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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.
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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.
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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.
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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.
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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.
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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. |
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| 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. |
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Rare Weston AAQ-1696
Output Meter
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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. |
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