03-28-2020, 10:49 AM
TP
This is what you are looking for.
Replace the selenium rectifier w/a silicon diode. Connect your set thru a variac to the ac power w/the variac turned down. turn it on. Look @ the right side of R101B w/a voltmeter. That voltage needs to be right at 7.5vdc. Turn up the variac till you get to 7.5v note the ac input voltage - your line volt voltage and that's how much of a drop you need across R-100. Adjust the value of R-100 till you get to 7.5vdc @ your line voltage.
If the 7.5v line in the set is too high it will burn out the tube's filament prematurely if it's too low poor performance/local oscillator won't run.
The hv line (90v) isn't particularly critical 10v either way is not got to be an issue.
This is what you are looking for.
Replace the selenium rectifier w/a silicon diode. Connect your set thru a variac to the ac power w/the variac turned down. turn it on. Look @ the right side of R101B w/a voltmeter. That voltage needs to be right at 7.5vdc. Turn up the variac till you get to 7.5v note the ac input voltage - your line volt voltage and that's how much of a drop you need across R-100. Adjust the value of R-100 till you get to 7.5vdc @ your line voltage.
If the 7.5v line in the set is too high it will burn out the tube's filament prematurely if it's too low poor performance/local oscillator won't run.
The hv line (90v) isn't particularly critical 10v either way is not got to be an issue.
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
