Re: [TenTec] Ig drift on amps

["Bob McGraw - K4TAX" <RMcGraw@Blomand.net>]

At the same time, Rich Measures has a nice Excel spreadsheet available on 
his website that does a good job of defining the values for L1, C1, C2 and 
L2 values for a Pi-L network for HF.  In moving transmitters from the BC 
band to the 160 M and 75 M bands, I've used his application on several 
transmitters with excellent results.
73
Bob, K4TAX


----- Original Message ----- 
From: "Bob McGraw - K4TAX" <RMcGraw@Blomand.net>
To: <geraldj@storm.weather.net>; "Discussion of Ten-Tec Equipment" 
<tentec@contesting.com>
Sent: Sunday, February 08, 2009 10:16 PM
Subject: Re: [TenTec] Ig drift on amps


> 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.
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message ----- 
> From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
> To: <tentec@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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