8
8
the figure. (Directly Adjustable via up or down arrow)
PROBE
( to Probe Select & Adjustment Menu. See Below )
GATES
( to Gates Adjustment Menu. See Below )
DISP
( to Display Adjustment Menu. See Below )
ALARM
( to Alarm Setup Menu. See Below )
SETUP
( to Instrument Setup, Save & Recall Menu. See Below )
PROBE MENU
SING/DUAL
Used to select transducer type. Options are single or dual element.
Dual can also be used for thru transmission applications
CONTACT / DELAY MODE
(CONT/DLY)
Contact or Delay style transducer. Must be in SINGLE Element Mode
for Delay Menu selection
DAMPING
(DAMP)
Changes receiver damping through these values : 25, 50, 75, 100,
125, 150, 175 and 375 ohms. As each new value is switched in, the
effect on the waveform in the A-trace display can be observed. Use
Damping to visually optimize the receiver / transducer performance
AUTOMATIC GAIN CONTROL
(AGC)
A unique feature of the TG400 is the Automatic Gain Control. This
control is is under hardware control and is fully automatic. The useful-
ness of this feature would be evident on material with varied attenuation properties such as
painted and non painted surfaces or corroded back surfaces. AGC may also help overall reading
accuracies due to the fact that the thickness gate will be reading to the same height on the echo
“flank” (first rising edge). It is generally not acceptable to use AGC with Dual Element Transduc-
ers used for corrosion surveys.
POLARITY
Selects thickness trigger to either Positive or Negative half wave.
HINT: Select the half cycle which exhibits the strongest first half cycle throughout the calibration
range.
RECTIFICATION
(Rect)
Sets the rectification mode for the echo signal on the A-trace display. Four selectable
waveform types scan be displayed :
+HW - Positive half-wave rectified
+HW
when selected, displays only the positive portion of the RF signal on the A-trace
display.
It is generally not acceptable to use AGC with Dual Element Transducers used for
corrosion surveys as sensitivity will be adjusted based on the largest returned echo. In the
case of pitting or corrosion the initial received signal will likely be somwhat smaller than
the baseline material back wall.
