12-14-2012, 03:56 PM
Yes:
http://www.philcorepairbench.com/schematics.htm
Well worth the nominal cost.
Now, as to your tubes. It should have 7V7s, not 7B7s. Both are pentode amplifiers and have the same pinouts, but characteristics are different. The 7B7 has much lower transconductance, lower maximum plate voltage, and higher plate resistance than the 7V7. The 7B7 might work OK on AM and SW but probably would not work at all on FM.
Yes, 7A4 is a sub for XXL.
The one you can't read the numbers on must be the XXFM. At least, let's hope so. Are you aware of the old "rub the tube on your scalp" trick?
One more thing. I would suggest that, instead of messing with the 42-350's FM oscillator circuit, that you read the following page:
http://www.somerset.net/arm/fm_only.html
http://www.philcorepairbench.com/schematics.htm
Well worth the nominal cost.
Now, as to your tubes. It should have 7V7s, not 7B7s. Both are pentode amplifiers and have the same pinouts, but characteristics are different. The 7B7 has much lower transconductance, lower maximum plate voltage, and higher plate resistance than the 7V7. The 7B7 might work OK on AM and SW but probably would not work at all on FM.
Yes, 7A4 is a sub for XXL.
The one you can't read the numbers on must be the XXFM. At least, let's hope so. Are you aware of the old "rub the tube on your scalp" trick?
One more thing. I would suggest that, instead of messing with the 42-350's FM oscillator circuit, that you read the following page:
http://www.somerset.net/arm/fm_only.html
--
Ron Ramirez
Ferdinand IN
