03-30-2020, 11:02 PM
tmr63,
if the resistances are good, the oscillator coil obviously isn't open. and, in my experience, is good. check the resistances in the RF transformer [part no. 9]. I don't know which pins are which, but 2 of the measurements should be small, the others infinite. you can check these with the transformer in the radio. i'm guessing that your offset signal thru the antenna is just bypassing the RF and det-osc tubes and going straight to the IF tube. i'm also guessing that the outer coil on the RF transformer is open.
i've also found that if the low frequency padder [part no. 15] is very far out of adjustment, i'll lose reception. pay close attention to it's setting and adjust it back and forth to see if that helps. you could also put a modulated RF signal into the grid of the det-osc tube. set the tuner to match the frequency. if it gets thru, the oscillator is obviously working.
i attached a scan of a document I got from Gary Schneider about open coils. he believed that the celluloid shield between the inner an outer coils released nitric acid which ate away at the outer coil. and turned it green. since the oscillator coil doesn't have a shield, and yours isn't green, most likely it's good. interestingly, Gary's web site is still up and running altho, sadly he isn't.
http://www.oldradioparts.com/
good luck. and keep us posted.
bob
if the resistances are good, the oscillator coil obviously isn't open. and, in my experience, is good. check the resistances in the RF transformer [part no. 9]. I don't know which pins are which, but 2 of the measurements should be small, the others infinite. you can check these with the transformer in the radio. i'm guessing that your offset signal thru the antenna is just bypassing the RF and det-osc tubes and going straight to the IF tube. i'm also guessing that the outer coil on the RF transformer is open.
i've also found that if the low frequency padder [part no. 15] is very far out of adjustment, i'll lose reception. pay close attention to it's setting and adjust it back and forth to see if that helps. you could also put a modulated RF signal into the grid of the det-osc tube. set the tuner to match the frequency. if it gets thru, the oscillator is obviously working.
i attached a scan of a document I got from Gary Schneider about open coils. he believed that the celluloid shield between the inner an outer coils released nitric acid which ate away at the outer coil. and turned it green. since the oscillator coil doesn't have a shield, and yours isn't green, most likely it's good. interestingly, Gary's web site is still up and running altho, sadly he isn't.
http://www.oldradioparts.com/
good luck. and keep us posted.
bob
