Hi all,
This may be a great opportunity to learn something.... having never used a
spectrum analyzer before and having only hobbyist knowlege of electronics
(hence the reason I sometimes ask really dumb questions) I'm not 100% sure
of what I'm looking at in that trace, but it appears as though the amp is not
any 'dirtier' than the exciter. Or am I showing my ignorance???
--
Randall D. DuCharme (Radio AD5GB)
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--- On Wed 03/23, Gary Schafer < garyschafer@comcast.net > wrote:
From: Gary Schafer [mailto: garyschafer@comcast.net]
To: MM@plextek.co.uk
Cc: amps@contesting.com, ad5gb@myway.com
Date: Wed, 23 Mar 2005 13:47:02 -0500
Subject: Re: [Amps] 4CX1000A for SSB??
But what does it tell you?<br><br>73<br>Gary K4FMX<br><br>Mark Marsden
wrote:<br>> Hi Randall<br>> <br>> Have a look at
http://granta.digital-crocus.com/Linear_Design_notes/Spectral_regrowth.jpg<br>>
<br>> That's a screenshot of the transmit spectrum of my 4CX1000A linear, (Va
2750V, Vs 350V, ZSAC 250mA). It was made by speaking into the microphone
normally for a minute and accumulating the trace with the spectrum analyser on
peak hold. The lower trace is a barefoot FT1000MP, the upper trace is the
output of the linear. <br>> <br>> 73, Mark, G4AXX<br>> <br>> <br>>
<br>>>>>"ad5gb" <ad5gb@myway.com> 18/03/05 20:33:36 >>><br>>>><br>> <br>> I
just found a chart that listed the distortion characteristics of varioius <br>>
tubes. I was really disappointed to see how poorly the 4CX1000A ranked
amongst<br>> the competitors. IIRC, I think it was the absolute worst in the
bunch. <br>> <br>> I got a couple of these things (with sockets) very cheaply
a little while ago<br>> (well may
be longer than that ) and hoped to build something nice for HF out of<br>>
them. I planned to try a grid-driven AB1 configuration at max anode
potential<br>> with the best screen/bias regulation I could come up with but
based on that <br>> chart.... it doesn't look like the most wonderful of things
to try to do.<br>> <br>> Anyway to make these run more satisfactorially?
Cathode drive /w NFB? Grounded<br>> screen (float the cathode below ground)
Anyone with any experience and <br>> distortion figures better than in that
Eimac chart I found?<br>> <br>> Thanks<br>> <br>> <br>> --<br>> Randall D.
DuCharme (Radio AD5GB)<br>> <br>>
<br> <br>>
<br>>
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