[Elecraft] KE8UW Re: Just finished K2 and finals look to be oscillating at 450KHz...

[Don Wilhelm]

Chuck,

Since you have a 'scope, I would suggest you remove the PA transistors 
from the picture and see if the oscillation persists.  You can easily 
de-solder T3 which will remove voltage from the PA collectors.
If you still have the oscillation at the base of Q7/8 (or at the 
collector) of Q6, then you can more easily troubleshoot it without fear 
of damaging the PA transistors.
Q6 can similarly be taken out of the operating condition by removing a 
choke or resistor.  I don't have the schematics with me while on 
vacation, so you will have to find out which one on your own.

73,
Don W3FPR

C. J. Hawley wrote:
> Yes the W6 point gets 8 volts either thru the diode D2 or D6 depending on whether in receive or xmit. I think I have an oscillator at Q5-Q6. I am checking all the feedback chokes and capacitors. I may need to unsolder C118 and see if it is infact a capacitor inside the shell and maybe also C120. RFC6 checks ok, R49, R470, etc. 
> Thanks for the interest and help. 
>
> Chuck, KE9UW 
>   
>