06-06-2017, 04:12 PM
Well the long answer is to look up the output tube's specs http://tubedata.milbert.com/sheets/021/4/41.pdf and look for load resistance. This is what the plate wants to see as a load. This is different from the dc resistance of the output transformer (530 ohms) or the plate resistance ( abt 68K).
At 180v it's about 9000 ohms for the primary, the secondary needs to match the impedance of the voice coil. The original spkr's vc is about 2 ohms. If you are using a pm spkr then most of those are 4 or 8 ohms.
So the short answer is you need a 9k to 4 or 8 ohm output transformer.
Check ur PM
At 180v it's about 9000 ohms for the primary, the secondary needs to match the impedance of the voice coil. The original spkr's vc is about 2 ohms. If you are using a pm spkr then most of those are 4 or 8 ohms.
So the short answer is you need a 9k to 4 or 8 ohm output transformer.
Check ur PM
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!
Terry
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
