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City: Irvington, NY
Yes, you probably were not feeding in enough signal to activate the AVC. You will need a somewhat strong signal as the 690 has a delayed avc circuit.
The 6J5 AVC rectifier cathode is biased a few volts positive, and the grid (used as the plate) is biased negative, so the IF signal amplitude must be high enough to overcome the initial bias before AVC voltage is generated.
The initial 2.4V negative bias applied to the grid of the 6J5 is what you are seeing on the IF 6K7 grids. It should increase with a strong enough signal.
Messages In This Thread
RE: 38-690 Code 125 - by Mondial - 01-05-2022, 05:59 PM
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Recent Posts
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Part numbers to model cross
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| That I wouldn't know, but sometimes the radio document itself shows one, same as the capacitor cans' etc pinouts.morzh — 12:46 PM |
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Part numbers to model cross
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| Thank you morzh, that is exactly what I was looking for. Now , is there some where that shows pinouts for Philco power ...Jim Dutridge — 11:37 AM |
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Restoration of the Canadian General Electric A-87
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| Thanks for your help Michael. In fact, this video is only an intermediate result. Later I had to apply another tinting l...RadioSvit — 09:01 AM |
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Restoration of the Canadian General Electric A-87
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| Great job on the cabinet.
PS. In the US notation, "kenotron" refers to specific type of tubes; we call re...morzh — 08:24 AM |
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Part numbers to model cross
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This document has at least some tables of models and parts used.
Example: Choke 32-7572, used in 604 radio.
Search f...morzh — 08:19 AM |
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Restoration of the Canadian General Electric A-87
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| I also checked all the radio tubes on my Hickok 530 tube tester. The 5Z3 kenotron turned out to be faulty, all the other...RadioSvit — 08:02 AM |
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Restoration of the Canadian General Electric A-87
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Well... While the varnish is drying up, I started repairing the chassis...
Of course I started by replacing the pa...RadioSvit — 07:12 AM |
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Philco Model 38-7: what caps & resistors do fail typically?
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| Hello Martin,
Welcome aboard our little community what great Model 38-7
Sincerely Richardradiorich — 12:30 AM |
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Philco Model 38-7: what caps & resistors do fail typically?
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| Welcome to the Phorum Martin.
I count about 9 paper caps, the 3 electrolytic caps and 2-Y2 safety caps to replace th...RodB — 09:44 PM |
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Part numbers to model cross
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| Jim,
We have this index put together by Dale Cook but I don't think that is quite what you are looking for.
The Parts...klondike98 — 09:37 PM |
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