75m. Slopbucket, circa 1934

[k4kyv]

I just picked up a collection of R-9 magazines from the 1930's.  I was looking through them and ran across a series of articles on SSB, starting in late 1933 and continuing over into 1934.  One episode is missing, but have all the others.  I haven't carefully read the entire series yet,  but they do have some strange explanations by to-day's standards.  The first episodes were theoretical, but the last article gives circuit details of an entire homebrew SSB rig.

The balanced modulator starts out at 10 kHz carrier frequency, with a sideband filter made from audio transformer cores.  The audio frequency response was limited to 500-3000 Hz, because below 500~ the filter wasn't sharp enough to sufficiently well separate the sidebands, and above 3000~ there were problems of overlap with spurious signal products and audio harmonics.

The 10 kHz SSB signal is converted to approximately 200 kHz, which is then mixed with a HF oscillator to convert the 200 kHz signal into the 3900-4000 amateur band.

It would be an interesting project for someone with a little time on their hands, to attempt to duplicate that transmitter and put it on the air.

[Herb K2VH]

And here I thought SSSC (as they used to call it) was MODERN, and AM was Ancient Modulation.  My oh my, I wonder if all the honkers, quackers, and oinkers are aware of that!

Actually, I believe that Single Sideband Supressed Carrier goes back to the 1920s.  Modern indeed!

vH

[AF9J]

Yes it does.  Actually, developement started back in 1914, at AT&T for use with long distance phone links.  Expiriments were done transatlantically with SSB in 1923, for this purpose, and by the 30s, it was being used for long distance telephone links.  It was all done with the phasing method.  QST printed an article on SSB's history in the January 2003 issue.  The reprint of this article is also in the compendium book the ARRL published, called Vintage Radio.

73,
Ellen - AF9J

[k4kyv]

Actually, developments started back in 1914, at AT&T for use with long distance phone links.  Expiriments were done transatlantically with SSB in 1923, for this purpose, and by the 30s, it was being used for long distance telephone links.  It was all done with the phasing method.

Some of the earliest work was done using the filter method - the antenna itself.  This was for transatlantic telephone work in the 100 kc/s range.  The tallest tower practical to erect was still a tiny fraction of a wavelength, and when tuned to frequency, the Q was too high to pass both sidebands.

[W4EWH]

Here's a thought - how about designing a high-fidelity version of SSB with carrier to get better power output for AM?

WBCQ uses LSB with reduced carrier on 5110 KHz, and it works great.  As AM'ers., we're fighting a 6db disadvantage from the start: we could reduce that to ~2db and really kick those amps into high gear.

FWIW.

Bill

[k4kyv]

One sideband plus carrier is not the same thing as AM.  It's merely SSB with poor carrier suppression.  There as a phase component in each sideband, but since with AM each sideband is a mirror image of the other, the phase component (also referred to as "quadrature distortion") of the two sidebands cancels out, leaving pure amplitude modulation, theoretically with no distortion.  But with only one sideband, the receiver detector sees both the phase component and the amplitude component, and the detected signal is a vector resultant of both components, highly distorted except at low percentages of modulation.