Please help with tp

[altadata]

Can someone please explain what a transponder is?
Do I need to fine adjust the antenna ( azymuth,elevation ) for targetting a specific transponder?

I'm getting the following behaviour while trying to target Galaxy 25 ( 97W):
- I'm getting 82%S and 50-60% Q on just a few transponders, but I'm getting 0% on the transponders I'm interested in.
- If I slightly adjust the azymuth, I get very good Q ( 75-82% ) on may of the transponders, including the ones I'm interested in.
The problem is that Q75-82% is not constant, it goes 0-75-0-75 very quickly ( it fluctuates ). Therefore it is unuasable.
Can someone have an explanation for this?
TIA.

 

[turbosat]

The way I read it someplace was, that the satellites have a number of individual transmitters, each one 'a channel' rather than one transmitter operating at 24 or 32 diff frequencies. That may be an over-simplification but you get the idea. And, some of them may operate at different power levels on the same sat, hence you get diff signal levels. Some may be spot beams, or not intended for national reception, etc.
It is possible to get one polarization better than another though, if you are not zeroed in on the satellite. I've seen that being off target a little may let you get vertical better than horizontal or vice versa. Check your pole for plumb, and the skew settings. If you have a motorized system the motor usually takes care of the skew, as it moves thru the arc.