1935 GE Model A-53 AM/SW Tombstone Radio

[Electronic M]

If your crafty you can make a temporary shield out of aluminum foil to use till you can find an appropriate original...

[vortalexfan]

I was able to jury rig a tall octal tube shield by cutting it down so that it was the appropriate height and it still seems to be having issues with motorboating when a signal is applied to it with my signal generator, it basically just hums like mad when a signal is fed through the radio, either through the grid of the 6A8 tube or through the antenna wires, and the hum goes away when you tune away from the signal, and also the hum gets louder or softer depending on how you adjust the gridcaps on the 6K7 and 6J7 tubes, any ideas as to what might be going on here?

[dieseljeep]

Originally Posted by vortalexfan

I was able to jury rig a tall octal tube shield by cutting it down so that it was the appropriate height and it still seems to be having issues with motorboating when a signal is applied to it with my signal generator, it basically just hums like mad when a signal is fed through the radio, either through the grid of the 6A8 tube or through the antenna wires, and the hum goes away when you tune away from the signal, and also the hum gets louder or softer depending on how you adjust the gridcaps on the 6K7 and 6J7 tubes, any ideas as to what might be going on here?

Did you ground the tube shield with as short of a wire as possible?
Also, was any component drastically relocated in the convertor or IF circuit?
The servicing instructions state that the set could be unstable under certain conditions.
Maybe you have to wait until you can obtain a metal 6A8.

[vortalexfan]

Originally Posted by dieseljeep

Did you ground the tube shield with as short of a wire as possible?
Also, was any component drastically relocated in the convertor or IF circuit?
The servicing instructions state that the set could be unstable under certain conditions.
Maybe you have to wait until you can obtain a metal 6A8.

The only "alterations" I made to the IF and converter circuit was replacing the grid cap wire leads for the 6A8 tube and the 6K7 tube because the wire leads for the wire leads were dry rotted and had exposed wire.

Other than that when I replaced old capacitors and resistors I put them back where they were originally in the circuit (I completely unsoldered each capacitor from their respective tie points and soldered the new capacitors back in where the old ones connected originally).

The only components I relocated were the two 8 MFD electrolytic can caps that were bad (the ones on top of the chassis), I disconnected the components from the old capacitor leads, and then took a terminal strip with a blank mounting tab (mounting tab with no terminal attached) and soldered it to the terminal on the old can cap that way the components and the new capacitor was isolated from the old cap but was mounted in a convenient spot.

I reattached the wires/components and the new capacitors to one of the isolated terminals on the newly attached terminal strip and attached the negative lead of the new capacitor to the chassis just like the old ones were, and I made sure that the leads from the new capacitors were as short as possible.

The only other thing I can think of is that maybe when I installed the new wire leads for the grid caps on the 6A8 and 6K7 tubes I might of made the leads too long, but it was kind of hard to know how much lead to use especially on the 6K8 tube's grid cap lead because I had to go from under the IF can to the top of the 6K8 tube which is about 2 inches, and I think I may have cut about 3 inches of wire lead because I wasn't sure how much I needed for sure and I didn't want to cut myself too short.

Could having too long of grid cap wire leads cause the issues I'm having?