The amplifier shown is not permeability tuned but uses a copper cylinder,
may be silver plated, to
reduce inductance of the coil. It also reduces Q somewhat. These amplifiers are
fixed frequency and are usually
on 13.56 MHz or twice that 27.12 MHz ISM bands. Usually used with plasma
generators. This method
is only good for a percent or so change in inductance.
When one is converted of "10 meters" it is usually used a bit lower in
frequency. Not in the ham band.
Just like all the 10 meter amplifiers listed on Eb@!.
73
Bill wa4lav
________________________________________
From: Amps [amps-bounces@contesting.com] on behalf of Chris Wilson
[chris@chriswilson.tv]
Sent: Wednesday, January 15, 2014 1:24 PM
To: amps@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@chriswilson.tv
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