The AM Forum

All,
  So I am getting ready for the Heavy Metal Rally and though that this year we would be tubes from the VFO all the way out. Disconnected the rice box used for driver on the big rig and hooked up a Heathkit Cheynne. Drives the 4-400 just fine to full output when tuned for AM. Should work great except for one little problem.... I can't hear the Cheynne in the receiver when in "spot" mode in order to zero beat another signal. There just isn't enough juice in the spot mode to be heard.
  The reciver is a R-390A and the Cheyenne and it are about 4 feet apart with the 4-400 cabinet between them.
  Has anyone else had such a problem and how did you solve it?

Thanks,
           Bill KA8WTK

I key my driver stage without the final B+. That's the only way I hear the DX-100. Same problem.
Keith
WA1HZK

Yep, that is what I do with my DX-100/SX-43 station. You can really hear DX-100. You can hear the Cheyenne in the Comanche receiver next it. It seems the R-390A is just too far away.

Ahhh...Solution found!
Like the DX-100, the "spot" function keys up through the driver stage. The driver is 5763 that is covered by a tube shield. I pushed a piece of insulated wire (cloth covered, not plastic) down into the shield next to the tube. The wire runs out of a convenient ventillation hole in the top of the case. I draped the wire over the transmitter to where the R-390A is located. Eureka! There is enough RF for the receiver to hear the driver when the spot switch is on. There seems to be no effect on the driver or final stage tuning. It ain't all that pretty, but it works. I'll try and hide the wire next week.

Hope this information helps someone else!

Merry Christmas, a Happy New Year and a Very Heavy Metal Rally!