Atwater Kent Model 30 Low Volume

[Winky Dink]

I just finished the cosmetics and electronics on an Atwater Kent 30 (6-tube TRF, DC) chassis. I rebuilt the paper caps, replaced the grid leak resistor and one open resistor. Remaining components were close to the original values. After doing some alignment of the tuning condensers, the set had pretty good sensitivity but the volume was low and the quality of audio was poor. The best sound I could get was like this (30-second video):

https://picasaweb.google.com/lh/phot...eat=directlink

(If the video doesn't play, just forget it)

Following advice for restoration of the AK Model 40, I doubled the grid leak resistance and lowered the grid resistors by 100 ohms (500 down to 400). Will wonders never cease?...it worked! Great improvement in audio quality.

But, of course this leads to several puzzlements. First, on the zero-to-100 tuning dial, the frequencies are received in reverse of the convention order.



Is this by design, or did someone make a mistake in assembling the center condenser? Looking at the picture below, I think that if the stopping arm on the condenser is repositioned 180 degrees, then the set could be realigned for reception in the conventional order. I wasn't able to loosen that nut easily, so I'll probably leave it as is.




The audio volume is still quite low. Sitting close to the speaker with maximum volume, only the strongest stations sound too loud. I've tried juggling RF and AF tubes; replacing the detector; and operating with both 90v and 135v plate voltage for the last AF tube, but that hasn't helped. Should I expect more volume?



Finally, I don't know what the detector rheostat is supposed to do. It's not even addressed in the instruction book! The RF rheostat control regulates the RF and detector filament voltagess from 2v to 5.6v. The detector rheostat does the same thing.