Date: Tue, 27 Jul 2010 01:01:13 +0200
From: "DF3KV" <df3kv@t-online.de>
Subject: Re: [TowerTalk] DX eng
I don?t think it is a good idea to use saddles with teeth.
Those will saw through the tubing on the long run.
## agreed. And when using heat treated 4130 chromoly tubing for the mast...
they won't bite into the mast anyway ! You have the same problem with the
fubar mast clamp m2 uses on their OR-2800. [ btw, a buddy of mine had 5 of the
6 x bolts fall out the bottom of his OR-2800]
I use single mounting plates on all of my antennas.
Mating plates are welded to the rotating mast.
## So you, in effect still use TWO plates.... and one of yours
is welded to the mast. Telrex did the same with their bertha poles..
and alternated the plates from one side of mast to the other.
All mounting holes are the same on all plates, so any antenna will fit at
any position.
## I took note of that... that's a superb idea... since I have 8 x more
identical plates
to drill out.
73
Peter
OptiBeam comes with all stainless steel hardware and they use a laser cut SS
saddle
with teeth which seems to be effective. What is wrong with their single
mounting plate?
## My experience with the single mounting plate scheme has always resulted in
a time
consuming install ! 1st you mount the typ 8" x 14" plate to the boom with
4-6
x U bolts and sheet metal saddles. [2-3 per side]. The inner U bolts have
to go on 1st...
loosely, so you can get the outer U bolts on. You then tighten all 4-6 of em
up.... and all
you are doing is crushing the boom.... since any U bolt has virtually no more
than 1/64"
bearing down on the boom. The parallel sheet metal saddles are equally
useless imo.
Neither of em has any surface area, so they both rely on huge pressure alone.
## step 2... you hall the yagi to top of tower... then do another repeat
performance
with the typ 4-6 U bolts and sheet metal saddles. This time around it's
worse...
a lot worse. Not only do the the inner U bolts + mating saddles have to go on
1st..
the boom has to be dead level parallel to the grnd. Also, the boom can't
rotate
on it's axis either. Always seems to be a bit of breeze at the top of any
tower..
even if a dead calm on the grnd ! THEN you have to align the yagi on the
mast,
so it's pointed correctly [esp with multiple yagi's]. Meanwhile, your grnd
crew has all along
been trying to raise/lower by 1/32" increments.
## Ok, now try the F-12 double plate scheme... whereby the 8" x 14"
vertical
plate is attached to the mast via 2-3 x DX eng super mast clamps.. that
have
just massive surface area on BOTH sides of the mast. They are essentially just
two giant 2" textured saddles... that are held together via a pair of G-8
bolts. Barely
tighten em... and the yagi will never slip on the mast..it can't.
## 2nd plate in my case is a 8" tall x 17" wide plate.. which is attached
to the boom
either with 4-6 x dx eng SS saddle clamps..which consist of SS U bolts and
solid
AL textured, 1.25" wide saddles..... OR a pair of super mast clamps are used
on the boom
[ 1 per side] .
Yagi is simply raised up to top of tower [ boom can be at at gross angle too]
... and
two plates are mated... initially by the 1/2" SS stud sticking out from
the mast plate.
This stud is just a 1/2" SS bolt that gets inserted along with the vert
mast plate..way b4.
Head of bolt is pinned by mast. Sometimes I drill and tap threads for the 1/2"
stud.
After yagi brought to top of tower by grnd crew... I transfer the load to the
2nd link...
and transfer the load to the cum-along that's attached higher up the mast. At
that point,
everybody on the grnd can go home. Main lift rope from grnd is tossed, no
longer required.
I lift the yagi with the cum-along until I'm lined up with the 1/2" stud...
and mate the two plates
[ and boom can still be cockeyed a bit, sloping up/down on an angle] .
Once the nut is on a few threads on that stud... you are laughing. Boom is
leveled by hand...
... until the other 4 x holes in the 2 x plates line up....and nuts installed.
A cordless impact gun
makes short work of all this. [ 5 x bolts, no big deal, and 1 is already
installed].
I made my own version of the F-12 plates..and used 3/8" thick 6061-T6.
Where the 2 x plates
over lap forms a 8" square [3/4" thick]. The 14" tall vert plate normally
has 3" sticking above and 3"
below the Horz plate. I shift the Horz plate down 1".... so I have 4" of
the vert plate above.. and 2"
below the H plate. This then allows me to use TWO dx eng super mast clamp
assy's on top 4"
portion... and ONE super clamp on the bottom portion. Then I end up with
THREE super clamps
on the mast. My mast is 2" OD... and the super clamps are exactly 2" tall...
so that's how I can fit
2 of em on top.. and one below. I can climb the mast.. and just climb up
the boom to mast plates as well.
[they are used as steps, with the real mast steps above and below the boom to
mast plates.]
This all may sound complicated, but it's not. Mating 2 x plates via a stud,
then stuffing 4 x bolts in with an
impact gun takes all of 40 x seconds flat. I'll never go back to a single
plate.. on any brand of yagi/hb.
The super metal market franchises all over NA carry this 6061-T6
plate..called... 'econo plate'. It comes
in 8" wide x 16-20' length's .. in various thickness's . They just lop off
what you require.
Later... Jim VE7RF
John KK9A
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