On Sun, 18 Apr 1999 17:59:19 EDT K7LXC@aol.com writes:
>In a message dated 99-04-17 22:12:10 EDT, km1h@juno.com writes:
>
>> The tower is very similar to Rohn 65, 20' sections and a 24" face.
>> Triangle mounting plates with 3 bolts per leg. The legs are 2" and
>about
>> .125" wall. Tower was part of a 3 bay 200' bcast array. No rust
>> anywhere.
>>
>> I have straight sections and the original base section which tapers
>and
>> terminates in a single point...forgot what the proper name is.
>>
>> The idea is to put up 120 or 140' with a much modified and
>strengthened
>> KLM 3 el 80M yagi.
>>
>> Questions are:
>>
>> What is the preferred base mounting and amount of concrete? Only
>18-20"
>> or so will be below grade and sitting on solid rock.
>
> I would use the Rohn 65 specs as a starting place but this is a
>real
>engineering question.
I aint no injuneer!
You should put some anchor rods into the rock
>and pour
>the concrete over them to give you a bombproof base.
Pretty much planned on that Steve but the big questions are:
Should I use the original pivot pin base or go to a mount based upon the
straight sections?
If I go for a straight section as the base what sort of mounting plate
should I have made up? Something of this magnitude is beyond my
experience and I would prefer to not screw it up.
The 20' sections ( except for the base) are not like 45/55G and can be
mounted either way. I can even use the pivot pin base in reverse as a top
section if I wish.
I have all 3 of the 200' b'cast towers so options are wide open.
>>
>> Can I get away with only 2 levels ( 50 and 100' ) of 5/16 EHS for
>guys
>> which will be out a full 75-80%?
>>
> Maybe. Probably. The Rohn 65 spec at 90 MPH has two sets of 5/16"
>guys
>up to 130 feet.
Maybe, probably is what I hope but the wife cant get an insurance policy
on guess work!
The antenna weighs about 450# and has a 30 sq ft wind load plus or minus
a bunch depending on how you measure that. Its the torque of a 65' boom
and 95' elements that has me concerned.
>
>> I plan to use a mid size prop pitch for the rotator ( worked fine
>for the
>> original owner for 8 years) . What read out options are available
>these
>> days? I sure dont want to regress to 1940's selsyns if I can avoid
>it. I
>> plan to mount the rotator at the same level as the top set of guys
>which
>> may be 20' below the antenna. The mast will be 3" x .25" SS.
>>
> The only other option is to send your PP to M2 and have them
>adapt it.
Your the 2nd to mention that; I was not aware that Mike did that...much
tnx.
>They put in a reed switch to adapt it to their digital control box.
>Several
>people I know have done this and they are happy with the results. I
>think the
>cost is around $500. I think they even add their industrial strength
>mast
>clamp so you get a real nice package out of it.
If it works and survives that is pretty cheap. I'll get on Mikes case
immediately and then holler at him in Dayton.
>
>> Why am I even doing this...must be getting senile!
>>
> Sounds like a fun project to me!
Big talk for someone 3000 miles away!
73 Carl KM1H
>
>Cheers, Steve K7LXC
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