[Amps] Permeability tuned tuning coils, with taps?

[Saandy]

Somewhere in the seventies, in the ARRL handbook, there appeared a 6 meter
amplifier tuned variometer style with a one turn shorted coil, rotating in
the stationary tank coil. It wasn't very wideband as I can recall, but it
worked.
It seems to me, Chris, that you won't have any qualms about plagiarism: it
was definitely more than 20 years back!
Alex	4Z5KS 

-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Chris Wilson
Sent: Wednesday, January 15, 2014 8:25 PM
To: amps at contesting.com
Subject: Re: [Amps] Permeability tuned tuning coils, with taps?



Wednesday, January 15, 2014, 10:22:05 AM, you wrote:


> I vaguely remember seeing a 4 channel, 2-10 MHz, 100 watt output 
> commercial amplifier using three 'instant heat' 6146s (actually 
> QZ06-20)which used permeability tuning on the PA coils. I think the 
> coil had three taps to cover the frequency range: it was driven from a 
> nominal 10 watt input SSB packset, and ran from a 12 volt vehicle 
> supply, with a germanium transistor DC-DC inverter. The packset was 
> mainly germanium transistors, too....That was 50 years ago.....

> 73

> Peter G3RZP

Maybe people wonder why I ask? I have a Henry 2000D RF generator a friend
and I are converting to a 10n meter linear. It's near as damn it done now, a
simple thing for many on here, a challenge for us beginners, as I had to
make the PSU and control stuff from scratch.

I bought two big vac caps off Ebay a while back, new old stock. One seems
fine, the other arcs on test at 50% below its rated DC volatge.
These things are *EXPENSIVE* new. Used ones are a lottery, as are old stock,
as there's no way to test the depression inside them without doing an HV
test, after you've bought the thing. So, I was looking at how Henry used a
brass slug permeability tuned tuning coil of heavy copper tube, instead of a
variable tune capacitor, and a sheet metal flapper cap for loading. I was
wondering if at a later stage I could plagiarise the design to make a 20
meter or even a 20 / 40 meter version and make a longer coil, with taps for
other frequencies, and just have to use one vac cap for load? I am in the
race car engineering business, so have good fabrication facilities, the
hardware for a bigger brass slug tuned circuit would be pretty
straightforward. Photo of the Henry 2000D deck is at
http://www.gatesgarth.com/henry6.jpg

Thanks everyone.




--
Best regards,
 Chris                            mailto:chris at chriswilson.tv

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