[TenTec] Ig drift on amps

Bob McGraw - K4TAX RMcGraw at Blomand.net
Sun Feb 8 23:16:47 EST 2009

Sorry, I didn't read it that way.  And in a Pi-L network the output C 
components are by design at the midpoint of the network.

Yes, without knowing the values of L, it is a challenge {best guess}  to 
figure the correct values for C and the network center is unknown as well.

Bob, K4TAX

----- Original Message ----- 
From: "Dr. Gerald N. Johnson" <geraldj at storm.weather.net>
To: <tentec at contesting.com>
Sent: Sunday, February 08, 2009 10:14 PM
Subject: Re: [TenTec] Ig drift on amps

> On Sun, 2009-02-08 at 21:36 -0600, Bob McGraw - K4TAX wrote:
>> The output of the amp is indeed a Pi-L network.  These work great and 
>> have
>> been in BC transmitters very successfully for years.  I wish more 
>> companies
>> would use Pi-L networks in their amps. Better attenuation of harmonics,
>> lower currents in the coils and components and a better match.  All at 
>> the
>> cost of increased costs.
>> I can't imagine any amp today being able to handle a 300 ohm load on its
>> output at rated power.  That's an SWR of 6:1.
> He was talking about the design impedance at the junction of the Pi and
> the L. Higher than the load Z, lower than the plate Z. 300 to 600 ohms
> are common values for that mid point in the output network. Higher takes
> more L section coil and a higher loaded Q but allows smaller load
> capacitors.
>> 73
>> Bob, K4TAX
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