Repair IF transformer in 39-6 - Printable Version
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Repair IF transformer in 39-6 (/showthread.php?tid=19637)
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Repair IF transformer in 39-6 (/showthread.php?tid=19637)
Repair IF transformer in 39-6 - Jake Blake - 02-08-2019
I have a 39-6 I'm trying to re-cap.
I accidentally pulled one of the wires off the IF transformer ( thinking it was a small piece of debris, my eyesight isn't so good ). Does anyone have any suggestion on how to go about getting that line back out of it? I've already removed most of the wax coating with a heat gun, and see red-colored glue probably holding the ends of the wires on the coils.
If it can't be fixed, how do I go about replacing it?Jake
RE: Repair IF transformer in 39-6 - morzh - 02-08-2019
Jake
I only vaguely can picture in my head what you've done; a photograph with good resolution and zoomed on the place in question could give us better chances to give you advice or any help if at all possible.
RE: Repair IF transformer in 39-6 - Jake Blake - 02-08-2019
Philco 39-6 IF Transformer assembly. One of the secondary leads is missing.... I pulled it off accidentally. I have already melted most of the wax coating off of it, but want advice on taking it apart to get the broken off lead back out of it. Any help would be appreciated. Maybe it can only be replaced. Any info on that would also be appreciated.
RE: Repair IF transformer in 39-6 - morzh - 02-08-2019
Just find where the othe end starts and pull one turn off, make it into the lead.
RE: Repair IF transformer in 39-6 - Jake Blake - 02-09-2019
Okay. Thanks.
RE: Repair IF transformer in 39-6 - Jake Blake - 03-09-2019
Just as a FYI follow-up Morzh,
I purchased another transformer online and am going to attempt to substitute it. Even if it isn't an exact match, I think I have a better chance of getting this thing to play again that way. The primary has more windings ( and resistance), so I may be able to remove some windings to get it in the ballpark, if it doesn't work as it is.
Thanks .
Jake
RE: Repair IF transformer in 39-6 - Radioroslyn - 03-09-2019
> The primary has more windings ( and resistance), so I may be able to remove some windings to get it in the ballpark, if it doesn't work as it is.
If the winding is designed to operate @ the proper IF frequency the resistance doesn't matter it's the amount of inductance that counts. If you remove enough turns this will cause the resonant frequency to go up making the unsuitable to use.
RE: Repair IF transformer in 39-6 - morzh - 03-09-2019
Do NOT touch that winding lest you have a dud that won't be an IF xfmr anymore.
RE: Repair IF transformer in 39-6 - Jake Blake - 03-14-2019
Ok...I appreciate that piece of information.
That seems to be the most-significant thing with these transformers, despite Philco's labeling of the resistance on the schematics. That led me down a primrose path. I do understand inductance somewhat, working on passive speaker crossovers, but the replacement transformer I bought is simply not going to work, to remove enough windings from it to equal the resistance of the original. I'll keep working with the original. Thanks!
Seeing your response late...I have a lot of trouble navigating this site.
RE: Repair IF transformer in 39-6 - Jake Blake - 03-14-2019
Yes.
Too much removed would change the value. Thanks
RE: Repair IF transformer in 39-6 - morzh - 03-14-2019
>>>>to remove enough windings from it to equal the resistance of the original.
Jack,
Not resistace. Inductance.
Try to read something on the subject (radio, general electronics/electricity).
Understanding what you do helps and will save money also.
No need to immerse yourself into studies but the bare basics are essential.
RE: Repair IF transformer in 39-6 - Radioroslyn - 03-14-2019
What you are looking for is a coil that =1.145mh if the total capacitance in parallel with the coil (fixed and trimmer) = 100mmfd. This combination will yield a resonant frequency of 470kc. If you reduce the inductance or capacitance the resonant frequency goes up. Conversely if you add inductance or capacitance the resonant frequency goes down.
RE: Repair IF transformer in 39-6 - Jake Blake - 03-14-2019
Thank you Terry.
Jake
RE: Repair IF transformer in 39-6 - Jake Blake - 03-14-2019
How did you come up with that 1.145mh figure? How on earth does inductance get measured? Is there a meter that does that? I sure don't have one that does.
RE: Repair IF transformer in 39-6 - morzh - 03-15-2019
the formula of the LC resonance is:
f = 1 / (6.28*SQRT (LC)).
Or...let me try the graphics here:
With Terry's values this formula gives us 470.584 kHz, to be exact.