[TenTec] RF speech processors

waltk8cv4612amos at att.net waltk8cv4612amos at att.net
Tue Feb 3 06:39:07 EST 2009

Hum ........ sounds like we need a updated / new version of the SM-220 here 

Maybe, I'll change my mind after the demonstration ? Had a VOMAX and sold 
that years ago , big mistake !

Do you use an external DSP with your ORION II because the internal DSP is no 
good ?

Is the new RF speech processor really a money maker and used with older rigs 
that have NO internal SP ?

Does excessive SP do any good at the other end of the QSO or is it just 

What we really need is something like the SM-220 to LOOK at the outgoing RF 
and really see if it is something to be proud of and write home about !

Walt K8CV Royal Oak, MI.

----- Original Message ----- 
From: "Ken Brown" <ken.d.brown at hawaiiantel.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Tuesday, February 03, 2009 1:08 AM
Subject: [TenTec] RF speech processors

> Hi all,
>     I think I know what an RF speech processor is. First I'll describe
> what I think it is:
> You connect your microphone audio to a little AM or DSB generator,
> working at some frequency such as 455 kHz. Then you compress or even
> clip that signal to increase the average power output. Probably goes
> though some bandwidth limiting filters. After that it gets demodulated
> back to audio, and feeds the microphone input of the SSB rig. Since the
> compression/clipping/whatever is done at some "intermediate frequency"
> and then demodulated back down to audio, the IMD "splatter" and
> harmonics that are generated, don't get transmitted. Only bandwidth
> limited audio goes to the microphone input of the SSB transmitter, and
> the SSB transmitter audio stages and RF stages are never driven into
> non-linearity. The transmitted signal bandwidth is limited by the usual
> crystal or mechanical filters. You get a really dense high average power
> signal.
>     I'm sure I may be wrong in some of the details, yet I'm pretty sure
> I've got the basic principle right.
>     What I don't get is, with DSP used in the transmit section of a
> modern rig, can't you write an algorithm running in the DSP system to do
> that, and do it better, without resorting to this old technology? I'm
> not saying it's bad. When a tried and true method works, it works. Just
> seems like this is one of those functions that DSP ought to be able to do.
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