[Orion] 3 PPM freq stability

[Martin, AA6E]

Hank,

I report my results and method at
http://www.aa6e.net/aa6e/blog/comments.html#freq . I figure that my
Orion oscillator is 4 Hz high at 10 MHz, about 0.4 ppm off.  I haven't
tracked it over extended periods.  That would be interesting.

Your result is 1.9 ppm off at 10 MHz, still within spec.  Except for
2.5 MHz, your results all scale well (same ppm offset).  That's what
I'd expect if all frequencies are based on a single TCXO.  
Propagation effects can fool you, and they are worst at 2.5 MHz.

One of my suggestions for a future Orion is to provide a TCXO tweak
adjustment in the menus.  That would let everybody get down to +/- 1
ppm at least.  If you want to be really elegant, provide  a zero beat
tuning indicator (or beat frequency counter) on the LCD screen.  Very
little hardware required.

73 Martin AA6E

On 5/17/05, Henry  Pfizenmayer <pfizenmayer at worldnet.att.net> wrote:
> Just curious from some of the Orion gurus - The past couple days I have been
> watching the readout at 10 mhz on my Orion. It looks like it starts almost
> dead on cold , then slowly drifts down to about 27 cycles low over several
> hours - then wanders around about 2 or 3 cycles . I am not really trying to
> pick fly specks out of the pepper but was curious what is going on , and am
> somewhat inclined to re-set the TCXO to be on closer after a couple hours
> rather than at cold.
> 
> Just for grins I checked 2.5 , 5, 10 , and 15 Mhz after it had been on a
> couple hours - and was a little surprised at what I see.
> 
> 2.5 mhz      1 cycle low
> 5 mhz         9 cycles low
> 10 mhz     19 cycles low
> 15 mhz     29 cycles low.
> 
> After about 10 hours , at 10 mhz it runs 23 to 26 hz low.
> 
> I cannot tell from the manual what the synthesizer scheme is - but I was
> surprised that with a fixed IF the mixing scheme would be off as a strong
> function of rx freq. Would have thought the injection would have been phase
> locked to be off the same amount on all bands. I would not think they have
> any conventional xtal oscillators for the offsets ?
> 
> Is there  any web site that shows the mixing scheme that I could look at ?
> 
> I was watching the zero beat with WWV by using either LSB or USB (both are
> the same) , agc off any playing between atten and rf gain and antenna to be
> able to hear the 1 hz or less beats . (Obviously  using the sub receiver )
> 
> Rgds- Hank K7HP
> 
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http://blog.aa6e.net