This information is outdated, as the ISS TNC has been configured now. However, i keep it has it may still be usefull.
As my geographical position , just in the middle of the North Atlantic Ocean allow me to be alone in the ISS´s range,a was able to make some testing on packet , and try a variety of settings.
I have transmitted a lot of packets, and all with very good success rate-no doppler correction.As soon as ISS goes over Europe , success rate decrease drastically .
The TX delay can be as low as 5 , that is quite impressive,but i think a more realistic TXD should be near 20 ,that is 200 ms.
I have succesfully digipeated with an HT , 3 watts output,6 meters of RG58 , and a 1/4 wave on the roof of my car, but only when ISS was at hight elevation.I think more power is a better, if not necessary.
Please do not connect to ISS while the callsign is NOCALL, it is useless an more dificult than simply digipeating.
The TX delay aboard ISS is very short, so you should avoid to use a preamp, when i use mine i simply stop to receive my own packets;it helps a lot, however, to receive other´s....
For monitoring ISS , you can try the command "PASSALL" "ON" if available on your TNC , this will let you monitor packets even with errors.This of course remove the "Error free" feature of packet, so you may see strange things appears,but helps a lot in marginal conditions.
Here are the qsl i have received from the first qso i have made with Susan Helms, NA1SS:
The corresponding recording is HERE.(196kb)
Click on the image for a larger size(400 and 200 kb)