unscrewed e.g. by a coin. Pour out wet silica-gel and fill the chamber
with a dry one. The desiccant chamber can be filled with a hot silica-
gel without a danger of damaging of the container.
The desiccant container can be left open without the fear from
contamination of CCD chamber interior by dust. There is a very faint
stainless steel grid between the CCD chamber and the desiccant
container, so dust particles cannot enter the chamber itself. It is even
recommended to keep the desiccant container cap off for a couple of
hours when the camera is in the room with low humidity. This helps
drying the CCD chamber interior and prolongs the silica-gel exchange
interval.
●
G2 revision 4 cameras brought larger desiccant container (equal to the
one used in larger G3 and G4 cameras).
Cameras supplied in 2016 and later are equipped with a redesigned
desiccant containers. New containers are no longer a fixed part of the
camera body with only a removable cap, but the whole container can
be unscrewed. The main advantage of this design is the ability to
exchange silica-gel without the necessity to remove the camera from
the telescope, which was necessary to be able to pour-out the silica-gel
and then to pour it in.
Silica-gel is held inside the container with a perforated cap. This cap is
also screwed into the container body, so it is easy to exchange the
silica-gel inside the container after it is worn out or damaged e.g. by
too high temperature etc.
The container itself does not contain any sealing (the sealing remains
attached to the CCD cold chamber inside the camera head), it consists
of aluminum parts only. So it is possible to heat the whole container to
desired temperature without risking of the temperature-induced sealing
damage.
This design also allows usage of some optional parts. First it is a
threaded hermetic cap, which allows sealing of the dried container
when it is not immediately attached to the camera head. And the
second one is an alternate (somewhat longer) desiccant container,
modified to be able to be screw in and tightened (as well as released
and screwed out) without any tool.
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