The Beginning

Last December, when I was lusting for a serious telescope, I really wanted the RCX, but that was too much money. The Domestic Authority would never approve. The LX200R was nice, but a thousand more than the GPS - On Clearance.

The LX200GPS came home with me.

A couple weeks ago, an LX200R OTA came up for grabs and I was the lucky guy. I thought why not swap out the tubes? Can't be that hard.

So, here is how I did it.


A Disclaimer

If, you decide to follow in my footsteps and you make a mess of eveything, well, Good Luck!


A Word To The Wise

If, you do not know your way around tools and/or just taking things apart, think twice before you rip into this project.


What To Expect

Our goal is to remove the exisiting OTA and replace it with the new one.

In order to accomplish this, I decided to completely remove the left fork arm. That one being easier than the right. The wiring inside must be carefully gotten out of the way. A special duty nut must be removed from the shaft. We must use tape and mark the arm/base so we can orient the pieces correctly again. We must physically position the unit in such a way when things start coming apart, we do not dent/mutilate the tube itself.


Here We Go

The LX200GPS still in one piece. The "R" OTA ready to go.


Here are the three spots we really want to get at. As you borrow deeper into this project, and you see the actual size of these three screws, be mindful of all the weight you hang on your scope and these three, little, screws must support it all.


Here, we take the screws from the bottom panel under the left fork arm, and thread them into the holes in the plate. Snuggle them up against the two mounting screws. This is done so later, we can return the new OTA to the same spot as the old one. These base castings are CNC machined, so I would wager, these things are pretty much the same, tube to tube.


After we snug the four screws up, two per plate ...

We back each off one half turn. That is so we do not mess up any threads when we remove the screws in the side plate. We will turn them a half turn back in again later.


We carefully, and I mean carefully, remove the white plug from the receptacle. Be --very-- careful with these connectors. the wires pop loose really easy.


Here, the wires are threaded down the left fork arm.


And thru to the base of the scope.


We --carefully-- thread the connector and wires thru the left arm, down thru the elbow and into the center casting that holds both forkarms in place. We need to get this wiring out of the way so we do not damage it.


The leveling gizmo and circuit board. We need to remove this.


We need to remove this special purpose "nut" on the shaft.


I inserted two drill bits that fit pretty snug. (A Poor Mans's way of doing this.)


A good sized Crescent wrench and it popped right loose. Off it comes.


Now, we need to disconnect the black connector.


And we carefully, with our finners, lift this plate and assembly off the shaft.


Here it is and we set it out of harm's way.


I laid the tube and base on its side for easier access. Note, I taped the wires out of the way.


Peterson Grips sure come in handy. Pete did not agree that I needed both sides, but, I knew they would come in handy.


Note carefully. I placed two strips of tape - one on the fork arm -the other on the base. But, I made a Big Mistake. Both pieces are on the fork arm. Make certain your tape is one on the base, one on the arm. Also note the little Tick Marks I placed on the tape. Both sides, and the top.

After you place the tape in the right spot, take a MarksAlot and mark it up with lines so when it goes back together, you can re-align everything alot better than I did.


The tube is propped up a bit.


Now that is done, we pay attention to these four screws.


We start cracking the four bolts loose for the left arm.


Place a piece of tape on this hole. Prevents washers from rolling where they do not belong.


Here, the left arm is removed. And we proceed to take off the plate on the topside of the tube.


Plate is gone and we are now at where we need to be. At those three holes.


Here is the side plate just removed. Note, those three tiny screws. I marvel they do their job with OTA's clobbered full of stuff.

Note, there is a washer that goes on this shaft, and stuck to the bearing on the inside of the fork arm. A photo later on shows it. Do not lose this little guy. You will be sorry.


Now, we need some assistance so when we crack the tube completely loose, the base and remaining arm do not tumble to the floor.

And, we remove the three screws from the right side plate working between the tube and the countertop..


When the last screw is loose, be very careful as, the OTA can go where it pleases now.

There it is. Pay Dirt!

We will now carefully place the new OTA on top of where the old one was, and thread the two socket head bolts in place. All the while, between the tube and the countertop. Do not tighten the screws, just snug them up.


Then we fasten the top side plate on. We snug up the two cap screws, and tighten the screws that half turn from so long ago.


This is where the two cap screws should snuggle up to.


Things should be snug, yet allow us to slide the plate with our finners. We push it towards the front of the OTA.


Tighten this screw first and then the other two.

We will get the bolts on the right hand side plate in a bit.


Oh. Here is that washer on the back side of the left arm ...


And we place it on the shaft so we know we got it in the right spot.


As I fouled up and taped the wrong area, we need to kinda get the fork arm back to the same spot it came off from.

Sometimes, when two parts are really bolted together tightly and the surfaces are painted, the paint will have a different sheen. Here, the light reflected off the paint and this marks where the fork arm was bolted tight.

My goal is to get it back to that spot again (some how?).


Before I placed the fork arm on the base casting, I placed tape on each side to indicate the bottom edge of those shiny marks on the paint. we need to line up the spot on the fork arm that made these shiny spot.


Here we are, adjusting things to line them up.

Note, the fork arm has slotted holes for the four cap screws. And that range should be at least an eighth of an inch. But, I found, I could barely move it back and forth less than a 1/16". The above image shows the arm pulled left.


This one shows the arm shoved right. Note, there is barely any travel in the slots.

This leads me to believe, the orthagahexanalinity will be close enough. As, there just is not that much adjustment to be had.

And, it still is a "Kinda Gets There" scope so all will be fine.

And we wrench the four bolts down tight.


Now that the left arm is on and the scope needs a break, I do too. Aaah, Janice Joplin's favorite brew ...


Time to get The Beast vertical again.

Here is the right side and we tighten these two screws one half turn as well.


One half turn for both.


Just as on the left side, by tilting the tube more vertical, the weight of the tube will force things down and we can snug up this screw.


Tip it a bit further and snug up the other screws and then, in position like this, we can thread in the third one and tighten it up as well.


The remainder is simply putting everything back together in some reasonable fashion and sequence as we took things apart. I will not bore you with those details.


About 1:00am, I got outside with The Beast, set it up, and to my surprise, the collimation was pretty good. The OTA came with the Meade screws and I replaced them with Bob's Knobs. But, later, I did do a fairly patient collimation.



The Bottom Line

Well, was the effort worth all the aggrevation and fuss? And expense?


Altho the skies were really good, I have looked thru the GPS long enough to kinda know what I have been seeing.

The R -does- show me more faint stars. You can see them "pop'' when you approach focus. After I sell the GPS OTAand balance the books, I should be about $2-400 for this upgrade.

And, the R really comes thru on the advertising. In my 41mm Panoptic, the stars are tack sharp right to the edge of the eyepiece. And all my other TeleVues as well.


Jon ...

Let us all remember to enjoy our toys and, the beauty above and within, each of us ...


Big Dog's Asylum
Woodbury Minnesota

LX200KGT 12" KindaGetsThere Scope