[TowerTalk] Add on 3" mast brake?

[Richard Thorne]

How about the DX Engineering RT4500HD. Published spec's are a bit better 
than the 2800.  Not sure if it's enough to make a difference.

Rich - N5ZC

On 11/14/2022 4:58 PM, Grant Saviers wrote:
> 
> 
>  > This post makes me wonder what rotator people with really large 80m 
> Yagi's
>  > like W0AIH use?
> 
> Makes me wonder too, since all high power gear trains have backlash.
> 
> The small PP I had from K7NV showed a surprising amount of backlash, 
> more than Kurt thought it should have.  He also commented that the small 
> unit has the highest total gear reduction and thus the most resistance 
> to turning.  I have a medium PP that needs rebuilt, but am not sure I 
> want to get into it and where would I get parts?
> 
> Ken G., Mr JKantennas, told me the Orion2800 was up to the job on his 
> 80m.  Which caused me to fix up an older 2800 and put it in while 
> waiting for Kurt to rebuild 2 small PP, which with his sad passing are 
> in limbo.  However, the 2800 broke off a gear tooth on the output shaft 
> gear in a wind storm 2 weeks ago.  It had a worn (badly rusted) spline 
> and I tried to fix that with 4 set screws into the shaft female spline. 
> That didn't work, they loosened an deformed and the gear tooth broke.
> 
> I've also learned to cross drill rotator mounting bolt heads and safety 
> wire them.  My tower guy said he finds a lot of loose/missing rotator 
> mounting bolts from the shock, vibration, etc.
> 
> Talking to M2 today I ordered a new output shaft and splined mast clamp 
> plate.  I was told "first time for a broken tooth".  The output shaft is 
> hardened and the plate mating spline coupling is soft and takes the 
> wear.  Replacing both about was worth it re a new 2800 cost.  A learning 
> was if there is spline backlash, replace the top plate since it is the 
> very short end of the gear/spline shaft + plate cost.  Removing the 
> motor is not recommended as the alignment is tricky.
> 
> Also, make sure the center bolt on the plate is well waterproofed to 
> prevent water intrusion rusting the spline.
> 
> Thanks so far for brake suggestions.
> 
> Grant KZ1W
> 
> On 11/14/2022 11:35, john at kk9a.com wrote:
>> This post makes me wonder what rotator people with really large 80m 
>> Yagi's
>> like W0AIH use?
>>
>> I believe that you want to brake the mast and not the rotator which is 
>> not
>> easy to add now. I am told that prop pitch motors originally had 
>> brakes but
>> I am not sure what happened to those mechanisms.  FWIW, I have a 
>> medium prop
>> pitch rotator on my Rohn 65 tower and it easily fits inside, perhaps a 
>> large
>> also fits.
>>
>> GL
>> John KK9A
>>
>>
>>
>> Grant Saviers KZ1W wrote:
>>
>> My 80m 2L beam is destroying rotators (sm PP and Orion 2800). So far no
>> problems with the beam.
>>
>> What is happening is any backlash in the gear train leads to rotational
>> oscillations from the turbulent high wind at my QTH plateau/ridge and
>> results breaking gear teeth off.  The 375# antenna and 100ft elements
>> provide the momentum/jerk at the stop of movement.
>>
>> So am looking for designs of a secondary brake I can fit inside Rohn 65
>> and retrofits to a 3" mast without taking the antenna down and mast out
>> (big crane work).
>>
>> Any experiences, products, ideas, designs welcome.  My shop is pretty
>> much able to make anything in metal.
>>
>> Grant KZ1W
>>
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