Hi Marius,
I've gone both ways, stepper motors & gearhead motors, for driving tunable
elements. I've found the gearhead motor route to be the most practical,
especially if you are considering true autotuning from phase & loading sensors.
A small gearhead motor (at 10 RPM or so) can easily drive any of the big RF
switches. Just remove the switch's indexing assembly and add a small wafer to
the shaft for position feedback. My 4CX600 project and 8877 project do this
with a Radio Switch 86 plus another smaller switch for grid component selection.
See the bottom of this page for "excessive motor drive details" on another of
my autotune designs.
http://qsl.net/wc6w/wc6wamps/index.html?fr11.html
I'm slooooowwwly uplosding the rest of the details on this amplifier.
73 & Good morning,
Marv WC6W
http://qsl.net/wc6w/
--- On Sat, 9/11/10, Marius Hauki <rezycle.bin@gmail.com> wrote:
> From: Marius Hauki <rezycle.bin@gmail.com>
> Subject: [Amps] Autotune amplifier. How to implement actuator / system for
> tank switching?
> To: amps@contesting.com
> Date: Saturday, September 11, 2010, 8:08 AM
> I am thinking about making my GS35B
> amp project autotune. A
> microprosessor circuit will remember the correct tune
> settings for
> each band (C1, L, C2) and when I switch bands the amp will
> tune
> itselves to presets that had been previously programmed. I
> have got
> hold of two nice big vacuum variable capacitors, that
> will be
> actuated with stepper motors via pulleys (some gearing /
> reduction) or
> via motors that have a gearbox.
>
> The question is how to implement the PI or PI-L coil
> switching.
> Several of the rugged swithces that are in use on manual
> tune amps are
> quite hard to rotate and needs to "snap" into contact
> engagement. I
> suspect those are not easy to actuate properly via a motor
> / gear
> system.
>
> I have been thinking about different options:
>
> -Several vacuum relays that are electronically controlled
> from a
> control board (will the added capacitance of the body /
> wiring be a
> problem?). Has a solution like this been attempted before
> by anyone on
> this list?
>
> -Normal relays that are electronically controlled from a
> control board
> (will the added capacitance of the body / wiring be a
> problem?) Has a
> solution like this been attempted before by anyone on this
> list?
>
> -A special switch that is designed for "motor actuation"
> (Where do I
> get hold of that and is the cost prohibitive?) Has a
> solution like
> this been attempted before by anyone on this list?
>
> Are there other ways that has been tested in practice to
> implement
> this? (Apart from a roller coil with a motor / gearbox on
> it of
> course).
>
> 73
> LB3HC
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