>
>
>
>
>>From: Jon Ogden <na9d@speakeasy.net>
>>To: Billy Ward <billydeanward@hotmail.com>, Amps Reflector
>><amps@contesting.com>
>>Subject: Re: [AMPS] Conjugate Matching In Class B and C Amplifiers
To: <amps@contesting.com>
>>Date: Tue, 15 May 2001 22:42:57 -0500
>>
>>on 5/15/01 4:45 PM, Billy Ward at billydeanward@hotmail.com wrote:
>>
>> > Linear Amplifiers may or may not be conjugately matched. For maximum
>>power
>> > transfer to occur both in and out, and for the amplifier to be
>> > unconditionally stable, there must be a simultaneous conjugate match.
>> > This is not always easy as the input match affects the input match and
>>visa
>> > versa. However, it CAN be done.
>
>
>>
>>Conjugate matching is not required for unconditional stability. That's
>>incorrect. Many low noise amplifiers are purposely mismatched because
>>simultaneous conjugate match generally does not equal minimum noise figure.
>
>I was not taking minimum noise figure into the context of what I said. I am
>willing to learn. I purposely mismatch for best noise figure. in low-level
>stages, also. However, I am curious how that makes my statement incorrect
>that Conjugate Matching is not required for unconditional stability.
>
>
>>Unconditional stability is determined by K factor of Linville's theorem (if
>I remember the name correctly, it's been a while.).
>
>I, also, do not remember the theorem name but it sounds correct.
>>
>>Additionally, adjusting input match does not necessarily always affect the
>>output match and vice versa. I am trying to think whether or not your
>>statement is correct. Too many cobwebs upstairs right now.
>
>Well, I came in on this thread late and my statement was referring to power
>circuits and it may not apply in low-level but I have spent my life in power
>design and manufacture.
>>
>>Generally speaking of this subject, I had always thought that the
>>efficiency of an amplifier and whether or not you simulataneously match it
>>were independent. It wasn't until coming onto this reflector and reading
>>stuff from the likes of Dick Erhorn that some people feel that a conjugate
>>match guarantees 50% efficiency or less.
>
>I haven't read after Dick Erhorn as I am on four reflectors and don't get to
>read everything but if he is teaching along this line I will pay more
>attention.
>
>However, The power transfer arrived at by the Conjugate Match is most easily
>proven by understanding the standard POWER THEORUM which states that maximum
>power transfer will occur when the resistance of the load is equal to the
>resistance of the driver. Then carry that further by realizing that when
>the impedance of the driver is equal in value but of the opposite sign to
>that of the load, it is, of course, cancelled leaving only the real part. I
>realize that you have had a good grasp of resonance for many years with your
>experience, but some folks over look the fact that when resonance occurs, it
>brings us back to the standard POWER THEORUM, so looking at a voltage
>divider which has equal resistances leaves half of the power across each
>resistive element which equates to 50% efficiency.
>
yea, verily, Billy
cheers
>>....
- R. L. Measures, 805.386.3734, www.vcnet.com/measures.
end
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