5
DX-3SP LINEAR AMPLIFIER
Serial No
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OPERATING MANUAL
January 2009
CAUTION
1 GENERAL DESCRIPTION
The Emtron DX-3SP Linear Amplifier is a 4000 watt 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 extra
suction 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.
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 available 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 forward
and 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.
The DX-3SP has been designed for 100% safe operation and long life. Interlocking
sensing circuitry constantly monitors conditions inside the amplifier. It must be
noted however, that the high voltages present inside the DX-3SP are
EXTREMELY DANGEROUS. Do not remove the top cover under any
circumstances if any leads are still plugged into the rear of the amplifier
-
especially if the AC lead is plugged in the power outlet.
Before any component
inside the high voltage, power supply or output section is touched,
unplug all rear panel leads and allow at
least 5 minutes of 'off
time'.
After that, you should further check this
by momentarily shorting the tube anode
to the chassis with a suitable insulated lead.
