Super C9

All,

Even though this is not quite telescope making, it will be a heavy modification.

The C-9 mods have begun! The optics in this scope have impressed me enough to begin some serious mods to make it a better instrument. A cheap APO killer for the lack of a better term. Since I can't afford a TAK, AP, or TMB in the 150 to 180mm size, I guess this will have to do.

The photo shows the newly finished ventilated dew shield (yes, it will be painted). I purchased the tube for the dew shield from Hastings Pipe. The ring was from a scrap piece of aluminum. A reduced secondary size (currently 36%) and closed loop cooling system is next.

According to my calculations the finished OTA should be at least as good as a 6" APO for contrast, equal to a 8" F/15 mak for pure high performance, light grasp equal to a 8.5" achromatic refractor and of course the resolution will still be what you would expect from a 9.25". Time will tell

Keith

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How are you going to reduce the secondary size?

Hi Keith,

Keep up the great postings !!

Always fun to see what you're up to next. 8)

Do you have a web page ?

All,

Uh oh, he went and done it Decided to go with a "air stirring" mod. Much easier to install. How well will it work :S Only time will tell

The fans are installed and the picture also shows the thick paper baffles designed to spin the air within the tube just behind the mirror. The only thing that remains is the electrical port and to finalize the wiring. So far so good. Hope to have the OTA up and running by sundown tomorrow.

My fingers are crossed If all goes as planned the fans should spin the air within the tube just enough to break up the currents from the secondary, the sheath of the primary and equalize the temperature of the air within the tube. If the mod works I will take pictures at the focus to show the difference.

Keith

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Motors and mount.

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Minimal Invasive. After the scope is put back together these six screws and the small electrical port will be the only give away of the mod. The performance should be "off the hook" for the moon and the planets I hope, I hope, I hope

Keith

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All,

Just mounted up the scope. The usual temperature plume was seen in the out of focus star pattern. Turned on the fans and instantly saw the plume start to spin and dissipate. Scope currently cooling from a temperature difference of 15 degrees. Garage 62 degrees/Current nighttime temp 47 degrees. The wind is blowing and the seeing sucks but I don't care. It works

I guess as with all designs we find better and easier ways to get the desired result we want. This was so simple I had it completed in two days. My other designs were not so easy.

Keith

Update to the update:
** Scope is ready for lunar/planetary use after 5 minutes. After 20min the swirling temperature pattern is barely discernible. Not bad for a temperature difference of 15 degrees. No filters needed. No outside air introduced into the OTA (no dust). Whoopee! Now if I could just get my hands on a C-14 (for me) Anyone need a 8.5" refractor?**

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