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[TowerTalk] New T2X

To: <>
Subject: [TowerTalk] New T2X
From: (H John Kohl)
Date: Sun, 30 Mar 1997 06:30:29 EST
On Sun, 30 Mar 1997 00:25:31 +0000 Robert Chudek <>
>At 12:45 PM 3/29/97 -0600, Dave Quick WD0EKL wrote:
>>At 11:52 AM 3/29/1997 -0500, Steve K7LXC wrote:
>>>In a message dated 97-03-29 11:29:34 EST, (Chuck 
>>>> I just received my new T2X rotor from Norm's and have bench tested 
>it and
>>>>  everything works just fine. I will be installing this within the 
>next week
>>>>  in my Rohn HDBX48 with top thrust bearing. I will be rotating my 
>>>>  Tri-Bander and a small 2M beam. I am installing new 8-wire rotor 
>cable at
>>>>  the same time. The cable run is only about 80ft.
>>>>  My question is:  Is there anything else that I should do before 
>>>>  this new rotor? 
>>>      Well, yes.  The T2X will fit but won't rotate in the BX series 
>>>towers without some modifications.  The case ears that stick out on 
>the T2X
>>>are the culprits.  One thing you can try is to bend out the X-braces 
>at the
>>>rotator.  This is from the 'bigger hammer' school of tower 
>construction.  The
>>>other thing that you can do is to remove the rotator shelf and 
>re-install in
>>>upsidedown.  This apparently gives you the clearance you need.  I 
>>>tried it personally but this tip comes from Bill, W7TI, and is worth 
>a try. 
>>>73,  Steve  K7LXC 
>>I know that a T2X won't fit in a BX-2 top section because a Ham IV 
>>barely fits,
>>but it might fit in a BX-3 top section. 
>>Depends on how the tower is configured. I believe an HDBX-48 is 
>sections BX-8 
>>through BX-3, with BX-8 being the largest available base section.
>>Dave Quick WD0EKL
>>Compuserve: 75526,2656
>>Grid square EN35jb
>>Minneapolis, MN
>Dave you are correct, the HDBX-48 uses sections BX-8 through BX-3.  
>Rohn drawing A-760001 states the following wind load specifications 
>the various combinations of BX-1 through BX-8 tapered tower sections:
>Allowable antenna load for 20 psf (70.7 mph) with antenna mounted 3 
>above the tower apex and a boom length of 10 feet or less:
>Height  Sections used      Rohn model     Area ft^2   Thrust lbs
>  24    BX-1,2,3              BX-24           6           120
>  24    BX-2,3,4             HBX-24          12           240
>  24    BX-3,4,5            HDBX-24          20           400
>  32    BX-1,2,3,4            BX-32           6           120
>  32    BX-2,3,4,5           HBX-32          12           240
>  32    BX-3,4,5,6          HDBX-32          18           360
>  40    BX-1,2,3,4,5          BX-40           6           120
>  40    BX-2,3,4,5,6         HBX-40          10           200
>  40    BX-3,4,5,6,7        HDBX-40          18           360
>  48    BX-1,2,3,4,5,6        BX-48           6           120
>  48    BX-2,3,4,5,6,7       HBX-48          10           200
>  48    BX-3,4,5,6,7,8      HDBX-48          18           360
>  56    BX-1,2,3,4,5,6,7      BX-56           6           120
>  56    BX-2,3,4,5,6,7,8     HBX-56          10           200
>  64    BX-1,2,3,4,5,6,7,8    BX-64           6           120
>To help identify the BX sections here is a chart of the center
>line width from leg to leg for each section at it's widest end:
>Section       Width
>BX-1           9.53 inches
>BX-2          11.86 inches
>BX-3          14.20 inches
>BX-4          16.58 inches
>BX-5          19.23 inches
>BX-6          21.89 inches
>BX-7          24.56 inches
>BX-8          27.41 inches
>These dimensions are from the center of the channel to the center
>of the adjacent channel so measuring with a tape on the outside of
>the structure will produce a slightly higher number.
>The concrete base specification is for 3,000 psi minimum ultimate
>strength concrete and were designed for 2,000 psi soil.  The bases
>range from slightly under 2 yards^3 to almost 5 yards^3.
>So there's just about everything you might want to know at a glance
>about this popular Rohn product used by many amateur radio operators.
>Well, okay... a little more?  Upright legs are ASTM A-446 Grade C
>steel (minimum yield point 45,000 psi) galvanized according to
>ASTM A-525.  Braces are cold rolled C-1017 steel (minimum yield point
>36,000 psi) also galvanized to ASTM A-525.  Leg splice bolts are
>SAE Grade 5 steel.  And last but not least (this holds the whole 
>thing together!), rivets are 2017-T4 aluminum alloy.  (I never know
>73 de Bob - K0RC
>FAQ on WWW:     
>Administrative requests:
The interesting comment from the Rohn spec sheet "DWG. N). A-760001R1"
for the BX towers.

Note:  Antenna types should be limited to those having a maximum boom
length of 10 feet.  No engineering data relating to the use of boom
lengths in excess of 10 feet is available and the use of such boom
lengths is not recommended.    

Nice disclaimer. 

73 John

FAQ on WWW:     
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