Triplett Model 630-NA Volt-Ohm-Milliammeter (1955)

        

This Triplett model 630-NA multimeter is a workshop classic. I own several similar meters, ranging from a vintage English ohmmeter in a walnut case to a 2008 Fluke, but this is a favorite.

The Triplett is well-built, compact, and portable. It measures ohms, AC and DC voltage, and amperage on a millammeter scale.

A view inside the back reveals a rosette of coils and precision resistors.

From the side, we can see the meter's multi-section switch, fuse, and two capacitors. I replaced the paper capacitor peeking out from below. The other capacitor is OK, based on the accuracy of the Triplett's readings.

Two batteries are required for this meter, a 1.5-volt D cell and a 30-volt Eveready type 413 cell.

I recommend downloading the Triplett's 34-page manual. It includes a comprehensive user guide, schematic, and even charts for reading resistors, capacitors, and transformer wires.

I bought this meter at a 2009 radio swap meet in West St. Paul, Minnesota. The seller told me it had been used in electronics classes at the high school in Mountain Lake. Stickers on the back indicate that it was regularly serviced and calibrated. The most recent tag is dated 1972.

A meter with an analog needle is very useful in radio alignment when you are watching for a peak point. It's easier to see the peak when a needle swings up and down, as opposed to a string of changing numbers on a digital readout.

Apart from replacing one capacitor and carefully cleaning the switch contacts with DeOxit, I haven't done anything to this meter. Its accuracy looks reasonable next to my modern Fluke, although I haven't compared them extensively.

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