>
>
>
>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....
>
The technical issues do not change. Not everyone here is familiar with
the DAF circuit. . The groupie-guru element is something I have not
discussed before on the AMPS group.
>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....;)
In English, the word is chew. One saying goes: "I don't chew my bread
twice".
>
>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 ...
There are three doors for humans to this house. I use all three. The
cats have their own door so that they can hopefully avoid becoming dinner
at Mr. and Mrs. Coyote's place.
>- cause you dont bother to look.....
>
>Absolutely nothing personal Rich, I´m just not that good to express
>myself....
>
You are doing rather well.
>By the way, any comment you want to share with us regarding the plots I
>sent you last x-mas?
>
no
>
- later, Lars
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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