[R-390] Solid State R-390, Why Not?

Tue, 13 Aug 2002 07:18:20 -0400

Hi,

It sounds like a few pages of data on the R-390A measured with modern
equipment would be a good idea. Something like a QST review (multiple bands
etc). The techniques and equipment to do so are not that big a deal, just a
pain to set up and take all the data.

    Bob

----- Original Message -----
From: "scott" <[email protected]>
To: "Cecil Acuff" <[email protected]>; "Bob Tetrault"
<[email protected]>; "Bob Camp" <[email protected]>; <[email protected]>
Sent: Tuesday, August 13, 2002 6:44 AM
Subject: Re: [R-390] Solid State R-390, Why Not?

> 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
> > > >
> > > >
> > > >
> > >
> > >
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> > >
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> > >
> >
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