Can anyone tell me the values of the four compensating capacitors (trimmers) on the model 57?
I took mine apart and carefully marked them but according to the schematic they were wired wrong. I want to put the radio together right so I am not sure where they go. Caps are 12, 15, 18, 19. Thanks.
Bob Atchison
Hi Bob, Welcome to the Phorum. Here's a
schematic link for folks who might be able to help with answers.
Unfortunately the diagram and parts list don't divulge the actual values of the trimmers. You maybe able to find out via the part #s. Or if you have a capacitance meter you could measure them and take an educated guess as to where they go ( the lower the fq the higher the capacitance)
Definitely will need to use a generator to align the IF trimmers, they will make a big difference if they are off.
Terry
Why do you need values?
I think those mounted on tuning cap, osc and ant, are the same, and the two in the back are likely shown correct. One of them, the 19, is the feedback regenerative circuit cap.
My guess as to the value of the ones on the tuning cap is maybe 20-30pF. But as long as you have them, the value is of no concern.
Well there two on the tuning condenser,one in the lo circuit, two across IF trans, the regen control. So there is six all together. Best I remember some of them are isolated from the chassis. It may turnout that they are close enough in value that it doesn't matter which one goes where.
Terry
Obviously regen cap should go where it was before as otherwise you won't have the regen control easily accessible as intended, from the back of the chassis.
The regen control has the fiber nut on it the other are brass.
Terry
OK That's one. There are still three that I can't figure out, and they are not the same value because there are a different number of plates. I do have a cap meter, but I need to know which one goes where. thanks all!
Take a look at the back side of each trimmer. The Bakelite insulator should have one letter stamped multiple times all over it. Match that letter to the parts list.
One should be stamped with the letter A, one with D, and one with S. The regeneration control, part (19), probably will not have a letter on it.
A - part (12), IF primary, part no. 04000-A
D - part (18 ), IF secondary, part no. 04000-D
S - part (15), low frequency padder, part no. 04000-S
I checked all the trimmers, they are correct. I still have this horrible oscillation at full volume, low frequency, not a hum, more like a screech. It breaks into it just about the time you get a station tuned in either on the main tuner or on one of the trimmers. Any ideas???
Too high (clockwise rotation) on the regen trimmer will cause screaching, does backing it off (counter clockwise rotation) help?
This radio should have a tube shield over one or both of the 77 tubes - I do not remember as I do not own one, but it is one or both of the 77 tubes. In any event...is (are) the shield(s) in place?
Nothing I do will stop it till I power it off then back on. I can back out the regen trimmer but then I lose everything