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2-B AGC voltage ¡ª possibly resolved


 

I checked into the Sunday net today and Jeff, WA8SAJ, suggested that I check?the RF GAIN pot. This is a 15M (!) pot and is not very easy to find, these days.?

I measured the pot across the entire part, since there¡¯s one end that isn¡¯t connected to anything.?

The pot measured 26M ohms.?

My parts receiver¡¯s pot measures 20M, as does my good 2-B. These parts obviously appear to age by getting more and more resistive.?

I should be able to get this 2-B to meet spec with the pot at 20M. With these resistances so very high, one can¡¯t really set the resistance to 15M ohms directly but we can set it indirectly by measuring the total resistance and subtracting 15M from it, then setting the resistance from the wiper to the open end to the value of the difference. One can then set up the sensitivity with the pot at 15M, which is what the value should be with the RF GAIN fully CW.?

It not the best way but it¡¯s a workaround for this nearly Unobtanium part as it ages.?

Thanks again, Jeff!

73,

Steve Wedge, W1ES/4

Time flies like an arrow. Fruit flies like a banana.


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