G11 Deluxe Hand Controller Cable

I have a Losmandy G11. It’s old now, but with the odd upgrade it still works OK. I had a problem with my deluxe hand controller, I must have dropped it one to many times and the cable at the hand controller end was dodgy. How hard can it be to replace the end, better than waiting for a cable to arrive?

Its taken all today but its finally working. The trick was in the Losmandy doco on page 83 it described the pin outs – which are straight through – but it notes that pins 12 and 13 should only be connected to ground for use with a serial connection (the port can be used for both serial or the hand controller). However to use it for the deluxe hand controller you have to wire all the pins including 12 and 13 along with with soldering the ground to the shield of the plug.

I was so relieved when it worked. All tested just fine, what else are rainy Sundays for?

Tracking

After weeks of mucking around I’ve finally achieved reasonable tracking. The stars are round – most of the time. Tests with 100 and 300 second subs yields nice round stars, I’ve yet to try 600 seconds.

First step was polar alignment, I used the PHD graphing technique. This doesn’t take very long and yields good results. Check out ftp://sarcasmogerdes.dyndns.org/download/Drift-alignment-using-PHD-graphs.pptx

Post alignment shots of 30 seconds still showed star elongation in only one direction, vertically in the image. Checking out the Maxim guiding graphs the Y axis (dec) had RMS of less than 0.1 but the X axis (RA) was around 2. 2 pixels!

I’m using a Megrez 88 as a guide scope. It has a focal length of 498 mm. Is this to short for the 3m focal length of the LX200? I tried a barlow. This only made it much worse.

So back to basics what could possibly be wrong? Backlash!! What is backlash? I had no idea. Don from Bintel sorted me out. The RA axis on my G11 moved when I wobbled the scope. It moved only a little but it was enough – backlash. I have the losmandy one piece worm gear installed so I refitted it, did everything up again and remeasured. It was better but far from perfect.

Down to this evening. I read somewhere last night on the Net that exposure time of the guider could contribute to guiding errors. So I went back to my 1 second exposures. I had used 3 seconds because I was attemping to avoid seeing issues with stars. Guess what perfection! The stars are not as round as my old refractor but the are very close. Tracking errors in RA are now RMS about 0.4. Much better.

PEC training time.

Autofocus Part 4

Finally a clear night. The settings for the for my LX 200 and Microtouch worked brillinantly. Focus achieved! 6.52 yields step sizes in the 1/2 Flux diameter changes of a little less than 2. See the image of the V curve below. Well done Maxim developers.

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Update: I must have done this 20 times since then with regular success. The choice of stars is quite important, anything that maxs out the intensity is bad.

Collimation

So tonight was one of those charmed evenings when all the configuration came together. Amazing what a bit of reading can do.

I started with collimation. After trying to complete it manually for a couple of nights and doing battle with the eyepiece, I gave up and downloaded CCD Inspector from CCD Ware. Installed and operational within a few minutes, it linked to Maxim smart quick and the realtime collimation, single star started. Initially the collimation showed numbers greater than thirty – great with the eyepiece eh? :( . The direction and magnitude was always consistent, same direction, same size.

To figure out which way to move the knobs I initially tried turning them about 1/8 of a turn to see which way the star moved. I did this for each of the knobs and after writing down the direction I could then move the star to follow the line pretty simply.

I got to numbers of around 7 and the line direction started jumping around, something fierce. I noticed that every 2 out of 3 refreshes the line still pointed in one direction but with varying magnitudes. After many small adjustments the line direction started pointing in any direction almost randomly but with all the magnitudes less than 7, with common occurances of less than 3. Pictures below. The larger numbers where form earlier in the process.

The resultant stars in Maxium showed showed elongation of 0.080 or less. Nice!

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