On 3/9/2024 5:43 PM, wb0gaz via Amps wrote:
I've put the covers back on and it's restored to it's "hangar queen" status at
this point. If you find yourself on I-70 westward (I don't know your home QTH) drop me a
line! As far as I can tell, barring power transformer failure (no signs of that), it's
probably a decent candidate for returning to service.
Hopefully, some time this spring, I can take you up on that! I'm in the
SoCal desert, BTW.
As far as 2M PA design using lumped plate tank at similar power levels, YU1AW published a
couple of designs (see https://www.nd2x.com/yu1aw-2m-easy.html). The subtitle of the page
is "144MHz PAs designed using HF techniques". I'm not aware of anyone that's
reproduced the designs (for a single or dual GI7 tube) so I don't know if they were
considered successful.
A long, long time ago, in a land far, far away, my Elmer, W6GGV (SK,
like so many Elmers amongst us), played with tank circuits like that.
Together, we designed and built several amplifiers and V/UHF
transverters during the '70s using what Hank called "Meander Lines" (I
think the term had been coined by others for the same purpose). The
inductors were copper wire or tubing lengths that were folded back on
theirselves, much like what K2AV has most-recently done to create his
FCP replacement for full-size radials on the lower bands, except much
smaller scale, of course. We used such techniques on several equipment
up through 220 MHz using tubes such as the 4CX-series and 8874s (this
was when the latter were both commonly-available and affordable).
Efficiency was about the same as a normal stripline V/UHF tank: 55% -
70% or so. The advantage was since the lumped L was folded on itself, it
occupied a whole lot less space than an equivalent stripline. It wasn't
a ground-breaking idea, by any means, as Hank got the inspiration from
some old VHF designs that the late Frank Jones (don't remember his call
now... W6A-something?) originally published back in the late '30s
through '50s.
Anyway, thanks to everyone who commented on reflector or by e-mail, taken
together I've decided to let sleeping amplifier lie...
Glad to hear that!
Steve, K0XP
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