Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

Philco 90 1st IF xfrmr question
#1

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.
#2

(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
#3

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...

--
Ron Ramirez
Ferdinand IN
#4

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.
#5

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.

--
Ron Ramirez
Ferdinand IN




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
54C Complete Teardown/Rebuild
Hello Roy, here is this one sincerely Richardradiorich — 12:45 AM
54C Complete Teardown/Rebuild
Richard, Had grabbed it already but thank you just the same.  I find myself wanting to find some way to block out the...glyphmon — 12:03 AM
54C Complete Teardown/Rebuild
Hello roy, here is a link to the schematic . Sincerely Richardradiorich — 11:54 PM
54C Complete Teardown/Rebuild
Richard, The Silvertone 2014 also is a transformerless set, so I am incorporating a 1:1 600 ohm audio isolation transfo...glyphmon — 11:37 PM
Preliminary work on wife's Silvertone 2014
Did an alignment today which was interesting.  IF alignment went great, almost all was already spot-on.  Adjusting on th...glyphmon — 11:35 PM
54C Complete Teardown/Rebuild
The main problem with adding a Bluetooth input is that this set lacks a traditional power transformer to isolate it from...radiorich — 11:19 PM
54C Cabinet Refinish
I started stripping this cabinet before it got super chilly out because I knew I wasn't going to be able to work on ...glyphmon — 11:18 PM
54C Complete Teardown/Rebuild
While I'm waiting to wrap up the final steps on my wife's Silvertone 2014, I started disassembly on the next project.  O...glyphmon — 11:07 PM
Preliminary work on wife's Silvertone 2014
Hello roy, that great news glad it worked out for you !! Sincerely Richardradiorich — 10:50 PM
Preliminary work on wife's Silvertone 2014
Safety caps arrived today.  Soldered one in and had a successful first power-up.  No magic smoke escaped and it tunes in...glyphmon — 09:53 PM

[-]
Who's Online
There are currently no members online.

>