It's most likely the jacket. I've had some old cheap coax that did the same
thing. RG-213 with the non contaminating jacket was to keep the shield from
decaying. As well as the center dielectric.
73
Jim W7RY
--------------------------------------------------
From: "Al Kozakiewicz" <akozak@hourglass.com>
Sent: Monday, June 13, 2011 5:46 PM
To: "'K0DAN'" <k0dan@comcast.net>
Cc: <towertalk@contesting.com>
Subject: Re: [TowerTalk] BLACKENED BRAID?
> Maybe it's the soil ph or something...
>
> I've taken to using black PVC water pipe. It's cheap and is almost as
> easily buried as coax. I jump on a flat bladed shovel to sink it full
> depth; yank the shovel back to expose a crevass; shove the PVC pie in
> place and drive the 4x4 over the top to relevel the grass. In a few
> months the damage has disappeared.
>
> That way replacing the coax is easy if it's ever needed.
>
> Al
> AB2ZY
>
> -----Original Message-----
> From: K0DAN [mailto:k0dan@comcast.net]
> Sent: Monday, June 13, 2011 8:38 PM
> To: Al Kozakiewicz
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] BLACKENED BRAID?
>
> Hmmm...interesting. We too have the invisible dog fence, and I have
> something like 100' of 14 or 16 gauge insulated household wiring as the
> buried loop. Have not had any occasions to dig it up or splice, but what
> you describe is what I see on the shield of my sliced RG213/U.
> Interestingly, the center strand (twisted) is OK but the shield is gnarly.
>
> As suggested by others I'm gonna pull it back til I find clean copper, but
> I have a feeling the whole run is gonna have to be replaced.
>
> So much for "Mil Spec" and "direct burial". Caveat Emptor.
>
> 73
>
> Dan
> K0DAN
>
>
> ----- Original Message -----
> From: "Al Kozakiewicz" <akozak@hourglass.com>
> To: "'K0DAN'" <k0dan@comcast.net>; "K8RI on TT" <k8ri-on-towertalk@tm.net>
> Cc: <towertalk@contesting.com>
> Sent: Monday, June 13, 2011 7:27 PM
> Subject: RE: [TowerTalk] BLACKENED BRAID?
>
>
> FWIW, we've always had one of those invisible dog fences. The antenna
> system for those is basically a loop of insulated #14 AWG wire shoved into
> a
> slit in the lawn cut with an edger.
>
> Early in their lifecycle they are prone to damage from the lawn mower when
> frost heaves or whatever expose a section. That wire is always black
> under
> the insulation after only a year of burial and is a bitch to get clean
> enough to solder.
>
> Al
> AB2ZY
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of K0DAN
> Sent: Monday, June 13, 2011 8:01 PM
> To: K8RI on TT
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] BLACKENED BRAID?
>
> Thanks...will see what we have. I have a vision of peeling the braid all
> the
> way back to the hamshack! Could be this "direct burial" stuff really
> wasn't,
> and the jacket allowed moisture to get into the shield.
>
> 73
> k0dan
>
> ----- Original Message -----
> From: "K8RI on TT" <k8ri-on-towertalk@tm.net>
> To: <towertalk@contesting.com>
> Sent: Monday, June 13, 2011 11:56 AM
> Subject: Re: [TowerTalk] BLACKENED BRAID?
>
>
>> On 6/13/2011 12:39 PM, K0DAN wrote:
>>> Seems I saw a post here within the last year that diagnosed the cause of
>>> blackened copper shield?
>>>
>>> My case: I have a buried run of Cable Experts RG213/U Mil Spec,
>>> supposedly
>>> good for direct burial. It recently got nailed by the lawnmower (thanks
>>> to
>>> the XYL!), but there's enough stub left above ground to repair and add a
>>> connector, salvaging the buried run.
>>>
>>> I looked at a few of the chopped up pieces and the copper braid is
>>> BLACK.
>>> The center conductor looks normal, slightly dull copper color but in
>>> good
>>> shape, easily cleaned with steel wool for solder/connector.
>>>
>>> I would expect to see some kind of green or brown corrosion, but black?
>>> Is
>>> this maybe silver plate braid and I'm seeing silver oxidation? Web site
>>> says
>>> it's copper, not silver.
>>
>> IIRC Copper Oxide is black. Sulfide (fertilizers and atmospheric crap
>> are *usually*green). Water varies depending on what's in it.
>>
>> Cut the jacket back until the braid is clean and shiny copper. Oxide is
>> a bear to try and solder. Don't let water get in there. If you can't
>> fix it right away, seal it thoroughly.
>>
>> 73
>>
>> Roger (K8RI)
>>> The cable otherwise looks in decent shape, and I do not believe it
>>> burned
>>> due to high SWR or lightning.
>>>
>>> I don't really want to replace the whole run but don't know the cause or
>>> extent of the blackened braid. I have doubts I can clean it up and make
>>> decent electrical connections but am willing to try.
>>>
>>> RF loss is not an issue, any antennas on this line will be below 7 Mhz.
>>>
>>> Ideas?
>>>
>>> Tnx es 73
>>>
>>> Dan
>>> K0DAN
>>>
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1382 / Virus Database: 1513/3699 - Release Date: 06/12/11
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|