To add to this thread, how can one ever turn a US Tower rotating tower
using the K-factor method since the weight of the rotating tower is
roughly 660#'s plus or minus the base assembly weight. Should the tower
itself since its similar to a mast be included in the calculations?
Thus a US Tower MARB-550 add a 55# antenna and turning radius 19' of
would equal a K-factor of 13,400
Not to many rotors capable of that figure, however, I believe the tower
does have a load bearing assembly thus removing the weight factor? How
much I am not sure and what effect the rotational torque of the tower
itself has is unknown to me.
Thus that type of tower/antenna by the K-factor would be 19*55 = 1045
plus the effect of torque and any transfered weight..
I am thinking of using a MARB-550 at 55 ft with a SteppIR plus the 40/30
add on but am confused as to how big a rotor is needed?
Would appreciate hearing from MARB-550 Owners and there experiences.
Ron, W4LDE
K4SAV wrote:
> I just pulled the info from the web for that calculation which didn't
> mention mast weight. I went back to the Yaesu manual, and yes that is
> what it says, it includes the mast weight in the calculation. But that
> really doesn't make sense. A mast contributes an insignificant amount
> of torque compared to the weight of an antenna, and they are counting
> them the same. (Antenna turning radius times mast plus antenna weight
> doesn't make a lot of sense to me.) So obviously the K factor is not a
> guideline for the amount of torque allowed, but must be some kind of
> general really rough swag at trying to sum up the total of what is above
> the rotator. I'm not sure that is a good way to sum up the requirement.
>
> Jerry, K4SAV
>
> John Elsik wrote:
>
>
>> >From the Yaesu manual
>> K = turning radius x (antenna + mast weight)
>> The mast weighs around 110lbs
>> So add 55 lbs to each antenna calculation. Then sum the two
>> They give a pretty lengthy example of this in the manual. Metric of course,
>> but the result is the same.
>> John
>> Wa5zup
>>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of K4SAV
>> Sent: Wednesday, March 19, 2008 5:03 PM
>> To: towertalk@contesting.com
>> Subject: Re: [TowerTalk] Does a M2 Orion 2800 fit in a LM354HD top section?
>>
>> Are you sure you didn't get a metric number mixed in with the English
>> numbers? Using Yaesu's method of figuring the K factor, I get 3264
>> ft-lbs for the antennas you have. The G-2800DXA is rated for 6870
>> ft-lbs. You are at 47% of the rating.
>>
>> Jerry, K4SAV
>>
>> John Elsik wrote:
>>
>>
>>
>>
>>> I have a new LM354HDSP crankup tower. I got the tower up, back in late
>>>
>>>
>>>
>> November. That is where the project stopped for the winter. All it is
>> holding up is an inv vee for 80 mtrs right now.
>>
>>
>>
>>> The antennas are a 4el SteppIR and a Cushcraft XM240 on a chrome moly mast.
>>>
>>>
>>>
>> Nothing is installed yet.
>>
>>
>>
>>> I purchased a Yeasu 2800DXA rotor to turn it, but now having second
>>>
>>>
>>>
>> thoughts if the rotor will handle it long term. The "K" factor is 85% of the
>> published rotor rating.
>>
>>
>>
>>> I called Yeasu and they told me to take the weight off the rotor. They
>>>
>>>
>>>
>> suggested adding a second plate and bearing between the rotor and tower top
>> bearing, and take the weight off. Sure did not come away with a warm and
>> fuzzy feeling that the rotor would handle the load.
>>
>>
>>
>>> So I am taking pause and sort of rotor shopping. I realize I would take a
>>>
>>>
>>>
>> hit selling the Yeasu. I would rather be safe than sorry later.
>>
>>
>>
>>> I was looking at the M2 Orion 2800 (rotor only) and a Green Heron
>>>
>>>
>>>
>> controller.
>>
>>
>>
>>> Will the Orion fit in a LM354HD top section? I called Tashjian and they
>>>
>>>
>>>
>> could not answer that.
>>
>>
>>
>>> John
>>> wa5zup
>>> _______________________________________________
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|