SWR up’s and down’s

LP-100 reading
I was on the air the other day using the MFJ loop and as I was trying to tune to the lowest SWR reading I noticed an odd thing happening! Available to me at the station are 3 separate points to view the SWR. I have the SWR reading on the K3, the LP-100 and the MFJ remote control for the loop antenna. While tuning the loop antenna I was able to get an SWR of 1.5.1 on 20m with the K3's meter this is a very decent reading. I had the same reading on the MFJ remote unit but the LP-100 was showing 2.08 SWR??? The way the meters read the SWR are as follows.....the K3 right at the radio, then the LP-100 and then the MFJ remote unit. Oh and in case you are wondering if I am SWR meter crazy, I have the LP-100 in the game plan as it also reads very accurate output power and when operating QRPp it comes in very handy. . as for the MFJ remote that just comes with the antenna package and is really used to adjust the antenna and I really don't rely on it's SWR meter. I have heard and read in the past that the remote MFJ meter should not be relied on to much. ANYWAY.............I am getting this odd reading on the LP-100 and it is on all bands that I get a differing reading from the other SWR meters. First thing that came to mind was faulty coax or faulty
K3 meter
LP-100. I bypassed the LP-100 ( I removed the LP-100 and attached the two PL-259 using a SO-259 coupling) using all the same coax that fed the LP-100 and there was no problem. I then setup the LP-100 on it's own, meaning out the K3 through the LP-100 into a dummy load and there was a perfect match. Then I simply removed the SO-259 coupling and added the LP-100 again....there was the funny SWR again. Not sure what is going on here. In my trouble shooting I tried the LP-100 on it's own into a dummy load and it worked fine. I then used all the same coax cables and bypassing the LP- 100 and all was fine. Therefore LP-100 is fine and cables are good??? Not sure what is going on here.

Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

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