[TowerTalk] BX/HDBX type towers

[Patrick Croft]

Hi Dave,
A couple comments on your post and a FYI file (or the delete).

I pulled a couple older Rohn Handbooks (1972, 1978) and both showed the 10
foot boom limit statements.  
Thus, not really a 'recent restriction'.   Based upon conversations with the
Rohn factory staff and personal experiences I fully agree with the limit.
The BX, HBX, and HDBX are ALL ASSEMBLED ALIKE - and in that assembly method
is the weakness.  An ALUMINUM rivet is used to secure the stamped steel
cross bracings to the stamped steel legs.  Under twisting conditions, which
a long boom type antenna amplifies, these rivets are subject to shearing.
The steel acts like a pair of sissors on the rivets.  In an effort to limit
this from being an issue the 10 foot boom limit has been noted for about
three decades.   These rivets are the reason one shouldn't sandblast or
pickle/acid bathe these towers during reconditioning as well. 

The basic history is on target about Spalding being the original producer of
the BX line.  Spalding's fab plant was located in Frankfort, Indiana.  The
company actually was a producer of steel farm accessories (gates, panels,
tanks, etc).  The TV growth( & need for antenna supports) was a great
additional market (to become a primary market) for the grain auger supports
and lighting towers they made.  I'd wager a cold Coors that some of those
towers in the rural areas holding grin tubes and old school athletic field
light towers are over fifty years old.  In the sixties Rohn purchased the
operation, dubbing it Rohn-Spalding. 

Today Rohn uses the Frankfort plant for the production of the Rohn 25 tower
sections, along with farm gates, animal stalls, and accessories.  Up until
this fall it was from the same Spalding plant.  In the 4th quarter their new
building was completed and Rohn moved about a mile away. They have stopped
production from the old Spalding plant, and they welcome your offer for the
property.  I suggest asking for a Environmental impact warranty, but thats
another issue!


Bests

Patrick
W9GTA
Greater Things Ahead!

  

At 01:17 PM 2/3/98 -0500, you wrote:
>I have a number of posts on this type of tower over the past year. The issue
>seems to be the size of antenna with Rohn specs limiting the boom to 10 feet.
>
>The BX/HDBX tower is nearly 50 years old in design.  The 10 foot boom length
>is a recent restriction based upon problems Rohn customers have reported.
>Rohn, being very conservative, decided that the 10 foot limit would solve
>the problems..and the problems are mainly with the top section twisting!
>
>The original BX was made by Spalding/Strato as a quality TV antenna.  In the
>late 40's and early 50's when the majority of the major TV stations came on
>the air they were a long distance from the TV viewer so a tower was required
>for reception. Plus we put some veryyy big TV antennas on them! Many like my
>family bought the Rohn push up masts, but the step up was the BX series.
>Strato even made some tall crank ups that got as small as 4 or 5" on a side
>on a 75'er.
>
>The HD version was made originally to WRL (Leo) specs for his Globe Spire.
>Read those old catalogs...there is no restriction on boom length!  Leo sold
>thousands, too.  Spalding made light ham/TV towers as the EP series, too.  I
>remember the ham in Jackson, MS who put up a 3 el Hornet on the EP 40.  The
>tower and beam were assembled on saw horses and we used a pull rope to pull
>up the entire affair next to his house (Spalding had details of how to do
>this in their literature.
>
>Rohn bought Spalding (sometimes spelled Spaulding) about 25 years ago, but
>only the BX/HDBX series has ever been sold to hams.
>
>A number of hams use this type of tower.  One guy has a Gem Quad mounted on
>his tower.  Another has a TA33 Senior.  One has a Th-6 on his 56 footer, but
>he has it guyed twice and has home brew stress bars at the top.
>
>Dave K4JRB 
>
>
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>


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