[Laser] X-Y translator

[ERIC GUINN]

Art, et. al.,


Yes, I bought an ETX-60 on eBay, in fact, just for the purpose of Laser Comm!  It's one of those hobbies that comes and goes, so all I've done so far is to rubber-band a laser pointer to it and see what the backlash and control looks like.  In manual mode the thing can go in the following resolutions: 2 degree, 1 degree, 0.5 degree, 64X, 32X, 16X, 8X,  and 2X, (no 1X)  In "2X" (that I guess is one motor step per keypad press)  it takes about thirty seconds of drive to transverse the diameter of a laser pointer beam!  That's slow!  The bigger problem is backlash.  The backlash isn't bad for astonomy work, but for laser work it doesn't really ever place the beam back in exactly the same place.  Theoretically backlash can be calibrated out in the System menu, but in reality it isn't so perfect.  I find, though, that scanning back and forth while progressing down across the target seems to work pretty well and repeatably.  The translation speed is so slow that the remote receive operator should be able to yell "Stop" over a radio link in plenty of time for the transmit operator to let up off of the telescope slew key.

My plan is to build a mechanical laser mount clamp which mounts on the telescope tube and is stable enough that I can align a laser to at least within a 9mm eyepiece field-of-view.  That way I can use the telescope itself for initial pointing AND possibly for an eyepiece-receiver.  (I'd prefer using my 8 X 11 fresnel-and-K3PGP preamp receiver, but it's too big to mount to the scope, so it is aimed separately)

So far the laser mount and a tripod have been the hard parts; neither has been built yet!

Um, the real hard part is that I can't get any of my ham buddies excited enough to build their laser station and I have noone to QSO with around East Tennessee!

If you have any ETX-60 questions I've forgotten, I'll see if I can answer them or test for you.




73,
Eric, AC4LS
Sevierville, TN