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Philco 46-1203, radio doesn't work.
#16

Neal:

You'll find a resistance & voltage chart for the 46-1203 at nostalgiair and http://www.oldtech.net/philco . I got my 1203 running fine and shipped it to a friend who bought it for her mother and had it shipped to me for restoration. I had replaced this 1203's capacitors also, but did it one at time, checking after each part replacement to see if the radio still worked.

Kevin
#17

Howdy all:
Just finished with my bro-in-law's brother's 46-1203. Replaced a few tubes, and did minor clean up (remove mud-dawber nests). Audio was fine from phono side, but radio inop. Grid-dipper showed dip from RF tuning LC. Started checking caps, and came to one measuring about 200k. Now, here's the kicker - this cap doesn't show on the Rider schematic, and was a .05 paper connected between 7A8 and 7C7 filaments. End result? Both tubes would get warm, but neither got enough voltage to reach operating temp, therefore no IF osc and no RF amp. Removing the cap solved the issue. Now, I can tell the cap was factory installed, and understand that changes happen mid-course, but what is the purpose of a .05 shunting two adjacent filaments? RF bypass? Needles to say, some secrets of the ac/dc age are still a secret to me.

Until next time,
Stirling KC0NXM.
#18

It attenuates any RF coupling that can occur between the heater filaments and cathodes. This is commonly used on FM and TV filaments strings where the frequencies are two magnitudes higher.

Richard




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