Modifications

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Introduction: things that have been made, modified, or improved.

Focuser Read Out

The focuser knob for the 12" does the job, but for CCD work a precision of position and reproducibility of position is required (5 degrees makes a difference). After market products exist that provide a digital readout of position. I have found a cheaper solution. A cottage cheese lid and a tooth pick provide a great analog dial. The toothpick is just taped to the adapter plate. And the 'dial' is center punched, marked, and pushed over the focus knob.

In practice I approach focus counter clockwise (to oppose gravity). When best focus is passed I will have taken note of the reading. A quick spin of a half turn clockwise, and then back to best focus takes out image shift and mechanism lash wrt gravity.

Keypad By Feel

The LX-200 keypad is well lit. However, when your eyes are at the telescope, it's difficult the figure out by touch what's what. I found some 1/4 inch diameter sticky backed clear cupboard door bumpers. One on each of the NSEW buttons gets the job done nicely.

2-D Weight System

The simple sliding weights system that Meade sells was OK until I attached the guide scope and Losmandy rings. This moved enough weight away from the center of the OTA that a 2-D system seemed required. Commercial units for the 12" scope are very expensive. So I have built a 2D balance system out of a few dollars in parts from ACE Hardware.  Then added a third dimension for the fork.

Approach:

Parts cost:

The result seems to work great. In the picture, also notice the fork weights. These are a pair of Velcro strapped wrist / ankle weights. See balance procedure for usage and adjustment.

Two Serial Ports

The LX200 has a single serial port, but it is wired for two connections. Since the 416XT needs to talk to the LX200 for some high end features, some form of external splitter is required to also keep the PC connection live. The wiring diagram and pinots can be found here. I found an adapter called a "BBT-11-6 6 conductor Modular Duplex Jack Adapter" manufactured by GQ (whoever they are) for $1.89 at Fry's Electronics.

This adapter snaps apart, and since it uses wires internally, it can be rewired very easily. (labeling turns out to be a bit tricky however). I wired port one to be straight through with all 6 wires. Port two has just ground and the LX200 2nd set of transmit and receive lines wired into standard pinout.

416XT Strain Relief

The 416XT has a single cable that connects to the back. However, there is no strain relief for the connection. As the scope moves about, the pins take a lot of twisting. I have even heard of a case where the wire disconnected in the middle of an exposure.

A couple of sticky backed wire hold ups do the job.

Dust Cover

Susan made me a large purple cover that will resists water (dew), and has a draw string. This picture also shows a big purple umbrella stuck into a brick on a board to generally keep the sun off during the day.

Hand Cart (Mark I Portable Observatory)

In order to support fast set up and take down at home a hand cart has been built. Starting with a standard Sears cart, I removed the shovel and replaced it with a long length of angle iron. A piece of plywood was hinged at the top to seat against the tripod head. It is then possible to tip the whole thing onto the pneumatic wheels.

Rolling out from the garage and setting up takes about 15 minutes including polar alignment. Take down takes 10 minutes. The cart is left in place during observing. The board serves as a nice table.

It is a little heavy and unwieldy, but fortunately, I only go 20 feet over level ground.

See Mark II, and Mark III.

RS-232 Connector Fix

Opened up RS-232 connectors (as shipped from Meade) to check for loose unused wires with pins that could cause shorts as per Mapug warning. Sure enough, it looked like a failure waiting to happen. I shrunk some heat-shrink tube around the loose pins and closed it all up. The loose pins would have been unlikely to short out against port 1 pass through lines, but port 2 circuit in the LX200 could have been shorted out (transmit to ground). I would think this is a required fix for anyone using these connectors.