[Amps] Fwd: Re: Bill Orr comment

[k9mk at flash.net]

     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 at 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 at contesting.com [mailto:amps-bounces at contesting.com] On 
> Behalf Of Gudguyham at aol.com 
> Sent: Mittwoch, 23. Juli 2008 18:30 
> To: amps at 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 
> 
> 
> 
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> .... Commander John .... 
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> W9ZY 
> .... Commander John .... 
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