41-258 B+ Problem

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41-258 B+ Problem

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03-06-2009, 03:23 PM

Hi folks. I have just finished recapping, replacing all resistors, and completely rewiring a Philco 41-258. The set plays well, except for some problems with "motorboating" in the upper part of the AM band. I ran a check on the B+ voltage, coming off of the filter caps, and it's way too hot. I am getting about 106 VDC. I tried turning down the line voltage to about 90 VAC with my variac, and the problem went away. So, I installed a 10K dropping resistor on the line right after the last filter cap. I got the voltage drop I was looking for. But, the set now has all kinds of whistles and motorboating on the entire AM band.

I have noticed that this set's oscillator seems to be very sensitive to even minor changes in the power side of the radio. Is there another location, or strategy, that I can use to drop the B+ voltage? Here is the schematic, over at Nostalgia Air:
http://www.nostalgiaair.org/PagesByModel...013411.pdf

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41-258 B+ Problem - by Guest - 03-06-2009, 03:23 PM

Re: 41-258 B+ Problem - by codefox1 - 03-07-2009, 12:48 PM

Re: 41-258 B+ Problem - by rghines1 - 03-07-2009, 06:04 PM

Re: 41-258 B+ Problem - by Guest - 03-10-2009, 12:09 AM

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