[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

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
_____________________________________________________________________________________
Get more from the Web.  FREE MSN Explorer download : http://explorer.msn.com

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home