[time-nuts] FW: Injection locking

Bob Camp lists at cq.nu
Tue Feb 2 22:33:28 UTC 2010


Hi

If you do go the injection locking route check a couple of things:

1) Be sure to do the math and keep the 3db bandwidth down to the ~20 Hz
range. Otherwise you will be getting more phase noise than you probably
should. Generally this means having some kind of control on how much power
you are injecting. 

2) Consider what impact (if any) the extra signals running around in your
radio will have. The harmonics of what ever you inject are one issue. The
intermodulation products between the injection and the oscillator in some
cases can be another.

None of this is to say it does not work. Only that there are a few things
that may (or may not) be issues.

Bob


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of francesco messineo
Sent: Tuesday, February 02, 2010 4:14 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FW: Injection locking

On 2/2/10, Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:
> However injection locking also works when the frequencies ratios involved
> are rational numbers.
>  For 22MHz and 10MHz, the corresponding ratio is 11/5 a rational number.
>  For 42MHz and 10MHz, the frequency ratio is 21/5 a rational number

Then 2 MHz would work for both, obtaining 2 MHz from 10 MHz is quite
easy, HP AN-301-1
plus a 74LS193 would do it.
If I can make it work with the current oscillator design I'm using, I
can easily adapt it also to already made transverters, very tempting.

Frank

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