[TenTec] RF speech processors

Ron Castro ronc at sonic.net
Tue Feb 3 12:05:46 EST 2009

In answer to your questions, I don't use external DSP since I don't think 
there is not much more that can be done to receive audio to make it more 
intelligible.  None of the implementations of DSP I've tried have made an 
uncopyable signal copyable, especially with SSB, although someday that may 

Old rigs without SP will certainly benefit from the new processor, or any 
processor for that matter, but it remains to be seen what it will do with 
new radios like the Orions, Omni VII's, K3's etc.  The only radio I ever 
owned with a true RF SP built in was my old Yaesu FT-301D and it was about 
the only thing good on the radio!  When I turned it on, I could see the 
average plate current on the amp nearly double.  But what will happen when 
highly processed audio runs into the 'over-protective' ALC in the Orion is 
the big question.  The 'dueling ALC's' in the Orions, one hardware, the 
other software, is why everyone has noticed that they just don't drive 
amplifiers the way other rigs do.  I did a careful comparison to my TS-870 
and the 870 was the clear winner.

Speech clipping (as opposed to compression) does result in a more usable 
signal and it also makes more noise, but in a pile-up, noise can obscure a 
competitor and get you the QSO first.  It sounds like "dirty pool", but it 
works :-)

You're right...a good o-scope will show you the average power better than a 
meter.  I need to dust mine off and hook it up!

         Ron   N6IE

----- Original Message ----- 
From: <waltk8cv4612amos at att.net>
To: <ken.d.brown at hawaiiantel.net>; "Discussion of Ten-Tec Equipment" 
<tentec at contesting.com>
Sent: Tuesday, February 03, 2009 3:39 AM
Subject: Re: [TenTec] RF speech processors

> 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
> NOISE !!
> 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.
>> DE N6KB
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