[SBE] "modifying co-ax" to drain moisture

[Dean]

I have a 300 foot run of 1-5/8” air-filled coax up one of our towers that
apparently has a bad seal at the top end, and it seems to be admitting water
(sort of like an open drinking straw) which is collecting at the bottom in a
“loop” of co-ax we left deliberately when it was installed to collect water
outside the transmitter and transmitter building.  The “low point” is
collecting water as we planned, but eventually it “fills” the insulation
space where the drip loop is, and causes the transmitter to drop way back in
power, due to high reflected power through the water route.  

 

I can give the co-ax a blast of compressed nitrogen, and after about 15
seconds the water is “forced out” through a small drain hole we have drilled
in the co-ax jacket and outer conductor, and the reflected power drops to a
normal value, the transmitter output current and power return to normal and
we’re off and running.

 

My problem is:  I cannot leave the co-ax pressurized or the leaky seals at
the top will bleed down my bottle of nitrogen in a short time (about an hour
or so).  So, whenever it looks like a rainy siege is coming, I give the
co-ax a “blast” of nitrogen, and hope it will keep the water out for the
duration of the rain storm.

 

What if I increased the size of my co-ax “weep hole” to about ½ inch
diameter.  Would this cause any problems?

 

What if I coupled a small air compressor (with a dryer attached) operating
off 120 volts to the co-ax and left it running (cycling on and off on
pressure)?  Would this work?

 

I’m looking for a long range answer, without having to climb the tower,
replace the co-ax, etc.  

 

Any suggestions?

 

 

DEAN SPENCER

WBIW/WQRK/WPHZ

dspencer at hpcisp.com

P.O. Box 1307

Bedford, IN.

Ph.812-275-7555  Fax 812-279-8046

Cell 812-797-3612

wbiw.com  superoldies.net

 

 

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