Instructions

Counter source
106 TGF4000 Series Instruction Manual
The counter can either count the signal present at the TRIG / COUNT (DC) IN socket or the
signal present at the REF / COUNT (AC) IN socket at the rear panel of the instrument. To select
from the two counter sources, press the Source soft-key.
The TRIG / COUNT (DC) IN socket is DC coupled and has an input impedance of 10kΩ. The
threshold is fixed at 1.2V to cater for 1.8V, 2.5V as well as 3.3V logic inputs. Select this input to
count signals from 100mHz to >125MHz (typically 150MHz). The input sensitivity is 100mV.
The REF / COUNT (AC) IN socket is AC coupled. Select this input to count signals from 3Hz to
>125MHz (typically 150MHz). The input sensitivity is 100mV.