Operating Instructions
1502C MTDR User Manual 1–7
Front-Panel Controls
1. CABLE: A female BNC connector for attaching a cable to the 1502C for
testing.
2. NOISE FILTER: If the displayed waveform is noisy, the apparent noise can
be reduced by using noise averaging. Averaging settings are between 1 and
128. The time for averaging is directly proportional to the averaging setting
chosen. A setting of 128 might take the instrument up to 35 seconds to
acquire and display a waveform. The first two positions on the NOISE
FILTER control are used for setting the vertical and horizontal reference
points. The selected value or function is displayed above the control on the
LCD.
3. VERT SCALE: This control sets the vertical sensitivity, displayed in mr
per division, or the vertical gain, displayed in dB. Although the instrument
defaults to millirho, you may choose the preferred mode from the Setup
Menu. The selected value is displayed above the control on the LCD.
4. DIST/DIV: Determines the number of feet (or meters) per division across
the display. The minimum setting is 0.1 ft/div (0.025 meters) and the
maximum setting is 200 ft/div (50 meters). The selected value is displayed
above the control on the LCD.
A standard instrument defaults to ft/div. A metric instrument (Option 05)
defaults to m/div, but either may be changed temporarily from the menu. The
default can be changed by changing an internal jumper (see 1502C Service
Manual and always refer such changes to qualified service personnel).
5. Vp: The two Velocity of Propagation controls are set according to the
propagation velocity factor of the cable being tested. For example, solid
polyethylene commonly has a Vp of 0.66. Solid polytetraflourethylene
(Teflon ) is approximately 0.70. Air is 0.99. The controls are decaded: the
left control is the first digit and the right control is the second digit. For
example, with a Vp of 0.30, the first knob would be set to .3 and the second
knob to .00.
6. POWER: Pull for power ON and push in for power OFF. When the front
cover is installed, this switch is automatically pushed OFF.
7. n
o POSITION: This is a continuously rotating control that positions the
displayed waveform vertically, up or down the LCD.
8.
n
o
POSITION: This is a continuously rotating control that moves a
vertical cursor completely across the LCD graticule. In addition, the
waveform is also moved when the cursor reaches the extreme right or left
side of the display. A readout (seven digits maximum) is displayed in the
NOISE FILTER
HORZ
VERT SET REF
VERT SCALE
DIST/DIV
Vp
.3 .4 .5 .6
.7
.8
.9 .00
.01
.02
.03 .04 .05 .06
.07
.08
.09
POWER
(PULL ON)
POSITION
n
o
POSITION
n
o