-----Original Message-----
From: Lamb <k7fm@teleport.com>
To: W8JI@contesting.com <W8JI@contesting.com>; amps@contesting.com
<amps@contesting.com>
To: <amps@contesting.com>
Date: 16 August 2001 06:20
Subject: Re: [AMPS] Tetrode poor IMD performance
>
>While not claiming to know the answer to Tom's question, I would like to
add
>some information using a similar tetrode.
>
>The 4CX1000 was originally not designed for linear amplifier service.
Eimac
>specifies the 3rd order distortion as -23 db and 5th order distortion is
>specified as -26 db. The Collins 30S-1 used that tube, but used a cathode
>drive configuration (which has inherent feedback) and applied additional
>feedback to arrive at a clean amplifier.
>
>Without feedback, though, a 4CX1000 with a resistive grid and perfectly
>stabilized voltages ought to yield no better than a -23 db 3rd order
>distortion.
There was a 2m amp described in VHF Comminications some years ago using
4CX1000A. I don't remember any 2 tone measurements, but there were spectrum
photos under voice mod. I know voice mod is not a controlled test, but the
output looked a hell of a lot better than I've seen while bench testing amps
that did have mid 20's 3rd order products.
Steve
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|