Fluke 8808A User Manual - Page 53

3 Operating the Meter from the Front Panel Selecting a Function Modifier Table 3-5. dBM Reference Impedances Impedance Impedance Impedance 8000 Ω 300 Ω 93 Ω 1200 Ω 250 Ω 75 Ω 1000 Ω[1] 150 Ω 50 Ω 900 Ω 800 Ω 135 Ω 125 Ω 16 Ω[2] 8 Ω[2] 600 Ω 124 Ω 4 Ω[2] 500 Ω 110 Ω 2 Ω[2] [1] Voltage annunciator lit [2] Audio power readings possible To access the reference impedance list, press Q then press W. The reference impedance currently selected is displayed, along with the "db" and "ohm" annunciators. Press U or V to scroll to the desired value, then press R to select a reference impedance and return the primary display to the measurement function. Press any function or modifier 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 W twice to select the audio power modifier. Power annunciator will be displayed. The following equation is used to make a power calculation (volts is the measurement value): Audio Power = Volts2 Rref Touch Hold Function (HOLD) The Touch Hold function holds the results of your measurements on the display. Touch Hold is helpful in difficult or hazardous circumstances when you want to keep your eyes fixed on the probes and reading the display only when it is safe or convenient to do so. When a new, stable reading is detected, a beep is emitted and the display is automatically updated. To select the Touch Hold function, press I. H is displayed. In Touch Hold, each time you press I, a new reading is displayed. To exit the Touch Hold function, press and hold I for 2 seconds. If you are in the autorange mode when Touch Hold is selected, you will autorange to the correct range. If you are in the manual range mode when Touch Hold is selected, you will be in the fixed range you were in when Touch Hold was selected. The Touch Hold function can be combined with the minimum/maximum modifier to hold and update only when a new minimum or maximum value is detected. To force the display to update, with Touch Hold selected press I for less than 2 seconds. The Meter allows you to choose the minimum response level needed for Touch Hold to capture and display a measurement. You can choose from the following four response levels: 3-19