[Elecraft] Strange SWR change on 20 at

[Clay Autery]

I have ALMOST the same setup....  horiz loop at approx. 40 ft cut for
80m, fed with 45 feet or so of 300 Ohm (18 GA) foam core, twin-lead to a
Balun Designs 6:1, to TMW 240-DB coax (18-20 feet) to the K3s.

Never experienced anything like what you are.... sounds like something
is heating up...  balun maybe?...  almost like something heating up and
opening...

______________________
Clay Autery, KY5G

On 5/13/2017 11:07 AM, Terry Brown wrote:
> I recently started using my horizontal loop that is about a full wavelength
> on 80, for 20 meters.  I took down my yagi as we are moving; drat!  My
> Horizontal Loop is at 40 ft.  height and fed with 450 window line into a 4:1
> voltage balun with about 15 ft. of coax to rig.  
>
>  
>
> I am running 100 watts through my KXPA100.  I tune a frequency in the CW
> portion of 20 to about 1.2 :1 and start sending CQ.  After about 3 to 4  3x3
> CQ's,, the SWR goes off the charts and power drops to zero.   I can retune
> the antenna and the process repeats itself.  20 meters is the only band
> affected.
>
>  
>
> I am wondering if I am having RF problems in that part of the 20 meter bands
> This only occurs on 20 meters.  The Amp is grounded, but the KX3 is not
> bonded to the Amp.
>
>  
>
> I would appreciate any advice.
>
>  
>
> Thanks and 73's,
>
>  
>
> Terry de N7TB