well the only difference between a 3 dial and a 1 dial (single TRF stage 1 dial) TRF is usually two identical stages. If signal is strong and shielding is not good the first two stages can be dead and it will still work. Signal injection troubleshooting can be frustrating on these because often one can find themselves unsure if the signal being heard is really originating from the injection point connected to or entering the set through some coupling/leakage at a different point while the injection point is not passing any signal.

You probably have an open coil. Check all of them for contInuity with an ohmmeter, working backward from the detector stage. Also, check the tuning capacitors for shorts.