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Philco 45C filter choke - Printable Version

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Philco 45C filter choke - jmac3ky - 04-24-2015

Currently restoring 45C "Butterfly." Instead of a filter choke, the last repairman had put in an output transformer, simply using the primary side. I need to have some idea what size choke I should look for since the schematic doesn't give any information.

Any help will be greatly appreciated. I'll try to load a photo that I saw online that shows one in place. It's the one on the right in the photo.

Thanks,
jmac3ky

RE: Philco 45C filter choke - Ron Ramirez - 04-24-2015

According to the Philco 1946 Quick Selector Part Directory:

32-7018 - 65 H @ 10 mA; resistance 2250 ohms.

RE: Philco 45C filter choke - morzh - 04-24-2015

Exact same as in 66, same arrangement too. Yes 10mA. According to what I remember when I calculated the current, it was a bit marginal, and since his is not the first choke I see burnt in this same place I think Philco cut corners on this one a bit rating it marginally.
Now a typical output transformer will likely be rated a bit better current-wise but then it can have lower inductance and surely lower DC resistance. DC resistance is not as important as it is still small compared to the resistors in series with it.
It might work just fine. Especially considering a 6uF cap after it.

RE: Philco 45C filter choke - jmac3ky - 04-24-2015

(04-24-2015, 11:36 AM)Ron Ramirez Wrote:  According to the Philco 1946 Quick Selector Part Directory:

32-7018 - 65 H @ 10 mA; resistance 2250 ohms.

Thanks for the quick information. Wow! You're the God Father of Philco radios.

RE: Philco 45C filter choke - Mondial - 04-24-2015

Yes, I agree with Morzh. The primary winding of the output transformer should work fine as a choke in that application. You can always use a larger filter cap after the transformer winding to compensate for its lower inductance if hum becomes a problem.

I would certainly try it out as is before looking for a replacement choke.