On Apr 3, 12:16 am, Art Unwin wrote:
On Apr 2, 11:31 pm, Rick Frazier wrote:



Art Unwin wrote:
Had a bit of luck when assembling the antenna to the pan and tilt
mechanism
prior to placing them on the tower. The PM motors do not have brakes
on them!
Fortunately the leverage of the tilting does not overcome the motors
inertia and I am in the clear.
For the future any ideas on a braking means to ensure stabilility in
position?
Both motors use chain drives and I suppose I could use solenoids to
tighten the chain
Regards
Art.

Most permanent magnet motors will resist rotation if you short the input...
When not driving with a voltage, place a short across the leads. This
essentially has the motor acting as a generator into a dead short, which
makes for significant torque to overcome the subsequent rotational
resistance. Not as good as a wedge (like many commercial rotators) or a
really high gearing ratio (worm and gear or worm and sector), but if
you've already got a reasonable gear reduction it may be all you need...

--Rick AH7H

Thank you very much for that.Fortunately the system appears to be
stable enough
as the antenna and mesh dish is very light and minimul wind
resistance.
Regards Art

Pan tilt and revolve now working perfectly. Antenna does not exceed
3.2 to 1 from
!.8 upto 170 Mhz just like a log periodic tho it can be adjusted at
any frequency
if I felt the need. Today I will be checking out the TV stations and
tonight
I will get on the air without the amplifier. Life is good
Art