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Model 38 serive bulletin No. 120-c Alignment
#1

Just finishing up a Model 38. Looking for information on alignment. I have the ryders info about compensating condensors and placement so was able to do an alignment of the IF to 460 Khz. However I dont seem to be able to get the alignment to track on the dial. Also any information on how the band switch works, there is nothing changing the oscillator circuit that I can see. Just adding two caps to the rf coil seconday top and tap. Broadcast band is working but police sw is not. Just gets oscillations. Coils all check ok.
Thanks in advanvce to anyones help.
David
Icon_confused:
#2

If you have already replaced wax-paper caps and checked all resistors for proper values (+/-20% max), then this Service Tip from my site may help.

PHILCO SERVICE HINTS & TIPS - NUMBER 26
Oscillator Failure in Model 38


The old, not used "police" band is nothing more than the standard AM band with an extended top end freq range to about 2,000 kHz or so.

You may want to try replacing the mica caps in the front end with exact value repalcements and/or cleaning the mica sheets in the compensating trimmer, part #14, 7, 6 in the Code 121 version. The front end is a more complicated circuit in the Code 123 version, parts are numbered the same.

Be sure you have the proper schematic for your set. You can tell because the early version uses a type 15 mixer and the later, Code 123, uses a 1A6 in the front end.




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