Hi Jan,
I've been down that path 4 times. Once 20 years ago and more
recently for 3 amps under construction.
The are:
A 4CX1500B with stepper motor driven Plate & Load caps plus Pi, L
& Grid roller coils. See: http://tinyurl.com/27qzs for some old photos.
A design with 9 stepper motors driving 5 caps & 4 coils -- Don't
ask what for!
A Transistorized design with 5 gearhead motors driving 4 caps and
a bandswitch.
A 4CX600JA(x2) with gearhead motor driven Plate & Load caps plus
a bandswitch -- The simplest configuation See:
http://wc6w.50webs.com/wc6wamps/index.html?fr20.html/
for a.... parts list.
In the design process, I considered the relative suitability of
relay selected fixed components versus continuously variable parts.
Motor driven designs with lumped variable components were selected in
each instance based on cost & complexity. Viewing the link you
included confirms my research! Here in the states, suitable vacuum
caps may be had surplus for $100-$200, add surplus gearhead motors for
$10-$20 each. Finally, a couple of gears plus a 10 turn pot and viola!
Motor driven tuning.
Roller coils were included in all my tube designs excepting the last
one where the plate choke problem will be "eliminated". See:
http://wc6w.50webs.com/wc6wamps/index.html?fr62.html/
For tune & load sensing, I've included ancient discriminator
circuitry similar to that shown at:
http://wc6w.50webs.com/wc6wamps/index.html?fr432.html/
Single Sideband Systems & Circuits (any editon) by Sabin & Schonike
also details these designs.
A PIC microprocessor is used to determine the operating frequency by
direct counting.
See: http://wc6w.50webs.com/wc6wtest/index.html?fr10.html/
And then to recall "preset" tuning positions from an EEPROM. Final
tuning is implemented by allowing the discrimator & load sensors to
drive the motors directly in an analog servo loop. The resulting
postions are then updated in memory.
It sounds almost easy when described in screen ink! :-)
73 & Good morning,
Marv WC6W
-- jan <jan@on6zg.be> wrote:
Hi,
Has anyone tried on building an autotune HF amplifier? Something like
the acom 2000 or like this http://kotisivu.mtv3.fi/oh3bu/ampproject.htm ?
I´m interested in ideas on making it with a processor.
73 Jan, ON6ZG.
*
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