Same here. I have been using old coax for years. I've seen many people
refuse to use old coax and throw it away.
Before I use old coax, I check it with my AA55 antenna, coax analyzer. Next
I use a Megger for any leakage or breakdown. The Megger runs 1000 volts
down the opened coax.
If I have any further doubts, I transmit a KW rf down it with Bird meters
connected at each end and a dummy load at the far end. Only results that i
remember for a 120ft of RG8 type coax is 1kw at source and near 950w into
the dummy load.
I never checked charts to see if this was acceptable, but I was happy and
used it for many years.
Using old tested coax has saved me many $$$.
Ray,
N6VR/W7YA
On Mon, Sep 29, 2025, 3:04 AM Jim Brown <jim@audiosystemsgroup.com> wrote:
> On 9/28/2025 1:19 PM, kq2m@kq2m.com wrote:
> > In the process I have been discovering old coax, some of it in possibly
> > re-useable and some of it ready for the landfill.
>
> About 15 years ago, I helped the widow of a neighbor ham with a fine
> station he'd built himself get rid of his stuff. In doing so, I
> coordinated the extensive help from his friends and other local hams.
>
> There was a lot of coax of varying vintage, some indoors, some outdoors.
> Nearly all of it was pretty good stuff, so I took most of it to an NCCC
> meeting. Everyone turned their noses up at it, so I brought it home and
> made a lot of stubs from it. Virtually all of the stubs measured as good
> (looking at depth of their nulls) as if they had been brand new. The
> sole exceptions were a few that had obvious water intrusion and extreme
> corrosion of the braid.
>
> There is no question that a LOT of perfectly good coax ends up in the
> dumpster out of stupidity and ignorance. If in doubt, open a connector
> and look at it. I strongly suggest that if you find no visual signs of
> corrosion that you consider it good as new, and donate it to another ham
> if you don't need it yourself.
>
> I had the experience of finding water intrusion in some RG11 that was
> feedling my high dipoles. I discovered it when I pulled a cable off my
> grounding panel and water leaked out. The coax was less than a year old,
> and the intrusion occurred due to insufficient moisture sealing of a
> very nice and very sophisticated center insulator that a friend, and
> first rate engineer, had built for us.
>
> I measured the two cables involved with a well-calibrated, high quality
> VNA, and found a fractional dB increase in loss in these cables, which
> were on the order of 160 ft long, in less than a year. There was obvious
> corrosion, but not a lot, and the moisture was still present.
>
> This is, of course, separate from any other issues involved with UV
> exposure to certain vulnerable cable components.
>
> 73, Jim K9YC
>
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