Thanks for the VERY good explanation on this issue.
73's,
Gary...wa6fgi
----- Original Message -----
From: "Peter Chadwick" <g3rzp@g3rzp.wanadoo.co.uk>
To: <amps@contesting.com>
Sent: Thursday, October 11, 2007 9:05 PM
Subject: Re: [Amps] Trimming the transmission line
> The 30S1 is a bit of a special case, since it relies on the length of line
> because of phase changes. Because there's a change in input impedance with
> power level, if the length of line isn't an exact multiple of 90 degrees,
> the input reactance changes faster than the change in the real part of the
> impedance, and thus you get phase distortion. Pappenfus states, regarding
> the 30S1, 'Other transmission line lengths can be used if the attendant
> increase in distortion is acceptable'. If you use a 30S1 with a modern
> solid state transceiver, a differnt length is going to be needed, since
> the length of line for the 30S1 is designed to go with the various Collins
> tube rigs of that era.. And I suspect the input SWR may not good enough
> for a modern solid state rig. It is perhaps arguable that all amplifiers
> should have a special length of line, but whether or not the phase
> distortion introduced is of such level as to be worth worrying about is
> another matter.
> There are other places where line length matters, such as phasing lines
> for vertical arrays, but they aren't trimmed for SWR!
> 73
> Peter G3RZP
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