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EMTRON All New DX-2SP......2000 Watts CW output!

Emtron DX-2SP Amplifier

General Description

The DX2-SP is Emtron's all new 2000 Watts plus CW, over 2500 Watts PEP output linear amplifier. All specs except the output power, as well as features, are the same for all Emtron amplifiers. Here we are utilizing one single FU-728F tetrode. This tube was designed as an improved Chinese militarized version of the popular Eimac 4CX1500B. These robust FU728F tubes are manufactured in present production and are available directly from the tube manufacturer or from Emtron exclusively for Emtron amplifier owners. We at Emtron, are enormously impressed with the capabilities of this tube, and proud to use it in this new DX-2SP amplifier. Also, this amplifier is directly compatible with the Eimac 4CX1500B. All one has to do, is change the tap on the filament transformer from 9 volts to 6 volts, if the Eimac tube is used!

With 3000 Volts HT on the plate, and a bigger heavy-duty power supply transformer as well as upgraded RF tank circuitry, this version amplifier delivers a very solid 2000 Watts plus CW output power, with 30 to 60 Watts of exciter drive power.

Weight: 35 Kg (100 lb), shipped in two separate boxes, transformer and RF deck.

Dimension: 470w x 230h x 470d mm, (18.5in w x 9in h x 18.5in)

Emtron DX-2SP Internals


Band Coverage

The Emtron DX-2SP covers all nine amateur bands from 160 to 10 meters including the WARC bands at full rated power. It utilizes a high quality ceramic 9-position band switch for selecting each amateur band. There are no compromises on some bands like on many other brand amplifiers on the market. The LOAD and PLATE tuning employ 6:1 vernier drives for precise and silky smooth tank circuit tuning.

Modes of Operation

The EMTRON DX-2SP has been designed and built to operate at full power in any mode such as SSB, CW, AM, FM, RTTY and SSTV, and any other digital mode. QSK module included.

Output Power

This amplifier will comfortably deliver 2000 Watts (2500 Watts PEP) continuous carrier ("key down") into your antenna. The conservative rating of the FU728F tube, the tank components, and the amplifier's efficient cooling system allows effective operation at this power level.

Tube Protection

The EMTRON DX-2SP has a very sophisticated tube protection circuitry, designed to protect against excessive plate current, screen grid current, screen grid voltage, control grid bias voltage, exciter overdrive, SWR, etc. The tube is also protected from excessive temperature by continuously monitoring the airflow exhaust temperature. In case of any fault, the amplifier goes automatically into By-pass mode. A 20 ohm, 70 watt resistor in the high voltage B+ circuit and a MOV in the screen circuit further protects the tube and the power supply from a possible tube internal flash-over.


A lot of attention was given to the design of DX-2SP's cooling system. A pressurized forced air cooling is achieved with a rugged temperature controlled two speed 72 CFM blower (turbine) which effectively cools the tube and all critical components of the amplifier. The blower is positioned in such a way that it prevents hot air being circulated through the system. Also, one additional axial sucking fan is placed just above the tube, to further improve the cooling efficiency!

Drive Power

In order to achieve full output power, an input power of approximately 30 to 60 Watts is required. If your transceiver delivers more output power, reduce the drive level. Specially when operating RTTY or any other continuous mode, reduce the drive level and let your transceiver run "COOL" with less strain on its output PA components. The EMTRON DX-2SP is comfortable with all popular transceivers such as KENWOOD, ICOM, YAESU, JRC, TENTEC, etc.

Overdrive Control Circuit

A unique feature in all Emtron amplifiers is the overdrive control circuitry. It is virtually impossible to produce a broad distorted signal. This "Overdrive Control Circuit or "OCC", senses any slight overdrive condition (less than 50 micro-amps of grid current and departure from linear AB1 operation), a LED warns you, and if you don't do anything about it, the amplifier will bypass itself for 2 seconds. The 2 second bypass is then repeated until the drive level is being reduced. There are only two cables required to connect the transceiver to the amplifier, the RF and PTT cables. For better performance, linearity and clean signal we prefer OCC to ALC.

Power Supply

The power supply of the EMTRON DX-2SP is also unique. It contains a "SOFT START INRUSH PROTECTION", a top grade heavy duty transformer, a full bridge rectifier and eight high voltage filter capacitors of 470 uF/500 volt rating. This gives a total capacitance in the high voltage section of 58 uF and a conservative voltage rating of 4000 volts DC. The soft start inrush protection circuit in all Emtron amplifiers is another unique design found in no other amplifier so far. It is the best soft start system available today. The phase controlled 40 Amp TRIAC will slowly turn on the amplifier using a 3-second gradual ramp-up function. The electrolytic capacitors are charged little by little and linearly over the 3 second period. This also affects all other circuit components in a similar manner, including the tube filaments which come up gracefully without large inrush current when cold. Stress in components, failure and "TRANSFORMER BONG" and deleterious current surges are nonexistent in EMTRON amplifiers. Another unique new design, exclusive to the EMTRON DX-series amplifier is its screen grid power supply. Fully voltage regulated for +ve and –ve screen currents, combined with very effective current limiting, not only totally protects the tube, but also due to its wide dynamic range, keeps the tube static operation parameters absolutely stable. The protection against excessive screen current is so good, that we have tested the operation with full screen voltage, while the plate voltage was absent, for extended time, without damage to the tube. Needless to say that there is quite a lot of sophisticated electronics present in all Emtron amplifiers and quietly working behind the scenes to protect your amplifier investment!

Emtron DX-2SP Power Supply

Controller Board

The most important module, containing most of the above unique circuitry is the "controller board", which is connected to all the other parts of the amplifier via a wiring loom harness. This board contains: the screen grid supply with voltage regulator and current limiting, the regulated control grid bias supply, QSK power supply, the 12VDC power supply, the overdrive / OCC, SWR, temperature control, EBS, plate over current protection, amp bypass switching, etc.

Emtron DX-2SP Controller Board


All important parameters such as plate current Ip, plate voltage Vp, RF output power, reflected power, screen grid current, linearity, ready, transmit, high SWR and fault are displayed on a single solid state display panel utilizing LED's of different colours. No switching of any parameters is required. We have chosen this sophisticated and advanced system in preference to conventional moving coil meters even though this system is about three times more expensive than the conventional analog meters used by other amplifier manufacturers. Amplifier health and key parameters can all be monitored simultaneously at a single glance of the display panel.

Emtron DX-2SP Display


Only the very best components with no compromise are used in EMTRON DX-2SP amplifier. All RF components such as band switch, tank coils, chokes, etc. are of high quality silver plating.


The finish is of high quality durable baked enamel texture paint and silk screening of a quality not found on any other similar equipment. The chassis is made of high grade 2mm dark yellow chromate coating, and the front panel is made of 3mm high grade aluminium.


We believe in our products and give FOUR YEARS full warranty which covers all parts and labor, and limited warranty on tube


The EMTRON DX-2SP is sold factory direct, no "middle man" mark up, you do business directly with the designers and producers, with people who know the heart and soul of the DX-2SP, and they will always be able to give you expert technical advice and after sales service. So, get the biggest bargain in top brand linear amplifiers. You are getting a Rolls Royce for the price of a Mini. The DX-2SP was especially developed by EMTRON for those discerning HAM operators who demand quality and performance. This power house will handle all the rigour and demands of contest, DX-ing and high duty cycle emissions.