03-24-2018, 10:21 AM
A) Change the output transformer to one that will be able to drive a 6 ohm PM?
If the primary is ok (not open) it will work ok. Is it a perfect match no but the audible difference is negligible. Typically the Philco spkr is lower abt 2 ohms.
B) Replace the field coil with a 3.2 K resistor? If so what wattage?
Yes it does has to have either a choke or a resistor there. Wattage would be determine be the current flow thru it. Doing some quick calculations the current flow thru the field coil and #57 (they are in parallel w/the hv) it comes to 5.4 watts. You'll want to double that so the resistor doesn't get flaming hot.
C) Increase the 2nd Electro cap from 6uf to 12 uf?
I would leave it unless hum is an issue. The field coil isn't doing much if any filtering.
D) Do I have to do anything with the filter choke?
No.
E) am I on the right track here ?
Depends some of us like to keep things original as possible so repairing the spkr would been top on my list rather than replacing it w/a pm job.
GL
ps started to post and made breakfast but didn't look to see if anyone answered your Q's before finishing the post.
If the primary is ok (not open) it will work ok. Is it a perfect match no but the audible difference is negligible. Typically the Philco spkr is lower abt 2 ohms.
B) Replace the field coil with a 3.2 K resistor? If so what wattage?
Yes it does has to have either a choke or a resistor there. Wattage would be determine be the current flow thru it. Doing some quick calculations the current flow thru the field coil and #57 (they are in parallel w/the hv) it comes to 5.4 watts. You'll want to double that so the resistor doesn't get flaming hot.
C) Increase the 2nd Electro cap from 6uf to 12 uf?
I would leave it unless hum is an issue. The field coil isn't doing much if any filtering.
D) Do I have to do anything with the filter choke?
No.
E) am I on the right track here ?
Depends some of us like to keep things original as possible so repairing the spkr would been top on my list rather than replacing it w/a pm job.
GL
ps started to post and made breakfast but didn't look to see if anyone answered your Q's before finishing the post.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got it!
Terry
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