It's unlikely you'll see anything abnormal with an audio spectrum analyzer.
The "dirtiness" that one hears from a Pegasus or Jupiter comes from phase
noise. These radios use economical synthesizers that are a compromise in
terms of cost versus phase noise performance. See the measured phase noise
and graph in the QST product review. (Res Ipsa Loquitur)
A great method for listening to the phase noise component is to engage an
I.F. notch filter of an external receiver while listening to the Pegasus.
As you null the CW note with the notch control, what remains is the Pegasus
oscillator phase noise. The better the notch filter depth of the external
receiver, the better you'll be able to hear only the phase noise. It works
great and I have to credit Mike Hyder for pointing out this technique some
time ago.
Try this technique with the Pegasus and another transceiver of known good
phase noise performance. The difference is quite apparent.
The noise is not of much concern to me. I much prefer a stable,
well-developed keyed waveform on CW and extended response on SSB, even at
the cost of a slightly raised received noise floor and the Pegasus is
excellent in this regard.
-Paul, W9AC
From: "David McClafferty" <at060@chebucto.ns.ca>
To: "Tentec Users Reflector" <tentec@contesting.com>
Sent: Saturday, March 03, 2001 12:52 PM
Subject: [TenTec] Jupiter & Pegasus CW note
>
> If there were something modulating the CW note it should show up on a
> spectrum analyzer. I don't see anything on my Pegasus with my homebrew
> spectrum analyzer.
> When I was running a slower computer(486 with windows 3.11) I had reports
> of bad keying and I could even see the tranmit LED blink in the middle of
> dahs. This only happened when I was running a DOS based logging program.
> With a pentium 100 and windows 95 there is no problem even running the
> same DOS program.
>
> 73, Dave, VE1ADH
>
>
>
> --
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>
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