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

To: Amps@contesting.com
Subject: Re: [Amps] amp with push-pull output and magnetic coupling to theantenn
From: Commander John <crazytvjohn@yahoo.com>
Date: Sat, 29 Jan 2011 21:30:56 -0800 (PST)
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Hi
I had one of those B&K set ups with the HDVL coils and a swinging link with a 
adjustment shaft from the front panel on a pair of 813 in Push Pull.
The 1952 handbook had one described as a amp construction.  One would want to 
check handbooks from 1950 through 1960.  The old crap from the  WW2 period and 
before had the antenna taped on to the tank coil.  As one followed the 
handbooks through the years first it was adjustable link couplings. Then in the 
later 50's introduced the link capacitor so the link didn't swing.
I like the 1959 or 60 handbook for the most modern information on this subject. 
Grounded grid and the Pi Net went strong from about 1958 onward with the 
introduction of single sideband and Linear amplifiers that were easier to 
construct.
john W9ZY 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
B&W actually had a swinging link version that had a 1/4 inch shaft 
connection to swing the link from the panel - and the swing arm also took a 
plug in link for various bands . The low freq link had two layers of turns 
concentric with each other . I built a pp 813 rig with the olde B&W plug in 
coils and links- damn near killed myself when one day I had turned off all 
ac - forgot to chicken stick the coil - and reached in to grab the coil and 
got knocked across room -  the plate contactor had welded shut and the 866's 
had not cooled off enough to quit rectifying yet .

Good thing is I survived and you and BET I never do or did anything that 
stupid again.

Hank K7HP


>
> <<<However, as many readers of this probably know, it is, ah, "uncommon"
> now.>>>
>
> Heh heh, tell that to all the guys running BC-610s.  It sounds like you 
> are
> trying to construct a linear amp but with a "retro" design.   If you have
> not already done it, I'd start looking for old ARRL Handbooks from before
> ~1952, as they'll have a lot of link coupled tank circuit designs, but
> mostly for AM and CW rigs.  They can be found at hamfests.  What I have 
> seen
> had the jack bar link connected to the feedline to the antenna.  The guys

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