How to measure octagonal dish for FD?

[delta_charlie]

Hi all, anybody have an idea on how to measure the diameter of an octagonal (Paraclipse clone) dish for an accurate focal distance calculation? Measure to the outer most points? Average the diameter of the high and low points? Measure both the inner and outer diameter? Or maybe use the inner diameter (low points in the dish outer edge) and take the depth from a string tied to the inner dish edge?

Then after I calculate the FD do I measure to the probe inside of the feedhorn or someplace else?

Thanks for any clarification, DC

 

[elzipa]

You may want to average the diameter of the high and low points to get a more reazonable dimension... I you feel a bit unconfortable about the extra area you lose then the inner diameter will give you a dimension for a smaller dish than the one you have

 

[guapoharry]

I would measure and do the calculation for both. Then compare them. It wouldn't surprise me if they are close or the same.

Wouldn't the depth be more when measuring to the outside. Likewise, it seems like the depth would be less when measuring the inside diameter.

 

[Anole]

just a thought . . .

Interesting quandary you have, there.

If it's a clone, how 'bout looking up the specs on a real Paraclipse and figuring that's correct?

If you really want to test the above suggestion, ya might get some measurements from real Paraclipse owners, and compare against your own.

 

[charper1]

Possible idea help?

http://www.satelliteguys.us/c-band-...lignment-tolerance-dish-string-tolerance.html

 

[delta_charlie]

Thanks for the replies.

I think I will calculate from both the inner circle and the outer tips and compare/split the difference.

Will also try and compare to a Paraclipse and see how it matches up.

Getting back to the other question - do I measure to the probe or some other spot when setting the distance to the center of the dish?

Thanks, DC