Note
FL-2100
QST, May 1973, p. 134. (FL-2100B)
QST, Nov 1974, p. 4.
QST, Jan 1979, p. 193 (FL-2100F, intro date unknown)
QST, May 1979, p. 192. ("Close out")
The Yaesu FL-2100, FL-2100B, and FL-2100F form a highly successful lineage of compact, self-contained desktop HF linear amplifiers manufactured throughout the 1970s. Designed as the primary high-power companion pieces to Yaesu’s legendary FT-101 transceiver family, this particular trio shares an identical chassis footprint, power supply configuration, and mechanical layout, representing an evolutionary progression of the same core design.
At the heart of all three models is a pair of 572B power triodes operating in a grounded-grid, Class B configuration. Known for their durability under mismatched loads, these tubes are forced-air cooled by a pair of internal chassis fans.
The series features a built-in AC power supply using a high-voltage voltage-doubler circuit, enabling the amplifiers to deliver approximately 500 to 600 watts of RF output power (1200 watts PEP DC input) across the amateur bands. The front panel layout remains functionally consistent across the trio, providing standard Plate and Loading controls, an internal SWR/Relative Power bridge, and dual front-panel meters for simultaneous monitoring of plate current and antenna matching.
Key Distinctions
While fundamentally the same amplifier under the hood, the three models are distinguished by their cosmetic styling and factory-configured frequency coverage:
Yaesu FL-2100 (Original): The early-1970s pioneer of the line, styled with a dark gray finish and distinctive round-pointer knobs to seamlessly match the early FT-101 and FT-101B transceivers. It provides factory coverage for the classic pre-WARC bands: 80, 40, 20, 15, and 10 meters.
Yaesu FL-2100B: Improvements to the internal biasing circuitry for enhanced stability.
Yaesu FL-2100F: A specific, late-1970s factory variant engineered to comply with strict FCC anti-CB (Citizens Band) type-acceptance regulations of the era. Mechanically and visually identical to the FL-2100B, the "F" model is defined by the deliberate factory omission of the 10-meter band position, input coils, and tank circuit components, limiting its native coverage to 80, 40, 20, and 15 meters.
Together, these three amplifiers earned a reputation for being reliable, compact workhorses. Because they share the exact same physical housing and power layout, they are easily distinguished from the later, redesigned FL-2100Z model which departed from this chassis standard to add 160-meter coverage.
Specifications
– Circuit: Grounded Grid Class B
– Frequency Coverage: 80 through 10 meters (except 2100F)
– Plate Input: 1200 Watts PEP, 1000 Watts CW and 600 Watts AM
– Plate voltage: 2400 Volts DC
– Drive Requirement: 100 Watts PEP
– Input Impedance: 50 ohms, unbalanced
– Output Impedance: 50-75 ohms, unbalanced
– Third Order Distortion: 30 db or better at 1000 Watts PEP
– Cooling: Forced-air cooling
Tubes: (2) 572B/T160L
Power Requirements
100, 110, 117 VAC, 50/60Hz, 18 Amps
200, 220, 234 VAC, 50/60 Hz, 9 Amps
References
Review. CQ, Apr 1979, p. 40.
