INFICON RQCM - Quartz Crystal Microbalance Research System - Manual (Page 22)

RQCM – RESEARCH QUARTZ CRYSTAL MICROBALANCE
GETTING STARTED 2-2
IEEE-488 communication option, install the proper cable.
Refer to Section 7.1 to install, setup and run the RQCM software.
Connect the crystal holder, with a crystal installed, to the SMB connector labeled Crystal
by means of the 24-inch SMB coaxial cable.
Observe the AC voltage setting on the rear panel. Make sure it is set for your local line
voltage. Plug one end of the power cord to a power outlet and plug the other end into the
power entry module in the rear of the RQCM.
Refer to Figure 4, and Figure 7 for complete system connections. If your RQCM is
equipped with optional cards, refer to their appropriate section for detail instruction on
installation and operation.
Switch the front panel power switch to on. All of the red communication LEDS on the
front panel will light up for two seconds then some will turn off reflecting the status of
the communication lines. The green System Ready LED will come on and remain on
until the RQCM power is turned off. If the System Ready LED fails to turn on then there
is an internal problem with the RQCM. Please refer to section 10 for troubleshooting.
Start the RQCM computer program. Note that you may have to set the RQCM address
and select the correct COMM port in the Setup Menu in order for the RQCM to
communicate with your PC. Click on the View Status button to bring up the Status
Screen. The Status Screen should indicate a crystal frequency within the specified range
for the type of crystals being used. The frequency should be stable to within a few hertz
and the crystal resistance should be between 5 Ω and 15 Ω for an uncoated polished
crystal in air.
Check the capacitance cancellation by pressing and holding the Reset switch. The green,
Lock LED should light. Keeping the Reset switch pressed, adjust the fine capacitance
trimmer counterclockwise (decreasing the capacitance) by about 5 degrees. The yellow,
Sweep LED should flash. Back the trimmer clockwise to the point where the Sweep
LED just stops flashing. The capacitance cancellation should be checked and readjusted
every time the environment of the crystal and holder is changed. i.e. if the crystal and
holder are moved from air to liquid or liquid to air.
Remove the crystal. The red, Unlock, LED should light. The green, Lock, LED should
go off. The Sweep LED should not flash. If the Sweep LED flashes the capacitance is
under compensated. Reinstall the crystal in the holder and repeat the process until it is
perfectly compensated (Sweep LED not flashing when the crystal is removed). Refer to
Section 3.4 for more details on adjusting the capacitance cancellation.
2.3.1 CRYSTAL MEASUREMENTS VERIFICATION
A quick way to test your RQCM is to verify its measurements of frequency and
resistance in air and in water. The measurement values of frequency and resistance are as
follows. For a thorough test, the crystal can be immersed in a series of viscous
glycerol/water solutions at 20ºC and compare its measurement values against the
predicted results shown in Figure 14 and Figure 15.
2.3.1.1 In Air
If you are using INFICON 1” Polished, 5 MHz Gold Electrode Crystal, after compensated
for the capacitance, the frequency should be between 4.976 to 5.020 MHz, and the
resistance should be between 5 to 15 ohms. Record the frequency and resistance values.