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@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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