[AMPS] G2DAF Circuit

[measures]

>
>Gents,
>
>I have to say that Colin and Marv seems to be the most open minded people
>on this reflector at the moment. At least they try to understand what is
>going on and even suggest some improvements.
>
>Two tone tests have been used as a standard to evaluate amplifiers since
>donkeys years. Now this test is not telling the truth say's the gurus.. ok,
>I accept the doubts on given grounds.
>But maybe we should start testing other amps than DAF's without using the
>two tone test. A poorly regulated screen power supply in a grid driven amp
>should maintain a pretty stable voltage with a two tone constant modulation
>not giving away that the amp would sound bad when modulated by speech. True
>or not .. ?
>
>Lars, SM3BDZ has published a number of plots on his website showing the
>performance of his DAF amp under different conditions. To rule out "the
>error" of a two tone test on a DAF he has plots of speech instead. Plots
>were made using first class commercial test gear. Check them out and you
>will see that the thing works.
>
>But I do most certainly agree with Marv and Colin that the DAF circuit is
>not going to work with every tube on the shelf, the 4CX250's for instance
>are a NO GO for sure. Just like some tubes don't work in GG. 
>
>One fellow on this reflector who certainly doubts the DAF circuit found me
>on the band by chance one time and listened carefully to my signal He
>reported on the reflector that it was clean and the IMD was indeed ok. But
>we must of course rule him out as he knew my call and could possibly be "a
>kind fellow". 
>
>Tom, you are correct about people reporting "excellent quality" to signals
>that sound terrible just because they lack knowledge or maybe sponsor
>"friendship". Therefore it is essential that bench tests are carried out
>and when testing on the air you must know that the fellow(s) are checking
>your signal out have the knowledge and the integrity needed. Very true.
>
>Rich will not check a signal out if he knows that the guy transmitting
>knows he is listening... follow me.. ? 

True.  There were too many instances of DAFers backing off on grid 
current if they knew I was making a measurement.  

> So, I can never get him to check my
>signal out with his proffessional methods/ears as we never meet on the
>bands and we can't make a sked because then I migh be cheating in his
>opinion.  
>
>So I continue to populate the bands with my DAF amp and get clobbered in
>the contests from people moving closer and closer in frequency because they
>are able to do so without suffering. 

You could obtain maximal peak anode current by regulating the screen at 
the max. rating. 
>
>I hear so many poor IMD signals on the band where I know the guys are using
>state of the art GG or grid driven amps that I am convinced that the -35db
>two tone IMD they "should" produce is just BS. Then again, there are many
>amps of the same kind that sound marvellous. What's the difference ? Let's
>find out !!!!!!! Let's start measuring speech modulated rf instead of
>steady two tone rf on ALL amps!
>
Amen to that, Peter

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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