I think the 12 V would only be relevant when there is a dissimilar metals
problem. In other words copper against aluminum.
Chuck W5PR
Sent from my iPad
> On Nov 7, 2016, at 4:16 AM, Franki ON5ZO <on5zo@telenet.be> wrote:
>
> A lot of useful replies about the black inner conductor and the green mush
> inside the connector. Many of which sent directly to me.
>
> Some people think that it water ingress even though I'm pretty sure it isn't.
> But if you ask advice, you must be open to views that don't match yours. So I
> looked for evidence.
>
> I took a one meter stretch that I cut off before soldering a new plug a while
> ago. It's only the inner conductor that got black. The braid (shield) is
> pristine: gold-yellow, not a sign of contamination. Even the inside of the
> braid that touches the dielectric.
> This end of the cable was never exposed to the elements. It sat in an outdoor
> cabinet. Although the inner conductor turned back, there was no green on the
> N-plug's pin.
>
> I only found the green 'powder' (like you sometimes find on battery
> terminals) on the other side of the cable, where it mated an N-style jumper
> that goes to the RX loop's feedpoint. I inspected both connectors (male and
> female). The green was only around both center pins, where they mated. There
> is no sign of green on the shield side of the plugs. I also can't find any
> sign of real water sipping through. Moisture can be the case though. With
> lots of oxygen because there is plenty of air space inside an N-plug,
> especially the female type.
>
> I unwrapped the sealing tape one of the jumper's N-plugs. No sign of water in
> any form. I took apart the plug (nut and grommet type). The plug is only
> green inside the shell, where it is exposed to air. By this I mean the air in
> the void between pin and shell inside the N-connectors when M+F get screwed
> together. The lower part of the pin (part that slides over the coax inner
> conductor and is soldered), where the white 'dielectric extension' spacer cap
> slides over the pin, was not green. This part of the pin is covered by this
> spacer and is not exposed to air.
>
> The sleeve says 'RG 213 / UBX' made in Germany'. I can't find a manufacturer.
> I bought this 50m run at a hamfest. I seem to remember it was pretty cheap. I
> bought it with 'RX only' in mind so I didn't actually think of losses and
> power handling.
>
> FWIW a sweep with the dummy from 1.5 MHz to 50 MHz shows a flat SWR graph.
>
> The main question however, remains unanswered: is there a link with the fact
> that this coax carried +12V DC, or not?
>
> 73
> Franki ON5ZO
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