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Re: Popularity of 2m I.F.



Rich Dailey, KA8OKH <okh.npi@gte.net> wrote:

>Was on the phone with a good friend the other day, extolling the
>virtues of ao-40 (of course). He has always been interested in
>satellite communications, and is real receptive to the idea
>of getting a mode S downlink setup running. But he posed a
>question that I had no clear answer for - "Why does every-
>body want to use 2m as an I.F., given the proliferation of
>good used hf radios? Why not use 10m?
>
>So, what should I tell him?

Image response.

At these frequencies it's a performance issue, since
with an antenna pointed at the sky, the probability of
anything other than noise being on the image frequency
is pretty slim.

You can use any IF you want with an image reject mixer.
These are available commercially as both packaged units
and as building blocks.

If you are prepared to eat the 3 dB SNR hit, you can also
use any IF you want, and can then dispense with image
filtering altogether.

Is it time for a new generation of converters?

Laura Halliday VE7LDH     "Que les nuages soient notre
Grid: CN89mg                     pied a terre..."
ICBM: 49 15.042 N 122 59.053 W       - Hospital/Shafte
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