G3SEK:
>>Yes, please send me a copy, Lars.
>>
>>Can you also say what tube, what anode voltage, and how the screen
>>voltage was generated (voltage doubler/tripler? solid-state rectifiers
>>or vacuum tubes? Value of DC smoothing capacitor?)
>>
>>Something tells me that all of these details could be important...
>>
>>One risk with the G2DAF configuration is that a screen rectifier with
>>poor efficiency would tempt the user to overdrive the whole amplifier in
>>order to generate sufficient output. Thus there could be a lot of
>>variation between a good G2DAF linear and a bad 'un.
>
AG6K:
>There should be little difference if the screen potential is not
>constant.
G3SEK:
>>
>>The choice of tube could also make a big difference between good and
>>bad. As far as I know, all the original published work was done with
>>813s and 4-125s.
>>
>813s and 4-125s have screens that follow the 3/2 power law.
>
>>In the late 1960s I had my education about SSB from listening to G2DAF's
>>80m net, whose members were bitingly critical of poor-quality signals -
>>so much so that like many other listeners I didn't even dare to check in
>>for a report! Certainly there were several G2DAF amplifiers in use on
>>that net, and if they hadn't generated a clean SSB signal the owners
>>would have been flamed to a crisp after the first transmission.
>>
>>Later I met Dick Thornley a few times, heard him talk to clubs, and saw
>>his construction work. He was a perfectionist in every detail
AG6K:
>- - except one.
>
G3SEK:
>>and he owned his own spectrum analyser which was a real rarity in those days.
>>Certainly he was the first to ask for criticism about his own signal
>>quality. He also wrote a regular magazine column on SSB techniques when
>>this was all new, experimental stuff.
>>
>>So I am in two minds about his amplifier. Part of me says "This should
>>not work."
>
AG6K:
>It isn't that it doesn't work, rather it does not deliver on the
>seemingly-miraculous promise of Class-C efficiencies And good linearity.
> By supposedly delivering the miraculous, a guy takes on prophet-like
>status, whereupon groupie types will symbiotically follow and sing his
>praises for crumbs of approval. . We see a similar mechanism in
>religious cults. The silent Bhagwan drove a fleet of Rolls Royces whilst
>his groupies swooned. Meanwhile, back at the Rolls Royce dealer in
>Seattle, the salesmen said that the Bhagwan had plenty to talk about
>during his frequent purchases.
>
G3SEK:
>>But having been around at that time, and known some of the
>>people involved, I also feel that G2DAF would not have given his name to
>>anything that put out a poor-quality signal.
>>
AG6K:
>The G2DAF-amp. signals I listened to on the air had tolerable distortion
>levels on frequency. The problem was the -22db/-23db adjacent splatter
>level when recommended amounts of grid current were being used. However,
>when zero grid current was used, splatter understandably decreased.
>After complaints of splatter, I observed that G2DAF proponents would
>Temporarily lessen grid current to make peace.
>- later, Ian
>
>
>Rich...
>
SM3BDZ:
Brilliant comments Rich. Somehow I feel Ive read you saying the same things
before....
Pse excuse my bad humour Rich, but here in Sweden we have a special word when
cows tjew and tjew
and tjew their food over and over again. I dont know the english word for that
syndrom, but somehow - cant help it- it gives me associations to your
argumental technique....;)
If you have two doors to your house, I´m quite sure that you have never ever
used more than one and perhaps
cant even find the other door - cause you dont bother to look.....
Absolutely nothing personal Rich, I´m just not that good to express myself....
By the way, any comment you want to share with us regarding the plots I sent
you last x-mas?
73 de Lars/SM3BDZ
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