13
* Might be black in some valves
3. Identify the poppet nut. It is the upper most beige or black nut that fits in an 8 mm open-end
wrench.
Loosen the poppet nut, while keeping the poppet position fixed using a flat screwdriver. Turn the
poppet slightly with the screw driver, steps of 1/10
th
of a turn should be enough, finally lock the
position with the poppet nut.
Screwing the poppet results in a tighter contact; unscrewing results in a looser contact.
4. Try to pump down the vacuum chamber. If the leak remains, repeat the procedure (step 3).
Note that locking the position of the poppet with the poppet nut tends to retract the poppet; hence
the leak might reappear. In that instance repeat the procedure from step 4.
If the leak remains after a few iterations completely unscrew the poppet to inspect the poppet O-
ring (no. 16). Replace if necessary.
Once the pressure in your vacuum chamber reach down to 10
-4
-10
-5
mbar you are ready for final
adjustments.
5. Plug the electrical connections.
Never adjust the poppet with the high voltage cable
connected.
For these test we recommend 150
μ
s opening time and a repetition rate of 1 kHz.
Vaccum chamber
KF 40 tube
+O-rings
Puppet nut
Puppet
Poppet*
Poppet nut*
