Quote:
Originally Posted by bgadow
Regarding the open end of the rheostat, that should be to A+, normally. On the AK 20 I have on the bench one end of the wire had detached. There was enough in the winding that I could carefully pull out 1/4" and solder that to the lead.
One of the rheostats controls the filament for detectors and the other for amplification. Depending on signal strength you may have to adjust one or both for best results. If one of them is open then some tubes won't light at all. If you needed to temporarily you could run a jumper and run all filaments off of the one good rheostat. For that matter, you could just run 6v direct to the filaments, for testing purposes.
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Thanks Bryan, I amended my schematic to reflect your information. I had a feeling that the rheostats were used for that purpose, but it's good to have confirmation.
There was another suspect connection shown in the "original" schematic I posted earlier, but it doesn't exist in my radio. It is shown coming off V3 pin 1 (F+) in parallel with V5 pin 1 (F+) going to the 25 Ohm pot. Would there have been a connection there, and if so, for what purpose do you think?
ERLA S-11 SN-16149 SCHEMATIC AMENDED 8-14-2019 FWP.jpg
As for a signal in, and a loudspeaker or phones, what should I use for a quick and dirty (reliable?) antenna, and what impedance loudspeaker can I get away with? I have a pair of old (1960's) Lafayette headphones that still work, and plenty of speakers laying around. Would an 8 ohm full range speaker be okay? I don't want to kill a good speaker screwing around - if I can help it.
