[TowerTalk] Joining sections of aluminum mast

[Kim Elmore]

I have an HDBX48 and have always found the 10’ boom length puzzling. Mine has 40CD2 perpendicular Tom a KT34A, each exceeding the 10’ limit, but under the 18 sq Ft overall load limit. It’s been through 84 mph and survived. 

The BX series was redesigned sometime in the (early?) 70’s and Rohn added an extra set of X-braces on each section but didn’t upgrade the ratings. So I have to wonder if the 10’ boom length is a legacy rating. 

As for climbing them: it’s misery. I now always use a bucket to do anything on mine. My experience with StepIRs in harsh winds is not good; I’d never put one up on anything but a crank-up or fold-over. 

Kim N5OP

"People that make music together cannot be enemies, at least as long as the music lasts." -- Paul Hindemith

> On Aug 25, 2022, at 6:52 PM, larryj at teleport.com wrote:
> 
> I went by Rohn's published specs so I could get a tower permit. The City required that they be followed to the letter, and sent out inspectors to verify the hole, rebar, concrete foundation and the final installation. Our local radio club did lots of work (with a local volunteer ham Attorney) to get the HDBX48 approved, at a time when they weren't approving any other ham towers.
> 
> I never would have gotten the permit if I hadn't used an antenna with a boom length of 10 feet or less. Maybe the City Engineers saw the same BX towers across the river that I saw, that had come down after being overloaded. They weren't rated to be used as guyed towers.
> 
> It was worth all the trouble for the permit, though, the quad busted many a pileup, first call.
> 
> 
> 
> -----Original Message-----
> From: Doug Renwick <ve5ra at sasktel.net>
> Sent: Aug 25, 2022 4:08 PM
> To: <larryj at teleport.com>
> Subject: RE: [TowerTalk] Joining sections of aluminum mast
> 
> I see you fell for the 10 foot max boom length. For years I have used BX
> towers with antenna boom lengths well over 30 feet. Towers are guyed.
> 
> Doug
> 
> Free Climbing - The ultimate test of strength and technique.
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
> larryj at teleport.com
> Sent: August-25-22 9:42 AM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Joining sections of aluminum mast
> 
> That tower load caught my eye, too. I have an HDBX tower, and I was only
> able to get the City's tower permit by staying within the Rohn published
> load limits. So I went with a 2-element tri-band quad antenna, which only
> had a boom length of 8 feet.
> 
> At a previous QTH, I had a Mosley TA-33 tri-band yagi. But I couldn't put it
> on this BX tower, since the boom length (I think it was 16 feet) exceeded
> the 10-foot allowable boom length in the tower ratings' specifications.
> 
> When I read this thread about a SteppIR was being put up on a BX tower, that
> caught my eye, immediately. I've seen two - folded-over/destroyed BX towers
> in this area, with antenna loads that exceeded Rohn's specs. Fortunately,
> neither of them were mine.
> 
> LJ
> 
> 
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