Subject: [Elecraft] Shutdown on 50MHz CW

[Ron Meiring]

Hi Ian,

Did some testing here.
No sign of RF into PA temp sensor on 50Mhz.
It didn't manage to get the PA running at 60 degrees at all, even 
after 10 min Key down. Probably because the room temp is 18 degrees 
now.

K3 #479, 100W, with the standard antenna board.(one antenna only).

Perhaps you have got a wrong decoupling capacitor some where in your 
circuit for the PA.

The only mods I did to my K3 are:
Shorten the antenna lead from PL-connector to antenna board by 0,5 
inch. My original lead was about 1.5 inch long. (this lead was quite 
long, and had the idea a shorter lead would be more appropriate for 
RF).

I sticked some adhesive plastic tape where the PCB touches the 
circuit board. In particular where tracks are crossing the PA shield 
between the shield and the main board. (vibrations could move the PA 
shield and "scratch" the thin Isolation layer, eventually this could 
shorten a track....). I used a hand file to create a clearance 
between the main board and some tracks. This was only needed on two 
places. A minimal gap of 1/16 inch or 1mm or so is more than enough, 
only where these wires are crossing the shield.
(this mod prevent problems in the future, shorting out the main 
board).

I have added an SMA relay on the antenna board, which improves 
Isolation when in transverter mode. 
(I used to hear a few locals on 20m on the IF when I was in 
transverter mode on 2m.)

Surely this mods have no effect on the temp sensing of PA on 50Mhz.
But are listed here just to make this picture complete.

Regards,
Ron VK4KDD