[TowerTalk] HDBX Version History...

[Kim Elmore]

I think we're referring to the difference between the AX (Spaulding) and 
BX (Rohn's redesign of the AX) tower sections. The difference between 
the BX, HBX, and HDBX is in the sections used. The tallest HDBX48 (48 
ft) and uses the BX8, 7, 6, 5, 4, and 3 sections. The tallest HBX56 (56 
ft) which adds a BX2 section to the top, and the tallest of any BX tower 
is the BX64 at 64 ft, which uses all the sections, BX8 to BX1.

We're specifically discussing the differences between the AX and BX 
series. The AX series had 5 X-braces per section while the BX has six, 
and the AX series used lighter gauge steel for the legs compared to the 
BX. The BX series *may* use heavier gauge steel for the X-braces and 
*may* use heavier rivets on the X-braces, but I don;t know and haven't 
found anything definitive on those last two points. The whole discussion 
started when I idly asked why all of the BX series of towers, 
regard;less of which sections are used, are all uniformly limited to 
only 10 ft length booms.

Kim N5OP

On 7/5/2019 5:29 PM, Ed Williams wrote:

> Hi All,
>
> The BX tower consists of three different version.  There is a BX, HBX and the HDBX and each increasing the strength of the tower. So please specify which version you are referring to.  I have owned all three of the version at one time.
>
> 73, de KN4KL ed
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Kim Elmore
> Sent: Friday, July 05, 2019 3:24 PM
> To: Mark - N5OT
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] HDBX Version History...
>
> 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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-- 

Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP 
SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)

/"In theory there is no difference between theory and practice. But, in 
practice, there is." //??? Attributed to many people; it???s so true that it 
doesn???t matter who said it./