[Elecraft] K2: Flaky 160M switching

[Don Wilhelm]

Jim,

Loosen the nut on the BNC connector or remove it entirely.  Since the 
BNC jack is soldered to the board, the nut is only there for "pretty" 
All will work fine without the nut.  The nut in any case should only be 
a bit more than finger tight.  "Beefing" the nut up tight can damage the 
BNC connector (same for the key jack).

Yes, tightening the nut up tight is likely bending the RF Board.

Check for the possibility that the rear panel is bent a bit in the 
vicinity of the hole for the BNC jack.

As for the high current on 80 meters after moving from a non-functioning 
160 meters, that is not unusual.  The Drive to the RF Chain is maxed out 
on 160 and when you move to 80, it will not be reset with a TUNE - 
normal keying or speech will quickly correct it, but not TUNE until you 
exit and re-enter TUNE.

73,
Don W3FPR

On 3/2/2019 2:30 PM, Jim KO5V wrote:
> After removing and replacing the heatsink panel to install an SMA connector for an IF-out port,
> 160M is working intermittently. I think I have narrowed it down to a problem with the antenna's
> BNC connector - It appears to be just slightly spaced away from the inside of the back panel,
> so when its nut is tightened up, it must be flexing the RF board enough to affect K8. I've loosened
> up the 2d connectors, to try and bring the connector/RF board into better alignment with the heatsink
> panel, but every time I tighten up the BNC's nut, 160 eventually dies (I listen to the birdie at 2Mhz).
> 
> When I switch from a working 160M to 80M and then "tune", 80M gives a "hi-Current" error, and I
> measure >20W on my external meter. A second "tune", and 80M is back to normal. Switching back to 160M,
> I find the birdie gone (and no power out). Switching to 160M from a higher-frequency band usually finds 160M
> working (but not always).
> 
> I have touched up the solder joints on all components involved with K8 and the BNC on the RF board, and all
> of the joints on the 160M board.
> 
> So, I am going to place a shim between the BNC connector, and the heatsink panel and see what happens. Does
> anyone have any other suggestions? I'm not sure K8 is bad, but maybe the BNC might be?