From GRWiki
Jump to navigation Jump to search
General Radio 247-E
Variable Air Capacitor
General Radio 247-E Variable Air Capacitor

Available from 1923 to 1931

  • Manual Needed.
Catalog History
 Document Year Page
Bulletins 1923 1923 B916
Bulletin 926 1924 9244
Bulletins 1924 1924 B917
Bulletin 928 1926 9070
Bulletin 930 1928 9379
Catalog E1 1928 14
Catalog E2 1928 14
Catalog F1 1930 9
Bulletin 933 1931 3
(All manuals in PDF format unless noted otherwise)

The General Radio 247-E Variable Air Capacitor was introduced in Bulletins 1923 and remained available through Bulletin 933 (1931).

The Type 247-E is a general-purpose, air-variable capacitor used in the construction of radio receivers and transmitters and experimental use. The 247-E is part of the 247 series of mounted variable capacitors. Unmounted versions were available as components at a reduced cost. Mounted versions were supplied with a dial, panel and drawn steel case. The 247-E is constructed of brass stator and rotor plates using soldered construction. The capacitor is operated by a slow-motion drive and counter-weighted die cast gear. The dial is calibrated in capacitance and 0 to 100 logging scale.


  • Capacitance: 500 pF
  • Zero Capacitance: 20 pf
  • Maximum Voltage: 500 V peak
  • Calibration:Dial is calibrated directly in pF, accurate to 3% of full-scale reading