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TONGKW
Pooh-Bah


Reged: 01/16/07

Install LXD75 8” SCT OTA to 8” LX 90 fork mount new
      #6153004 - 10/23/13 06:02 AM Attachment (16 downloads)

Install LXD75 8” SCT OTA to 8” LX 90 fork mount
While many members here are doing deforking by removing the OTA from fork mounts and put the OTA on a GEM, I have just done the opposite.
For my newly acquired Meade LXD 8” SCT OTA with ACF, I have been trying to obtain a LX type fork mount. The reason being that I would like to add one more telescope with double tine fork mount to my existing list and use it at star parties for visual observations by the public as I find OTA on AltAz type mounts has better viewing positions than OTA on eq. mounts.
I have finally obtained an old 8” LX90 fork mount from a local club member who had deforked his LX 90 many years ago and just leave the mount lying around.

Unfortunately the screw holes on both do not match as this old 8” LX90 fork mount has the long trunion arms whereas my LXD 8” SCT OTA has the three screw holes on the body drilled for the new short trunion arms.
Rather than drill holes on the OTA body, I make use of the existing central hole and drill two new holes on each trunion arm of the 8” LX90 fork mount to suit the holes on the LXD75 8” SCT OTA body. There is a gap between the trunion arm and the OTA body for which I put a piece of packing under the trunion arm to take up the gap. I line up the OTA to the fork mount as best as I could in the fore and aft directions and with the hope the curved part on the trunion arm that press against the OTA body shall keep the alignment acceptable and the OTA orthogonal to the mount.

K W TONG
C8+CG5 GT, TSA102+HEQ5 PRO, MK67+Voyager, NexStar 6SE, C5+Mizar K, WO ZS80FD+Kenko NES, Megrez 72FD+Kenko KDS, Mini Borg 50, PST


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TONGKW
Pooh-Bah


Reged: 01/16/07

Re: Install LXD75 8” SCT OTA to 8” LX 90 fork mount new [Re: TONGKW]
      #6153006 - 10/23/13 06:03 AM Attachment (15 downloads)

The photo below shows the LXD75 8” SCT OTA riding on the 8” LX 90 fork mount.
The setup weighs 30 lb without any accessories.
The setup is back heavy and I plan to install a counterweight system underneath the OTA.
I have powered up the setup and tried mock alignment inside the house. The motor on both axis appears to run and without apparent problem.
Bad weather so far prevents an actual test in the field.


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TONGKW
Pooh-Bah


Reged: 01/16/07

Re: Install LXD75 8” SCT OTA to 8” LX 90 fork mount new [Re: TONGKW]
      #6153007 - 10/23/13 06:04 AM Attachment (15 downloads)

I make a wood platform on top of my old Gitzo 1505 aluminum photo tripod for use with this set up.
Though not as stable as the stock tripod, it is sufficient for visual observation.
The Gitzo 1505 tripod, at 22” long, weighing 9 lb, is more portable.


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TONGKW
Pooh-Bah


Reged: 01/16/07

Re: Install LXD75 8” SCT OTA to 8” LX 90 fork mount new [Re: TONGKW]
      #6153009 - 10/23/13 06:06 AM

There is a problem with the Autostar 497 hand controller.
I have to press very hard on the buttons and even have to “mash” at them to get a response. I have been told this is a typical problem with an old Autostar 497 hand controller.
I order a rubber keypad repair kit from Scopestuff to refurbish the Autostar 497 hand controller.
I took the Autostar 497 hand controller apart and cleaned the contacts. Then I mix the compound from the repair kit, applied the mixed compound to the small rubber contact points on the touchpad, allow to dry for 24 hours. I reassembled the hand controller.
Now the Autostar 497 hand controller responds instantly with just a light finger pressure on the touchpad.


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Matthew Ota
Hmmm


Reged: 04/30/05

Loc: Los Angeles, California
Re: Install LXD75 8” SCT OTA to 8” LX 90 fork mount new [Re: TONGKW]
      #6153654 - 10/23/13 01:03 PM

Let me know if you want a custom decal for your frankenscope. I made ones in the past for other. You can call it an LX D75 90 or something...

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Bill Barlow
Carpal Tunnel
*****

Reged: 12/03/07

Loc: Overland Park KS
Re: Install LXD75 8” SCT OTA to 8” LX 90 fork mount new [Re: TONGKW]
      #6154450 - 10/23/13 09:29 PM

Nice job, K W. Enjoy your new scope and mount.

Bill


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TONGKW
Pooh-Bah


Reged: 01/16/07

Re: Install LXD75 8” SCT OTA to 8” LX 90 fork mount new [Re: TONGKW]
      #6154538 - 10/23/13 10:31 PM

I think the original Autostar 497 hand controller is with this 8” LX 90 fork mount. On powering up, the screen reads “ C (07) Meade [43E] Autostar ” .
Some sky objects appear to be missing in the menu, such as the double star Epsilon Lyra 1 and 2. They should be there but I just cannot find them in the listing.
I would like to upgrade the Autostar hand controller. I heard some new versions of firmware can cause problem with the original Autostar 497 hand controller, may I ask what is the highest firmware version that can be upgraded with this Autostar 497 hand controller.


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psyhiker
member


Reged: 02/28/13

Loc: Burbank, CA
Re: Install LXD75 8” SCT OTA to 8” LX 90 fork mount new [Re: TONGKW]
      #6156501 - 10/24/13 10:33 PM

I tried the same thing, mounting my 8" LX 3 onto an LX 90 fork...I also had the problem with the shorter trunions, althoght I didn't drill like you did, I mounted using just the two back holes. That shifted the OTA even further back than you have. It was so back heavy, no amount of counterweights balanced the tube. I wound up returning the mount and getting an LXD 75 GEM. It works ok, but I wish the lx 90 had worked for me. Good luck, I'd be interested how it balances for you

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Geo.
Carpal Tunnel
*****

Reged: 10/01/08

Loc: Upstate NY
Re: Install LXD75 8” SCT OTA to 8” LX 90 fork mount [Re: TONGKW]
      #6159128 - 10/26/13 12:49 PM

Quote:

I think the original Autostar 497 hand controller is with this 8” LX 90 fork mount. On powering up, the screen reads “ C (07) Meade [43E] Autostar ”.

I would like to upgrade the Autostar hand controller. ... may I ask what is the highest firmware version that can be upgraded with this Autostar 497 hand controller.




You've got it, 4.3Eg. The upgrade path is either an Audiostar or the 497EP. Not sure there's any real added value for you there.


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