3
Manually operating the PC-USB controller
Now if all connections are made, the PC-USB controller is
ready. Press the “On/Off“ button. After a short initialization the
controller will evacuate the Pressure-Tuner chamber. This
process brings the Etalon cavity to the ambient pressure and
insures a correct pressure reading of the chamber. It will take
around 30 seconds. The display will show “Evacuating scope
chamber” and the needed time.
The display will now read the current pressure inside the Etalon
chamber (“Scope PSI”) and the pressure that is adjusted at the
PC-USB controller (“Setpt PSI”). At the beginning both data are
at 0.0, and are shown in the unit PSI in steps of 0.1 (0.1 PSI is
equivalent to 0.0069 Bar). Now press the “PSI (+)” button, the
“Setpt PSI” data will increase. The tolerance of the PC-USB
controller is 0.4 PSI. If the difference between “Setpt PSI” and
“Scope PSI” becomes larger than 0.4 PSI then the air pump
inside the controller will start. Press the “PSI (+)” button until “Setpt PSI” reads 2.0. The PC-
USB controller will pump up the PT chamber to “Scope PSI” 2.0 and stop. If the unit continues
pumping then check all connections to make sure they are inserted fully.
If all is okay then you can now tune the system to the H-alpha wavelength. Look through the
eyepiece and increase the pressure with the “PSI (+)” button until the prominences and other
details will become visible at the sun. Normally the pressure will be then between 10 and 20
PSI. Now you can increase the pressure by the “PSI (+)” button or decrease the “PSI (-)” button
in small steps until you have achieved the optimum setting of the H-alpha wavelength, there the
most details on the sun are visible.
Once you have achieved your optimum tuning setting you can
save it, to reset without waiting. Press both the “PSI (-)” and
“PSI (+)” buttons at the same time. “Goto center PSI? Yes / No”
will now be displayed. Then press again both buttons and hold it
until “Writing center pressure value” is displayed and release.
The PC-USB controller will then list center pressure value
saved. If you now change the pressure (for example to observe
the Doppler effect at a filament) then you can return to the
saved pressure setting point at any time you want. Simply press
again both buttons “PSI (-)” and “PSI (+)”, and at the question
“Goto center PSI?” hit “Yes” by pressing the “PSI (-)” button to
re-center.
This value will be also stored when the PC-USB controller is
switched off. At the next observing session it is not needed to
search again the optimal setting with an effort, you can use the
query "Goto center PSI?" to find the optimum setting instantly.
When the PC-USB controller is turned off, it can of course remain still installed at the Pressure-
Tuner. A new assembly and disassembly is not necessary every time.
