Sonics VCX600 - Manual (Page 10)

10
TUNING
Tuning optimizes performance and insures maximum transfer of energy by matching the
frequency of the power supply to that of converter/probe assembly. The power supply
should be tuned 1) every time a new probe or accessory is used, 2) on occasions to
compensate for the frequency variation caused by cavitation erosion 3) following 10
minutes of continuous operation and 4) when the sample temperature is significantly
higher or lower than room temperature.
The piezoelectric crystal within the converter is part of the circuitry, which controls the
frequency at 20kHz. Any changes in t the crystal’s capacitance resulting from a variation
in temperature, will cause the equipment to operate in an out-of-tune condition. For
reliable performance, and equipment protection, it is important that the unit be tuned after
the probe temperature has had a chance to stabilize. When relocating the ultrasonic
processor from a very cold or very hot environment, allow 30 minutes for the unit
temperature to stabilize before operating. Continuous operation causes temperature
elevation in the sample. This increase in temperature is transmitted through the probe to
the crystal assembly. Always tune the power supply after the probe has reached operating
temperature. When working with low or high temperature samples, immerse the probe in
the sample for a few minutes, withdraw the probe from the sample, then tune the power
supply. When working with temperatures in excess of 100
?
, contact the factory for
recommendations on how to air-cool the converter.
To tune the instrument before processing, proceed as follows:
1. Ensure that the probe or microtip is not immersed in the sample and that it does not
come in contact with anything. If a cup horn is used, make sure that the water has
been drained out of it. If a flow through cell is used, make sure that the sample has
been drained out of it.
2. Set ON/OFF power switch to ON. The switch will illuminate, and the LCD screen
will display the power rating of the instrument, cautionary notices and functional
prompts.
3. With a microtip, rotate the AMPLITUDE control for a 20% reading on the LCD
screen – Ampl 20%. With any other probe, rotate the AMPLITUDE control for a
50% reading on the LCD screen – Ampl 50 %.
IMPORTANT
Tuning must be performed in air with the probe out of the sample. While tuning,
do not allow the probe to contact anything.
CAUTION
When tuning with a microtip or extender, never allow vibration in air for more than 10 seconds
or the amplitude to exceed 40%. Ignoring these instructions will cause the microtip or extender
to fracture.