On Mon, 2006-07-03 at 11:58 -0400, CaseKE@aol.com wrote:
> Sorry this is so long - the question is short, but the extended story is long.
>
> OK. This MAY be a senior moment. I have owned both an Orion and an Orion
> II. When I look at the sweep on USB and tune such that the PEAK of the
> signal
> on the sweep is at 0, I must then tune down approximately 1.8 kHz to hear a
> natural voice. Put differently, when I am listening to a natural voice on
> USB,
> the peak on the sweep is then showing about 1.8 kHz above 0, of course.
>
> On LSB, the effect is the same, but reversed as would be expected (the sweep
> peak is 1.8 kHz lower than 0 when listening to the natural voice).
>
> On CW, a perfect audible 700 Hz signal is right at the peak - WONDERFUL!
>
> NOW FOR THE QUESTION (I understand already about sidebands, etc., and don't
> need a technical explanation): HAS IT ALWAYS BEEN THIS WAY? I WAS TOLD BY
> TT
> THIS MORNING THAT BOTH THE ORION AND THE ORION II HAVE ALWAYS BEEN LIKE THIS
> AND THAT IT IS OPERATING EXACTLY AS IT SHOULD. IS THIS TRUE? I want to
> recall
> on the Orion and even during the first two months of the Orion II (pre-return
> to the factory to fix another problem - see below) that the peak was right at
> 0 when listening to the natural voice of a station, regardless of USB or LSB.
> Since the current offset bugs me so much, I'm surprised that I never noticed
> it before. AGAIN, HAS IT ALWAYS BEEN THIS WAY?
>
> IF YOU ARE STILL WITH ME, LET ME TELL YOU WHY I AM ASKING YOU. When I first
> got my Orion II, I could not make AFSK operate correctly using EXACTLY the
> same setup that worked so well with the Orion where you need to set the PBT
> at
> +1.96 kHz per TT instructions. I called TT service about three times and
> finally, after much experimentation and discussion, I discovered that AFSK
> would
> work fine using a PBT setting of -1.96 kHz (minus 1.96 Hz). During the next
> call
> to TT to report that this was happening and indicated a possible problem, I
> was told that OF COURSE a value of -1.96 kHz should be used and that that was
> how it was on the Orion, also. Well, I still had my Orion at the time and
> could prove differently. That seemed to carry NO WEIGHT. Well, there is
> more to
> the story. Another problem came up and I had to return the Orion II to the
> factory. They not only fixed the problem, but when the rig came back, AFSK
> worked perfectly JUST LIKE THE ORION at a PBT setting of +1.96 kHz!!!!!
>
> What did I learn?
> 1. Just like in REAL LIFE, people are somewhat disinclined to listen to the
> facts and to assume that JUST MAYBE the caller has a point and even some hint
> that should be investigated because it may indicate a more pervasive problem.
> 2. Just like in REAL LIFE, people's defense mechanisms go sky high right
> away and they seek to justify whatever is the current situation.
> 3. IF YOU ARE TICKED OFF THAT I SEEM TO BE BASHING TT, READ THIS ONE. I
> still think TT is the BEST. I've been a TT user since 1976 and would rate TT
> 9.5
> on a 10 point scale. I am now, and will continue to be, a repeat buyer.
> Their service, when something goes back to the factory, is prompt and
> excellent.
> 4. I am exceptionally pleased with my Orion II.
>
> 73 to all, Ken K5KC
Frequency control is the injected carrier frequency, not mid spectrum.
Received audio for SSB peaks at 1.8 KHz, not DC. That spectrum peak will
vary with the voice observed, the microphone in use, the radio that
transmitted it, and any microphone equalization used. It will even vary
with the distance the microphone is from the speaker's lips. It will be
modified further by the receiver creating the spectral display.
These facts are true for any ham rig, past present, and most likely
future.
Government frequency settings are defined at center of the spectrum and
likely some radios display the center channel frequency. Finding the
correct carrier frequency has confused many hams going to MARS
frequencies, including some who shouldn't have been confused. The
results were that they interfered with nets assigned to adjacent
channels. Our 60 meter channels are assigned as center frequency.
So you have to tune for copy. SSB will tolerate maybe a 200 Hz error,
but don't expect to get answers if you mistune that much.
The best tuning for SSB is when the harmonic pitches of the lower
frequency voice pitches come out of the speaker as harmonics, not
shifted a bit from the true harmonics. One would think that in time the
DSP would get smart enough to pick those and set the dial automatically,
but so far such hasn't happened. Such a frequency setting scheme would
be truly handy for checking the precise carrier frequency of a SSB
signal off the air. Today many services have frequency tolerances far
smaller than the tolerable error of copying SSB signals.
--
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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