How do I take apart a PST?

[cshahar]

Hi Everyone:

I want to get at the etalon inside of the PST (to use for double stacking my current setup involving a 5-inch refractor and a Daystar Quantum filter) but I am having trouble unscrewing the optical tube from the focusing box. I don't want to break the tuning ring. Or is there another way of getting at it?

Any suggestions?

Thanks,

-Charles

[Uplooker]

Best to use a strap wrench such as this

https://www.amazon.co.uk/BOA-13-2612-Standard-Strap-Wrench/dp/B00096JDKS

best to buy 2 off for when you come to separate the etalon.

Before you start though be cautious. Carefully remove the knurled rubber ring that sits around the circumference of the etalon. Under this you will see that the tuning ring is held on buy a single screw. Carefully remove this screw, but mark the hole that it cam out of, for when you come to re-assemble the etalon.

The reason for removing the screw is that it may easily snap /shear off when trying to remove the etalon from the black box & objective tube.

The black box and the objective tube are locked onto the etalon with thread lock. It can take quite a bit of pressure to get them moving but they will.

Just another note - you can also use the strap wrench to remove the EP holder and collar from the black box. If you purchase a Revelation or Celestron 1.25 diagonal and unscrew the EP holding collar you can screrw the PST EP holder straight in i.e. giving you a BF5 :-)

Hope that helps. Bit rushed, but drop me a line if you want further info or clarification

[cshahar]

This is excellent. thank you so much for this valuable information!

-Charles

[Merlin66]

Charles,

I have a write-up available on PST Mods.

Just drop me an email for a copy.