[TowerTalk] Homebrew tower...

[Roger (K8RI) on TT]

I think, meaning I don't know for sure, but I have the background to 
make an educated guess, when comparing tubing and pipe, particularly 
water pipe they are two different animals.  The difference in alloy and 
hardness is substantial.

If you take one leg of a 25G, I see it comparable to thin wall conduit 
(not the same, but comparable).  It's fragile, easily bent, or crushed.  
The tower gains the majority of its strength from the construction.

Water pipe OTOH is "relatively" soft like rigid conduit and easily 
bent.  Compared to a 25G tower leg it's very heavy, so I'd expect a 10' 
section to be notably heavier than a 10' section of 25G.  Per size, or 
length, I'd expect such a tower to be as durable as a 25G up to 40 
feet.  BUT...

The idea of using 1" pipe as a sleeve coupling is a sound one  I'd make 
them about 6 or 8 inches long with 6 being the absolute minimum.  Use 2 
bolts per section, or 4 bolts per coupling as ROHN does.
Bear in mind, this is not an engineered tower that "MIGHT" be similar in 
strength to the 25G.   It's built of a material not designed to support 
a load.  Based on that I'd be very hesitant to climb one.

As for corrosion, as long as it's well coated with a rust preventative 
paint ( Cold Galvanizing, or zinc based paint) at sufficient intervals I 
would expect it to hold up.

As I mentioned earlier, water pipe is relatively soft and bolt holes are 
prone to "egging out" (holes get larger from wind induced tower 
movement). A good reason for tight/snug fitting bolts.

For my own comfort, I'd make the "water pipe" tower with the leg spacing 
of  a 45G, rather than 25G and I would definitely refrain from climbing 
it.  Using the falling derrick to raise and lower it for maintenance 
would be my preference.  I think a tower made 3 lengths of 3/4" water 
pipe 40 feet long plus bracing. antenna and rotator  might be a bit 
heavy for two to "walk" it up.  Again, the falling derrick sounds good 
to me.

I have never painted a tower that needed it.  I have painted a couple of 
the old American Steel as they were beginning to look pretty rough with 
the original paint peeling off after 20 to 30 some years, or wearing off 
from me climbing it.  I had 25 to 30 years on a 25G and about 15 on a 
45G that never needed painting.  However, I'm in Michigan, about 25 
miles W of Saginaw bay and over 700 miles from salt water unless you dig 
a hole. Then it's 200 to 300 feet down.

OTOH Acid rain keeps removing the solder joints from antenna connections 
around here.  Every C3i antenna I own ( 5 of them) has had the coax come 
off.  So I resolder the connections and apply several liberal coats of 
liquid tape which seems to work.  The clear Krylon paint (which is 
recommended) is completely gone in just a year or two.

With plenty of paint, I think your tower will stand up well.  Don't 
neglect the inside of the pipe.

73 and good luck,

Roger (K8RI)

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