Topband: high power filters

[Dick and Adele Bingham]

Greetings everyone

See my comments below ==>
.........................................................
Message: 4
Date: Tue, 28 Feb 2006 06:01:24 -0500
From: "Tom Rauch" <w8ji at contesting.com>
Subject: Re: Topband: high power filters
To: "Dick" <knaap159 at zonnet.nl>, <topband at contesting.com>

> I want something that I can use behind a 160m MOSFET
amplifier, which
> haven't much filtering in the output.
> The amp has to be runned in a multi-multi station.......

BIG SNIP

The only good solution is to build a simple multiple section
low pass filter using transmitting components. Don't try to
use one of the narrow extra-deep notch resonant filters that
have second harmonic traps and the like. In the first place
you probably won't need it, in the second place voltages and
currents will be too high, and in the third place you might
not terminate the PA stage with the proper load impedance on
harmonics to prevent high voltages from damaging the FET's.

ANOTHER BIG SNIP

73 Tom
......................................................
Tom and others have provided many good suggestions. 

You might also check some of the construction techniques 
provided in a _Microwaves & RF_  magazine article titled 
"Designing High-Power Series Inductors And Shunt Capacitors" 
published October 1987 pp 97-98,  101, 103, 105 and 107.

Some of the ideas presented may be a bit large on 160-Meters
but definitely useful as one goes higher in frequency..

73 - Dick - w7wkr


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