90600 Series Frequency Meter
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The 90600 series of midget absorption frequency meters were designed to cover differing
frequency ranges from 150 KHz through 210 MHz. According to Millen documentation
these units were designed to provide direct frequency readout to an accuracy of
1% or better. In use, the unit is held near the inductor in a tuned circuit and
the knob is rotated for a dip or peak in current reading of the grid or plate current
in the circuit of interest. Frequency or wave meters are not used very much anymore,
as they have been replaced by better and safer instruments. So unlike other Millen
equipment, these have a tendancy to be display devices only. This product made it's
appearance in 1947. In the first picture a Millen 90600 series wavemeter is shown next to an early style wavemeter for size comparision. This early style unit has a Millen manufactured dial, but I can't guarantee that it was a Millen manufactured unit. Instead it may be a home built wavemeter. The second picture depicts a 90600 series set made for the U.S. Signal Corp. This set was assigned the number I-129-B. The complete set shown here covers the frequency range of 1.5 MHz through 40 MHz. |