Philco 90 1st IF xfrmr question - Printable Version
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Philco 90 1st IF xfrmr question - TA Forbes - 03-10-2012
Discovered that the 1st IF transformer in the Philco 90 early model I am restoring is open on the primary side. Does anyone know if there are any suitable replacements on other Philco models? The secondary reads ~65 ohms, I assume that the primary was the same, as the xfrmr links two 24 tubes.
RE: Philco 90 1st IF xfrmr question - Radioroslyn - 03-10-2012
(03-10-2012, 01:01 AM)TA Forbes Wrote: Discovered that the 1st IF transformer in the Philco 90 early model I am restoring is open on the primary side. Does anyone know if there are any suitable replacements on other Philco models? The secondary reads ~65 ohms, I assume that the primary was the same, as the xfrmr links two 24 tubes.
I would think that as long as the fq is the same and the mdl 90 doesn't have any extra windings you should be ok. I know that some of the early Philcos use 175kc or 260kc. 262kc was popular among the tube type car radios. As for Philco perhaps a model 70 or 91.
Terry
RE: Philco 90 1st IF xfrmr question - Ron Ramirez - 03-10-2012
The early (2-45) and "mid" (1-47) versions of the 90 used a 175 kc IF. The late 90 with push-pull 47 tubes used a 260 kc IF.
A 1st IF transformer from a 111 or 112 should work also, since they also use a 175 kc IF. The part numbers are different but they appear to have the same type of mounting. Worth a try if you have a junk 111 or 112.
I used to have a couple 111/112 junk chassis around here, but I got rid of them a year or so ago. And I don't have a spare dual volume control, either; if I did, I'd send them your way...
RE: Philco 90 1st IF xfrmr question - TA Forbes - 03-10-2012
I tried one from a PP47 112 chassis that measured almost the same resistance- ~65 ohms both primary and secondary. It worked! But the set needs an alignment as the reception is not consistant across the dial.
This set had some wild "interpretive fixing" done on it at some point in time. I had to trace most of the wiring and in several cases re wire these fixes. Additionally, several resistors were drastically out of tolerance. The 1M ohm was reading 2 meg, and all 3 .25 meg were reading .35meg, .45meg, and .6 meg!!
The local distance switch was disconnected, and the leads of it and both 6mFd mershons were loosely twisted together.
It appears that all except one trimmer were screwed down tight. The one that was not was almost all the way out. Soooo, I adjusted them all to more or less center and did minor adjustments using strong local stations for a temporary fix once I got the set to play.
I installed the PP output xfrmr from the console speaker on the cathedral speaker I have, which was formerly for a single 47 output.
RE: Philco 90 1st IF xfrmr question - Ron Ramirez - 03-11-2012
Excellent! Good that you had a spare 112 chassis. I looked in the garage yesterday, and sure enough, I don't have my 111/112 parts chassis anymore.