[TenTec] Omni 6 sensitivity, DSP, SDR, and general rants!

Sun Dec 19 11:45:54 EST 2004

"It is 5am and I am not able to sleep"
 
Jerry:
Try counting rigs 


Steve N4LQ
----- Original Message ----- 
From: "Jerry Volpe" <kg6tt at tomorrowsweb.com>
To: <wf2u at starband.net>; <tentec at contesting.com>
Sent: Sunday, December 19, 2004 11:32 AM
Subject: [TenTec] Omni 6 sensitivity, DSP, SDR, and general rants!


> It is 5am and I am not able to sleep so you are all in for it! :(
> 
> I recently did a bit of revamping of my shack placing two more HF rigs 
> on line with my Omni-6+ (I also have two Scouts but they are a different 
> breed) and subsequently I have been doing a lot of listening comparisons 
> between my three main rigs. Certainly not scientific evaluations 
> nevertheless I have gained some personal perspectives. Recently I have 
> worked several contests with my Omni-6+ and I am very pleased with its 
> ability to separate the 'wheat from the chaff'. I have all the standard 
> Ten-Tec filters including the 1.8 and 500 hz roofing filter options. The 
> Omni can zero in on a sideband signal slicing it out of the QRM and QRN 
> but it really isn't a pleasant rig for general armchair  listening. I 
> had a Jupiter before and although an SDR (with bad along with the good) 
> it sort of set some expectations as to what is possible, but that is 
> another story.
> 
> A few weeks ago I added a really  nice 9+ Paragon to my station. It too 
> has all the standard Ten-Tec filters. On listening tests I would say 
> that the Paragon is characteristically similar to the Omni just not as 
> sensitive overall. This is especially noticable on 15 and 10 meters. The 
> difference is mostly in how much s-meter deflection you see as generally 
> if you can hear it on the Omni it is there on the Paragon... well 
> almost. For me the difference is certainly moot. Now on CW I truly 
> prefer the Paragon's Tone/Fade/BP analog controls to the lack of same on 
> the Omni. I can peak in on a CW station much faster. On sideband I 
> definely give the nod to the Omni's spartan but effective DSP. Turn that 
> baby on and back off the RF gain control and enjoy the ride. For some 
> reason doing this seems to open up the audio a bit.on the Omni.... I am 
> sure this is just a perception effect and not a reality.... and of 
> course you get that 'DSP' mungled audio... certainly NOT natural but you 
> get use to it pretty quickly. In contrast, I did not like the DSP-based 
> noise reduction on the Jupiter that I owned earlier. The audio gain on 
> the Jupiter simply dropped toooooo far resulting in an apparent lack of 
> gain when listening to a group of stations with some being appreciably 
> weaker than others. The Paragon's AGC seems to operate similar to the 
> Omni and both rigs seem to have comparable levels of residual background 
> noise levels. I am always on the hunt for that infernal 'Phase Noise' 
> demon as I know it is out there somewhere. Audio-wise the Paragon and 
> the Omni sound much alike... this is not a bad thing.
> 
> Last week.... and don't ask me why.... I accepted a Kenwood TS-940SAT in 
> trade for my old faithful Omni-C station. Now my original intent was to 
> sell the Omni-C to pay for the Paragon, but the trade was offered to me 
> and I talked myself into it. It has been nearly 20 years since I last 
> owned a non-Ten-Tec HF rig although I have used many that belonged to 
> other hams. Aside from the fact that the TS-940 has some intermittent 
> issues (this particular example was fairly heavily used and apparently 
> in a cool/damp environment as can be witnessed by the high amount of 
> oxidation on the internal aluminum and steel... blah, blah, blah) the 
> Kenwood has a very nice receiver overall as it should as it was an 
> Expensive transceiver in its day. My particular TS-940SAT has INRAD and 
> Fox Tango filters rather than stock Kenwood filters (good or bad I have 
> no direct way to verify). In general listening tests between the Omni, 
> Paragon, and Kenwood, and using a Kenwood HS-5 headphones or my 
> SoundsSweet external speaker, I definely give the Kenwood a better 
> overall grade. It is just more listenable to my 53 year old ears... more 
> open sounding. The Kenwood's AGC seems a bit smoother and with a tough 
> better dynamic range. Sensitiviy and selectivity wise the Kenwood is 
> definetly somewhere in between the Paragon and the Omni, but it is very 
> difficult to quantize the differences here. On the other hand I can make 
> personal judgements on 'creature comforts'. When operating CW I prefer 
> the Kenwood's Pitch/RF Tune and CW VBT control functions to the lack of 
> which on the Omni. I also like the Paragon's Tone/Fade/BP/PBT contols 
> when compared to the Omni.... The Paragon is more intuitive though so I 
> like using it most in CW. Kenwood's controls take a bid of getting use 
> to but for a rig pushing nearly 20 years in age it isn't half bad.
> 
> All three transceivers have very quiet receivers. If I have to give the 
> nod to one over the others then I guess the Kenwood is generally 
> quieter. This is purely subjective on my part BUT when I change antennas 
> from rig to rig I never have to turn the Kenwood's audio down as I 
> simply don't hear it but I DOOO have to turn the Paragon and the Omni's 
> volume down as they produce a noticable audible 'rushing' sound with no 
> antenna attached. Now for an unusual observation which I am still trying 
> to figure out... and which has a lot to do with what I just wrote.....
> 
> In my setup the Omni, Paragon and Kenwood have their antenna terminals 
> going directly to a venerable Heathkit coax switch which is of the 
> 'shorting' variety (shorts out un-used connectors). If the Paragon and 
> Omni are turned on, but the Kenwood is off) changing the coax switch 
> from one rig to the other doesn't result in much residual background 
> noise from the non-selected rig. HOWEVER, if the Kenwood is also ON AND 
> selected with the antenna switch both un-selected Ten-Tec's produce 
> rather dramatic and objectionable audible noise levels getting worse on 
> the higher frequency bands. The reverse is not true. An unselected 
> Kenwood does not respond audibly to either or both of the Ten-Tec's 
> being on regardless of what band and is tuned to. What this means in 
> practical terms I am not sure. I just turn the volume controls on the 
> Paragon and Omni down when I am listening to the Kenwood. Oh, and I have 
> tried several different coax switches with the same results.
> 
> On the discussion of DSP and SDR...... Though I have a frairly technical 
> background and tend to naturally  appreciate and welcome technical 
> advances 'as they mature', my general feeling is that DSP and SDR is not 
> yet ready for prime time. I bought a new Jupiter last year but traded it 
> off rather quickly. Bought a new JRC NRD-545 and sold it within months! 
> Of course DSP and SDR technologies are not going away.... the scale of 
> economies and the need to reduce part counts and manufacturing costs 
> dictates that manufactures replace hardware with software But like any 
> fairly new and radically different technology it takes time to 'get 
> there' and just because you can doesn't always mean you should. And to 
> 'get there' will probably require far more capable microprocessor/DSP 
> combinations than what are currently being offered.... and far more 
> complex firmware. For now, absent the 'gee wizz' effect, give me a good 
> old descrete design. AND give me KNOBS to TWIST and buttons that LIGHT 
> UP! And real MECHANICAL meters. And sharp florescent or LED-based 
> displays with just the essential information PLEASE! don't build in any 
> operating modes like RTTY, PSK and CW receive... just built in 
> obsolesence waiting to happen and never implemented nearly as well as 
> what can be done externally.AND MOST OF ALL I don't want to wade through 
> menus except for an incredibly rare functions.
> 
> OK, I've ranted long enough. :) And someday I will own an Orion, but 
> probably not till there it is an Orion III.
> 
> 73 All,
> Jerald, KG6TT
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