Scientech 801C
Scientech Technologies Pvt. Ltd.
17
Probe Compensation:
For the undistorted display of signals, the x10 attenuator probe must be compensated to
match the input impedance of the vertical amplifier. This is done by connecting probe
tip to the mini-socket on the instrument marked with a square wave, and adjusting the
trimmer tool supplied with the probe. In
Scientech 801C
,
the probe compensation is
easily achieved due to the built in Square Wave Generator with a repetition frequency
of approximately 1KHz and an output voltage of 0.2Vpp. The correct display is shown
in figure given below.
The "Time Base" switch should be in the 0.2ms/cm position. The signal has an
amplitude of 0.2Vpp ±1 %. If the attenuator switch is set to 50mV/cm, the display will
have a height of 4cms (1:1 probe). Since an attenuator probe is constantly subjected to
considerable stresses, the compensation should be frequently checked.
Figure 3
Operating Modes:
The required operating modes are selected with push buttons in the vertical amplifier
section. For selecting either channel, CH1/CH2 is pressed or released, while selecting
either channel; it also selects triggering of respective channels. For selecting both the
channels, Dual is pressed, the alternate or chop can be selected by pressing Alt/Chop
switch. For addition of channel, release Mono/Dual switch & press Alt/Chop push
button, which will display addition of CH1 & CH2. Similarly, subtraction of CH1-
CH2 can be achieved by pressing Invert CH2 & Add mode.
For X - Y operation the "XY" button must be pressed. The X signal is connected via the
input of channel 2. The sensitivity of the horizontal amplifier during X - Y operation is
selected by the CH2 attenuator switch. The sensitivity and input impedance for both the
X & Y axes are equal. Note that the frequency limit of the X axis is approximately
2.5MHz (-3dB). Therefore, an increase in phase difference is noticeable at higher
frequencies. The phase shift is 3 degrees approximately at 60KHz.
