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Bud OCL-40, 40 Meter 75 Watt Oscillator and Buffer Coil in Excellent Condition #1

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OCL-40
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Description

 
Bud OCL-40, 40 Meter 75 Watt Oscillator and Buffer Coil in Excellent Condition #1
 
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The Bud OCL Series is a vintage line of plug-in oscillator and buffer coils from Bud Radio Inc. (Cleveland, Ohio), dating to the late 1930s–1950s era. These were part of Bud's O-series inductors for amateur radio (ham) transmitters, designed for oscillator (crystal/VFO) and buffer (isolation/doubler) stages in low-to-medium power HF setups.The "OCL" stands for Oscillator Center-Linked (fixed link at the center of the main coil, with the main winding center-tapped). This configuration was ideal for balanced circuits, push-pull stages, or certain tube types requiring center-tapping for symmetry, neutralization, or even harmonic suppression (contrast with OEL = end-linked/no tap, OLS = adjustable/swinging center link, OCP = pentode-specific fixed link, OES = adjustable/swinging end link).Key Specifications
  • Power Handling: Rated for 50 watts input in early catalogs (e.g., Bud Parts Catalog No. 140, 1939), though some later/surviving examples (e.g., OCL-20) are labeled or sold as 75 watts (likely minor design updates or conservative derating for oscillator/buffer use in CW/low-duty modes—derate further for phone/AM).
  • Construction: Air-wound tinned copper wire on a glazed ceramic base/form with banana plugs (fits standard 5-prong tube sockets). Fixed center link for inductive coupling to antenna/grid circuits; windings cemented on acetate locking strips for stability; base elevates coil from chassis to minimize stray capacitance and losses.
  • Purpose: Band-switching in multi-band low-power transmitters (e.g., exciter stages). High Q for efficiency; plug-in for quick band changes in homebrew, kit, or commercial rigs.
  • Tuning Data (from 1939 Bud catalog; approximate total capacitance needed to resonate at band low end with typical variable capacitor):
    • Higher bands need lower capacitance due to smaller inductance.
Known Models in the OCL SeriesFrom Bud catalogs (e.g., 1939 No. 140), eBay/surplus listings, Radiomuseum.org, and ham archives:
  • OCL-160 — 160-meter band (1.8–2.0 MHz); ~90 mmfd capacity.
  • OCL-80 — 80-meter band (3.5–4.0 MHz); ~75 mmfd capacity.
  • OCL-40 — 40-meter band (7.0–7.3 MHz); ~50 mmfd capacity (common survivor).
  • OCL-20 — 20-meter band (14 MHz); ~33 mmfd capacity (frequently listed as 75W variant).
  • OCL-10 — 10-meter band (28–29.7 MHz); ~28 mmfd capacity.
  • OCL-5 — 5-meter band (VHF, ~50–54 MHz era); ~18 mmfd capacity (rarer).

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 This coil is in great shape. The Cross support material has a split in it but it is solid and does not move and is not deteriorating. 

The Bud OES Series is a vintage line of plug-in oscillator and buffer coils from Bud Radio Inc. (Cleveland, Ohio), produced in the 1940s–1950s for amateur radio (ham) transmitters. These coils were part of Bud's O-series inductors, optimized for oscillator (crystal/VFO stages) and buffer (isolation/doubler) applications in low-to-medium power HF setups.The "OES" designation likely stands for Oscillator End-linked Swinging (or similar adjustable end-link variant), featuring an adjustable/swinging link at one end for variable coupling and impedance matching (unlike fixed-link OEL/OCP or center-linked OCL/OLS types). They were built on glazed ceramic bases with banana plugs (fitting standard 5-prong tube sockets), air-wound tinned copper windings, and high-Q design for efficiency.Key Specifications
  • Power Handling: Rated for 75 watts input (conservative for oscillator/buffer stages; suitable for CW or low-duty modulated use—derate for phone/AM to prevent overheating).
  • Construction: Fixed or adjustable end link (swinging for fine loading control); main winding typically not center-tapped (suited for pentode/triode configs); cemented windings on acetate strips for stability; compact form to minimize chassis interaction.
  • Purpose: Band-switching in multi-band low-power transmitters (e.g., homebrew CW rigs, exciter stages before final amps). The adjustable link allows dynamic tuning of coupling to antenna/grid circuits, reducing harmonics and optimizing power transfer.
Known Models in the OES SeriesFrom vintage references (e.g., Radiomuseum.org entries, eBay surplus sales, and cross-referenced Bud catalogs like No. 140 from 1939, plus later mentions in Walter Ashe/ham archives), the series includes:
  • OES-160 (or OES-160-A) — For 160-meter band (1.8–2.0 MHz). Documented example with suspended coupling link on lead wires; rated 75W; ceramic base with 5-pin US plug; dimensions approx. 69 x 85 x 45 mm.
  • Other likely/probable variants (based on patterns in Bud's O-series like OEL/OCL/OLS/OCP):
    • OES-80 for 80-meter band (3.5–4.0 MHz).
    • OES-40 for 40-meter band (7.0–7.3 MHz).
    • OES-20 for 20-meter band (14 MHz).
    • OES-10 for 10-meter band (28–29.7 MHz).
    • Possibly OES-15 or others for WARC/higher bands, though rarer.
Lower bands (e.g., 160m) are more frequently documented/sold as survivors, while mid-HF like 40/20m appear in lots.
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