Re: New KX1 low power and 20m oscillation

Posted by IanMW on May 09, 2012; 4:34pm
URL: http://elecraft.85.s1.nabble.com/New-KX1-low-power-and-20m-oscillation-tp7531133p7543523.html

Stan Gibbs wrote

Don, I tried your experiment but it had no effect. I just grounded point A because it is damn hard to jumper Q7.  R28 measures good and is well soldered.  It has -0.25V or so on the base side and 5.5V on the other during transmit.

I also tried reducing the drive pot and, while the signal definitely declined in amplitude, the sidebands were still present.

Could this just be an artifact of using my K3/P3 to view the waveform?  If so, why would the 40m signal be so different?

Stan,

Just to recap my earlier thoughts, I think your Q7 is fine, the negative voltage is a red herring. It's due to the RF that is being grounded via Q7 (its task).

Do you know any other hams who might tell what their Q7 DC voltage is, from functioning rigs? I gave you mine and they match yours within a reasonable tolerance.

I will see if I can get to a ham with a scope and report to you when I can, maybe this weekend.

In the mean time, I'd get up a hill!

73,
Ian MM0GYX