Quote:
Originally Posted by electroking
This radio has preset capacitors, as eall as a main tuning capacitor on the chassis.
If there is anything wrong with this assembly, the radio won't work. Check the
schematic, and then make sure the main tuning capacitor has continuity
to the rest of the circuit. You should then be able to verify local oscillator
operation as follows:
Get a working radio (a small transistor portable will be fine) and set it to about
1100 kHz. Set it on the table close to your tube radio. Set the tuning knob
of the tube radio around 645 kHz, and move it back and forth a bit. You should
hear some noise in the small radio, indicating that the LO of your tube radio
is working at 455 kHz above the dial frequency as it should.
You may then increase the setting on both radios and see that the LO is tracking.
There are many more parts in a radio than the local oscillator, but that has
to be operating properly in order for the radio to operate.
I you have two working AM radios, you may also try that with them just to
find out how it should sound. Good luck!
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Thanks, I'll try that.
I have progressed backwards, only half the tubes light up now. I found that the electrolic capacitor was backwards according to the schematic, indicates black and red and black and yellow for the paper cap can that was in there, someone had replaced it.
Black is neg side and red is postive side and also black is neg and yellow is positive side of the electrolic capacitor on the schematic. It does not have the + sign like some of the newer schematics have.
I ran out of time , but I when I unsoldered the cap, I must have had a wire come off at the same time.