There was an article in QST, about a year ago, regarding homebrew
remote antenna tuner with just a few controls.
Something like L-network, both C and L are driven by the same motor,
but there is a gear between them, so for one full cycle of roller
inductor there is like a hundred turns of variable capacitor. The only
controls you need are forward/reverse buttons for your motor.
On Mon, Nov 24, 2008 at 8:26 AM, Dennis OConnor <email@example.com> wrote:
> Pete - right on!
> I am dismayed by the lack of the old ham spirit that I see in todays
> Pete pointed it out quite clearly...
> 12 relays @ $3 a pop - $36
> Roll of quarter inch dia. soft copper tubing (home depot) - I dunno, maybe $50
> 2X4 Sheet of .060" aluminium - maybe $50 ( I buy a half dozen full sheets at
> a time so I don't know price of small amounts) Lots less if you harvest some
> scrap aluminium from old freezers, etc.
> Anyway, cobble up a test coil by winding some turns of #14 on a 2 - 3 inch
> pvc pipe and get an old variable condenser and some jumpers, and use them to
> test tune each band... Measure the inductance and capacitance you find for
> each band......
> Wind a coil from the copper tubing to the found value(s)..
> Make the condensers by cutting two plates from the aluminium sheet and
> spacing them apart with little buttons of plastic - lexan from the hardware
> works good - and adjusting the overlap of the plates for final tune... When
> tuned squirt a dab of crazy glue on the buttons to lock the plates into
> Repeat 5 more times and voila - 6 bands
> Another $20 for a covered plastic storage bin to mount the parts and relays -
> and for ~$150 you have a six band, switchable tuner, that will take ALL the
> power your amp can make and then some....
> And for lots less than $150 if you have some scrounging skills...
> denny / k8do
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