[R-390] R390/Solid State

Thu, 8 Aug 2002 22:33:49 -0400

WARNING:  THE FOLLOWING IS A DIATRIBE & MANIFESTO

Michael, Michael <sigh>  (as in Lee Strassberg to Al Pacino in Godfather II)

Where have you been?  Actually, you've been in the thick of it.  Me?  I'm
not even in electronics by trade, but have witnessed what you must also have
witnessed.

One of the reasons for converting to solid state might be that, like
diamonds, silicon is forever -- NOT -- on two counts.

Another might be improved performance -- not likely.  There are many
"premium" military and commercial units that may outperform the R-390 in one
area, but not another two or three.  There always seems to be a tradeoff -
noise, susceptability to overload or front end burnout, etc.  Power
conservation -- not particularly.  Less heat, maybe, but it's amazing how
much heat some solid state equipment puts out.  Longevity? Well, that gets
back to the "two counts".

One:  Solid state stuff fails also. Usually the active components aren't
plugins.  Some SS components degrade -- not true that they either work on
spec or not at all.  As front end FET's take hits, they can weaken gradually
before they fail.

Two:  To borrow someone's sig line "They don't make tubes like they used
to."  However, the most common tubes in the R-390 and '390A are still highly
available at reasonable prices, with maybe two or three exceptions, however
those are reversably solid-statable.  I have a passel of tube radios of
various stripes.  I have also acquired a number of high end solid state
receivers of the last 3 decades.  Take a look at the component complement of
the W-J's, Racal 6790's, R-1051's and so on.  How many of those components
are still widely available?  I have a Debeg 2000 that needs work.
Fortunately, it doesn't appear to have any latter day custom LSI or VLSI
chips -- mostly all standard, including a raft of CMOS and Schottkey IC's as
well as an 8080 microprocessor.  (Leading, bleeding state of the art 'late
60's early 70's.)  They used to be as cheap as dirt.  Now find them, other
than collector's items for show.  Some of the CMOS and Schottkey numbers are
familiar to me from when I worked a parts counter.  Now, one digit off is a
miss that's as good as a mile.

Problem is, a lot of the solid state components had a limited product life
cycle and are no longer in production.  What components will you choose,
considering that some may fail, particularly in an experimental mode?

As Tom L. pointed out, the R-392 is a much better candidate for solid
stating.  I have one that someone did a full SS job on.  It arrived in the
form of a surprise.  It appears that many of the transistors were a one for
one replacement for the tubes.  There is somewhat more rationale for doing
this to an R-392 -- the 26 volt tubes are getting harder to find in general,
not as if it were just one or two like the R-390's so far.  However, when I
first made some inquiries on this list about it a 2-3 years ago,  I learned
that the most likely transistor types -- with high enough impedance -- were
already of the unobtainium variety.  Hopefully, there's something else to
use.  Oh, yeah, my SS R-392 works, drawing only about 80 ma with the dial
bulbs off and 250 ma with 'em on.  But it doesn't work nearly as well as a
stock R-392, but that's not to say it couldn't be improved upon.

Now, if you really want to whip up a solid state R-390, I suggest the
following:  Purchase a front panel and set of handles in good shape and
refinish as needed.  Use a standard chassis or modified '390 H mainframe
behind it.  Get a Sony 2010 and make some modifications -- externalize the
LCD and place it behind the Veeder cutout, get rotary pots to replace the
volume control, etc.  Get some of those digital rotary controls or
cannibalize some computer mice, etc. to bring the controls out to the front.
Secure the 2010 to the chassis and you're done.  Or you could do this with a
PCR-1000 or a Ten Tec RX-320 and a used laptop.  Just position the laptop
computer with the screen opened so you can look at it through the Veeder
port.

OK, sorry, but here's a bee for your bonnet.  The "manifesto" part.

Thirty-two years as an EE and recently retired?  I have an assignment for
you:

1.  Start from a blank piece of paper.
2.  Tweak your non-A to a fair-thee-well and give it a good workout and
evaluation.
3.  Study the treasure trove of documents available (another thing missing
from those latter day wonders -- most don't even have decent troubleshooting
sections. You're supposed to master the theory section and then theorize
what's broken)
4.  Carefully review the mission of the R-390 series -- the extremely wide
usage in various situations -- military, NSA, CIA, commercial, hobbiest,
etc.over the last 40-50 years. The historical perspective.
5.  Review all the significant receivers that followed it -- the Racals,
W-J's, Harris, the military plus commercial, and high end consumer,
including current wideband Icom, Yaesu etc. Also consider computer
connectivity and control.
6.  Anticipate later, recent and coming changes in "software" -- namely
digital transmission, satellite, MP3, whatever signal "modalities" (always
wanted to use that word).
7.  Design the functional successor to the R-390A. R-390B?  At least, on
paper, and see what it looks like.

OK, some hard-nosed requirements -- low/no noise, wide selection of
bandwidths, tuning accuracy, long term serviceablility (like 50 or 100
years, not 7), same form factor of 19 inch standard panel by 10 whatever
high and about 14 ins. deep.  No need to make it small -- whatever room is
left over will be needed for optional expansion modules or storing things
like Bristol wrenches and spares.  Probably need a tube front end to ensure
protection of what follows from overload and nearby lightning strikes.

Oh, BTW, it's top secret, so if you tell I'll have to kill you, but the
latest greatest is guess-wot?  Thermionic emission technology on a micro
level.  Yup, LSI chips with a jillion micro 5814A's inside.  Someone on this
list told me, but I'm not tellin' who.  (Of course, now he'll have to kill
me.)  A few years off before it hits the commercial markets, and by then,
all the silicon stuff will be designated obsolete.

Should you decide to accept this assignment Mr. Young, the agency will
disavow, oops -- scrap that -- I'm sure you can count on a lot of help from
your friends.  This email will self destruct in 10 seconds, or maybe I will
..... <poof>

Barry

P.S  "Michael, Michael, we could be bigger than US Steel!"

----- Original Message -----
From: "Michael Young" <[email protected]>
To: <[email protected]>
Sent: Thursday, August 08, 2002 4:26 PM
Subject: [R-390] R390/Solid State

I have an R390 (not A) receiver that I have been wanting to convert to solid
state for many years.  Now that I am retired after 32 yrs as an electronics
engineer (communications and instrumentation) I am ready to have a go at it.
One of the things I bought a few years ago is the IF strip from an R390A
(tubeless -- but with all Mech Filters).  I have the depot manuals for both
the R390 and R390A.

Can someone point me to some sites that have information on my proposed
venture?  I am not particularly interested in reinventing wheels.  I also
want to build and install a electronic digital counter or the vfo.

TNX

Mikey

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