[Elecraft] Strange SWR change on 20 at

[Terry Brown]

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