I'm considering building a remote controlled balanced tuner. Some type
of low RPM motor 12V reversable motor is what I have in mind to accomplish
the tuning. I will have two fairly hefty variable caps to turn along with
a moderatly sized roller inductor.

Can anyone here recommend a particular type motor, and a reasonable
source for the the type of motors I need? Tnx.


Ed K7AAT

I'm considering building a remote controlled balanced tuner. Some type
of low RPM motor 12V reversable motor is what I have in mind to accomplish
the tuning. I will have two fairly hefty variable caps to turn along with
a moderatly sized roller inductor.

What you're probably going to want is a gearhead motor, with a
relatively low RPM rating (1 - 4 RPM is probably the right sort of
range). These have plenty of torque, and you can probably slow down
the rotation even further by using a lower DC voltage or by pulse-width
modulating a 12 VDC drive.

It'd be worth checking out a 24 VDC gearhead motor - it would run at a
slow speed on 12 VDC but might well have plenty of torque to rotate a
cap or inductor.

You'll need some sort of external limit-switch arrangement (e.g.
lever-type microswitches with bypass diodes) to cut off the drive
current when the inductor reaches the end of its range - gearhead
motors have more than enough torque to drive the inductor into its
stops and damage it.

Can anyone here recommend a particular type motor, and a reasonable
source for the the type of motors I need? Tnx.

Check the various surplus outfits on-line: All Electronics, Ocean
State Electronics, Electronics Goldmine, etc.. Going prices for DC
gearhead motors seem to be in the $10-$15 range. Goldmine has some
small gearhead motors (3 RPM at 6 volts) for $12, which might do the
job.

Also, check local surplus-machinery stores if there are any in your
area, and local hamfests/swapmeets. I picked up a bunch of 24 VDC
gearhead motors for a buck apiece at one of the latter.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

electric screw driver.

"Ed" wrote in message
. 192.196...


I'm considering building a remote controlled balanced tuner. Some type
of low RPM motor 12V reversable motor is what I have in mind to accomplish
the tuning. I will have two fairly hefty variable caps to turn along with
a moderatly sized roller inductor.

Can anyone here recommend a particular type motor, and a reasonable
source for the the type of motors I need? Tnx.


Ed K7AAT

I'm considering building a remote controlled balanced tuner. Some type
of low RPM motor 12V reversable motor is what I have in mind to accomplish
the tuning. I will have two fairly hefty variable caps to turn along with
a moderatly sized roller inductor.

Automobile electric-window motors should do the trick. I had to replace
one once and was impressed by it. But don't buy a new one; visit your
local auto junk yard!

--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

Hobby Engineering has a bunch of gearmotors...

http://www.hobbyengineering.com/SectionM.html#IX1415

I bought three to remote my tuner. Plenty of torque to turn the caps
and inductor switch in a "1500W" MFJ tuner. They're only $5.50 apiece
new.

They're also all-plastic gearboxes and output shafts, so you don't have
to worry about insulating shaft couplers, etc.

My gut feeling is that the ones I bought (Gear Motor 9: Right Angle
Shaft) could be a bit undersized to turn a roller inductor, especially
since you probably want to go a bit faster.

http://www.n3ox.net/projects/servo has info about my remote tuner.

73,
Dan
N3OX

Thanks, Dan. Yours was a different take on what I was considering.
Will look into it.

Ed



" wrote in
oups.com:

Hobby Engineering has a bunch of gearmotors...

http://www.hobbyengineering.com/SectionM.html#IX1415

I bought three to remote my tuner. Plenty of torque to turn the caps
and inductor switch in a "1500W" MFJ tuner. They're only $5.50 apiece
new.

They're also all-plastic gearboxes and output shafts, so you don't have
to worry about insulating shaft couplers, etc.

My gut feeling is that the ones I bought (Gear Motor 9: Right Angle
Shaft) could be a bit undersized to turn a roller inductor, especially
since you probably want to go a bit faster.

http://www.n3ox.net/projects/servo has info about my remote tuner.

73,
Dan
N3OX

My thanks to Dave P, Dave, Dan, and Myron for the input. All was
useful, and has given me plenty to think about before I settle for any one
solution.

Thank you.


Ed K7AAT