Here in the USA ALL Electronics had 12volt 6RPM DC motors. I drive my large
4600v variable with it using a DC pulse width motor speed control. The motor
control was around $22 as a kit in the USA. I would actually like about 3RPM
since the motor control slow speed needed for fine tuning is in a small
range. I could gear it but a mechanical mess. A simple DPDT switch is used
to reverse direction.

Check your electronic parts dealers to see if they have motor with built-in
gear boxes. Best way to do it.

Dick N3HKN
PS: My loop is 1 meter on a side square and is used on 20 meters in the
attic. I have set it outside where the noise level is less but on really
cold days the motor will not turn. Used a simple plastic container from a
local discount store. I'll stick to the attic since I have a GAP vertical as
well. Yes, they are comparable given the dipole like pattern of the loop.


"Owen Duffy" wrote in message
...
On Sat, 08 Oct 2005 06:26:31 GMT, "Lee"
wrote:

To continue the saga......

I fitted a variable capacitor to my 10 foot circumference 1mtr loop and am
able to tune 80 to almost 15 meters...works well..but.........

How to fit a motor drive !!!.....there seems to be nowhere to acquire
cogs,
pulleys or gear sets....no model shops around that carries components,
that
i`ve googled for anyway..(now when i were a lad! ).... ;-)

Can you imagine how fast that electric motor turns the capacitor, even
with
reduced voltage???..you have to be quick i can tell you or you miss the
sweet spot heh,heh....

Seriously, any ideas to slow the tuning rate will be most welcome .

Assuming it is a permag motor, reduce the motor voltage... add a
current limited driver to limit the torque, an electronic shear pin if
you like... except it doesn't shear.

I am assuming that you are trying to tune the reactance out, to
achieve an acceptable VSWR on the line to the ATU/transceiver. Have
you considered automating the capacitor drive. You could build a phase
detector (between V and I at the antenna input) as a sensor to control
the motor drive.

Owen
--

"Adelphia" wrote in message
...
Here in the USA ALL Electronics had 12volt 6RPM DC motors. I drive my
large
4600v variable with it using a DC pulse width motor speed control. The
motor
control was around $22 as a kit in the USA. I would actually like about
3RPM
since the motor control slow speed needed for fine tuning is in a small
range. I could gear it but a mechanical mess. A simple DPDT switch is used
to reverse direction.

Check your electronic parts dealers to see if they have motor with
built-in
gear boxes. Best way to do it.

Yes, thanks Lee....G6ZSG......


Dick N3HKN
PS: My loop is 1 meter on a side square and is used on 20 meters in the
attic. I have set it outside where the noise level is less but on really
cold days the motor will not turn. Used a simple plastic container from a
local discount store. I'll stick to the attic since I have a GAP vertical
as
well. Yes, they are comparable given the dipole like pattern of the loop.

On Sat, 08 Oct 2005 12:58:53 -0000, Lee
wrote:
Hi Lee,
Some years ago i used a 1 RPM reversible dc motor from Edmond Scientific
supply. you may want to look see if they still carry them if not an Email
to them may produce the Manufacter's name. It work very well with my home
brew 30 to 15 mtr Mag loop.






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