The PHILCO Phorum
Philco 112 speaker specifications? - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Philco 112 speaker specifications? (/showthread.php?tid=13140)


Philco 112 speaker specifications? - FStephenMasek - 09-19-2015

Do you know the field coil specifications for the speaker in the late model Model 112 with the '47 output tubes?  Somebody gutted the speaker in mine, and used one winding of some puny transformer in place of the field coil.  

RE: Philco 112 speaker specifications? - Nathan Slingerland - 09-19-2015

If you haven't already, check Ron's spreadsheet of Philco speaker specs (speakers.zip) which can be found here:

http://philcoradio.com/phorum/showthread.php?tid=215

RE: Philco 112 speaker specifications? - FStephenMasek - 09-19-2015

Thanks! The clown who worked on it previously used a winding with just a few hundred ohms resistance, when the correct choke should be 3,200 ohms. That would have made B+ way too high.

RE: Philco 112 speaker specifications? - Arran - 09-19-2015

 Clearly something went wrong with the speaker field coil in this set, which was why they attempted to make a choke or of a small transformer. Either it was damaged by a shorted filter cap or the winding just failed mechanically for some reason. In any event it's the inductance that matters not the DC resistance, the DC resistance of a proper iron cored choke can be lower then a type H Philco speaker and still work as long as it has the same number of Henries. It would be easier just tracking down a replacement H series speaker rather then rewinding the field coil, but if the original speaker is otherwise intact, and you can get the bobbin out of the frame to rewind it, why not give it a go just for the experience?
Regards
Arran

RE: Philco 112 speaker specifications? - FStephenMasek - 09-19-2015

The original speaker was gutted, as I wrote above. The end of the field coil enclosure and mounting bracket closest to the cone was drilled out to make room for the magnet of a PM speaker fastened into the old basket.

Yes, I should have written about the Henries, and I do have a meter to measure Henries, but do not know the specification of the original in Henries, just the DC ohms listed on the spreadsheet. There is no way the one winding of the small transformer the hack used would have the same rating in Henries as the large old field coil.