Measuring Ac Voltage On A Dc Source Bias - Radio Shack 22-218 Owner's Manual

Measuring AC Voltage on a DC Source Bias

WARNING: NEVER MEASURE MORE THAN 30 VOLTS AC
ON A DC SOURCE BIAS.
When an AC voltage has been superimposed on a DC source
bias, you cannot take ordinary measurements. The readings
wander on the scale and are not accurate.
However, if you know the approximate AC voltage and it does
not exceed 30 volts AC, you can measure it by connecting a
0.1 mF, 100-volt polyester film capacitor in series with the pos-
itive (+) voltage source and the meter's red probe.
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