[TowerTalk] Coax, conduit and toroids

Perry - K4PWO k4pwo at comcast.net
Wed Jun 27 18:23:41 PDT 2012

I only had mine down a foot as I was crossing buried 220 volt AC lines that
were down about 4 feet (according to power company - I didn't see any signs
of them).  I also have very rocky soil with lots of limestone "shelves" that
I hit when digging my tower base.  I actually poured my base on one of them
that the backhoe/jackhammer operator worked on for an hour.  It was a very
big hunk of limestone.
Buried waste drain (poop chute) has to be schedule 40 minimum (depends on
local code) but French/foundation drains can use the pref'ed thin wall.  It
doesn't matter if it gets compressed.  You may be able to use thin wall for
waste system vents also.
I laid two 80' runs of 3" gray PVC conduit, one run of 2" and a 1" run for
about $150 in material.  I guess if you had a 200+ foot run the thin stuff
would look attractive.
There are cleanout boxes you can get for drain systems that have a open
bottom for a gravel bed but they are designed to be mounted flush with the
ground.  You can get them with solid or grate lids but they sure aren't
water tight!

73 de Perry - K4PWO

-----Original Message-----
From: Larry Loen [mailto:lwloen at gmail.com] 
Sent: Wednesday, June 27, 2012 5:31 PM
To: Perry - K4PWO
Subject: Re: [TowerTalk] Coax, conduit and toroids

I discussed this very thing with my father, who is a civil engineer.

He said that once you got far enough underground (don't know the minimum,
but I'm planning on four feet) he said that vehicles wouldn't be a big
problem -- forces are spread through the soil.

The main thing is to make sure there isn't any rock in immediate contact
with the tubing, especially above and below.  A nice sand base below the
trench is vital.

Around here, the cost difference is very substantial between thick wall and
thin wall.

Moreover, it must be routine to make this work -- the thinner PVC is used to
conduct waste water from homes to sewers.  No one wants them to break!

Larry Wo0Z

On Wed, Jun 27, 2012 at 10:26 AM, Perry - K4PWO <k4pwo at comcast.net> wrote:
> Another issue is that most "drain" tubing has a very thin wall 
> compared to PVC conduit.  If you have rocky soil or will have the 
> "conduit" buried under a path where vehicles will travel, you will 
> want heavy walled tubing (PVC EMT conduit).  I have discovered that the
"gray" PVC is cheaper than "white"
> water PVC in most sizes (in my area of the US at least).  The gray 
> also stands up better exposed to sunlight.
> 73 de Perry - K4PWO
> -----Original Message-----
> From: towertalk-bounces at contesting.com 
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Missouri Guy
> Sent: Tuesday, June 26, 2012 11:15 PM
> To: kiessig at gmail.com; TowerTalk at contesting.com
> Subject: Re: [TowerTalk] Coax, conduit and toroids
>> What should I do to help ensure that the inside of the conduit stays 
>> dry? Is applying some sort of weatherproof sealing compound to each 
>> end enough?
> Rick,
> I have a large "conduit" running 200' to one of my towers.  So, 
> speaking from experience, there is no easy way to keep water out 
> unless you want to pressurize the conduit with say, dry nitrogen
> gas.   That isn't going to happen!!  :D)
> Air will get in there even if you attempt to seal it off, and then it 
> will just form condensate in the cool ground.
> Mold will grow, etc etc.
> I found the best way (for me, anyway) is to install a Tee connector at 
> both ends of the run.  Face the Tee part downward and screen it over 
> to keep out bugs, snakes, or whatever.  Air will flow through your 
> conduit everytime the wind blows and will keep things nice and dry.  
> Here in the US, and probably in AU, there are some screened aluminum 
> louvers that will work for most of the larger conduits (like, in my case,
4" PVC tubing).
> As for your other questions...there are some experts on the list who 
> will address those.
> 73,
> Charlie, N0TT
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