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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.

The HROII-PDA precision dial assembly includes the counting dial and mounting collar coupled to a ten turn precision potentiometer. The user may interface the variable voltage from the potentiometer to control a variety of devices, including varactor diodes in RF tuning circuits. The customer may select from three different values of potentiometers: 10,000 ohms, 50,000 ohms, or 100,000 ohms. Additional values are available upon request and additional handling cost.


The HROII-PD assembly does not include the potentiometer assembly. The user is responsible for interfacing the dial to a 10 turn (minimum) drive. Please note that the PD assembly is not a vernier drive mechanism.


For Pricing and Availability of the HROII-PD assemblies, please contact National RF, INC. , 7969 Engineer RD, Suite 102, San Diego, CA 92111

The company Phone number is (858) 565-1319 Fax (858) 571-5909


Ordering Part Numbers:

HROII-PD Precision Dial

HROII-PDA-10k    Precision Dial Assembly

-50k    including potentiometer

-100k    (specify 10k,50k or 100k potentiometer value)

Overseas Customers: Please note that an additional overseas shipping charge will be applied to your order. National RF will notify you of the exact amount of shipping to your country via e-mail, after your e-order is placed. The customer is responsible for all and any customs or tarrif charges applied to your order.

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