[TowerTalk] HDBX Version History...

[Kim Elmore]

Yes, from what I understand now, you are correct. According to some info in found in some archives, Rohn redesigned the AX, creating the BX (B-model using X bracing, I guess). Not only did they add an X-brace to each section, but they made the steel gauge heavier for at least the tower legs. From what I read, I couldn’t tell if they made the X-braces themselves heavier, or if they beefed up the aluminum rivets. I also don’t know if (or how much) Rohn modified the published data on their beefed-up BX series. If they left it unchanged from the original AX, it would leave them a much larger safety margin. 

Kim N5OP



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

> On Jul 5, 2019, at 11:37 AM, Mark - N5OT <r-emails at n5ot.com> wrote:
> 
> I am enjoying Kim's thread on BX towers.  Steve mentioned that the other guy had an AX not a BX and I need some clarification from guys who know more than I do.  If the fellow who's antenna twisted itself to pieces had and AX I would have thought the more notable deal with the X-bracing would be that on the AX the braces don't take up as much vertical space, and don't touch each other.  On the BX they do.  Clearly the BX is a better design?  (Hell to climb though, just sayin'):
> 
> Examples of what I am talking about:
> 
> https://www.n5ot.com/AX.jpg
> https://www.n5ot.com/BX.jpg
> 
> If I have this wrong I would appreciate knowing it.
> 
> Thanks,
> 73 - Mark N5OT
> 
> 
>> On 7/2/2019 3:22 PM, Kim Elmore wrote:
>> Ah! OK — I began to wonder if I was losing my marbles. Well... I obviously lost ‘em long ago, but still...
>> 
>> Kim N5OP
>> 
>> "People that make music together cannot be enemies, at least as long as the music lasts." -- Paul Hindemith
>> 
>>>> On Jul 2, 2019, at 11:49 AM, k7lxc at aol.com wrote:
>>>> 
>>>>  I recently asked a question about HDBX 48 torque loading. Another
>>> towertalkian told me his failed in about 80 MPH winds. He sent me a
>>> picture of his failed HDBX 48 (more heavily loaded than mine by a fair
>>> bit) that failed. Something I noticed in the picture was that his
>>> HDBX48?? had only *five* X-braces per section; I thought it looked odd,
>>> so I went out and looked at mine: mine has *six* X-braces per section.
>>> He said his was manufactured sometime around 1968-1970 while mine was
>>> put up around 1986, so was probably made around that time.
>>> 
>>>>  Did Rohn change the design of their BX towers to add another X-brace to
>>> each section, or am I seeing things?
>>> 
>>>     Nope, your eyesight is ok. The original tower you saw was the AX.
>>> 
>>> Cheers,
>>> Steve    K7LXC
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