HT instruments HT157 - Manual (Page 9)

HT155 - HT157
EN - 7
4.2. DESCRIPTION OF FUNCTION KEYS
Key Description
Pressing the ON key allows turning on and internally resetting
the instrument at any time
The OFF key allows turning off the instrument
The CANCEL key allows deleting the saved data from the
instrument’s memory
Activates/deactivates the display’s backlight. Backlight turns off
automatically after 15s
The ENTER key allows entering the internal programming
screens and confirming the selections made
The OUTPUT key allows stopping the measurements and
automatically saving the result in the memory
The START/PAUSE key allows activating or pausing a
measurement
, , ,
The arrow keys allow navigating the programming menu,
increasing/decreasing the parameter values by one unit (press
and hold the keys for fast advance) and adjusting the display
contrast
The SETUP key allows rapidly accessing the programming
menu without passing from the main menu when a
measurement is in progress
4.3. ANALOGUE OUTPUT DESCRIPTION
The instrument is provided with an AC voltage analogue output proportional to the input
signal measured in dB, which can be used to connect a 3.5mm output jack with the
characteristics shown in Fig. 3
Fig. 3: Description of jack for AC analogue output
The proportion between the output and the input signal depends on the measuring range
of the instrument and is shown in the following table:
Gain range Output/input ratio Measuring range [dB]
-10dB 0.316 50~140
0dB 1 40~130
10dB 3.16 30~120
20dB 10 20~110
30dB 31.6 10~100
40dB 100 0~90
The impedance of the AC output signal is 1k
. We recommend that the charge resistance
connected to the AC output is at least 100k
 and that the charge capacity is lower than
200pF. The ratio between the input and the output signal is 1mV / 0.1dB. The max output
voltage is 3.2V.