[TenTec] [Orion] "Technical Correspondence", August 2007 issue

[Ernie Walls]

I hope, against hope, that the Orion is NEVER made into an all singing all
dancing radio like the big three have done with theirs.

 

Why?

 

Well, you often (always!!) end up with a unit that is good in very many
respects, but excels in absolutely none of them - as well, in my case, as
offering me features that I simply do not want or need. BTW, I do digital
and CW, as well as phone.

 

The reason I bought an Orion is because it hears better than almost any
other amateur transceiver I am aware of, and it has the ability to reject
loud close by signals, when I am working marginal ones, better than all
others.

 

That, solely, is the reason I bought mine. 

 

When you DX from VK, believe me, they are the two fundamental requirements
of any transceiver - the Orion doesn't look great, doesn't have VHF/UHF et
al, or do many other absolutely inconsequential chores but, by golly, it
does the two listed above magnificently.

 

I understand that the reason they may have introduced the general coverage
receiver is to widen their offer, possibly, to places like the US military
and/or US government agencies, which is fair enough if they want to retain
scale in their operation.

 

If I want to listen to short wave stations, in fabulous stereo, with a
variety of audio accompaniments, or look at signals on a flash looking,
exorbitantly priced monitor (data management unit) etc etc I will buy a
2000. 

 

If I want to hear a tough station, give me the Orion.

 

My two (Aussie) cents worth. 

 

Ernie Walls VK3FM

vk3fm at wallsy.com.au

vk3fm at arrl.net

 

 

 

-----Original Message-----
From: Gregory Knapp [mailto:n6gk at n6gk.com] 
Sent: Thursday, 26 July 2007 8:53 AM
To: geraldj at storm.weather.net; 'Discussion of Ten-Tec Equipment'
Subject: Re: [TenTec] [Orion] "Technical Correspondence", August 2007 issue

 

Thanks for the great short, practical explanation...it helped remind me, in

simple language, of the wonderful method used in the Orion to decipher

signals. 

73,

Greg, N6GK 

"Looking forward to the Orion III, which hopefully will also have 6, 2, and

440, making it the only radio one would EVER need (after all, why should my

little cheap IC706 Mk2G have this and not my Orion?)!  C'mon TT, capture the

market!"

 

 

> 

There is a fundamental difference between the TenTec and the various ham

SDR that have open source software. The many SDR use PC audio cards for

the A/D and then do ALL the computation in the PC external to the radio.

Sometimes only a certain few audio cards will work fast enough. TenTec

radios use a special purpose collection of micro and DSP chips IN the

radio where the needed compilers are not necessarily available on the

consumer computer market.

 

And then the SDR of the current market are direct conversion radios with

RF stage, a LO with quadrature outputs and a couple mixers with low pass

filters and gain stages having probably no more than 150 KHz bandwidth.

The software controls the LO in large (maybe 10 to 50 KHz steps) and ALL

the fine tuning, filtering, and detection is done in the DSP software

running in the attached PC. The simple rock locked radios neglect the LO

tuning and cover a big chunk of band all with the DSP software in the

computer. The ultimate radio performance depends on the dynamic range of

the RF and mixer and tremendously on that of the A/D converter. And for

the PC many compilers are available allowing diversity in programming

language as well as operating system.

 

In TenTec radios, the LO is controlled to the finest of frequency steps,

the RF is bandpass filtered then at the IF its filtered more with the

"roofing" filter, then converted down to a 15 KHz IF where the direct

conversion Q and I process is done and then the fine filtering, very

finest of tuning (if the roofing filter allows), and detection is

accomplished in the DSP. So the software does a great deal more radio

control before the DSP and with the use of narrow "roofing" filters the

DSP hasn't all that much to do. That makes most of the dynamic range

depend on RF hardware and allows a smaller dynamic range and narrower

bandwidth A/D but exposes the radio design to all of the same foibles in

dynamic range and close in intermod of multiple conversion analog radios

that have been fought for decades. But TenTec has known how to produce

radios with good dynamic range for nearly that long too.

-- 

73, Jerry, K0CQ,

All content copyright Dr. Gerald N. Johnson, electrical engineer

 

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