Philco 90 restoration - Printable Version
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+--- Thread: Philco 90 restoration (/showthread.php?tid=22832)
RE: Philco 90 restoration - Bob Andersen - 11-29-2021
Absolutely. If the value was critical, they put a variable cap in parallel with the fixed cap.
RE: Philco 90 restoration - Ron Ramirez - 11-29-2021
Yup, as Steve and Bob said. After all, these were consumer products, not scientific instruments. Usually "good enough" was...good enough.
RE: Philco 90 restoration - cknob - 12-01-2021
I watched a YT video from Mr Carlson last night on restoring an FADA radio. That's where I heard the comment. Doesn't mean he's right though! Maybe it was something unique to that manufacturer.
RE: Philco 90 restoration - Steve Davis - 12-01-2021
Could the components even be selected before the radios have been completed and powered up? Anyway, just think about the bottleneck this would create on an assembly line.
Steve
RE: Philco 90 restoration - Ron Ramirez - 12-01-2021
The design engineers selected the components when they designed the circuits, prior to the beginning of production. Changes were (often) made during production, and these changes were then incorporated into production and usually (but not always, as we know) documented.
RE: Philco 90 restoration - Steve Davis - 12-01-2021
It just wouldn't be economically feasible to select components on the fly.
Steve
RE: Philco 90 restoration - cknob - 12-02-2021
Makes sense guys. Wow...these pictures on the Philco radio website are haunting. I live right outside of Philadelphia and know exactly where this area is.
https://philcoradio.com/library/index.php/philco-history/chapter-9-the-end/
RE: Philco 90 restoration - Arran - 12-04-2021
I believe that the old style molded mica caps had a tolerance of + or - 5%, and since the values were usually posted right in the service data, either on the schematic or on an included parts list. Of course they also included trimmers, and padder condensers in series with, or in parallel with a coil to compensate for the variations in manufacturing tolerance between one coil and another, some would take shortcuts though and use fixed micas rather then trimmers. I've never worked on a Philco superhet of this era, but I have worked on RCA/G.E/Westinghouse sets, and it is possible to get the alignments on those almost bang on in terms of dial tracking.
Regards
Arran
RE: Philco 90 restoration - Simon Wa3uay - 12-04-2021
Bob, PM'd you regarding your "parts chassis"
Thanks,
Simon
RE: Philco 90 restoration - Bob Andersen - 12-09-2021
I'm calling the chassis done. It would be nice to have a matching pair of tube shields but I'm not going to lose any sleep over it.
Next, I'll give the speaker my full attention.
[Image: https://live.staticflickr.com/65535/51734926878_ba7db91586_c.jpg]
RE: Philco 90 restoration - radiorich - 12-09-2021
Hello Bob,
beautiful job!!
Sincerely Richard