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Precision Dials
HROII-PD and HROII-PDA - National RF, Inc
National RF’s HROII-PD and PDA precision dials were inspired by
the earlier National Radio Company’s famous HRO series of communications receivers. This earlier equipment incorporated a ten turn dial with a rotating number plate on the inside. Every 72 degrees of rotation, a new number appears in a rectangular cutout in the dial skirt. The numbers count from 0 to 500 in decade intervals. The HROII-PD and PDA duplicate this counting action but in a smaller diameter assembly than the earlier dial.