EH Scott Radio Enthusiasts

The Fine Things are Always Hand Made

Hooking up an ordinary field coil speaker to a Phantom amp chassis

I've completed a long and torturous restoration of a Phantom AM Deluxe radio.

I cannot locate a speaker that is for this model because it has a center tapped field coil as well as a center tapped output transformer primary.

I have a conventional field coil speaker to use but am mystified as to how to hook it up.

Has anyone tried this before?  Or is the speaker available somewere?




Views: 201


Reply to This

Replies to This Discussion


The center tapped output transformer should not be difficult to find.  They were used on all radios and amplifiers having a push-pull output stage.  As for the speaker, either or both of the field coil windings may be substituted by a hefty resistor of similar DC resistance.  Therefore a speaker having a single field coil may be used in place of one of the field coil windings shown on the schematic (place resistors in series or parallel to match the correct DC resistance of the winding being substituted) and substitute a resistor in place of the other winding.  Of course, you will want to know the correct DC resistances of the two windings shown on the schematic.  This data was inconveniently omitted from the Scott service data.  I'll get back to you with those resistances.


The DC resistance of the field coil between the Black-Red wire and the Slate-Red wire is 535-ohms.  The DC resistance between the Slate-Red wire and the Yellow-Red wire is 400-ohms.


Thanks Norman for all the great information you provided.

 I see that my work in the future is going to get very interesting.

Thanks again,


Reply to Discussion


© 2023   Created by Kent King.   Powered by

Badges  |  Report an Issue  |  Terms of Service