Operational Precautions and Characteristic
Peak Test Voltage at 50/60 Hz
This refers to a limit value of dielectric breakdown voltage between electrodes.
Before shipment, MEIDEN checks the vacuum capacitors to confirm that no dielectric
breakdown occurs when the rated voltage is applied for the specified time.
Peak RF Working Voltage
This refers to the rated voltage value capable of being applied continuously. The
peak RF working voltage is set at 60% of the peak test voltage.
Maximum Permissible Current
This is the maximum rated current capable of being carried continuously. At higher
frequencies, the maximum permissible current decreases with a greater loss due to
the skin effect. The maximum rated current is defined as follows:
Vacuum variable capacitors can be adjusted to any capacitance value within the specified
range by the linear sliding motion of the moving electrode assembly, which is converted
to the rotary tuning via the capacitance adjustment shaft. Capacitance decreases
with rightward (clockwise) rotation of the shaft and can be adjusted to the minimum
capacitance in the end-stop position. Likewise, capacitance increases with leftward
(counterclockwise) rotation and can be adjusted to the maximum capacitance in the
end-stop position. Although two capacitance range end-stops are incorporated into
every variable capacitor, please note that the motor should not collide with the
maximum capacitance end-stop. Otherwise, it may impair the screw.
The permissible collision torque value at the minimum capacitance end-stop is as
VM Type…40N · cmVT Type…40N · cmVH Type…40N · cm
- For variable capacitors, the life span depends on the expendable bellows material
and the capacitance adjustment mechanical part.
- Please use the variable capacitors within the range that does not exceed the total
number of tuner turns. Exceeding any of the conditions below may result in an extreme
decrease in the life span.
- High acceleration (greater than 30min-1/ms)
- Ultra-small motion (less than several degrees)
- High speed (greater than 600 min-1)
- Re-greasing is recommended after every 200,000 cycles. (Definition of Re-greasing:
spreading the uneven coating of grease uniformly over the entire screw surface)
Please re-grease the whole operating range; otherwise, re-greasing may be less effective
in performance. Re-greasing is recommended when giving the capacitors a prolonged
rest or using them after storage.