[AMRadio] Speech Processing AM (COMDEL CSP 11)


Brian Carling bcarling at cfl.rr.com
Thu Jul 8 15:49:59 EDT 2004


Hello John,

"Katsumi Microphone Compressor"
Extra sharp-looking unit for processing your transmitted 
audio signal. Great for AM stations. Has level controls and 
an additional filter setting too. 
Available for $45.00 plus shipping

Picture at:
http://www.af4k.com/imag/ham/katsumi.jpg

Give it a few minutes - they were doing maintenance just now...

73 - Brian, AF4K

On 6 Jul 2004 at 10:08, John King wrote:

> What is it and what price?

> ----- Original Message ----- 
> From: "Brian Carling" <bcarling at cfl.rr.com>
> To: "Discussion of AM Radio" <amradio at mailman.qth.net>
> Sent: Tuesday, July 06, 2004 8:20 AM
> Subject: RE: [AMRadio] COMDEL CSP 11
> 
> 
> > I have a really nice Japanese speech compressor for sale if anyone
> > would
> like it.
> >
> > Regards - Brian, AF4K
> >
> > On 18 Jun 2004 at 17:39, Donald Chester wrote:
> >
> > >
> > >
> > > >Any one out there got comments on the Comdel speech processor
> > >
> > > They work on AM as well as SSB.  I built a homebrew version back
> > > it the late 70's using a set of 64 kHz mechanical filters removed
> > > from telephone multiplexing equipment.  Mine had better audio
> > > quality than the original Comdel and was quite effective, but it
> > > was nothing to write home about.  The design eliminates the
> > > harmonic distortion of speech clipping, but does nothing to reduce
> > > intermodulation distortion.  Intermod is much more objectionable
> > > than harmonic distortion.
> > >
> > > The purpose of the Comdel was to allow for speech clipping on SSB,
> > > since due to fundamental modulation theory, simply clipping the
> > > audio to flat peaks before applying it to a SSB generator
> > > generates high amplitude rf peaks, just exactly the opposite of
> > > what you are trying to accomplish with clipping.  The extreme case
> > > of applying squarewave audio to a SSB generator produces peaks of
> > > theoritically INFINITE amplitude.
> > >
> > > The processor works by generating a low-frequency SSB signal
> > > (below 100 kHz), clipping and filtering the SSB signal, and
> > > demodulating the clipped SSB and applying the resulting audio to
> > > the transmitter.  The result is a near 1:1 peak-to-average ratio
> > > with heavy clipping, but the intermod makes the audio sound mushy.
> > >
> > > -k4kyv
> > >
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