[TowerTalk] Hytower Base Insulators(Long)

[dan hearn]

I built my first 80m 4sqr array about 12 years ago using 4 Hytowers of
various ages and conditions. Most did not have the tiltover base
insulator assembly. The ones that did, showed considerable weathering of
the fiberglass. 
  While visiting my brother in Sand Springs, Okla, he told me about a
surplus yard run by Fibercast company nearby. I found there many pieces
of fiberglass rod and pipe which were run ends or out of spec material.
It was sold by the pound and the price was very low. I don't remember
the exact figure but $20 would get you a car trunk full.
  I understand that the surplus yard is no longer in existance and
possibly the stuff is sold in bulk to scrap dealers. 
  Most of the rod was around 1 inch in diameter. I believe it was used
for operating downhole pumps in oil wells which had corrosive liquids in
them as many do. I believe this is called "sucker rod" and the pump
jacks on the surface push and pull on the rod to pump oil to the
surface.
  I also found a lot of fiberglass pipe for carrying corrosive liquids.
Most of it was about 2.375 od, the usual size of 2 inch pipe. In every
case, there was an inner core of some brown colored plastic tubing. The
pipe seemed to be made with different pressure capabilities. The higher
pressure pipe had smaller ID, thicker wall plastic tubing, and thicker
wall fiberglass outer. 
  I used this pipe as insulators for my Hytower 4 sqr as follows. For
each tower, I cut 3 pieces of 2 1/2 x 1/4  angle 3 ft long. I cut 3
pieces of the fiberglass pipe 2 ft long. The insulators were placed
inside the tower leg and drilled thru to match the tower holes.3/8 x 16
bolts were installed thru the holes with large washers on each end using
lock washers and nuts. The angles were bolted to the lower end of the
insulators in the same manner (2 bolts/leg). I ground a flat place on
the outer corner of the angle so I could drill thru the angle at the
corner. I tack welded several pieces of rebar between the 3 angle pieces
to hold them in position.The lower section of the tower, with angle assy
attached,can now be set into the footing holes and the cement poured. 
  The usual Hytower configuration uses an insulated tubular section with
a wire down the center of the tower to the base. Total height is 52 ft
and the bandwidth is quite narrow. I used this configuration for several
years. Since I work both CW and SSB on 80, I decided to improve the
bandwidth and efficiency by extending the tubular section to a total
height of 65 ft and strapping the tubular section to the top of the
triangular tower. 
  This setup was used for 3 years in Dallas where severe winds are
common. I have since moved to Spokane and am using 2 of the same towers
in a broadside/ endfire array. It is not as good as the 4 sqr by a bit
but was good enough to work JT1CO for my last 80m zone.  I have had no
problems with the insulators or the towers during all this time. 
  I believe the Fibercast company is still around and I bet there are
lots of other companies who sell fiberglass pipe. 

73, Dan, N5AR

--
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com