It would be one thing if the old coax were just lying on the ground feeding
a ground mounted vertical, but quite another when it feeds a 20 meter Yagi
at 100 feet. I think we can probably agree that new coax of the same brand
and type will probably be serviceable for longer than old coax which has
been exposed to the elements for years. My preference is to use it for
other purposes.
Chuck W5PR
On Wed, Oct 1, 2025 at 5:40 PM Raymond Benny <rayn6vr@gmail.com> wrote:
> 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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