04-27-2013, 11:50 AM
I'm working on a 1934 Packard radio. Philco PA Packard but Chuck is sending me paperwork for a Philco Model "A" Receiver. Riders stuff isn't too good but I'll post the link anyway.
http://www.nostalgiaair.org/PagesByModel...014113.pdf
Here's a picture of the can.
[Image: http://speakeasyradios.com/yahoo_site_ad...42_std.jpg]
The Riders paperwork calls this out as part #48 which just says condenser but with a part# of 7774. The part number on the can is 7440-X.
The schematic also shows this capacitor as being part of a biasing circuit for the 1st Audio #37 tube. This is not what was originally in my radio. Just #38, 2.5K resistor was biasing the cathode of the 37 and this #7440-X can was connected to the cathode of the 2nd Detector #85 tube along with a 5K resistor. And a switch that appears to be some kind of "Sensitivity" switch.
So I'm trying to locat exactly what value of capacitor was in this can. One end connects to the cathode of the 85, other end to chassis ground. Across the leads of the can it reads about 135pfd right now and each lead reads about 45-55pfd to the can itself. So the cap is dead.
Any ideas of what was in a can with the Philco part #7440-X or #7774 on it? I'm gonna guess a .05 or .1ufd.
Pepperoni
http://www.nostalgiaair.org/PagesByModel...014113.pdf
Here's a picture of the can.
[Image: http://speakeasyradios.com/yahoo_site_ad...42_std.jpg]
The Riders paperwork calls this out as part #48 which just says condenser but with a part# of 7774. The part number on the can is 7440-X.
The schematic also shows this capacitor as being part of a biasing circuit for the 1st Audio #37 tube. This is not what was originally in my radio. Just #38, 2.5K resistor was biasing the cathode of the 37 and this #7440-X can was connected to the cathode of the 2nd Detector #85 tube along with a 5K resistor. And a switch that appears to be some kind of "Sensitivity" switch.
So I'm trying to locat exactly what value of capacitor was in this can. One end connects to the cathode of the 85, other end to chassis ground. Across the leads of the can it reads about 135pfd right now and each lead reads about 45-55pfd to the can itself. So the cap is dead.
Any ideas of what was in a can with the Philco part #7440-X or #7774 on it? I'm gonna guess a .05 or .1ufd.
Pepperoni
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