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Philco 37-630, Low volume, 1st IF problems??
#5

Thanks for the comments and the purpose of the black wires on the 1st IF.  I replaced all the insulation on this wire.  There was no short between it and the secondary coil.

I isolated the secondary coil.  Resistance is 15 ohms.  Circuit diagram indicates 11 ohms.  No change after connecting to the trimmer.  Primary measures 13 ohms and circuit diagram indicates 7 ohms.  The trimmer and mica piece looked good.

R44 was replaced with a 1 meg resistor.  I verified that I replaced it with the correct resistor.

Capacitors 67 were replaced and they are grounded.  Still get more volume with a ground.  

I went through another complete IF and RF  alignment of the short wave and BC bands following the Riders proceedure. The link on the aerial/ground terminal was between the black and ground screws.   With the exception of the secondary of the 1st IF I was able to peak all the trimmers.  I screwed the trimmer on the 1st IF secondary trimmer all the way down and then backed it off until it peaked.  Further backing of the screw produced no change.  I would say volume on the BC band is slightly better but not the best. Still have to have volume control turned most to all the way up.   Volume at the lower end of the dial was very low until I detuned the 600 trimmer slightly from the setting that was made during the alignment process.

I get no reception on the other two bands. 

I also have a post on this radio over at the antique radio site.  See http://www.antiqueradios.com/forums/view...6&t=320133
One comment asked about the effect of touching the grid caps of the RF  6A8 and 6K7 tubes.  Touching the 6A8 silenced the radio and touching the 6K7 reduced the volume.

Bob


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RE: Philco 37-630, Low volume, 1st IF problems?? - by rck46 - 04-24-2017, 08:28 PM



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