[Collins] Screeching KWS-1 Fixed!

[Dr. Gerald N. Johnson]

On Fri, 2006-05-12 at 10:50 -0400, Roger Shultz wrote:
> Thanks to all who offered suggestions about what might be causing the intense "screeching" coming from the PA cage in my new-to-me KWS-1.
> 
> It seems the problem is directly related to the 6CL6 driver grid to cathode neutralization described in section 5.3.2.6d. While I am pretty sure I tried that procedure according to the book, I also recall that it was vague as to if it worked as described and I'm also now pretty sure I was adjusting the wrong cap when doing it. Mind you this "screech" existed before I got it so I suspected more complicated things. 
> 
> The correct cap to adjust is referred to as C-715 in the procedure but labeled FB NEUT on the chassis yet never referred to as that in the procedure. What "FB" means is a mystery to me at this point.
> 
FB means FeedBack as in RF FeedBack.

> At any rate, once I just touched the cap the "screech" immediately stopped and it looks like I can move forward and complete the work to get this great transmitter going once again. I will do a complete adjustment this time and I'll bet I 'll see the results as described.
> 

Likely that variable capacitor is open and needs a quarter drop of
DeoxIT on its underside and some wiggling to get contact again.

> 73, Roger, NJ2R

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer