"It is 5am and I am not able to sleep"
Jerry:
Try counting rigs
Steve N4LQ
----- Original Message -----
From: "Jerry Volpe" <kg6tt@tomorrowsweb.com>
To: <wf2u@starband.net>; <tentec@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
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|