Thread: Philco 77
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Old 10-12-2018, 01:54 PM
old_coot88 old_coot88 is offline
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Quote:
Originally Posted by Zsuttle View Post
No output transformer that I can see, the 45's plates go directly to the speaker.
Your schematic definitely shows the output xfmr, designated #24. The field coil is #26, and the power supply choke #35. Can you post pics of the top and underside of the chassis? The output xfmr has gotta be there somewhere unless it's been physically removed.

(This design uses a dedicated field coil, whereas later designs made the field coil double as the choke).

(Edit.) In your photo of the speaker, it looks like the speaker has been replaced with the later type that uses the field coil as choke. Notice the two black wires coming out of the field frame. Those go to a 'hum bucking' coil which is in series with the voice coil. It serves to null out the field's ripple. Your radio doesn't need hum bucking, since the field coil does not double as choke. So just take the HB coil out of circuit, and run the voice coil direct.

Last edited by old_coot88; 10-12-2018 at 02:27 PM.
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