On Wed, 31 Dec 2003 07:11:34 GMT, Zoran Brlecic
wrote:

Dave Woolf wrote:

I had a fellow ham that took the precaution of
pressurizing this type of coax to maintain
positive pressure and keep out outside air.
Seemed like a lot of effort but maybe it is necessary.

Just out of curiosity: how exactly did he do this?

I'd go the commercial way and just purge it with a slight positive
pressure.

With 9913 you can seal the ends and use a small plastic tube in
through the side. Flood the bottom connector to seal it (just the
opposite of normal) then work a small hole through the jacket, braid,
and into the inner tube. You can build a tap sorta like they use for
a gas line, or water line, but smaller. You can also put a tap on the
side of the coax connector. As far as I know you'd have to make your
own as I've not seen any for the PL259s or N connectors although they
may be available. The only coax I've ever seen purged was commercial
hard line. (It looks like copper water pipe) They actually had a tap
soldered on the side of the line with a flow meter connected. It was
a very low flow and on a 900 foot run that was gasketed. They
replaced it with what appeared to be 4" Heliax. (How'd you like to
lift 900 feet of that?) You hook up a tank of N2, only run a few
inches of water pressure and use a small flow meter to regulate the
flow. Typically you'd purge the thing and then flood the top as well.
you will still get a small flow. If the coax seal loses integrity the
flow will increase.

Lot of work and about $20 to $30 for N2 every few months.

It's almost impossible to keep something like 9913 completely sealed.
Even the PL259s and N connectors will leak through some.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair?)
www.rogerhalstead.com

73 .... WA7AA