[TowerTalk] CAT 5 as Rotator cable

[Georgens, Tom]

No advice just a story.

I used Cat 4, non plenum rated cable once to control and 8X2 relay box out
on the tower.  All it was was two banks of 8 switches in the shack selecting
any of eight antennas to either of two feedlines.  Each bank of switches had
and its own eight conductor cable out to the relay box where they combined
at a DB25 connector.

Late in a contest (SS I think), I noticed my SWR higher than usual.  I was
fiddling with the switches and came to the conclusion that I was connecting
more than one antenna even though only one switch was thrown.  It was a
typical contest and debug at the same time type of operation.  I assumed I
had some type of short or stuck relay and just kept operating.  I later
observed that choosing antennas for the second radio was impacting the SWR
on the first.  This was odd since they used two separate cables and two sets
of relays.  Combine that with the fatigue of contesting and it was too much
for my mind to handle.  I just figured there was a short in the DB25 where
the cables came together.

To skip to the end, the problem was that rodents had entered the conduit out
to the tower and chewed off the outer and individual wire insulation of both
cables for about 2 feet.  Instead of 16 number 26 solid wires, I had one,
roughly number 10, stranded wire.  I was very lucky I did not blow up the
radios.

That said, they did not touch the rotor cables or coax in the same conduit.

The coyote urine may be a good idea after all (ick)

73, Tom W2SC

-----Original Message-----
From: Pete Smith [mailto:n4zr at contesting.com]
Sent: Wednesday, June 23, 2004 9:55 AM
To: keith at dutson.net
Cc: towertalk at contesting.com
Subject: RE: [TowerTalk] CAT 5 as Rotator cable


At 10:14 AM 6/23/2004, you wrote:
>This thread is getting quite long in the tooth.  However, it caused me to
>wake up and realize I will be making a mistake to put up cat5 for the relay
>boxes on the 40 meter beams.  Had not thought about the weather issue
>relating to cable jacket.  So, I am now looking for an alternative cable.
>Any recommendations?  The relays draw only 40 ma or so, and the run will be
>about 200 feet.
>
>For my application cat5 is too small for the rotators.  On the 150 foot
>tower there is a Yaesu 1000DXA at the top and three TIC 1022's below.  I
>have Wireman rotor cable for all.  I wanted the recommended 6-18ga for the
>Yaesu, but that is on back order, so I just bought the next higher cable:
>6-18ga + 2-16ga.  The two 16's and four of the 18's are used for the TIC's.
>The Yaesu uses the six 18's.


I'm not confident about the jacket deterioration issue.  I have only had 
one run of CAT-3 in place, and that for only a year, but the predominant 
damage mechanism so far is small rodents.  I sprinkled the cable with a 
coyote urine critter repellent (not a nice job) and things have been fine 
since.  now this isn't up high in the air, and not in Florida or Arizona, 
but it'll be interesting to see what happens.


73, Pete N4ZR
The World HF Contest Station Database
was updated on June 5, 2004
2728 contest stations at
www.pvrc.org/WCSD/WCSDsearch.htm  

_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.

_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk