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Re: [Amps] amp with push-pull output and magnetic coupling to the antenn

To: amps <amps@contesting.com>
Subject: Re: [Amps] amp with push-pull output and magnetic coupling to the antenna
From: Ron Youvan <ka4inm@tampabay.rr.com>
Reply-to: ka4inm@tampabay.rr.com
Date: Fri, 28 Jan 2011 20:03:33 +0000
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Gene May wrote:

> 1.  Does anyone know of a source for components or parts that could be used 
> to make such a system?  I am willing to consider taking it/them out of 
> existing assemblies (e.g., military surplus) but would prefer assemble it 
> from "basic" parts.  I won't go so far as to say I'm desperate, but after 
> considerable looking, I am very flexible and open-minded.

   B&W made "plug in" P-P coil assemblies in 100 Watt and 1,000* Watt sizes, I 
am looking for a set 
of each each myself.  The coil sets can all be plugged in and relay switched, 
my plan.
100 Watts is the input coils, I plan on grid driven and input swamped.

> 2.  It is necessary for the Q's of the tube circuit (probably to be around 10 
> to 15) and antenna circuit (probably to be around 1) to be compatible with 
> the range over which the coupling coefficient between the two coils could 
> vary.  As I understand, it is difficult to impossible to get coupling 
> coefficients higher than about .3 using coils that would be compatible with 
> the voltages and currents associated with an output of 1.5 KW.  Comments, 
> please?

   The swinging link (or in the case of B&W a rotating link) adequately loads 
the resonant circuit.
These coils did not have the third harmonic suppression (the second harmonic 
distortion is canceled 
out by the P-P circuit) that we need now so it should be followed by a low pass 
filter for each band 
and the swinging link should be made from coaxial cable, the ridged mw kind the 
size of # 6 wire to 
minimize the capacitive coupling.  (Cross neutralization is required!  And 
Easy!)

   I plan (5 or 6 projects down the road) on using a pair of 4-1000s or Russian 
tubes class "B."
Another advantage of P-P is the absence for the need for a "plate choke."
   The 100 Watt coils plug into a 5 pin tube socket (like the 807)
The 1,000 Watt size (frequently used with a pair of 813's) connector was a row 
of (5 I think) male 
banana plugs.

* not 1.5 kW OUT size, 1kW INPUT size!
-- 
    Ron  KA4INM - If you have any criticism for me constructive or otherwise
                  keep it to yourself, at my age I just don't care anymore.
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