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Re: choice of IF frequencies

John Stephensen, KD6OZH <kd6ozh@gte.net> wrote:

>Yes, it can be done and most of the 1296 MHz transverters
>in the 1960's and 1970's used a 28 MHz IF. However, they
>all used fairly large narrowband interdigital filters built
>up from sheet metal and tubing. This was required to get a
>Q high enough to reject LO and image frequencies...

There is of course nothing preventing you from building
an image-reject mixer, in which case you can use any IF
you want. Even baseband. All you need is enough image
rejection to keep the image from killing the noise
figure. If you can't be bothered, you can also just
eat the noise figure hit. Based on what I've heard from
AO-40 so far, this won't be much of a problem...

Laura Halliday VE7LDH     "Que les nuages soient notre
Grid: CN89mg               pied a terre..."
                                   - Hospital/Shafte
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