Tuesday, March 06, 2007

Disassembling a PST, first night

I had school yesterday night, but I still got a short moment to try out my belt wrench.

The wrench is not as powerful as I imagine, or better said, the PST required far stronger torque than I imagine to unscrew!

On unscrewing, the black body of the PST serves a very good function: you can lay it flat on a chair or table or whatever, and then step on it, and use the other hand to unscrew with the belt wrench! After one or two minutes struggling, the golden tube is loosen and then I can use bare hands to unscrew the rest. Some red "screw" glue can be found on the thread and that explains why it's so hard to turn.

I even tried to unscrew the etalon module from the black body, but I ran out of time and also force, my arm was feeling weak and so I called it a pause.

Now, the blocking filter/visual back is removed, the extension tube before the visual back is removed. And the objective along with the tube is removed from the black body. The last thing to do is to remove the etalon from the black body.

The optical window on the etalon module is pretty large to my eyes, it measures ~2cm with a ruler. From my understandings, this optical window is part of an afocal lens system to make sun light parallel again before passing through the etalon. Therefore, it does not mean to be the size of the etalon.

The black body should contain the focusing prism, which is spring loaded to the focuser knob. And it also contains the sun finder, which I think, is pretty good to use. Maybe I will find a way to re-use it somehow.

Once the etalon is detached, I shall find a local friend to cut down the original tube to be inserted into 2" focuser, and to machine a 1.25" visual back to allow the BF10 to be attached on.

On the other hand, here's a drawing of a cell mounting to my mounted Cheapy-ERF, which is indeed a filter for an aerial camera:-

Here's the Cheapy-ERF:-

I have also inspected the rusted objective, I found it's really pretty opaque. I've looked through an objective of a new clear blue PST objective before, and this one is really way different.


The second night is hard night, keep unscrewing with the belt wrench, but in vain after ~30 minutes, very tired.

Removed some allen screws from the black body, but two remained in place, the hexagonal pattern is somehow distorted, might not be able to remove them easily.

No comments: