PT-6 antenna - Printable Version
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+--- Thread: PT-6 antenna (/showthread.php?tid=25162)
PT-6 antenna - bridkarl - 08-03-2024
I’ve been fussing over this PT-6 and am at my wits end. I think I’ve somehow disconnected the antenna. Or I have a bad tube. That seems unlikely however as since this is an AA5 design a bad tube would kill the radio. I have filament voltage in everything. I’ll check over the tubes tomorrow.
I replaced all the caps, radio powers up. I get some buzzing when I move the tuning cap through a rotation at one particular position. I just think I have the antenna hooked up wrong or something on the tuning cap.
I checked over all the wiring which seems correct.
I connected one side of the antenna to the aerial transformer and the other side to the tuning cap.
I just don’t get the buzzing noise at one place.
RE: PT-6 antenna - RodB - 08-03-2024
Try feeding a modulated IF signal to the antenna. If you get a tone at the speaker then check to see if the local oscillator is running.
RE: PT-6 antenna - bridkarl - 08-04-2024
I checked and the 7a8 oscillator tube shows a short. That’s probably the problem. Thanks
462ron - 462ron - 08-05-2024
Those locktal tubes are notorious for oxidized pins making poor/intermittent contact with the sockets. Might want to try scraping the pins and cleaning the sockets with deoxit and pipe cleaner or some such small brush.
Ron
RE: PT-6 antenna - bridkarl - 08-06-2024
I did clean the pins. I now seem to have good volume but still no signal. I clipped the loop antenna with one lead on the tuning condenser and the other on the antenna coil. I hope this is right - it seems to be correct.
Touching the antenna raises noise level. I have a 7A8 new oscillator tube on order.
RE: PT-6 antenna - MrFixr55 - 08-08-2024
If the set as a 455Hz IF, you may be able to totally replace the antenna coil with the loop. Disconnect the coil.
One connection should be to If the large section of the condenser. The other should be to the AVC line.