45
Users Manual
modifier is selected, the relative base is shown in the secondary display. To turn off this feature, press Sand, while holding it down, press K.
dB (Decibels and Audio Power) Modifier
The decibels modifier takes a voltage measurement, converts it to dBm (measure of decibels relative to one milliwatt), and displays the result on the primary display.
Press Ito toggle in and out of the decibels modifier. When the decibels modifier is selected, "dB" is shown on the primary display.
Decibels can be selected only when a voltage function is selected on the primary display (volts ac, volts dc, or volts ac + dc). Decibels are always displayed in a single, fixed range with 0.01 dB resolution. However, the basic measurement itself (e.g. volts ac) autoranges.
A voltage measurement is converted to dBm using the following formula:
dBm = 10*log (1000*value2/reference impedance)
where "value" is the measurement value. The reference impedance can be set to any of 21 reference impedances listed in Table
Table
8000
1200
1000*
900
800
600
500
* Voltage annunciator lit
† Audio power readings possible
300
250
150
135
125
124
110
93
75
50
16†
8†
4†
2†
To access the reference impedance list, press Sthen press I(REF e). The reference impedance currently selected is displayed, along with the db and eannunciators. Press
Uor Tto scroll to the desired value, then press Eto select a reference impedance and return the primary display to the measurement function. Press any function (white) or modifier (light grey) button to exit the reference impedance list without selecting a new value.
Setting the dB reference resistance to 16, 8, 4, or 2 ohms allows you to use the meter to calculate audio power. After the reference resistance has been set to 16, 8, 4, or 2 ohms, press Itwice to select the audio power modifier. "POWER" will be shown on the secondary display.
The following equation is used to make a power calculation:
Audio power = Volts /reference resistance
where volts is the measurement value.
