A couple of people have asked me to relate this story that I had hinted at
in CQWW Phone score on 3830. I hope this will help others in some of the
pitfalls that can happen and what maybe done to overcome them.
First of all anything I build on a Tower is very heavily influenced by what
I have seen at W7RM and discussions with Rush himself, the man is a
"GoldMine of information", he is always thinking of things to try.
My tower is 132feet of L&R 24 inch series(this is a CSA approved tower I was
fortunate enough to get second hand and can be built to 400FT).
I didn't have any 15 or 10 meter antennas rotating on the tower so I thought
I would just whip up a side mount and put up a Cushcraft 4 element 15 and 4
element 10 that I have and had used them fixed towards the Caribbean. I
wanted these to be about 1 wavelength above ground which is about 45ft for
15 and 35ft for 10 and could be turned on the same mast. The rotator was a
HAM III I had traded from a friend.
I had some angle aluminum stock 3" a side and 1/4" thick that I had scronged
years ago and some steel rack rails 1 1/2" wide and 1/8" thick that I was
sure I could use, the reason for using two different sizes of material is
the side moumt would be on the south leg of the tower which would allow
rotation to almost West and back around to about 220-230 degrees into South
Pacific, is all my coax and control cables are on the outside of the
SouthWest face of the tower. I figured it would be easier to slide the steel
1 1/2" pieces under the cables than the bigger 3" aluminum ones.
These angle pieces form an X with the tower at the top and the rotator and
bearings at the bottom of the X. There is three sets of these one set for
the rotator, one set for a flange mount bearing just above the rotator and
the last set at the top of the mast where I used a pillow block style of
bearing mounted on a piece of angle iron.
By the way the mast is a 12 foot piece of 1.9" steel tubing certified for
66,000 lbs tensile strength.
The plan is to have the 10M ant. mounted just above the first bearing on a
piece of pipe that extends from the mast to just past the tower edge which
is braced with an angle iron piece going back up to the mast. The 15M ant.
would be done the same way at the top of the mast just below the top pillow
block bearing, this gives me separation of close to ten feet.
Well I thought I would of course be clever and I can construct his on the
ground at the base of the tower, mark and drill the apropriate holes for the
U-bolts to attache the angle material to the tower legs, also cut two
triangle pieces of metal using a skil saw with metal abrasive blades out of
3/16 sheet material(again just lucky to have that my father had laid on me a
few years ago and I just have been holding onto). I first make sure I have
the two plates lined up so I can be sure of good alignment for the rotator
and first bearing. I cut a hole in one plate with a flycuter using a Carbide
bit that I spent some time in sharpening to get it to cut the steel with on
my drill press at the slowest speed possible with lots cutting lubricant.
Well onto mounting the hardware up I climb and haul the first set of pieces
up to at about the 33 foot level and start to put the pieces on, everything
looking great until it came time to mount the plate and the pre-drilled
holes in the plate don't line up with the holes in the angle pieces(What
the????), well this probably won't happen to most guys but I forgot that the
two bottom sections of my tower have 1 1/8" legs all the rest of the
sections have 1" legs (solid steel by the way)this was enough to throw the
holes off at least in one side of one angle piece. This is where a good
battery operated drill is worth its weight in gold believe me plus make sure
you have a coulple of "sharp drills" with you when you drill on the tower.
This part really went smoother than I would have thought.
Finally side mount is finished (remember I used the term whipped up, try
almost a month), now to put up the Antennas which I have cleaned up checked
the measurements and are preassembled just waiting to be pulled up, The 15
first then the 10, Hmmmmmm, gee that first director sure looks close to the
tower oh well. Climb down. Go get little intercom and get wife to come down
to the station and tell her how to run rotator will call her on intercom
from base of tower( I have what I call a small house for the cables,power
supply for prop pitch at top of tower and and switching at base of tower).
Please turn to right, well you can guess what the Cushcraft's are too small,
not enough distance between the driven element and first director,
Terrific!! Well first thing I tried was to move the antennas forward too
give more room for the first director, after messing aound with that I
decided the only solution was to reconfigure the antennas to something which
would give me the porper spacing(I needed about 82 inches between the driven
element and first director to make this work). I decided to configure the 10
as W2PV 4 element and used Eznec to get the elements scaled right, the 15
was a compromise design I gleaned from ON4UN's set of antennas, which gave
me the spacing I needed(I would have prefered to have the 15 be a W2PV as
well but didn't think there would be enough room below first set of guys.
Well to shorten up already long story the 10 Meter and 15 Meter antenna seem
to perform well I am very pleased with how they seem to hear and play.
Early next year I will be putting up the side mount for the lower 20 I must
say I am glad of all I have been swill make such things easier to do in the
future.
Oh there was one small glich I almost forgot to mention after I had these
antennas mounted and was getting the wife to turn them so I could watch see
how they clear the Tower OK. The one thing I didn't think I would have
trouble with happened. As the antennas came around all of a sudden the tip
of 15 catches in the bottom south guy wire,NUTZ!! Well I had been going to
move this anchor I had a hole dug about two years ago but too many other
things kept getting in the way to finish this off. Only solution to move
anchor which meant rather than mixe my own cement which I have done for
virtually all my anchors, time constaint meant paying for Ready mix, which I
did and that conludes this story. Moving the guys back gave me the room I
needed.
Although this has been kind of long hope it helps some of the guys to go
ahead and try what ever you can, this to me is part of the fun, finding ways
to improve the station in the most economical way one can.
73 Earl VE7IN
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