Vintage Test Equipment


This is a Biddle Frequency Indicator.  Its range is from 20 to 80 cps (Hz).  This device  uses the Frahm System which is tuned reeds or thin brass strips each being sympathetic to a specific harmonic. There are two roes of electromagnets which are all energized at the same time.

Up until the late 60s, variations of these were used as tachometers for AC generators.

The hand written date on the back of this kilowatt meter is 5/24/39.  The manufacturing date was 11/1/27.

For the last 30 years, I used it to measure electricity usage for devices that have 5 amps or less.

The Heathkit IN-37 Resistor Substitution Box and the IN-47 Capacitor Substitution Box. These were one of the last Heathkit substitution boxes that were available as a kit starting in 1967 and ending in 1978. There was one set of small box kits after that. The tolerances for both of these boxes is an amazing ...  +10%.

Note. Unlike today, 5 and 2% precision resisters and capacitors were very expensive in 1967. 

Weston Model 622 DC Volt Meter

The following two meters are my reasonably calibrated standards for DC voltage and DC amperage. I obtained these from two friends. One was my sister’s boyfriend who worked in the 70s at a company that made computer controlled respiratory medical devices. He said he got this from the company when they were clearing out surplus equipment. The second meter was obtained in the 90s from another friend who had it in his home in California before moving to the Midwest. It was around his childhood home as a display item. Both are in remarkably good condition and as of the late 1990s are supposed to be in calibration. In comparing them to my Fluke 77, they read the same as the 77.

This meter is selectable from 2 volts to 1000 volts DC.

Its calibration card says that it was officially calibrated on April 22, 1957 – three months after my 7th birthday.

Weston DC Ammeter Model 50722 - 15 Amps Maximum

The calibration card says:

This instrument indicates International Amperes and its indications are correct within ¼ percent of full scale value at any point of the scale at 25oc.

Resistance of 15 Ampere Range 0.0036 Int, Ohms at 25oc

For all ordinary measurements, no temperature correction is required. If greater accuracy is required, multiply readings in amperes by [1-0.000,2(t-25oc)].


The card says this meter was calibrated on August 22, 1933.  

This is a TS-297/U which is a small, rugged military millimeter. AC/DC voltages from 4 to 1000 V full scale in six ranges (1Kohm/V), DC currents from 4 to 400 mA in four ranges, plus ohms x1, x10.

This is a meter I purchased at a Hamvention during one of my old house restoration phases.  At that time I had set aside my electronics interests in lieu of old house reconstruction and decorating. It would be within the last 15 years when I finally got back into electronics and ham radio.
It's interesting to note that most old pre-50s meters are made up of hand-made wax-coated components.  The reason for this was so manufacturers could build meters with accurately calibrated components that were protected from the elements.
Rare Weston AAQ-1696 Output Meter
From a 1934 magazine advertisement:

Measures Voltages Output and computes Power Output of radio sets, determine maximum gain with lining up R.F. and I.F. stages if radio sets. Compares the gain of radio tubes, determines gain within a calibrated input voltage is applied to radio set or audio amplifier. Measures comparative selectivity of R.F. tuners. Used to observe period and percentage of fading and to keep volume of sound projection equipment at an approximate constant value; and to determine the amount of hum. Consists of a five range copper oxides rectifier type voltmeter enclosed in a sturdy Bakelite case with ranges of 150, 60, 15, 6 and 1.5 volts A non-inductive impedance of 4000 ohms for all ranges.