Sounds like a perhaps a waveform issue.
This is especially critical on rotors that use a
series capacitor on the motor.
The Inverter may not be putting out a good sinewave.
Perhaps it is more like a square wave.
Have you looked at it with a scope?
If it is not a good sinewave, or is dirty, you might be able to
clean it up a little by adding a series iron core choke.
Sometimes a 1:1 isolation transformer or 120 volt variac
will round off the waveform peaks enough for it to work.
73s de Jim
> -----Original Message-----
> From: email@example.com
> [mailto:firstname.lastname@example.org]On Behalf Of Dan Evans
> Sent: Monday, June 20, 2011 3:58 PM
> To: email@example.com; VHF Reflector
> Subject: [TowerTalk] Rotator problems
> I have an odd Rotator problem.
> In my Rover setup, I have an old Hygain AR40 rotor. For the past
> several years I have been having an annoying problem. Whenever I turn
> the antenna the rotor moves to the desired position but instead of
> stopping, as it should, it keeps "bouncing" back and forth several
> degrees. And it will keep bouncing until it over heats, or
> until I shut
> off the power.
> My "work around" has been to switch off the power when it reaches the
> correct heading.
> While preparing for the June VHF contest I discovered it
> doesn't do this
> when plugged into the household 120v outlet. But it does do it when I
> use my deep cycle battery and inverter. So it seems to be a
> power issue.
> I don't believe the inverter is the problem. The rotator is rate at 85
> watts. My old inverter was a 100 watt model, and my current
> inverter is
> a 400 watt continuous / 800 watt surge. So it really
> shouldn't be much
> of a load...
> Any ideas?
> The reason I had it on the bench was to take it apart, check the pot,
> clean and grease the bearings, check the connections, and replace the
> rotor cable. None of which seems to have helped. I'm a bit
> I am considering just wiring up a box with momentary switches for left
> rotate, right rotate, and a meter for direction....
> Oh, load on the rotor for my application is a push up mast, and 3 VHF
> yagis, and cables. Altogether maybe 30~35 lbs...
> Scratching my head,
> Amateur Radio Emergency Service, Clark County Indiana. EM78el
> K9ZF /R no budget Rover ***QRP-l #1269 Check out the Rover
> Resource Page at:
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