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EMTRON DX-1SP......1200 Watts CW output..... FCC approved!

Emtron DX-1SP Amplifier

General Description

The NEW DX-1SP with 1200 Watts CW, 1500 Watts PEP of clean signal output is Emtron's latest and smallest amplifier. It has all of the renowned functions and features of all other Emtron amplifiers, except the power output. The new FU-728F (4CX-1500B) tube can run 1200 watts key down indefinitely, for as long as you want, or 1500 watts PEP. As this mil-spec Chinese tube quite comfortably delivers 2000 watts CW, the attainable power output in the DX-1SP design is limited only by its smaller power supply and tank circuit! Also, this amplifier is directly compatible with the popular Eimac 4CX-1500B tube. 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! We believe that the DX-1SP amplifier is unique and has no competition in craftsmanship, performance, engineering and price. Due to its light weight of 20kg and small foot print, this compact desk-top amplifier is also ideal for DX-peditions. This model Emtron amplifier has outstanding performance in its class and represents truly exception value for money.

DX-1SP operates at input AC voltages of 100 to 240 volts. Current at 240 volts is 10 amps.

Weight: 20Kg, (44lb)

Dimensions: 380w x 190h x 355d mm, (15"w x 7.5"h x 14"d)

Emtron DX-1SP Internal


Band Coverage

The Emtron DX-1SP covers all nine amateur bands from 160 to 10 meters including the WARC bands at full power. It utilizes a proprietary ceramic high quality 9-position band switch for selecting each amateur band. There are no compromises on some bands like many other brand amplifiers on the market. Tank tuning precision is provided by 6:1 vernier reduction drives on the PLATE and LOAD controls.

Modes of Operation

The Emtron DX-1SP has been designed and built to operate in any mode such as: SSB, CW, AM, FM, RTTY and SSTV and with an optional QSK module for handling all current digital modes.

Output Power

This amplifier will comfortably deliver 1200 watts (1500 watts PEP) continuous carrier ("key down") into your antenna. Its conservative rating of all components and efficient but quiet turbine blower cooling system allows effective operation at this generous power level. The FU-728F tube is undoubtedly the best value linear amplifier tube available in the market today, and importantly, is in current factory production for ensuring ease of availability.

Tube Protection

The Emtron DX-1SP, like all other Emtron amplifiers, has a very sophisticated tube protection circuitry, designed to protect against excessive plate current, screen grid current, screen grid voltage, bias voltage, exciter overdrive, SWR, etc. The tube is also protected from excessive temperature by continuously monitoring the required airflow exhaust temperature. In case of any fault, the amplifier is automatically cut off. A 25 ohm, 50 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 has been given to the design of the DX-1SP's cooling system. A rugged temperature controlled 2-speed 72 CFM blower (turbine) effectively cools the tube and all critical components of the amplifier. The volume of cooling air far exceeds manufacturer's specifications for all critical components. The blower is positioned to prevent hot air being circulated through the system.

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 components. The EMTRON DX-1SP 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 output signal with dirty splatter. 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), an 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 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 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 filter capacitance in the high voltage section of 58 uF and a very conservative voltage rating of 4000 volts DC. The soft start inrush protection circuit, standard 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 non-existent in EMTRON amplifiers. The screen grid power supply is fully voltage regulated for +ve and -ve screen currents. Very effective current limiting, not only totally protects the tube, but also due to its wide dynamic range, it keeps the tube static operating 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 the DX-1SP and quietly working behind the scenes to protect your amplifier investment.

Emtron DX-1SP Power Supply

Controller Board

The most important module, containing most of the above unique circuitry is the "controller board heart", 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-1SP 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 colors. 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-1SP Meter


Only the very best components with no compromise are used in EMTRON amplifiers. All RF components such as band switch, tank coils, chokes, etc. are of high quality silver plating, ceramic bobbin core for lower frequencies is also used.


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 strong and rigid chassis is made of high grade 2mm dark yellow chromate coating, and the front panel is made of 3mm high grade aluminum.


FOUR YEARS full warranty covers all parts and labor, and limited warranty on tube.


The EMTRON DX-1SP 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-1SP, and they will always be able to give you any expert technical advice and after sales service. So get the biggest bargain in top brand linear amplifiers. The Emtron DX-1SP is the most technically advanced RF linear amplifier operating on all of HF amateur radio bands; it was specifically developed with quality, reliability, performance and price in mind.