ACOM 2000A automatic tuning
Automatic HF linear amplifier with two 4CX800A (GU74B) tetrodes, 1500 W, built-in tuner, remote control unit
The ACOM 2000A is an HF linear amplifier with fully automatic tuning: it follows the transceiver's band and frequency in less than a second and matches loads with SWR up to 3:1 without an external tuner. It uses two grid-driven 4CX800A (GU74B) tetrodes.
Product description
The grid-driven configuration was chosen for its inherent stability and very low spurious emissions. The transceiver sees an excellent load (input SWR typically below 1.2:1) and the regulated screen grid voltage gives typical IMD of −40 dB (3rd order) and −45 dB (5th order). The Pi-L network with air-wound coils brings harmonics down to −55 dBc (2nd) and below −70 dBc (3rd and higher).
Antenna matching is automatic, typically in 1 second, for SWR up to 3:1 (2:1 on 160 m), even at full power. To change band a single CW dot or a short SSB transmission is enough, with no special cables. Each band is divided into segments and up to 10 tuning settings can be stored per segment, i.e. one per antenna.
Full break-in (QSK) uses a vacuum relay with sequencing handled by a dedicated microprocessor. The remote control unit (RCU, 167 × 130 × 25 mm) sits near the operator, while the main unit can be up to 3 m away (20 m with optional cable). The RCU shows status on an LCD and monitors the 20 main parameters, with troubleshooting hints and an hour meter.
All functions are accessible from a PC via RS-232 and several amplifiers and antennas can work in a network. Protections cover tube voltages and currents, power supply, overheating, overdrive, airflow, internal and external RF arcs, T/R sequencing, reflected power and safety interlock. Data from the last 12 protection trips are kept in memory for remote diagnosis.
Key features
Typically 1 second, up to 3:1 SWR.
Low IMD and low harmonics.
Settings for multiple antennas.
RS-232, network of several units.
Coverage
Standard coverage is 1.8–24.5 MHz; 28 MHz is available only with a modification for licensed radio amateurs.
Technical specifications
| Output power | 1500–2000 W in CW or SSB · 1500 W continuous carrier with no time limit with auxiliary fan |
| Coverage | Amateur bands 1.8–24.5 MHz (28 MHz with modification) |
| Tuning time | < 3 s initial (typical 0.5 s) · < 0.2 s same band · < 1 s band change |
| Tuning memories | up to 10 antennas per segment, non-volatile |
| Drive | typically 50 W for 1500 W |
| Input impedance | 50 Ω, SWR < 1.5:1 |
| SWR tolerance | 3:1 (2:1 on 160 m) at full power |
| Harmonics | at least 50 dB below peak at 1500 W |
| Intermodulation | at least 35 dB below peak at 1500 W |
| T/R | Vacuum relay, QSK |
| Tubes | 2 × 4CX800A / GU74B tetrode, Pi-L output |
| ALC | Negative, up to −11 V, adjustable |
| Transformer | 3.5 kVA |
| Power supply | 100/120/200/220/240 V AC, 50–60 Hz, 3500 VA single-phase |
| Dimensions | RF unit 440 × 180 × 450 mm · RCU 135 × 25 × 170 mm |
| Shipping weight | 42.5 kg in two packages |
HamRadioShop | Linear amplifiers
