[Ron Ramirez]

OK, Terry (and anyone else interested)...

I measured the heater voltages of the 75 and 43 tubes.

75 - 6.7 VAC
43 - 24.1 VAC

Not bad.

I looked...I do not have a PM speaker with an output transformer attached to it.

Then I remembered my Eico signal tracer. This signal tracer allows you to use its output transformer and speaker as a test speaker with output transformer...and the signal tracer does not have to be on to perform this test. (A good thing, because both the signal tracer and the 604 are AC/DC...and the two connected together and powered up would certainly cause the GFCI in line with my basement outlets to trip.)

I disconnected the plate leads from the 43 tube. I then connected the signal tracer's output transformer to the 43 plate and to B+.

The 604 plays loud and clear...

[Image: http://www.philcoradio.com/images/phorum...4_0026.jpg]

If I turn the volume control about 1/3 of the way up, I get a normal listening level with the 604 tuned to my SSTRAN at 660 kc. Which is how it should be.

So, it looks like I need an audio output transformer. Which should be interesting...it will need to match a 5000 ohm load to a 0.89 ohm voice coil...unless I change the speaker, too...and then there is the problem of speaker mounting...