[fields 100]

I have PM speaker and would like to replace it with a field coil one. How far higher in the FC resistance (if it is possible at all) I can go. The original FC is 1250 ohms DC, but most available are either below (not good) or higher than that. Thanks.

http://www.nostalgiaair.org/PagesByModel...025207.pdf

[Radioroslyn]

Well the things to consider are the inductance of the field coil. Higher the inductance the better it will filter. Generally the higher the resistance the higher the inductance. It's current carrying abilities. Wouldn't want to use one from a 20 tube set on your set. The current demands wouldn't be enough to energize the field get full magnetism.

The simple answer is like 750-2000 ohms and from a 5 or 6 tube set.
Terry

[codefox1]

Agree, if hooked up correctly no problem trying whatever you have on hand. If the set works and you have ample volume, you're done.

[Radioroslyn]

A while ago Ron mentioned that some the the Philco car radio spkrs have a very low resistance FC.  Like a few hundred ohms. Those my not work so well. Some AC set will use the FC as a bias resistor or to develop the -bias volt by placing them from the HV cap the chassis gnd. These will have a fairy low resistance too.
Terry

[fields 100]

Thanks guys,
So up to 2000 ohms it should not be a problem. I was just concerned about B+ drop. Do not want to go with a PM speaker/choke/resistor thing.