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
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