On Thu, 2006-08-10 at 10:45 -0400, Martin AA6E wrote:
> There are two technical issues here. Stability is not the same thing as
> accuracy.
>
> While you can track a definite warm-up drift of about 1 ppm over some
> hours, the stability of the Orion's TCXO is fine for most any ham
> operation. See
> http://blog.aa6e.net/2005/08/orion-frequency-calibration.html .
>
> Accuracy is a different matter. The actual setting of your TCXO can be
> several ppm off, depending on the factory's precision, your ambient
> temperature, crystal aging, etc. This means that when you dial in your
> favorite net frequency, you could be more than 20 Hz off at 14 MHz, and
> worse at higher freqs. That is enough to notice on SSB for a trained
> ear. (Many rigs on the air are a lot worse, of course. Either that, or
> a lot of ears are not well trained. Or both!)
>
> If you are interested in accurate frequency measurement, it is possible
> to use the Orion for sub-ppm measurements by careful calibration against
> a standard like WWV. See
> http://blog.aa6e.net/2006/01/2005-freq-measurement-test-results.html .
The one place a ham might need better proven accuracy and stability is
in MARS and CAP programs that now demand the volunteer's equipment meet
current excessively tight federal standards where a 20 Hz error is
looked upon as horribly bad (which it might be for some digital modes)
but is far better than the net controls can tune their super precise
radios.
While it can seem to make better than 1 ppm using WWV, old timers who
have made a life of measuring propagated signals report that HF
standards can be receive at sky ranges with precision about 1 ppm if the
propagation errors are averaged over a month. It takes 20 or 60 KHz
signals to achieve better accuracy in a short time and then I suspect I
see more than a little propagation short time variations when I try that
and I'm also seeing the slow phase noise of my local frequency standard.
>
> The Orion "dial" can be set to 1 Hz at 30 MHz. If that were fully
> accurate, it would be better than .03 ppm. So there is room for
> improvement!
>
> How much is that worth in terms of selling price? Not a lot for most of
> us, but the good news is that a better oscillator need not be
> expensive. Icom's IC-7000 claims 0.5 ppm (6 times better) for a cheaper
> rig than Orion. An after-market add-on would cost more, of course. I
> suppose I'd pay $50-100 without complaint, but not $300. No reason this
> has to come from TT. It could be a good deal for a 3rd party entrepreneur.
>
> A caution: make sure the phase noise is no worse than the current TCXO.
> Many voltage-trimmable oscillators have worse phase noise specs.
>
> 73 Martin AA6E
>
> James Duffer wrote:
> > snip
> >
> > Sorry but from my point of view it isn't worth that much additional cost
> > for
> > that improvement. The stability of my Omni VI, and FT-1000D is more than
> > satisfactory for my use. Maybe an option where those who think they
> > require
> > that additional stability??
> >
> > Looking at the radios that I have owned in the past, SB-300, KWM-2, Swan
> > 350
> > (!), HW-16, TenTec 544 etc. Frequency stability has improved with the
> > newer
> > radios and I have no problems with the current frequency stability.
> >
> > Jim wd4air
> >
> >
> >> If we want real frequency stability, here is what is needed:
> >>
> >> http://www.bliley.com/n47x___nv47x___co_08.pdf
> >>
> >> I wonder if TT would be willing to order a few of these custom since a
> >> volume purchase would be needed, and offer them as an option on new units
> >> and a mod to existing units? It would require a simple board to solder to
> >> the existing circuit board, but there is plenty of room to accommodate it.
> >> They could also add a trim pot on the board to fine calibrate if the 'EFC'
> >> version is used. Imagine having frequency stability and accuracy to one
> >> part per 10 million and 10 dB better phase noise, too!
> >>
> >> I'd pay $200-$300 for that, which would build in a fair profit for TT if
> >> more than a couple dozen were sold.
> >>
> >> Ron N6AHA
> >>
> >>
> > snip
> >
> >
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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