[R-390] Solid State R-390, Why Not?
scott
scott" <[email protected]
Tue, 13 Aug 2002 06:44:13 -0400
This is a complex subject and it sure would be nice if some of you
highly eddiecated folks would share it with us plain old folks. How
about writing a chapter for submission to the Y2K manual???
And remember. No big fancy words. Yall hear?
Scott
----- Original Message -----
From: "Cecil Acuff" <[email protected]>
To: "Bob Tetrault" <[email protected]>; "Bob Camp" <[email protected]>;
<[email protected]>
Sent: Monday, August 12, 2002 11:06 PM
Subject: Re: [R-390] Solid State R-390, Why Not?
> Greetings group...
>
> I would be interested in reading more about the methodology...not much
> published that I have been able to find....I am sure it's out there...I
just
> need to know where to look....
>
> I have the instrumentation......not sure the degree is necessary! I have
> worked with many highly degreed folks... some know how to make use of it,
> others get the most mileage out of it as wall decoration!
>
> Cecil Acuff
> The R1051 Shop
> [email protected]
> www.r1051.com
>
> ----- Original Message -----
> From: Bob Tetrault <[email protected]>
> To: Bob Camp <[email protected]>; <[email protected]>
> Sent: Monday, August 12, 2002 7:25 PM
> Subject: RE: [R-390] Solid State R-390, Why Not?
>
>
> > I've got the instrumentation and the degree and the methodology. You
might
> > also read the website of Sherwood Engineering that discusses many
> receivers
> > and their measured performance. My numbers are consistent with those
> > numbers. Sherwood does competent work.
> >
> > -----Original Message-----
> > From: [email protected] [mailto:[email protected]]On
> > Behalf Of Bob Camp
> > Sent: Monday, August 12, 2002 4:40 PM
> > To: [email protected]
> > Subject: Re: [R-390] Solid State R-390, Why Not?
> >
> >
> > Hi,
> >
> > Not saying you are wrong, but those numbers are about 40 db better than
> > what's been published elsewhere on the R-390A.
> >
> > Bob
> >
> > ----- Original Message -----
> > From: "Bob Tetrault" <[email protected]>
> > Cc: <[email protected]>
> > Sent: Sunday, August 11, 2002 8:21 PM
> > Subject: RE: [R-390] Solid State R-390, Why Not?
> >
> >
> > > Dynamic range is pretty hard to beat:
> > > IP3=+10dBm at 10kHz separation
> > > IP3=+20dBm at 100kHz separation (the difference is in the tunable
front
> > end)
> > > 4dB noise figure on all bands.
> > >
> > > One can buy receivers with better IP3 numbers, but they don't have a
4dB
> > > noise figure. It's debatable whether or not anyone can use 4dB, since
> it's
> > > commonly thought that the HF noise level is 10+dB, but that isn't
always
> > the
> > > case...and we watch and wait for those openings...
> > >
> > > One could experiment with pushing the distortion levels even further
> down,
> > > but it requires pushing the tubes harder since the standing current
> > > determines their threshold of distortion. Turning up the juice means
> > they'll
> > > exhaust the cathode emission sooner.
> > >
> > > Having extra modules does give anyone the option to play all they
want.
> > I've
> > > heard that ome people have replaced the first two mixers with 7360
> > designs;
> > > this is a double balanced tube mixer designed for SSB detection and
> > > generation. Rumor has it that they are noisier than the 6C4W, but I've
> > never
> > > seent the numbers or methodology. How much it improves the front end
is
> > also
> > > anecdotal. There was a considerable body of literature about similar
> mods
> > to
> > > the 75A4, since that receiver was/is(to some, even now) considered one
> of
> > > the best DX'ing receivers around. Again, my exposure never got beyond
> the
> > > anecdotal level, though I'd relish a review of all that was published
on
> > > that topic. If memory serves, there was quite a lot in QST and CQ back
> in
> > > the 60's and early 70's. Anyone got any numbers on this mod?
> > >
> > > The drawback to modifying an RF deck is the RF deck, as anyone who has
> > ever
> > > taken one out will attest.
> > >
> > > But let's remember that there were 50K of these made, and while there
> are
> > an
> > > uncounted number of them that were lost, stolen, spindled, stapled and
> > > mutilated, modifying one is a drop in the bucket.
> > >
> > > Imagine what a great exciter a 390 would make! Imagine a pushbutton
> where
> > > the diode load is so that you could zero-beat a carrier.
> > >
> > > pot-stirring in Portland,
> > >
> > > Bob
> > >
> > > _______________________________________________
> > > R-390 mailing list
> > > [email protected]
> > > http://mailman.qth.net/mailman/listinfo/r-390
> > >
> > >
> > >
> >
> >
> > _______________________________________________
> > R-390 mailing list
> > [email protected]
> > http://mailman.qth.net/mailman/listinfo/r-390
> >
> > _______________________________________________
> > R-390 mailing list
> > [email protected]
> > http://mailman.qth.net/mailman/listinfo/r-390
> >
>
> _______________________________________________
> R-390 mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/r-390