Featured: Fluke 117 Electrician's Multimeter at Amazon.
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Nearly every amplifier job starts with a multimeter: checking the supply rail, confirming a relay is getting voltage, finding an open connection, or setting bias. A meter you can trust matters more than almost any other tool on the bench, because every other decision rests on its readings. The Fluke 117 is a compact electrician's meter that shows up on a lot of electronics benches too.
What the Fluke 117 measures
Fluke lists the 117 as a True-rms meter with a 6,000 count display that updates 4 per second. Its DC voltage ranges start at 6.000 V with 0.001 V resolution, and its current function covers AC and DC up to 10.00 A, with a maximum resolution of 1 milliamp. It also measures resistance, continuity, capacitance and frequency.
For amplifier work, the features that matter most are the everyday ones:
- DC voltage for supply rails, bias voltages and relay coil voltage.
- Continuity and resistance for tracking down cold joints, broken wires and shorted parts with the power off.
- Current for checking idle current in a low-current stage, within the meter's rating.
A word of caution about current
The Fluke 117 current input is listed at 10 A, with a 20 A continuous overload allowed for 30 seconds max, and it is protected by an 11 A, 1000 V fast fuse. Solid-state linear amplifiers can draw far more than that from their supply when transmitting. Never put a meter in series with an amplifier's main supply lead to watch transmit current. Use the power supply's own meter, a proper shunt, or a clamp meter designed for high current instead. Reserve the meter's current function for small, known currents, and move the leads back to the voltage jack when you are done.
Low input impedance and non-contact voltage
The 117 is sold as an electrician's multimeter with non-contact voltage detection. It also offers a low input impedance mode, which helps prevent false readings from ghost voltage on unconnected wiring. That is mostly an AC wiring feature, but it is a useful habit around mains-powered supplies: confirm what is live before you open anything up.
Fluke rates the meter IEC 61010-2-033 CAT III 600V, with a maximum of 600 V between any terminal and earth ground. That rating is about safety on mains wiring. It does not make the meter suitable for the high-voltage plate supplies in tube amplifiers, which demand proper high-voltage probes and procedures.
What you get and where it fits
In the box, Fluke lists the meter, a pair of 4 mm silicone test leads, a holster and a quick reference guide. It runs on a 9 volt alkaline battery, with battery life listed at 400 hours typical without backlight.
A good meter will not tell you everything. It cannot show oscillation or RF output, and it cannot measure RF at all. But it will answer most of the basic questions every build raises, and it will do it reliably.
As always when amplifiers come up: external linear amplifiers are not legal for use on CB radio. Measurement tools like this belong in any legal station and on any repair bench.
Where to get it
Check current price and availability: Fluke 117 Electrician's Multimeter at Amazon.
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