One of the original theories for the LSB/USB differences was brought about
by the use of a 9Mhz. "IF" frequency in some of the early SSB gear.
Originally, there was no voice modes at all on the 40 meter band. Also 15
meters hadn't been opened yet and there was little SSB activity on 10
meters. Hence, the "primary" SSB activity was mainly on 75 and 20 meters.
Generating SSB on 9 Mhz. was chosen for ease of operation and also to
minimize "spurious mixing byproduct signals." This was heterodyned to 4 and
14 Mhz bands by use of a 5 Mhz VFO (hence 14-14.3 and 3.8-4.0 Mhz bands used
the same VFO range.) If Upper sideband was selected on the 9 Mhz. SSB
generator, this would result in USB on 20 meters and LSB on 75 meters for
basically the same VFO range.
The first widely popular SSB transmitter was the "SSB Jr." exciter which
came out in GE Ham News as I recall. The circuit was adapted and refined by
Central Electronics when they manufactured their then famous model 10A and
later, 10B exciter/transmitter. A paltry 10 watts SSB! SSB advocates were
quick to point out how well SSB "got out" compared to AM voice using much
less power and band space. The practice of using LSB on 75 and USB on 20
continued, as changing over would necessitate turning another switch, and
the practice of not switching sidebands in the 9 MHZ. SSB generator had been
the "norm" for several years so the practice persisted. For those who don't
know it, the "phasing" method of generating SSB was the "most used" method
in the beginning and lent itself to homebrew construction from junkbox parts
of SSB gear in the early days. HF filters were then very expensive, and few
amateurs who "built" gear could afford the Collins mechanical filters! The
complex crystal filter much used these days, hadn't come into widespread use
yet.
When 40 meters was eventually assigned a "voice" sub-band and 15 meters was
opened, the practice of USB from 20 meters to 10 meters and USB on 160-40
meters was established. I have no idea just "who" established it! ARRL?
General use? The "little band of SSB advocates" in a world of AM diehards?
Ideas any of you old timers?
When use of SSB became popular in commercial marine radio circuits and
eventually the military and aeronautical long haul communications, Upper
Sideband was "standardized" for these services. (By the FCC?) The amateur
services did not follow suit.
Should we do that today? Some people say yes, some say leave it as it is.
It WOULD simplify manufacturing the radios by elimination of un-needed
parts/switching devices. I would imagine very little vacuum tube homebrew
gear is still in use that worked only USB on 20 and LSB on 75 meters!
Anyway, that's the "WHY" of sideband use on the ham bands today digging back
to when SSB was for all practical purposes, "non-existent" practiced by a
few radical amateurs during the days of what turned out to be mostly
unstable receivers in the "old days". Am was "too easy" to keep using on
the hundreds of watering holes on 75 meter AM for "local" operation before
the widespread popularity of 2 meters!
73,
Sandy W5TVW
----- Original Message -----
From: "Jim Miller" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, May 23, 2008 10:37 PM
Subject: [Elecraft] USB on all bands ??
----- Original Message -----
From: "Ron D'Eau Claire" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, May 23, 2008 5:38 PM
Subject: RE: [Elecraft] Dayton Discovery [OT]
.....snip......
Indeed, one of the first things I expect to see is pressure on Hams to
adopt
USB as the "standard" sideband on all Amateur bands so the manufacturers
don't have to consider sideband switching in their product offering.
Ron AC7AC
Anybody been around long enough to explain the theory behind the use of
LSB
on the lower bands vs. USB higher up? What is the advantage to doing so?
73, de Jim KG0KP
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
--------------------------------------------------------------------------------
No virus found in this incoming message.
Checked by AVG.
Version: 8.0.100 / Virus Database: 269.24.1/1464 - Release Date: 5/24/2008
8:56 AM
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
