[TowerTalk] TowerTalk Digest, Vol 122, Issue 58

[Patrick Greenlee]

Lots of opinions and no consensus.  Typical.

I didn't have nary a drop of water in my 3 inch conduit 6 months ago but I 
will check again because of all the folks who think all buried conduits have 
water. I allow as to how it is conceivable water is getting in there by 
whatever means. I do have dried shop air available at both ends of my 
conduit so I suppose a "calibrated leak" to put just a few cubic feet of dry 
air per day into the run would totally remove any concerns for condensation. 
If all air entering the conduit is really dry air there should never be any 
condensation in the conduit.  In one of my previous conduit runs to the 
barn, I ran a small flexible plastic tube Rated for 200 PSI to a repurposed 
35 gal air compressor tank from a portable compressor with a dead motor. 
This gives me air in the barn for tires etc.  It recharges slowly but I'm 
not trying to power impact tools so no big deal.  It could provide a little 
air to the coax conduit to keep it under a slight positive pressure and dry. 
At the other (house) end of the conduit I can install a small flexible 
plastic tube with a check valve in-line.  This tube can be run to a 
convenient location and there immersed in a clear water container 
(repurposed peanut butter jar. )  At a glance you can tell if there is an 
occasional bubble coming from air exiting the conduit.  Any leakage of air 
through wires or coax shields or loose jackets would be of dry air getting 
out not damp air getting in. Problem solved. (If there is one.)

Total system cost in time and materials?   Maybe as much as as a dollar in 
materials (but more likely from scraps and such on hand) and maybe 15 
minutes to drill the two holes and put in the tubes, gluing them in place. 
This time estimate includes making the calibrated leak (small scrap petcock 
almost shut off. If my cost estimates are totally bogus it will still be 
under $2 and 30 min.

An alternative would be a periodically replaced silica gel pack desiccant. 
I use these for other purposes so have them on hand and periodically 
recharge them in the oven.

Patrick AF5CK