I can't speak to todays class of ceramic tubes but in the 70's I built a
number of 3-1000Z amps. The rule of thunb for a well designed AB amp was 2:1,
output power vs. dissipation. So, yes I agree with the Orr's "rule of thumb"
here. The 3-1000Z typically did 2:1 RF out 80m-15m but it did require a well
thought out RF deck. I will not name names here but I saw a dozens of what I
call stressed 4-1000A amps that made it to the 2.5:1 ouput ratio.
It is probably related to the manufacturers design but I have never seen
3KW from an 8877 or even 1600W from a 3CX800... Either something is being lost
in translation or it kinda makes you wonder about the claims surrounding our
modern ceramic tubes...
73's Mike K9MK/5
-------------- Original message from Commander John <crazytvjohn@yahoo.com>:
--------------
>
> Commander John wrote: Date: Wed, 23 Jul 2008 10:23:38
> -0700 (PDT)
> From: Commander John
> Subject: Re: [Amps] Bill Orr comment
> To: Peter Voelpel
>
> Who is this "quack" guru?
> john w9zy
>
>
> ~~~~~~~~~~~~~~~~~~~~w9zy
>
> Peter Voelpel wrote:
> 2-2.5 times the dissipation is normal.
> Assume 1500 out, at 70% efficiency that is 643W dissipation, 1500/643=2.33.
> Eimac claims 75% efficiency on their 3CX3000A7 datasheet in AB2.
>
> 73
> Peter
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Gudguyham@aol.com
> Sent: Mittwoch, 23. Juli 2008 18:30
> To: amps@contesting.com
> Subject: [Amps] Bill Orr comment
>
> I was reading the Bill Orr handbook and on his section about amplifiers he
> says.....A properly designed grounded grid amplifier should produce 2 to 2.5
> times the plate dissapation of the tube in output. He did not put any
> limitations on the statement as to IMD or anything like that. He did not
> say if the tubes ratings would be surpassed (I am sure they would), but I
> think what he was saying is that the tube should continue to make power to 2
> to 2.5 times it's dissapation before it would not make any more power and
> flatten out.
>
> Upon speaking with an amp "Guru" about this subject, he procalimed that
> Bill Orr was a "QUACK". The basis of his claim was that he was never able
> to build an amplifier that obtained that kind of results.
> What say you? Lou W1QJ
>
>
>
> **************Get fantasy football with free live scoring. Sign up for
> FanHouse Fantasy Football today.
> (http://www.fanhouse.com/fantasyaffair?ncid=aolspr00050000000020)
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
>
>
>
>
> W9ZY
> .... Commander John ....
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> W9ZY
> .... Commander John ....
>
>
>
>
>
>
>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|