08-07-2014, 08:07 PM
Great information, Ron, but I discovered a simply stupid mistake on my part since we talked last. I was working on a recent Ebay purchase (a Heathkit VTVM) when I discovered I had been using a bad alligator clip to measure the output transformer and the field coil. Everything I measured was open because the alligator clip was broken off at the connecting wire. Now, I'm getting 3400 on the field coil (I don't know what the output transformer should measure, but it shows some substantial resistance.
The speaker is still without a cone, voice coil, and spider, but that puts me in a different place. I wonder how hard it would be to rebuild the voice coil and re-cone this speaker? The voice coil is intact, but has a couple of inches of winding that has come lose. I've never done it before, but it might be fun to try. Do you know anything about re-coning? Can I buy a modern cone and trim it to fit, I wonder? Think I'll start reading up on the subject. Looks like the restoration is back on the front burner.
One last question: when I take a more careful measurement of my output transformer, I should be looking for a specific ration between the primary and secondary? The 2848 part is not on the Philco Repair bench, but the one that is there for a push-pull 45 has a 100:1 ratio. Do I look for something like that?
The speaker is still without a cone, voice coil, and spider, but that puts me in a different place. I wonder how hard it would be to rebuild the voice coil and re-cone this speaker? The voice coil is intact, but has a couple of inches of winding that has come lose. I've never done it before, but it might be fun to try. Do you know anything about re-coning? Can I buy a modern cone and trim it to fit, I wonder? Think I'll start reading up on the subject. Looks like the restoration is back on the front burner.
One last question: when I take a more careful measurement of my output transformer, I should be looking for a specific ration between the primary and secondary? The 2848 part is not on the Philco Repair bench, but the one that is there for a push-pull 45 has a 100:1 ratio. Do I look for something like that?
