[R-390] SSB on the 390 series

[jlap1939@yahoo.com]

Friends,

A few have asked about the item I sent a few years
ago, relating to reasonable SSB on a unit not intended
for SSB. They wanted the method again.

We have so many experts on this list...I hesitate to
write up the method taught me long ago. I got it
straight from cpl. Stone . ... when I was young and
viable...(?) But you don't have to be highly sentient
to do this..The ability to listen is the most
important requirement..

First of all, while pitch discrimination ranges from
perfect pitch, to tone deaf, my understanding is that
all can generally detect a very small change in pitch.
As a result, the best, (or lowest, in case of the
390), point for the osc, (usually called BFO..)can be
determined easily. The change detected by most people
is 4 to 5 cents, or 4 to 5 / 100 of a half step in
music pitch, a very small ammount indeed. It is, by
the way, this ability that allows highly experienced
persons to align w/ amazing sucess, with only the ear.
(That is, "manually", as is often said). In mil.
practice, I saw alignment done to near perfection with
this method..

On the above, I refer you to an enormous amount that
is available just using the term "sound"..on the
internet...Add "music", or "physics" and you could not
read it in less than a lifetime..I will not continue
on acoustics, but suggest you might want to read, if
you never have..(By the way, my minor was Acoustics. I
once thought I was bright enough to be an engineer..)

It is important to remember that you will always hear
a harmonic content in any sound, and you have to
listen carefully. It is of interest that the result
for all radio SSB transmissions, is sometimes as good
as the best converter..It will depend upon being very
careful to find the correct settings, and on your
filters.

The Method for the 390 series Is...:

1 Remove ant. and go to a very quiet point (rel. to
the
  internal noise). Remove BFO knob, and with BFO
switch
  on, tune BFO to find point where the pitch, or the 
  harmonic complement is at the lowest pitch. (In
other
  words, the "hiss"...). Check several times, then you
  will tighten the knob at "zero". All this assumes 
  that alignment and BFO neut. and so on, has been
done
  already.

2 When you calibrate for a band, turn the BFO value,
  to + 1 for LSB, or - 1 for USB, and then run your 
  calibration at the nearest point for your radio.
  In other words, you will calibrate with the BFO at 
  + or - 1, not at 0. At + 1, you will place that low 
  point, near over the point where the USB complement
  of any signal would be..(+ or - a little...) In use
  I vary from 1 to 1.5 with the BFO position. This
will
  result in your LSB component appearing  at "0", on
  the BFO scale..Don't get mixed up about upper and 
  lower..BFO positive is lower, and neg. is upper...
  Some find 1.5 a more reasonable starting figure for
  setting up the BFO..bandwidth for signals does vary,
  after all..

3 In calibration, the accepted method is to find the 
  highest meter reading, but for SSB, tend toward 0,
  rather than the highest reading..In other words, 
  compromise, and seek zero, if you wish an accurate
  freq. indication.

4 Select a filter position of 1 or 2, for the 390, and

  2 or greater for the 390a, (as the mech. filters
  will not allow the harmonic complement as well, and
  you have to allow more room, (as the skirts are so
  sharp...))

5 On the 390 use the medium setting on the response.
  (A position that, it turns out does have a value
  on this radio...)

6 set your RF and Local gains around 6 to 7 to start
  with. Be aware that the most common mistake made is
  setting the RF wide open...The smaller gain you can
  use with sucess, the better will be your signal.

7 It will now be necessary to play your controls 
  against one another, and the signal. Note that your
  indicated freq. is right on, with the correct sound
  to the vocal if you have followed the list above. I
  find the miscue in freq. smaller than  can well
  be resolved by the eye...However you may remove a
  bit more at times, to avoid interference. (And I 
  assume you can tell human speech, from "Donald.."

I use the following example:   

Do all the calibration for LSB, and do it at 3900.00.
Now tune 3898.5, and listen to the chicken farmer and
friends..check out by using ONLY your main tuning,
(not BFO..Leave it set at about + 1 to 1.5). You will
note that the "excellent" and "useful" digital readout
of the 390 series is right on 3898.5...! (depending on
align.)..Yes.It is much closer than you can resolve on
most dials like the, for ex, HQ 180...!! Well Well..

Try 20 meters, follow a few contests...you will be
"right on", in freq., or try a few nets...They are
usually "at or about.." so you will be closer than you
might expect..or than the net actually is..(Try
Hurricane net at 3935.)

In other words, its' darn near as good as some of your
electronic digital...and this in a unit dating back to
the late forties..

May I add at this point; It seems that some are not
willing to become used to the sound. Others are not
keeping the gain of the unit low..or don't stop to
realize where the signal for a given sideband actually
falls.

I also add, that the 600 works very well...just no
decent read-out..And.. I want to point out that I have
done this since a child, and got excellent results
with the most economical Nat. and Halli. radios..even
the 38 series...In those days there was almost no SSB,
and you really had to look to find some...Of course,
you have to change the method a bit for different
radios, according to filters and controls..

It only remains for me to offer my apology for the
long-winded post, in the event you have no interest.
In addition, I realize that many may find fault with
my method, or some may be kind enough to correct me
where I have made a mistake. Please feel free to
comment, whatever it may be..For those who think I am
full of strong wine...try it..you might be
surprised...

Regards, John  (JLAP)

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