[CQ-Contest] Re: Bandpass filters, front end protection
Marijan Miletic, S56A
artinian at siol.net
Fri Nov 9 19:59:51 EST 2001
All you need to reduce input drive power requirements for SB-220 is a short
piece of wire to connect grids directly to the ground improving the
amplifier operational stability at the same time!
Very good Pi type input filters on SB-220 may require some tuning after that
in order to achieve perfect 1:1 input SWR.
The best bandpass filter article was written by OM Tom, DL7AV in the very
first issue of CQ-Contest journal. L/C circuits have better Q then coaxial
cables.
73 de Mario, S56A, N1YU, proud owner of SB-220 with original PSU
unfortunately limiting output power to 1 kW.
----- Original Message -----
From: dennis o'connor
To: n4zr
Cc: cq-contest
Sent: Friday, November 09, 2001 6:23 PM
Subject: Re: [CQ-Contest] Re: Bandpass filters, front end protection
A friend did an upgrade on his 220 with an outboard power supply, better
fans, etc... It was a killer amp at 1500W out, all day key down, and he
used it for several years very effectively before going to a bigger amp..
.
I remember my 220 of some 20 or more years ago as having poor input
circuitry...
Denny
Nah, just a lousy input circuit SWR, which I need to attack one of these
days.. I know I could get more out at higher plate voltage, but then
other
things in the design start to go.
73, Pete N4ZR
www.qsl.net/n4zr
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