[TowerTalk] Air dielectric cable

[mcduffie at actcom.net]

On Sun, 07 Sep 2003 13:20:40 -0400, Roger D Johnson wrote:

> I'd put a connector with an air fitting
> on the shack end of the cable and run a piece of tubing
> thru the lid of a gallon jar containing silica-gel. That
> way when the line "breathes", the air would be pulled
> from the dry air in the jar.

I've never seen that done, but it might work for short runs.  One of
the neatest tricks I've seen over the years was at a station in
Mark's area.  The wave guide had the nitrogen tank on it to raise
the pressure when it got too low, but that was turned off under
normal use.  This is normal.  But, there was an inner tube hooked to
a T connector on the line so it would keep constant pressure on the
line and at the same time allow it to go back into the inner tube
when pressure increased with higher temperatures.  Most loss is
caused by higher temperatures causing higher pressures to force some
of it out of the small leaks that are almost always present.  If you
keep the pressure low, it won't leak out as fast.  The inner tube
allows low positive pressure plus allows it to get rid of the excess
pressure.  It worked very well.

Gary

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