c. 1930s Lightning Radio Calculator Type A-American Radio Relay League-ARRL

Description

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Features
Please also see Additional Notes section below
Copyright 1932
Type A calculator
Printed on thick cardboard
Measures: 8.5 x 11 in. (22 x 28 cm)
Condition
Light general wear, including light discolorations
Crease at right side (see 2nd-to-last image)
Plastic needle: Hairline crack down center (last image)
Plastic needle: End is non-pointy; may have been pointy originally, but we are unsure (last image)
Overall condition: Good Plus
Additional Notes
The following text is from a print advertisement promoting "Lightning Calculators"  :
"Type A - For problems involving frequency, inductance and capacity, in design of radio frequency circuits. Direct reading answers for size of coils and condensers for any range between 400 kc. and 150 mc..."
The following text is from the website "rfcafe.com" :
"The ARRL (American Radio Relay League) might be considered as one of the first app developers. At 50¢ and per app, the price was in-line with one of today's typical not-for-free Apple or Android app. A user willing to shell out for all six had at his fingertips calculators and reference tables for capacitive and inductive reactance, resonant frequency, gain and power, conductor amperage, transformer turns ratio, resistor, capacitor, and inductor series and parallel combination, and other values. These six apps, dubbed "Lightning Calculators," were comprised of bit of cardboard, plastic, and a metal eyelet, not data bits."
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For Internal Use
INV: PB2-62
M:
S:
L: M
LD: 210413