Posts: 112
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Joined: May 2015
City: Brandon, SD
So received the AES oscillator coil and wired it in circuit... Still have no reception anywhere across the dial... Did notice however that if I touch the grid cap of the 78 IF tube, a station comes in load and clear... While touching the grid cap, I can turn the dial and no change, the station is there from 550-1700KC... I traced all my components back to the antenna coil and they all check good... Even tried replacing the 6A7, no change...
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Joined: Oct 2011
City: Jackson, NJ
Check the 1st IF xfmr and the 6A7.
Also check if the oscillator oscillates without you touching the 78 grid by using the second radio.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
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Joined: Dec 2009
City: Roslyn Pa
This is what I would do. Connect your signal generator the grid cap of the 6A7 and the chassis. Set the generator to 470kc and align the two IF transformers. All three trimmers should have a pronounced peak if not check the winding for continuity.
Alter that is done measure the dc voltage on the 6A7's control grid (pin5) w/a high impedance volt meter (no vom). Should see some negative voltage there (a volt or 2) if the osc is running. You take a listen for it as Mike mention but may be nowhere near where it should be (470kc + the dial frequency). If not disconnect the wire connected to pin 1 of the osc coil and measure the resistance across the osc side of the tuning cap while rotating it from one end to the other. Should show no resistance at all (open). If not find the bent plate and straighten.
Check for hv on the screen grid of the 6A7 (pin4). If not osc coil is miss wired or open. Reverse the wires on pins 3 and 4 on the osc coil. Check #5 and 6 for tolerance. #6 can be substituted w/a 100mmfd cap.
GL
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
(This post was last modified: 11-18-2018, 04:11 PM by
Radioroslyn.)