Photo by Emtron
Description:
The Emtron DX-3SP Linear Amplifier is a 4000 Watts average output power, for the 160m through 10m amateur bands (9 bands), housed in a desk-top cabinet with self-contained power supply and cooling system. It utilises a two high performance tetrodes, type FU-728F, a ceramic metal tube with a plate dissipation of 1500W. The tubes are air cooled by a commercial grade forced air turbine blower system and two extrasuction fans above the tube. Tetrodes offer exceptionally stable operation and levels of quality performance far exceeding that which can be expected from triodes. The harmonic output and intermodulation distortion achieved with this tube are exceptionally low. This is especially important when dealing with a high output power.
Photo by Emtron
The Emtron DX-3SP is supplied as standard with a host of features including solid state metering and comprehensive protection systems. In addition, a unique Emtron QSK module is availabl
e as standard. With this installed, extremely rapid switching times between transmit and receive are possible, with consequent advantages when using CW or the digital modes. Operation of the DX-3SP is greatly simplified by the absence of meter switching and of front panel level setting controls. The front panel moving LED display systems indicate simultaneously: the output forwa
rdand reverse power, screen grid current (positive and negative), the plate voltage and the plate current, while 5 single LED’s indicate: Ready, Overdrive warning, High SWR cut-off indication, On Air and Fault. The Emtron Electronic Bias Switch (EBS) automatically switches the standing current (typically 0.5 A) off when there is no modulation. This reduces the average tube dissipation. On initial switch on, the unique Emtron “soft start” circuitry ensures that no damaging AC surge currents are generated. Professional, fine output tuning adjustment is possible, due to the 6: 1 reduction mechanism fitted.
Photo by Emtron
Technical Specifications:
FREQUENCY COVERAGE:
Complete (manually tuned) coverage of the nine HF amateur bands:
1.800 – 2.000 MHz
3.500 – 4.000 MHz
7.000 – 7.500 MHz
10.000 – 10.300 MHz
14.000 – 14.350 MHz
18.000 – 18.500 MHz
21.000 – 21.500 MHz
24.000 – 24.500 MHz
28.500 – 29.990 MHz
TRANSMITTING MODES: The DX-3SP supports SSB, CW, AM, FM, RTTY and SSTV.
OUTPUT POWER: Typical 4000 watts carrier or up to 5000 W PEP
DUTY CYCLE: Suitable for SSB operation.
CW: 4 minutes transmit, 1 minute receive.
AM: 3 minutes transmit, 1 minute receive.
DRIVE POWER: Nominal 60-90 watts for full rated output.
INPUT IMPEDANCE: Nominal 50 ohm passive impedance, unbalanced. VSWR 1.4:1 or less.
OUTPUT IMPEDANCE: Nominal 50 ohm passive impedance, unbalanced. VSWR 2.6:1 or less.
DISTORTION: Third order intermodulation products are more than 35 dB below rated output.
HARMONICS: Harmonic output is better than 50dB below the rated output.
FAULT PROTECTION: The comprehensive fault protection system includes circuitry to monitor :
• plate current: should the plate current exceed a safe value, the amplifier goes to standby for 2 minutes. The nominal trip plate current is 2.5 A
• screen grid over-current: Absolute tube protection is offered with visual warning and a reduced power level being enabled if the screen current exceeds apre-set limit. The screen current is limited to about 50 – 60 mA total, for the 2 tubes.
• temperature: Should the tube’s temperature exceed a specific level, amplifier operation is suspended until the temperature drops to a safe level. The cut-off temperature sensor has a nominal value of 110° (230F). The fan speed control temperature sensor has a nominal value of 80° (176F).