Hi Tom,
Yes, but if even if the spurious signal is coming from an unintentional
oscillator, it appears to be phase-locked (at least crudely) to the
14 MHz fundamental. This implies that the unintentional oscillator is
injection locking to a frequency to which is it has a non-integer
relationship (Fosc = Ftx/2, Fosc = 3 Ftx /2 , etc).
BTW, I am not disputing your 30 years of observations. This is the
first time I have run across this kind of thing. I have never seen it for
myself in anything that I have worked on.
73 de Mike, W4EF..............................
----- Original Message -----
From: "Tom Rauch" <w8ji@contesting.com>
To: "AMPS" <amps@contesting.com>; "Michael Tope" <W4EF@dellroy.com>
Cc: "David Robbins" <k1ttt@arrl.net>
Sent: Wednesday, May 22, 2002 3:00 AM
Subject: Re: [Amps] Subharmonic
> > Yes, it would seem a bit improbable for a system like this
> > to just happen by accident, although as the IEEE paper
> > points out, it is theoretically possible, which was, in and
> > of itself, news to me.
>
> A major point of all this is whether the effect is common or even
> occasionally occurs at HF, or even is possible to occur without
> special circuitry.
>
> In over 30 years, I've never seen it happen. I've never seen a half-
> frequency signal appear in a PA or non-linear system of any sort with
> the system having an oscillator. I've watched plenty of spectrum
> displays and short of instability in PA's and transmitter systems
> have never seen the effect.
>
> > Whether you believe its due to parametric division, super-
> > harmonic injection locking, or some other less esoteric
> > mechanism (like a D flip-flop), the tracking relationship
> > between the 14 MHz fundamental and the 21 MHz
> > spurious suggests that an F/2 component is coming from
> > something (either in the transmitter or receiver).
>
> Of course it is coming from something, the question is what is it
> really coming from. I suspect it could be products from mixing with
> some intentional or unintentional oscillator.
>
> > David, please let us know what you find out with regard
> > to the 3F/2 mystery. I am really curious to understand
> > what is causing it.
>
> I'm interested in the cause also. It is an odd and rare problem.73,
> Tom W8JI
> W8JI@contesting.com
>
>
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