(sorry if this is a repost, I submitted this a first time but by the time I had finished typing I had to log in again, and was redirected to a blank page, not sure if it did anything.)

Hello all,

I've finally decided to get around to studying for a Technician license test since my friends and I have started to work on a high altitude balloon project. Our eventual goal is to have a two way data link (we don't care about the speed, we only need to get a gps position every couple minutes or so) between a car and a balloon. I have seen some out of the box data transceivers which appear to have the range, but I think it would be a lot more fun to build my own over this summer if it can be done for the same price or cheaper.

Anyhow, from what I understand from google, both the balloon and the car will each need a transmitter, receiver, and a TNC (or possibly just a laptop's sound card instead of a TNC for the car). I was going to settle for a one way downlink with a model rocket gps 2 meter tracker, until I found this kit:

http://www.brocott.co.uk/25-30mhz-tr...kit-p-400.html

At a cost of about ten bucks plus shipping, it seems too good to be true. From the way I see it, this combined with a receiver kit (I haven't narrowed one down yet but they also appear to be fairly cheap) and the pic-e "packet radio encoder" (it's not called a TNC on the site, perhaps I'm missing something?) should easily get a clear line of sight signal from 80,000 feet.

pic-e link:
http://www.tapr.org/kits_pic-e.html
I'm not fully settled on this particular kit (especially as I will have to buy the parts separately since they only have the pcb in stock).

So, my questions are as follows:

1) Am I missing anything blindingly obvious? Can you actually just wire the output of any old TNC (at low enough baudrate) to the input of this transmitter?

2) (US specific) Am I misreading the US ARRL hambands pdf for the 10 meter band? It appears to allow Technician liscencees to operate rtty and data from 28 to 28.3 mhz. (Pretty sure I read it right, just looking to double check.)

3) Is this transmitter too good to be true? It seems to me as though there must be a downside to its low price. Is there a possibility of frequency drift, randomly exploding, or the listed transmit power a lie?

4) What sort of steps should I take to make sure I don't interfere with other peoples' use of this band? And is there a better place for these sort of data transmissions? It would be great to just let this thing loose whenever I feel like it, but I don't want to jam anyone else. I chose the 10 meter band simply because of the low cost of this particular kit, and haven't been able to find anything nearly this cheap for other bands.

Thanks a lot for your input.