08-18-2013, 01:40 PM
Looks like I got it working. Tube combinations did no good as did reworking the grounds by trying to clean and solder them. Noticed that there was microphonic sound through the speaker just after the radio was turned on if I tapped the chassis and especially around the # 22 compensator.
I removed the little metal tail that was rivoted to the chassis that served as the ground connection for 400 ohm/.05MFD cap of the 78 tube. I installed a small 2 terminal strip and bolted that to the mounting screw for the 2nd IF can, making sure that all the metal surfaces were clean.
Didn't change a thing. Then I noticed that if I played around with the tube shield for the 6A7 that I got intermittent static. OK, try cleaning the inside of the shield connection on the socket as well as the outside on the shield. Also reshape the sides of the socket to tighten up the shield connection. BINGO, now I can pickup stations all across the AM band with no squeals/motorboating and there is no motorboating on the SW band.
I removed the little metal tail that was rivoted to the chassis that served as the ground connection for 400 ohm/.05MFD cap of the 78 tube. I installed a small 2 terminal strip and bolted that to the mounting screw for the 2nd IF can, making sure that all the metal surfaces were clean.
Didn't change a thing. Then I noticed that if I played around with the tube shield for the 6A7 that I got intermittent static. OK, try cleaning the inside of the shield connection on the socket as well as the outside on the shield. Also reshape the sides of the socket to tighten up the shield connection. BINGO, now I can pickup stations all across the AM band with no squeals/motorboating and there is no motorboating on the SW band.
