Starting to piece it together
April 2003 - 2.4 GHz Downconvertor
I realized that the first thing to do, is try and hear the downlink. Since I already owned 2m multi-mode receive capability (FT-100 and old FT-290), I needed a down converter. Downconverters comparison for Mode S is written by AMSAT-ZL. This article lays out some of the down converter options available to receive the 2401Mhz downlink.
After looking at some of the options, I decided that for starters, I would buy a down converter. This is an off-the-shelf solution, but I figured there are lots of other challenging areas to play with (downlink antenna's, uplink system, etc.) I opted for the K5GNA down converter at around $100. (go to Ebay.com, and search for AO-40)
If you are interested in building or converting your own, start with the following pages:
Cal Amp 31732 modifications for AO-40 by WC0Y
K5GNA also offers an unmodified converter that you can hack away on yourself
April/May 2003 - 2.4 GHz Receive Antenna
Next, I needed an antenna. As I mentioned these endeavors around work, one of my colleagues offered to give me an old RCA DSS dish. I looked around the web some more, and discovered that a lot of people are making it work with similar dishes; thus I decided to put making the cardboard antenna's (that originally got me into this!) on the back burner, and try with this dish...
I started with reading G6LVB's article Modify an Anologue Sky TV Dish for AO, and Dishes for Amateurs, again by Robert, W0LMD, which has dishes of all shapes and sizes.
I found Paul Wade, W1GHZ's website, and his excellent Antenna Book. The chapters on parabolic dishes and offset-fed dishes are a great help in understanding how this all works. The addendum on common offset fed dishes describes most of the commonly available small dishes, and it even had my RCA dish! This same addendum also has a good method of finding the focal point of the dish; since this is where you have to locate the antenna, this is very important. (see below)
May 2003 - Learning about feeds
Next, I needed a dish feed. I read, among others, the following pages:
Helix Feed for Small Offset Dishes, again W0LMD, has an overview of various feed systems; a good place to start.
G6LVB's article Modify an Anologue Sky TV Dish for AO has a good section of helixes.
K5OE's website, the sections on Helix Experiments and Helix feeds for MMDS Dishes.
At this point, I decided it was time to build a few things: a test signal generator, and a helical feed for my dish.