[NLRS] [BC'ers] How to troubleshoot a flaky feedline?

[Greg K0PJ]

Dave,

I do not believe I've seen this yet in a reply. Do you have any Barrel Connectors, Adapter fittings (N to PL259) etc? I have seen and odd 5:1 jumps once or twice when a N Barrel failed or when a drop of water is in a barrel connector. I had intermittent SWR issues on my 80 meter Array and found the barrel connectors at the vertical feedpoints were bad (no water, intermittent contacts. 

Also, check to see if your coax as pulling away from your connectors.  Over time, the outside insulator pull loose out of a PL-259 shell and causes intermittent or failed braid connection.

Finally, and increase in the base noise level to me usually means failed connector. The past few years I needed to replace old 1/2 hardline chucks due to small cracks in the outer copper shell (~braid side of the cable).

73,
Greg
K0PJ/9

-----Original Message-----
>From: David Palm <thepalmhq at gmail.com>
>Sent: Sep 12, 2019 12:29 PM
>To: NLRS List <nlrs at mailman.qth.net>, Badger Contesters List <badgercontesters at mailman.qth.net>
>Subject: [BC'ers] How to troubleshoot a flaky feedline?
>
>I'm reworking my antenna stack in preparation for this weekend's contest.
>I was able to replace my broken homebrew 222 quagi with the K1FO-style yagi
>I got from the W0GGM estate via W0ZQ and then WA2VOI (thanks men! and W0GGM
>RIP.)  I'm not yet able to rotate the stack right now, but it's pointing
>basically southeast.  Imagine my utter surprise when I turned on my
>transverter just to check the antenna's SWR and I heard some modulation
>near 222.100 -- tuning up a bit brought in N4PZ calling another station.
>How often does that happen?
>
>I have also put up a long conventional yagi on 1296 and a long loop yagi on
>902 from the K0FQA estate (again, thanks WA2VOI! And K0FQA RIP.)  Those
>aren't fully connected into the shack, but I'm a lot closer to having a
>footprint on those bands.
>
>Now, to the meat of this email.  My 144 MHz yagi has been showing highish
>(is that a word?) SWR for a while now.  After the antenna shuffle I'm
>seeing about 5:1, which causes the transceiver to fold back.  I've checked
>and the antenna itself and the rotor loop are fine.  It's the feedline from
>the shack to the rotor loop that's the problem.  Terminated with a 50 ohm
>load, I'm seeing that same 5:1 on this feedline using my MFJ-259.  Wiggled
>the connectors and didn't see signs of intermittent connections.  I did
>some preliminary googling on how to identify where this fault may be and
>came up empty.
>
>Any advice on how to troubleshoot and repair this?  Obviously I can pull
>and replace the connectors on each end, but since I'm not seeing obvious
>intermittence there, that seems like a crapshoot.  Obviously I can just
>replace the entire feedline, but I hate to scrap an entire length of
>LMR-400 if some can be salvaged.  Ideas?
>
>73,
>
>David  W9HQ
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