[Elecraft] SWR issue with K3

[Mike Weir]

While on 20m I tuned the MFJ 1788 to the lowest SWR which was 1.2:1. I did this using the tune button on the K3. I noticed the SWR on the K3 was bouncing around from 1.2, 1.3, 1.7, 1.4 and so on and never settling on just one reading. This only happens on 20m and no other band that I tuned on. Here is some of the trouble shooting I did.

  1.  I have a KX3 and hooked it up to the MFJ 1788 loop antenna and read the SWR. It showed 1.2:1 and no "bouncing" issues. I did remove the PL259 from the K3 ANT1 port and connected it to the KX3 so the test would include all that was in line with the K3. In line meaning coax, antenna switch and MFJ tuner box.

  2.  I opened up the K3 and tightened all screws ( boards, case, SO-239 and any checked out the seating of coax jumpers in the rig for a secure fit.

  3.  I tried the K3 on a dummy load and all was good.

I am at a loss as to what is going on and am looking for some input? I check the rig again today on 20m and it's still having SWR bouncing issues. I have never had this in the past and am looking for feed back on things to check?


Setup information

Radio K3 with antenna tuner (not being used rig is on bypass)

Antenna MFJ 1788 mag loop

Power 5 watts QRP

Coax RG 8X 30 ft

Thanks in advance

Mike VE3WDM