SV: [AMPS] daf amplifier circuit, on air testing...

[Lars Harlin]

-Snip-

> Twas I who mentioned Norms amplifier, both Rich and I had 
> many a conversation with Norm about the circuit. Rich convinced 
> him to retrofit his circuit with something more conventional. 
> Since I know what he used, let me tell you what was involved. 
> 
> A portion of the drive signal was used to control the screen 
> current potential. His notes to me were for a dual 4cx250 amp. 
> The circuit details show most of the work done with solid state 
> devices although a tube equivalent was available. 
> 
> I'm under the impression one daf circuit actually uses rectified rf 
> for the applied screen potential. This seems a rather odd arrangement 
> to me as a portion of the actual rectified drive supplies the screen 
> power.  Norms circuit was a pair of hv transistors used to control 
> the screen potential from a power supply.  The circuit is a much higher 
> z load on the drive source vs the daf circuit I've seen on the web site. 

As Colin, K7FM correctly states; There is one *important* difference. The time 
constant in Norm´s screen circuit was way to slow !!

> Would this change the end result..?  

It most certainly would!

>The dynamic screen potential is 
> the tell-all. Both designs would probably place  lots of "el torro
> poo-poo" 

Now, if your only reference is one guy with an appearantly flawed design - then this
truly is a "paper brain statement" !


> :Running a DAF amp for a couple of years now I can say that it is good
> :design and I get NO complaints for splattering or sounding bad. (Using a
> :similar tube as in SM3BDZ amp, a QBL5-3500)
> 
> If your blowing holes in the band, others might think you just 
> another contest operator. 

??

>If I heard you on the bands, I'd say 
> something quick. Reference "The Emperors New Cloths" for 
> a similar example.  (Han Christian Anderson)  Sorry, I had to 
> say that at least once in my life...

Guess you would gain a lot if You work on your arguemental technique...


Finally, I´m no salesman of the DAF amp and I really dont care if you never ever think
of using that circuit. For me, the whole idea with this issue was to maybe learn something
as this is supposed to be a knowledge based reflector.  I´m in doubts....

73 de Lars /SM3BDZ


--
FAQ on WWW:               http://www.contesting.com/ampsfaq.html
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm