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[TowerTalk] DX eng

To: <>
Subject: [TowerTalk] DX eng
From: "Jim Thomson" <>
Date: Tue, 27 Jul 2010 07:30:35 -0700
List-post: <">>
Date: Tue, 27 Jul 2010 01:01:13 +0200
From: "DF3KV" <>
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. 


 OptiBeam comes with all  stainless steel hardware and they use a laser cut SS 
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 
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 
with the typ 4-6   U bolts  and sheet metal  saddles.   This time around it's 
a lot worse.   Not only do the the inner U bolts + mating saddles have to go on 
 the boom has to be dead level parallel to the grnd.   Also, the boom can't 
on it's axis either.   Always seems to be a bit of breeze at the top of any 
even if a dead calm on the grnd !   THEN  you have to align the yagi on the 
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"  
plate is  attached to the mast via   2-3 x  DX eng super mast clamps.. that 
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 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 
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"  

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 

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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