10-29-2016, 10:19 PM
Check all of the carbon resisters values. Very common for them to drift upwards, spec is 20 percent. 10 might be a little better. Try adjusting the sensitivity (on the back apron) inward to hear if you can get the detector to oscillate. Don't over tighten as you will break the fiber adjustment nut. If you can get it to oscillate loosen about 1/4 of a turn.
Set the dial at 1000kc and listen in a portable placed near the 77 mixer tube at 1460 or so. Should hear a loud hum in the portable, you may have to tune it around a bit to find the signal. If you can't find it check the osc coil for open feedback winding.
Unplug it from the outlet. Turn volume full up. Measure resistance from the ant post to the gnd post. Should just a few ohms (10 or less) If higher ant coil primary is open.
Don't know if you know but the volume control isn't really a vc it's a rf gain control. Can't touch it to make the set hum or feed an audio signal in to it. However you can touch pin 4 of the 42, that's the input to the audio stage.
Set the dial at 1000kc and listen in a portable placed near the 77 mixer tube at 1460 or so. Should hear a loud hum in the portable, you may have to tune it around a bit to find the signal. If you can't find it check the osc coil for open feedback winding.
Unplug it from the outlet. Turn volume full up. Measure resistance from the ant post to the gnd post. Should just a few ohms (10 or less) If higher ant coil primary is open.
Don't know if you know but the volume control isn't really a vc it's a rf gain control. Can't touch it to make the set hum or feed an audio signal in to it. However you can touch pin 4 of the 42, that's the input to the audio stage.
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
