[TenTec] Classic TenTec QSK, etc.

[Rick at dj0ip.de]

Excellent detailed information from Steve.

The only thing I would change is, you can't just think of todays dollars
when evaluating the theoretical cost of the radio today.
Xtal filters now cost about 3 to 4x as much as they did back in the 1980s.
Tendency:  increasing

I don't know how many filters the Corsair II has but you would have to add
about $100 to $150 to the price for each optional filter.

And as Steve rightly pointed out, 250 Hz bandwidth (today) is like a barn
door.

I ran QRP in CQWW CW last year and only worked Search and Pounce (S&P).
I ran almost the entire contest using 30 Hz bandwidth.  (thirty Hertz).
QRM was non-existent.  

BTW, that was not with my IC-7300; its filters are not good enough for that.

It was with an ALT-512 QRP transceiver.

73,
Rick, DJ0IP
(Nr. Frankfurt, Germany)
May the Sunspots be with us!

-----Original Message-----
From: TenTec <tentec-bounces+rick=dj0ip.de at contesting.com> On Behalf Of
Steve Ellington
Sent: 13 January 2020 04:29
To: Discussion of Ten-Tec Equipment <tentec at contesting.com>
Subject: Re: [TenTec] Classic TenTec QSK, etc.

When I compared the 7300 and Corsair II, I was comparing them under a very
limited / narrow range of functionality.
There are just a few things that the old Corsair II can do better, limited
to low bands 80, 40, 30 meters, CW, QSK.
Other than those, the 7300 excels. The Corsair II would be a horrible choice
for any digital mode due to drift and no computer interface and SSB isn't
all that great. So don't misunderstand me on this...The Corsair II was
excellent at the time and still runs rings around newer radios but only in a
few areas.

The biggest topic these days is NOISE and with no antenna, RFG turned up and
AGC way up you would think the 7300 is horribly noisy.
However under typical band conditions you never hear that kind of
noise..It's all way below the ambient noise coming in on the antenna.
Naturally we
still wonder how an SDR radio can manage to make any noise...After all,
there are no conversion stages and no IF amplifiers, just a ADC which I
assume makes it's own racket but still below the band noise threshold.

As for Corsair vs Corsair II. There's a significant difference. The original
Corsair had a lot of annoying white noise when using narrow filters. It's
gone in the Corsair II. The Corsair was heir to the nagging AGC thump on
strong CW signals. That's gone in the Corsair II. AGC is quiet smooth and
actually the only audio derived AGC I've seen that actually works without
"riding" the RF Gain control. Too bad since the C-II was the end of the road
for TT's analog series.

QSK is pretty smooth but that varies with the particular radio. Some had
thumps and clicks in the headphones, mostly due to the design of the
sidetone circuit. I've managed to hack most of that out of mine. The front
end in them isn't all that tight. I've had to use a high-pass filter to
block AM BCB signals. I think the old Omni Series did better with it's
variable tuning front end. Lots of diodes can cause this.

As for the 7300. It's weakness is lack of front end selectivity and as
someone mentioned, Field Day can be a problem. We used my 7300 for FD this
year but it was necessary to use a band-pass filter in line with the
antenna. That totally cured the problem and this is common when you have
antennas 30 feet apart. The 7300's bandscope was a key factor in us getting
2nd place for our class in NC. Having that little gadget is invaluable once
you get used to using it.
Selectivity between close-in stations is like a brick wall on the 7300. The
Corsair II is pretty decent but even with it's 250 Hz filter plus the audio
filter it's not enough for FD or at least it leaves room for improvement.

Like I mentioned, I removed the 7300's amp control relay and bypassed it.
Now it's quiet enough... Not as quiet as the little reed relay in the
Corsair but bearable.

I can't remember the price for the Corsair II but with extra filters I think
it would be around $750 or so in 1986. If so, that's equal to about
$1,700 in today's dollars, about double the 7300's cost. Those filters are
killers!

Here's an interesting review of the Corsair II
https://www.americanradiohistory.com/UK/Short-Wave-UK/80s/SWM-1986-06.pdf

On Sun, Jan 12, 2020 at 9:44 PM Bwana Bob via TenTec <tentec at contesting.com>
wrote:

> Wait a minute...
>
> The Corsair receives better than a IC-7300?  My Corsair is a "keeper", 
> but why would I want a 7300, even to replace my Paragon.  Maybe a  
> 7300 is better than a Paragon.  Even so, I would expect a "modern"  
> radio to perform better than a vintage one.
>
> 73,
>
> Bob WB2VUF
>
> On 1/11/2020 12:35 AM, Don Rasmussen via TenTec wrote:
> > I don't think you want to compare RGO to IC7300 or IC705, if you do 
> > then
> just buy one of those. They are greatly more feature rich for the dollar.
> But, if you already have one of those - I have IC7300, maybe an RGO 
> can find a place in the shack. Steve N4LQ did a video comparing CW 
> with IC7300 and Corsair II. Corsair II won very big, IMO even when 
> noise reduction was turned on for the Icom. But, this specific 
> comparison is for the sound from the speaker, not frequency stability, 
> memories, or modes! Corsair wins on quiet rx. I find that IC7300 is 
> vastly closer to Corsair when I turn the AGC off. I would like to hear 
> how RGO compares to Corsair and IC7300 on CW as Steve set things up - 
> with equal speakers. My guess is RGO will have notably quiet audio 
> from the samples I've heard. That could make it a nice niche machine. 
> I posted about this because it seems like the project is moving ahead, 
> as compared to others - like the Palstar transceiver project that faded
before launch.
> > de Wb8yqj Don
> > _______________________________________________
> > TenTec mailing list
> > TenTec at contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
>
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