Most operators know the FT-101 and matching FL-2100B — reliable, 572B tubes, quality construction, and a fair second-hand price. That evolution did not happen overnight. By 1964 Yaesu’s “F” line was refined in 1965 with transceiver capability and a matching 1200 W PEP input linear amplifier.
Yaesu FL-1000
Four 6JS6C finals in grounded-grid configuration with capacitor coupling to cathodes and no tuned input. Rated 1200 W PEP input; typical output ~450 W with strong tubes.
Comparing early FL amplifiers reveals similar circuit layout foreshadowing the FT-101/FL-2100 series.
Yaesu FLdx2000
Ground-grid 6KD6 configuration like the FL-1000 — no tuned input. Drive from SO-239 through RL-1, capacitor-coupled to cathodes. Transceiver finals were tuned for maximum power transfer, much like modern 50 Ω solid-state rigs.
- 3.5–28 MHz, AB2, 100/117/220 VAC
- Drive: 30–100 W PEP
Yaesu FL2000B
Yaesu moved from sweep tubes to parallel Cetron 572B triodes in grounded grid. Individual tuned input coils and dual PA cooling fans — much like the later FL-2100B.
- 3.5–28 MHz; SSB 1500 W PEP / CW 1000 W input
- 117 V @ 17 A / 234 V @ 9 A; 55 lb; Japan 1969
- 2× Cetron 572B parallel
Yaesu FL-2500
1500 W input with 100 W drive. First Yaesu amp covering 1.9–28 MHz continuously. Five horizontally mounted 6KD6 tubes with dual fans. Dual-purpose meter: plate current and forward/SWR; CW/Tune vs SSB switch.
Yaesu FL-2100 / B / F
Conservatively rated companion to the FT-101E. Three variations: FL-2100, FL-2100B, and FL-2100F (no 10 m from factory). Dual rugged 572B carbon-plate tubes; Sommerkamp FT2277 rebrand in Europe.
FL-2100F — Adding 10 Meters
The FL-2100F omitted 10 m operation. Yaesu offered a 10 m add-on kit (P/N on original page). Key caps: C211 200 pF, C215 100 pF (same as FL-2100B).
Buying Used & Service Tips
Before buying a used FL-2100B, check the band switch (S1a) — expensive if damaged. Cracked ceramic caps and parasitic oscillations are common issues. A 22 Ω 2 W grid resistor on the cathode circuit can help stability.
See also: Richard Measures AG6K — improved anode-circuit parasitic suppression for 572B amplifiers.
220 VAC Wiring
Proper wiring for 220 VAC operation affects HV (~2600 VDC on 117 VAC). Documented configurations for Europe 220 VAC and USA 234 VAC (both 117 V primaries in series). Save the extra jumper when converting — double it up rather than leaving it loose inside the cabinet.
Can We Talk? — Fans!
FL-2100 series fans match FT-101 fans. Japanese units were designed for 100 VAC @ 60 cps — test on a variac at 100 V if possible. Clean armature and field coil; verify free rotation before reassembly.
Yaesu FL-2100Z
- 10–160 m + WARC; AB grounded grid; 2× 572B
- 100–117 / 200–234 VAC; 117 V @ 18 A / 220 V @ 9 A
- CW 1000 W / SSB 1200 W PEP input; 20 kg
More details on the FL-2100Z — work in progress on the original site.
Web page by Fox Tango International and member contributions.
Carol L. Maher W4CLM