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

[David Palm]

Jeff,

I just checked it and a DC continuity test shows 50 ohms.  So that would
indicate compromised coax, I presume?  Surprising, since the waterproofing
seemed really tight when I pulled it off, but of course looks could be
deceiving.  If this is the cause, is it enough just to cut this back a
couple of feet or so on the tower side and put on a new connector?

Thanks and 73,

David  W9HQ


On Thu, Sep 12, 2019 at 12:39 PM Jeff Berman <k9yr at yahoo.com> wrote:

> Hi David,
>
> When terminated with the 50 ohm load did you put an ohmmeter on the coax
> and measure the resistance?
>
> This will give you an indication of an open or short, otherwise you might
> have water in the coax
>
> 73 Jeff K9YR
>
>
> Sent from Yahoo Mail for iPad <https://overview.mail.yahoo.com/?.src=iOS>
>
> On Thursday, September 12, 2019, 12:29, David Palm <thepalmhq at gmail.com>
> wrote:
>
> 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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