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EF Johnson 152-502 / 300CD45 Dual Section Air Variable Capacitor, 326 pF Each

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MPN:
152-502 / 300CD45
Condition:
Used
Shipping:
$30.00 (Fixed Shipping Cost)
  • EF Johnson dual-section Type C air variable capacitor. ≈37-326 pF per section, 0.125" spacing, ¼" shaft, 19" long. Rugged high-voltage design for ham radio amplifiers & tuners. Vintage surplus.
  • EF Johnson dual-section Type C air variable capacitor. ≈37-326 pF per section, 0.125" spacing, ¼" shaft, 19" long. Rugged high-voltage design for ham radio amplifiers & tuners. Vintage surplus.
  • EF Johnson dual-section Type C air variable capacitor. ≈37-326 pF per section, 0.125" spacing, ¼" shaft, 19" long. Rugged high-voltage design for ham radio amplifiers & tuners. Vintage surplus.
  • EF Johnson dual-section Type C air variable capacitor. ≈37-326 pF per section, 0.125" spacing, ¼" shaft, 19" long. Rugged high-voltage design for ham radio amplifiers & tuners. Vintage surplus.
  • EF Johnson dual-section Type C air variable capacitor. ≈37-326 pF per section, 0.125" spacing, ¼" shaft, 19" long. Rugged high-voltage design for ham radio amplifiers & tuners. Vintage surplus.
$139.99
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Description

EF Johnson 152-502 / 300CD45 Dual Section Air Variable Capacitor, 326 pF Each

Likely part number / type:
Tag missing, so exact catalog number is unknown. Based on measured capacitance (≈37–326 pF per section), ⅛" (0.125") plate spacing, dual-section construction, ¼" shaft, and large frame size (≈5⅝" × 5⅝" cross-section, 19" overall length including shafts), this is a Type C dual-section air variable. Closest standard catalog matches from period Johnson data:
  • 152-502 / 300CD45 — dual, ≈26–290 pF per section, 0.125" spacing, ≈21 plates per section.
  • Similar higher-capacitance variants or specials in the 300CD45 / related Type C dual family.
Your measured 326 pF maximum is consistent with a slightly higher plate count or production variation of the 300 pF-class Type C dual. Voltage rating for 0.125" spacing on Type C units is typically ≈4500 V peak. The larger frame (vs. the smaller Type D) and overall length confirm Type C construction intended for medium-to-higher power RF use.
 
Confirmed / measured specifications:
  • Number of sections: 2 (electrically isolated, mechanically ganged).
  • Capacitance: Maximum 326 pF per section; minimum 37 pF per section.
  • Plate spacing / air gap: ⅛ inch (0.125").
  • Voltage rating: Unknown from label (estimated ≈4500 V peak based on spacing and Type C design).
  • Shaft: ¼ inch.
  • Dimensions (including shafts): Length 19", Width 5⅝", Height 5⅝".
  • Construction: Aluminum plates and end frames, steatite insulators, typical Type C heavy-duty style with mounting provisions.
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