DaveC wrote:
Microwave corrugated horn at the end of the wave guide has multiple choke
rings.

What point is considered the focus point of the horn. The feed point for the
dish is calculated and known, but I'm not sure what point of the feed horn to
considered when aligning the horn to the dish.

I'm not going to use this horn, but simply want to determine where the focal
point of the horn is so as to place my own 2.4 GHz feed at that location.

This is on a surplus Direct TV feed.

Hi Dave.

W1GHZ has an application that will determine the focus of your dish for you.

However, I find it easier just to attach a few small mirrors on the dish
and point it at the sun to determine the focal point of your dish. See

http://www.qsl.net/va3rr/dualmode/dual_mode.htm

Now you just have to figure out where the phase centre of your feed is...