The PHILCO Phorum
Model 42-321 wavetrap - Printable Version

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Model 42-321 wavetrap - 45philcodon - 01-10-2022

The schematic for the Philco Model 42-321, shows a "condenser and choke assembly"; schematic no. 8; Philco part no. 76-1198.

On the radio I have, this part has been replaced with a capacitor only; no choke.

Does anyone have any info for this part? From the schematic, it looks like the capacitor value is .2 mf. No info on choke.
Is this meant to be a 455 HZ trap?

Any information on this part would be appreciated.

Thank you,

Don

RE: Model 42-321 wavetrap - Radioroslyn - 01-10-2022

https://philcoradio.com/library/download/service%20info/yearbooks/1942/split/Part12-Philco%201942%20RMS%20Year%20Book.pdf
The .2 cap is the b- rail ground return to the chassis. The inductor is a choke to discourage longwave signals from interfering with the IF stage at 455KC.
Since we don't have much if any longwave signals these days the choke is unnecessary.

RE: Model 42-321 wavetrap - 45philcodon - 01-11-2022

Thanks, Terry

Don

RE: Model 42-321 wavetrap - morzh - 01-11-2022

There are no more waves left to trap.

RE: Model 42-321 wavetrap - Arran - 01-11-2022

Where I am there could be a use for the wave trap, there are a few beacons operating on longwave, I assume they are part of the LORAN system, or are related to a nearby airbase. There is one where you can sometimes hear a harmonic in the background of a station at 1040 Kc, though once that station was bought out and switched to a sports-gossip station I stopped listening to it, apparently it's a comedy station now. Anyhow reconstruting the choke is fairly easy, some sets used a proper coil form slipped over the cap, but with others they just wound some 18 or 20 gauge wire around the cardboard shell of the cap ten times, and called it done.
Regards
Arran