Gary,
You bring up an excellent point. The early Ten-Tec radios all had an
elevator-preselector inside.
They really added out-of-band rejection in fact since they were tunable,
even in-band rejection to some extent.
When using a large antenna which delivered lots of voltage to the RX's front
end, I found that if I detuned the radio's pre-selector to the low side, it
would reduce the garbage from the 40m shortwave broadcast stations (who were
higher in the band) quite a bit more, while only losing about 1 S-Unit of my
desired signal.
The Corsair is a downward conversion radio and is not bad in the European
conditions.
Of course it did not have the elevator pre-selector.
I can't say how much RF voltage is needed to overload them; I never had or
used one and only saw one once in real life.
I feel like I missed out on free tickets to the super bowl by not having
owned one of these.
With the pre-selectors, these older radios out-performed the Japanese radios
of the time by a significant amount.
In this case, not just the narrow spaced BDR3 was important. You also
needed rejection of strong stations 20 or 50 kHz away (or more). So even
though a JA radio might place higher on Rob Sherwood's BDR3 chart, I can
assure you the Ten-Tec would out-perform it on the band by a significant
margin!
I never measured it but I have a hunch that the BDR2 was better on the older
radios than on our modern radios. There was a lot of merit in having a
pre-selector built in. The down side is, when working split, if the two
frequencies are too far apart, one of the two is not going to be as
sensitive as it would otherwise be.
A poor BDR2 here in Europe has a different effect on our radios.
Instead of affecting the low bands, it affects 20m.
Radios like the IC-706, when used on a large antenna will have a very strong
carrier every 10 kHz or so. This is the result of two shortwave broadcast
stations mixing and having their mix product be in the 20m band. The only
way I could use my 706 at night was to insert a Dunestar BPF-20 in the
antenna line. This is a 100w 20m bandpass filter. Then all those carriers
were magically gone.
Modern Ten-Tecs are not strong on BDR2. If I remember correctly, the Orion
was about 68dB. Many of the JA radios were about 80dB. I've never seen any
specs on what it needs to be but I have a hunch it ought to be about 75 or
more. AND, I think BDR2 is a misnomer. It would probably be better to call
this problem an "IP2" problem. Maybe Rob can weigh in on the proper
terminology here.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Gary - AB9M
Sent: Friday, October 03, 2014 2:23 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Modern version of the Tec Tec Corsair - please Ten
Tec!
Rick, is there any truth to the old RF Technician's tale that it takes more
than a Volt of RF to overload a PTO on a Corsair II? Does the 560 / 561
play nice on the low bands in Europe at night or do you need a 546 / A / B /
C... with the pre-selector?
73 & DX,
Gary - AB9M
-----Original Message-----
From: Rick - DJ0IP / NJ0IP
Sent: Thursday, October 02, 2014 1:48 PM
To: 'Discussion of Ten-Tec Equipment'
Subject: Re: [TenTec] Modern version of the Tec Tec Corsair - please Ten
Tec!
Wade,
I quit wearing the cape; no more phone booths here.
They went away years ago.
People who have never operated in Europe simply have no perception about how
much worse condx are here on the low bands.
It has gotten better since the broadcast stations on 40m moved up and out of
our band, and they widened the band from 100 to 200 kHz.
The problem most radios have here at night is with Intermodulation
Distortion.
We have a nice name for it in German. We call it "Wave Salad".
It is basically an S5 to S9+30 noise level across the entire band, depending
on which radio you have.
The problem is front-end overload.
The better the BDR3 is on the receiver, the lower this noise level will be.
Keep in mind that these are noises which are not really there.
They are basically phantom signals caused by the front-end of the receivers
overloading.
In general (with extremely rare exceptions), radios with upward conversion
have about 20dB worse BDR3 than radios with downward conversion.
To understand the magnitude of the problem, each dB improvement in BDR3 will
reduce the IMD by about 3dB.
So if I improve the RX front end by 20dB, it reduces the IMD by 60 dB, which
means it pretty much disappears, except for a few exceptions.
There are a couple of things you can do.
First and foremost, use an attenuator.
10dB of attenuation will reduce IMD by 30dB.
Of course if the station you wish to work is a weak DX in the Pacific and he
is only S1 or S2, switching in 10dB or more attenuation drops him into the
noise (the normal noise).
Better is a good preselector. These typically have 6dB insertion loss but
drop IMD by 30 or 40dB.
This is the route I went prior to the Orion.
The Orion was the first radio I ever operated in Europe that did not need a
pre-selector.
I never experienced intermod on it except when operating with a 3 element
yagi on 40m and pointing the antenna N-NE.
In that case I could hear a few phantoms at about S2 or so.
In the meantime there are several radios that are this good.
The K3, several of the Flex radios, the Eagle, the TS-990, and of course the
Hilberling are all good radios needing no pre-selector.
Nearly 15 years ago I made some recordings of a Jupiter with and without the
pre-selector and sent it to Ten-Tec.
After reviewing them, Jack commented that he had always heard condx were
worse here in Europe, but never knew they were of that magnitude. As a
result, he immediately added provision for a pre-selector to the Omni VII
design, which was still on the drawing board.
The Argonaut V was pretty much a disaster here.
The author of the QRP section of a local magazine described its receiver as
pretty much useless on 40m.
Sales here were pathetic.
Yet in the states it is a fine radio.
The Paragon with its upward conversion will have a blanket of noise (wave
salad) across the 40m band, when used with a good antenna.
The good news is, if you live in the states, you will never experience this.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Wade Staggs
Sent: Thursday, October 02, 2014 7:49 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Modern version of the Tec Tec Corsair - please Ten
Tec!
*Hello Rick,*
* Over the last several years, I have found real
respect for your Facts and Opinion. Could you please expand and explain. I
know that in Europe, you have a whole different bunch of problems from
Broadcast Stations but, can you explain just what feature... IF, Selectivity
or other, where the Paragon falls short? Would a Band Pass filter help? I
call 4 to 7 HF Nets a week on 80/75 Meters. With the RF Gain backed off ((
like we ran our Corsair )) and the 1.8 KHZ Filter selected, even with Loads
of QRM, we can still hear stations that others miss. Even to the point that
other NCS stations always ask me to relay weak signals into the Net. When
they know I am on frequency that is. Of course they are running mostly
KenYaeCom Rigs. My antenna is nothing special. 126 feet of Flat Top Dipole
with Windows ( 450 ohm ) Line into the tuner. A real Cloud Burner (( NVIS ))
at about 30 feet high. While I have your attention Rick, Thanks for
answering my many questions that we would have ask, if others had not ask
first. Do you wear a Solid Blue Shirt with a Big Yellow S on the front?? Do
you get your Cape caught in Car Doors? Well. I believe that you do. Do they
still have Phone Booths for the quick wardrobe changes in Germany? *
* Thanks Rick 73 from
Wade/KJ4WS*
On Thu, Oct 2, 2014 at 11:34 AM, Rick - DJ0IP / NJ0IP <Rick@dj0ip.de> wrote:
> Come to Europe Wade, you'll learn the difference (in favor of the
> Corsairs).
> Upward conversion struggles here.
>
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Wade
> Staggs
> Sent: Thursday, October 02, 2014 6:15 PM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Modern version of the Tec Tec Corsair - please
> Ten Tec!
>
> *Good Morning,*
> * While the Corsair and Corsair II are fine
> radio's. If you really want to split hairs, my Paragon ( 585 ) has
> everything they have, plus very accurate ( no drift at all ) frequency
> control. Don't believe me? Just find someone who owns one and sit
> down in front of the rig. Now engage the 20 Db. pad and turn the RF
> Gain back just a little bit. ( this is on the low bands ) It just
> seems like a different world. And while I am posting. Why did the
> Paragon and Paragon II have relatively short production runs? I know
> about the Dreaded ... PLL Out of Lock ... problem with the 585 but
> once fixed, they are such Great Radio's.
> Mine was acquired while broken but a thorough re-work of the Major and
> Minor Loop Boards has turned it into a real Keeper. Almost 6 years now
> with no failures or issues of any kind. Although about 6 months back
> we did replace all capacitors in the PA enclosure. So, in summary, has
> anyone used a Paragon ( 585 ) lately ? ? ? And who wants to trade
> their broken one for something else? All input about the Paragons
> receiver appreciated.........
> The Transmitter is Awesome also.*
>
> *
> 73 from Wade/KJ4WS*
>
>
> On Thu, Oct 2, 2014 at 6:42 AM, Rick - DJ0IP / NJ0IP <Rick@dj0ip.de>
> wrote:
>
> > As nice as its audio was, the KWM-2 would not be very good with
> > today's crowded bands.
> > The famous "Collins mechanical filter" was not really very good by
> > today's standards.
> > A 4-pole crystal filter on 455 kHz is as good or better and of
> > course you can buy 6 or 8 pole filters now.
> > And the DSP filters on lower frequencies are even better, sharper,
> > and have steeper skirts.
> >
> > As long as we're dreaming, I wish I had 1960's band conditions again!
> >
> > All things considered, it's hard to beat the Corsair with its
> > combination of good audio and good crystal filters.
> > Newer radios have better filters but worse audio.
> >
> > For my money, the best compromise is the Eagle.
> >
> > 73 - Rick, DJ0IP
> > (Nr. Frankfurt am Main)
> >
> >
> > -----Original Message-----
> > From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of
> > Martin Sole
> > (HS0ZED)
> > Sent: Thursday, October 02, 2014 11:37 AM
> > To: Discussion of Ten-Tec Equipment
> > Subject: Re: [TenTec] Modern version of the Tec Tec Corsair - please
> > Ten Tec!
> >
> > I've long liked the analogue radio sound. So far my all time fave,
> > just for the audio, is a KWM2 with that big 6x4 speaker, something
> > about that warm sound seems magical. Next up from my current radios
> > would be my Omni V. Not sure how that might differ from the Corsair
> > but whilst generally pleasant it's not in the KWM2 league. Then the
> > Orion 565 and Elecraft K3, bit of a mixed bag these two as they are
> > both very variable but I've not yet been able to recreate the
> > analogue sound. I might need to experiment with amplifiers right at
> > the point the signal becomes analogue. A god analogue audio amp with
> > LTP input and complementary pair output in discrete silicon feeding
> > a big speaker,
> might sound very different.
> >
> > The TS940 had good audio too but for me about the same as the Omni V
> >
> > Martin, HS0ZED
> >
> >
> > On 02/10/2014 12:03, Barry N1EU wrote:
> > > On Wed, Oct 1, 2014 at 5:12 PM, John Farler
> > > <k4avx1@windstream.net>
> > wrote:
> > >
> > >> I have a Corsair II with the DDS VFO, which works nicely. I
> > >> think it's a single conversion though.
> > >
> > > Normally it converts to 9MHz, then to 6.3MHz, and then back to
> > > 9MHz, unless you bypass the 6.3MHz PBT i.f. which can be done
> > > fairly easily but you lose PBT and narrow filters and don't gain much.
> > >
> > > I agree on the CAT comment. I always dreamed of adding a CAT port
> > > to the DDS cpu firmware.
> > >
> > > 73, Barry N1EU
> > > _______________________________________________
> > > TenTec mailing list
> > > TenTec@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/tentec
> > >
> >
> > _______________________________________________
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> >
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