[Heathkit] Popping DX-40

[Bill Stewart]

Good morning all, 

I have a DX-40 which constantly puts out a popping noise in the rcvr. Its about 2/sec and varies....once in a great while it will stop. But I can flip back to tune, then to standby and it cranks up again. It does NOT do it in the tune or off  position...all other positions it does. I have run an antenna input wire to a test rcvr and probed around and it seems to be maxing out around the electrolytic area. But this is not a very good test due to coupling to the wiring. When carefully listening under the chassis, by ear, I can hear a slight arcing but can't tell just where its coming from...being careful not to stick my ear on something hot. All tubes are removed except the 5U4GB. Here's what I have tried so far: 



Replaced the 5U4GB 

Sub'ed the lytics 

Re-soldered 5U4GB socket connections 

Disconnected DC load coming off the center of the bleeder/lytic connection and the load coming off the output side of the choke and also the 1Kohm/.005 cap hooked onto the ctr tap lead 



The xmtr does work, as I made a couple contacts with it yesterday. 



None of the above cured the problem. I'm beginning to get that feeling that its the power trans. Anyone had a similar problem and what was the outcome? I vaguely recall something about raising the trans. above the chassis with plastic spacers and screws (internal arcing to the case?)....was this the solution to this problem? Another question...if it is the trans., can anything be done at this point, before a complete failure, to fix the trans....such as heating it up to move the tar around (probably not a good idea). Any suggestions would be helpful. 

Thanks...73 de Bill K4JYS