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[AMPS] Re: Calculating input vs output

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Subject: [AMPS] Re: Calculating input vs output
From: gdaught6@leland.Stanford.EDU (George T. Daughters)
Date: Mon, 20 Jul 1998 15:49:42 +0008

hi all,

> Al KE3OK wrote:
> > Hi Gang, is there a formula or standard ratio of input
> to output?  Does this ratio change for different
> amps/tubes/designs/modes/class? 

i didn't reply to this, because i wasn't sure what al was asking.  i 
figured he'd get lots of responses, and he has... the answers have 
been of two sorts, because his question can be interpreted two ways:

what is the ratio of output (rf) power to input (drive) power?  this 
is the "gain" of the amplifier, and is usually expressed in db 
(that's simply ten times the log of the power ratio)

what is the ratio of output (rf) power to input (d.c. plate power)?  
that ratio is the "anode efficiency" of the amplifier, and is usually 
expressed in percent... (it's simply 100*RFpower out/[plate 
voltage*plate current])  the "missing" power (the percentage of the 
anode power supplied that doesn't come out as RF) is converted to 
heat, mostly in the anode of the tube, but sometimes in tank coils, 
plate parasitic suppressors, etc.

i hope this helps to clear up the different answers you're getting, 
al.

vy 73,
  
George T. Daughters, K6GT

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