Instruction manual

HB 08-18-2010 5
buttons, connectors, etc. The controls that are used mainly for dual trace or x-y use will
not be discussed other than to adjust them for single trace use. There are a lot of controls,
and unless you have a physical picture of what the controls do you will not be able to use
the scope in a reasonable sort of way. Review the previous section and Fig. 1 as necessary.
Fig. 5 is a picture of the front panel of the BK scope. The controls are numbered. The
paragraphs that follow shortly are numbered according to the control being described.
At the left in Fig. 5 is the screen where the trace appear. On the right are the controls.
The controls are grouped in “boxes” according to function. All the boxes are named in Fig. 5
except the one containing items 9 and 10, which below is called GND and CAL. The boxes
are listed below along with the general function of the controls in each box. After the name
of the box, in parentheses, are the numbers of the controls that appear in that box. As you
read, identify the boxes in Fig. 5. The box names are hard to read; the numbers are not.
“FUNCTION” BOXES OF BK SCOPE
(Numbers in parentheses refer to the controls in the box)
• POWER(1,3)-Button (3) turns the scope on and off. LED (1) indicates when the scope
is on.
• CRT(4-6) (cathode ray tube)- controls the intensity and focus of the electron beam,
and the sharpness of the trace.
• GND and CAL(9-10)- This box is not named but provides a calibration voltage and
ground. These will not be used in this lab.
• VERTICAL(12-22)- This box is really divided into two boxes. The scope has two voltage
amplifiers for two possible input voltages. Recall that these voltages are applied to the
vertical deflection plates which is why these controls appear in the “vertical” box. The
controls for the gain of these amplifiers are in this box, channel 1 on the left and
channel 2 on the right. In this box are also controls for moving the traces up and down,
and for choosing single trace, dual trace, and x-y modes. There are also two connectors
for possible input voltages.
• HORIZONTAL(time base)(23, 26, 34)- Control the rate at which the horizontal deflec-
tion voltage is changed.
• TRIGGER(27, 29-33)- The ramp voltage that sweeps the electron beam horizontally
across the screen has to be told when to start. Rotating knob (33) enable you to select
V
T
. If knob (33) is in, the trigger pulse occurs on a positive slope of the input signal. If
this knob is out the trigger pulse occurs on a negative slope of the input signal. Knob
(27) moves the trace left and right.
There are a lot of knobs, switches, and connectors. If you keep the boxes in mind, and
the function of the controls in each box, you will be able to find the control(s) you need
expeditiously. The controls, numbered in Fig. 2, are now discussed, along with the initial
settings you should give them. The push button switches toggle between in and out. These
buttons should only be pushed (not pulled). Missing numbers are for controls not present
on model 2120B.
As you read through this list it tells you to set some controls at certain values or positions.
Be sure to do this so that when you turn the scope on you see a trace. With a strange scope
just finding a trace can be difficult!