Roy, I agree. This came up because I found a schematic for a pair of
Gi-7b's and was kinda using it as a guide. Meanwhile back at the ranch, I
looked up the formulas for calculating the values in a pi-network in the
ARRL Handbook, and put them into a Microsoft Excel spreadsheet.
Interestingly, when I did the calculations for my operating conditions, and
those in the schematic, they were far apart as far as values are concerned;
thus the reason for the inquiry here on the reflector. I will probably go
with the values that provide the correct match for the operating conditions
in my amp. Thanks for the response.
73,
Mike, W5UC
http://members.cox.net/w5uc
----- Original Message -----
From: "Roy Koeppe" <royanjoy@ncn.net>
To: "Amps Reflector" <amps@contesting.com>
Sent: Sunday, July 02, 2006 9:32 AM
Subject: Re: [Amps] again
> This question,
>
> "There clearly are individuals on this reflector who are more
> knowledgeable than me, so I will ask this question again, but in a
> differently worded form. How does the impedance of the PA tank affect
> the over-all efficiency of the amplifier? W8JI said yesterday that a
> tank whose impedance is, say 2100 ohms, and connected to a Pa with a
> calculated load impedance of 1333 ohms would produce a very efficient PA
> but it would have poor linearity. BUT, what happens to efficiency if
> the tank impedance matches the load impedance? Again, how does the
> impedance of the PA tank affect the over-all efficiency of the
> amplifier? Inquiring minds want to know."
>
> Hi,
>
> I think your question is of a much more elementary nature than others
> have assumed it to be. In the case of a typical tank circuit having
> typical operating Q of say 12, when you adjust C1 and C2 for maximum
> output, you are indeed adjusting for an impedance match of the tube and
> the load and for maximum efficiency all at the same time without
> consciously or deliberately thinking about it.
>
> 73, Roy K6XK
>
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