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.
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