General Radio 516 Impedance Bridge Calculator
General Radio manufactured an early RF impedance bridge in the late 1930's and early 1940's. Not many
seem to have survived, but the 516 bridge is ideally suited to LF and AM broadcast measurements. The
516C was the final (and best selling) version. That model normally had a wooden case, but a metal-case version
was produced for the Navy under the model number CAG-60009. These bridges were superceded by the 916
series, but the 516 is very accurate and easy to use.
The only catch with the 516 bridges is the amount of calculation necessary to translate the dial readings
into the measured impedance. I have used little calculator programs to speed this up, but it seemed to be
a good idea to put a more intuitive program on a computer so that I didn't have to remember arcane
variable names and storage register labels. The resulting program was written in Visual Basic, and
should provide quick answers to common measuring problems. Please feel free to contact me if you find
any bugs. The error trapping is simple, but will hopefully cover most situations.
Download GR516 Calculator. (16.3k, Zip file)
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