[TenTec] On the Corsair II revival idea and receiver noise

Mon Nov 28 11:39:58 EST 2016

A couple of points off the top of my head if I'm remembering correctly:

1) I think a main expense for ladder filter production would be the 
requirement for crystal matching: the more closely the resonant frequencies 
are matched, the closer the filter comes to its theoretical performance. That 
being said, the matching process might be something which could be automated.

2) Ladder filters handle transients better than lattice filters, thus the 
cleaner sound.

(Both of these items are covered in ARRL publications like SSDRA/EMRFD and 
have been discussed in the past on this reflector.)

73, Al

On Mon November 28 2016 9:00:47 am Steve Ellington wrote:
> I have heard it said that the crystal ladder filters used in TenTec rigs is
> what gives them their unique sound for cw that pleases so many of us.
> Something sure does!
> Steve N4LQ
>
> On Mon, Nov 28, 2016 at 7:53 AM, Paul Christensen <w9ac at arrl.net> wrote:
> > Ladder and Cohn IF filters are easily made with 6-8 common HC-6 or HC-49S
> > crystals.  In production quantiles, these should be no more expensive
> > than the original Ten Tec IF filters modules.
> >
> > https://www.arrl.org/files/file/QEX_Next_Issue/Nov-Dec_
> > 2009/QEX_Nov-Dec_09_F
> > eature.pdf
> >
> > Paul, W9AC
> >
> > -----Original Message-----
> > From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Bwana
> > Bob Sent: Sunday, November 27, 2016 10:32 PM
> > To: Discussion of Ten-Tec Equipment <tentec at contesting.com>
> > Subject: Re: [TenTec] On the Corsair II revival idea and receiver noise
> >
> > There is another problem with crystal and mechanical  filters:
> > Availability.  Collins recently discontinued their filter line. With the
> > DSP
> > revolution ongoing, analog filters will become even more expensive.
> > One of the filters in my Paragon went bad with high insertion loss, and I
> > bought a replacement from INRAD.
> >
> > 73,
> >
> > Bib WB2VUF
> >
> > On 11/24/2016 6:25 AM, rick at dj0ip.de wrote:
> > > Even if it equaled the K3 performance, it would be outstanding.
> > > But the problem is and remains Xtal Filters.
> > > We'll need 6, maybe 8 of them and we'll be lucky if they are priced
> > > under
> > > $100 each.
> > >
> > > 73 - Rick, DJ0IP
> > > (Nr. Frankfurt, Germany)
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Barry
> > > N1EU
> > > Sent: Thursday, November 24, 2016 11:31 AM
> > > To: Discussion of Ten-Tec Equipment
> > > Subject: Re: [TenTec] On the Corsair II revival idea and receiver
> > > noise
> > >
> > > If the Corsair III ended up equaling or exceeding the K3S in
> > > performance with the body of an Omni VI+, I'd buy one.
> > >
> > > 73 & Happy Turkey Day,
> > > Barry N1EU
> > >
> > > On Thu, Nov 24, 2016 at 4:13 AM, GARY HUBER <GLHuber at msn.com> wrote:
> > >> Before I bought my Corsair-II and was looking at the Paragon and
> > >> Corsair-II, I was asked by one of the TenTec staff manning their
> > >> booth at Dayton, "What radio are you using now and what is your
> > >> principal use, DXing, nets, rag chewing or something else?" When I
> > >> responded that I was using a model 546-C and matching external VFO to
> > >> chase DX from a quiet rural location, his response was, "you'll be a
> > >> lot happier with a Corsair-II... you'll be able to hear weak stations
> > >> with it that will be covered in noise in the Paragon!" I bought the
> > >> Corsair-II and sold my OMNI-D to my best friend who had just become a
> > >> General licensee and was looking for a radio.
> > >>
> > >> I still have that Corsair-II which was built in the last production
> > >> run of model 561s. I did A-B tests with it and the Paragon (model
> > >> 585) I bought several years later for MARS work for Operation Desert
> > >> Shield and Operation Storm. In those tests which were done using a
> > >> DOW Key Relay reversed so that only one radio was connected to an
> > >> antenna or with a coaxial jumper between the two radios with one
> > >> switch set for AUX ANT and the other to AUX RX and with the radio
> > >> with the switch set to AUX RX having a good antenna connected to its
> > >> SO-239, the Corsair-II was always slightly better. Its those signals
> > >> below S-2 and into the RX/band noise where the Corsair-II comes out
> >
> > ahead.
> >
> > >> I also had a fully loaded OMNI-VI+ (model 564) and found it, through
> > >> testing in the manner above, to be at least equal to the Corsair-II,
> > >> mostly due to 1.8 kHz and 500 Hz filters in BOTH I.F.s, making it
> > >> more selective and a bit quieter. The CAT serial port on the 564 is a
> > >> huge advantage for those doing computer logging while DXing or
> >
> > Contesting.
> >
> > >> The lack of frequency / mode information from an un-modified
> > >> Corsair-II like the one I own is its major drawback, in my opinion.
> > >>
> > >> I currently have an OMNI-VII (model 588) with a FLEX-1500 as its
> > >> sub-RX (N4PY mod) as my primary radio and with the Corsair-II as the
> > >> back radio. (see AB9M at QRZ.com for the station photo) While the
> > >> OMNI-VII is a great radio for my needs, in my opinion (and
> > >> experience) it needs to some careful adjustment of the RF gain to
> > >> avoid digital artifacts which are created from strong signals in the
> > >> passband when trying to work 2 kHz to 10 kHz from the DX station with
> >
> > lots of callers.
> >
> > >> Regarding the cost of any Corsair-II replacement; I know there is the
> > >> issue of price, but I believe its also a matter of value for an
> > >> experience which cannot be matched by others. If you provide a pure
> > >> analog receiver and transmitter chain like the model 561 with only
> > >> DDS VFO and CAT serial ports then perhaps your market segment is in a
> > >> different range than the IC-7300. Today absent any product from
> > >> TenTec to replace my OMNI-VII and FLEX-1500, I'll keep my Corsair-II
> > >> and buy a FLEX-3000. The Eagle may need a replacement, but one for
> > >> the OMNI-VII and ORION is long overdue.
> > >>
> > >> --
> > >> 73 ES DX,
> > >> Gary - AB9M
> > >>
> > >> _______________________________________________
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> > >> TenTec at contesting.com
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