Featuring Fine Vintage and Modern Amateur Radio Gear For Sale

Bud OES-20, 20 Meter 75 Watt Oscillator and Buffer Coil in Very Good Condition #1

Write a Review
MPN:
OES-20
Condition:
Used
Shipping:
Free Shipping
$29.99
Frequently bought together:

Description

Bud OES-20, 20 Meter 75 Watt Oscillator and Buffer Coil in Very Good Condition #1

**Free Shipping in the USA**

 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.
View AllClose

Related Products