[Moon-net] Damp cable help...

[G1OGY (Dave)]

>> ----- Original Message -----
>> From: "Jordan" <outposter30 at shaw.ca>
>> To: <microwave at lists.valinet.com>; <moon-net at list-serv.davidv.net>
>> Sent: Saturday, July 26, 2008 1:50 PM
>> Subject: Damp cable help...
>> 
>> 
>>> I have a single section of LDF4.5-50 which appears to have gotten
>>> moisture into the connector at the top of the cable run.
>>> We have had quite a few severe hailstorms here, and the sealcap was
>>> cracked and allowed the moisture in.
>>> 
>>> I've tried to remove the connector up there, with no success
>>> whatsoever.... 
>>> 
>>> Should I seal the top end with some dessicant packs and let the
>>> moisture be absorbed, connect the cable to my 12 battery charger ,
>>> or bring the cable down and try tools on the ground.
>>> The connectors were professionally installed by an Oilfield tower
>>> and supply Co., and I haven't found any online docs with a blow-up
>>> of the connectors.... 
>>> 
>>> This line is for my 1296 system, but for now I'll switch the
>>> antennas to the 432 cable and continue testing..... 73...VE6ZT
>>> Jordan....... 
>>> 
>>> 

>> -----Original Message-----
>> From: moon-net-bounces at list-serv.davidv.net
>> [mailto:moon-net-bounces at list-serv.davidv.net] On Behalf Of Jordan
>> Sent: 27 July 2008 03:47 To: microwave at lists.valinet.com;
>> moon-net at list-serv.davidv.net Subject: Re: [Moon-net] Damp cable
>> help... 
>> 
>> Well, after a nice BBQ'd steak and potatoes, I decided to bring the
>> cable end down  and get the connector apart , and it worked....
>> Problem is, no moisture whatsoever, but I did learn that the
>> connectors for the LDF4.5-50 cable uses a press fit captive center
>> conductor. Seeing as the only other connector left to check in the
>> entire system is the 
>> 
>> shack end of the 4.5-50 cable.
>> When I opened the connector at the shack end, sure enough there was
>> maybe 5ml of water inside... Now to clean things up and get the
>> cable back together before it's too dark to see out there...
>> 73...Jordan.....
>> 
>> 
"John Lemay" <john at carltonhouse.eclipse.co.uk> wrote:
>> Hi Jordan
>> 
>> I wonder if you have asked yourself how water got into the shack end
>> of your cable ? I'd be worried !
>> 
>> The nature of the dielectric in Andrews Heliax seems to allow water
>> to travel a limited amount, so it might be wise to cut off 100mm of
>> cable and re-terminate it. 
>> 
>> For the record, plugs for LDF4-50 have a solder connection for the
>> inner pin, LDF5-50 has a push-fit or screw-on (can't remember which).
>> 
>> Regards
>> 
>> John G4ZTR
>> 
> Message: 9
> Date: Sun, 27 Jul 2008 08:15:04 -0600
> From: "Jordan" <outposter30 at shaw.ca>
> Subject: Re: [Moon-net] Damp cable help...
> To: "John Lemay" <john at carltonhouse.eclipse.co.uk>,
> 	<microwave at lists.valinet.com>, <moon-net at list-serv.davidv.net>
> Message-ID: <851903FD0BFC402686A20978C44DB119 at NIS942960248>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original 
> 
> Hi John...Yes, the center conductor is a pressure fit contact ... It
> seems that the best solution is to remove a few inches of each end
> ,check for corrosion replug and re-test...
> 
> The run is actually about 80 feet horizontal, and then another 20
> feet up onto the roof.....73...Jordan....
> 



Hmmm....

Sounds like water migrating under the jacket of the cable (John:
Remember 'FUF's solution? Connectors could well be more modern than
ours, BTW)

Jordan: if you are sure that the cable is LDF4-50 (with a foam
dielectric) and not [F]HJ4-50 (semi airspaced) AND that there is little
evidence of water ingress at the top of the cable then it is likely that
the water (condensation, possibly) has succumbed to gravity's rule and
migrated south.  There is "no way" that water can travel on the inside
of a good and sound piece of LDF4-50: so the likelihood is that the
water has travelled between the black plastic outer sheath and the solid
copper screen.

The way to prevent this from entering your equipment is to cut a
quarter-inch long piece of the outer sheath away from the cable on the
inside-shack final run.  The water (wherever it gained access) will then
run out onto the floor over time.  Catch it in a jar if you don't want
to spoil the carpet!

'enjoy
-'OGY 

Dave Gilligan, G1OGY
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United Kingdom.  JO01GR
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