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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | EMTRON DX2sp Help

Reviews Summary for EMTRON DX2sp
EMTRON DX2sp Reviews: 18 Average rating: 4.6/5 MSRP: $4,181
Description: The very special DX-2SP H.F. amplifier stands on its own and has no competition. Produced for the military, the SVETLANA GU-84B tube, with plate dissipation of 2500 watts, when installed in the new EMTRON DX-2SP produces a solid 2000 watts continuous RF output (2500 watts PEP). The tube and a very special high voltage, high current band switch, as well as a 4KVA mains transformer, Distinguishes the DX-2SP model from the DX-2 unit. MSRP does Not include Shipping from Australia which currently runs US$195.00 to nearest airport Or US$289.00 to your door. Optional QSK module (factory installed): US$100.00
Product is in production.
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VK4HF Rating: 5/5 Aug 29, 2014 15:59 Send this review to a friend
My 3rd Emtron Amp  Time owned: 0 to 3 months
Over 35 years of "Hamming" I have had many HF Amps and I still have 5 Tube type HF amps and 2 solid state HF Amps. This is the newer DX2-SP with the Chinese tube and it does not disappoint at all. I had a DX-3 with the russian tube and that was a real power house too. This latest offering from Emtron is still using the same modular construction as all previous amps so should the need ever arise, servicing would be an easy D.I.Y option without having to send the whole unit in for repair.

This DX2-SP is built in the same size case as the DX3-SP that runs 2 chinese tubes and as such there is plenty of room around the different stages to be able to get at everything to work on it. However, I don't see that being the case in the near future as this is a beautifully designed and manufactured piece of equipment. I ran it into a 1KW Bird Dummy Load and 3kw pep is easily achievable with about 60 watts drive and our VK legal limit comes with only 10 watts drive.

If you're contemplating an Emtron Amplifier, get your order in now before Rudi retires.
ZS4U Rating: 4/5 Aug 26, 2013 12:36 Send this review to a friend
Huge and powerfull  Time owned: 0 to 3 months
I took over this amp from a ham who imported it brand new and never used it. It is huge and heavy, and packs a BIG punch (2.5 kw +). It is not for the faint of hart and must be operated with care, make sure that your feed lines and antenna system can handle what this amp can deliver. It puts out a clean signal and is well built. Mine has the new Chinese mil spec tube and can accommodate 2 inputs and two antennas. It has the soft start feature, QSK and has a couple of built in protection features to safe guard your investment. It is an amp for the serious contesters - I would not recommend this model for a casual operator - rather look at the DX-1SP or an Alpha. My biggest gripe is the noise emitted by the cooling fans - although it is at a low frequency, which is perfect to be concealed on your outgoing audio, BUT, you have to crank up the receiver audio level to hear the weak stations above the fan noise...... (with headphones) It will not be noise friendly to a ham using his radio's loudspeaker.

In summary, a good, well built amp with a 24/7/365 @ 1.5 kw capability for the serious contester.
K8RI Rating: 5/5 Jul 8, 2010 21:00 Send this review to a friend
Great, Rugged Amp with a clean signal!  Time owned: 3 to 6 months
I've had the DX-2sp now for about 4 months. I have the new version with QSK as a standard feature.Construction is modular with many components common across the line. Emtron changed to the Chinese FU728F tube, which except for the filament voltage is directly interchangeable with the 4CX1500B. Emtron has included a voltage tap on the transformer for the 4CX1500B filament. The centering pin in the socket for the FU728F is *slightly* larger than the one for a 4CX1500B, but Rudi is using custom sockets that will fit both tubes and I'd call the tank circuit a "heavy duty, work-of-art". With this change of tubes, Emtron has answered the tube availability question.

When I have e-mailed Rudi with questions he has usually called me on the phone within 24 hours unless on vacation. He even called after a couple of months to make sure I was satisfied with the DX-2sp. How many companies do that with their customers?

I have had many amps (probably far more than most) over my 50 plus years as a ham and I'd call the DX-2sp the best overall. I've received nothing but good on-the-air signal reports, the QSK has worked great so far, I've finally found an amp that is capable of "legal limit" digital 24 X 7, and I have never received this level of service from any other company.

My previous amp was a solid state KW with auto band switching and beautiful workmanship, but I prefer the DX-2sp. Would I choose a different amp were I to do it over? I might choose the DX-3sp which I could run class A and still get the legal limit out, but I am definitely happy with the DX-2sp.

To sum it up, the Emtron DX-2sp is a rugged, heavy duty amp with enough overhead to allow digital in the true "key down" 24 X 7, yet can still easily run one of the cleanest signals on the air with the drive reduced for the legal limit out on SSB and CW.

Now I just need to get rid of some *stuff* to make room for the 6-meter version, the DX-2v.
VK5KLT Rating: 5/5 Jan 10, 2010 20:21 Send this review to a friend
January 2010 Update  Time owned: more than 12 months
I have now owned the DX-2SP amplifier for almost 3 years and during that time has performed flawlessly. It works impeccably well, is stable and predictable in its behaviour, and teams well with my Yaesu FT-2000 exciter rig.

Does precisely what a high-end amplifier should do; transparently and cleanly increase the Tx power level without adding any extraneous and deleterious signal products. Never fails to receive excellent signal quality reports.

The well conceived DX-2SP model desktop amplifier is a muscular fire breathing brute with finesse; sustained bench testing shows the published spec of 2.5 kW PEP is conservative.

The DX-2SP amplifier is also spectrally very clean with typical IM3 is circa −40 dB down from PEP on two-tone testing, the IM3 and IM5 and higher order IMD products being amongst the lowest I’ve seen during bench testing with a spectrum analyser and dummy load; a far cry improvement over certain well known buckshot generating solid-state amplifiers. An increasingly important factor and consideration for QRO use with some of the latest generation SDR transceivers with their clean pure Class-A bias exciter stages and exceptionally low IMD performance.

Emtron’s professionally executed exceptional build quality and superb craftsmanship is in a unique class all of its own and a wonderful sight to behold, as is the massive high current ceramic band switch, the heavily silver plated tank components, and weighty dual loop C-core 4 kVA power transformer with Emtron’s unique phase controlled triac based soft-start circuit to control inrush current and bring the load and tube filaments up slowly and gently.

The big 1.8 kg bullet-proof external metal anode fin / ceramic Russian military GU-84B / 4CX2500A style Svetlana made tube is conservatively cooled by a quiet internal temperature controlled centrifugal squirrel cage two-speed turbine blower. When the amplifier is operated for extended periods in low duty cycle SSB PEP mode the blower seldom ever switches to high speed. The thermal engineering / heat extraction is soundly and pragmatically executed with an auxiliary sucking axial fan in the top of the cabinet directly above the tube chimney to augment the cooling in high duty cycle RTTY, SSTV, or continuous FM or digital modes.

The amp manages a frightening PEP output power if driven so. More than ample here in VK land with plenty in quietly understated reserve power! I noted during bench testing / soak test on initial receipt of the amp that my DX-2SP readily produced in excess of its manufacturer rated output into my QRO dummy load during a two-tone test and when whistling into the mike! Needless to say at more moderate / sensible power levels the amp just loafs along very authoritatively and cleanly with lots of spare dynamic range and headroom. It has impressively low IMD / IM3 IM5 products when driven conservatively. BTW, to tame and moderate back the beast I run a precision Weinschel / Narda 6 dB 50W power attenuator pad between the exciter rig and amp; which also helps keep the Yaesu FT-2000 exciter in its optimally clean IMD “sweet-spot” region. The Yaesu rig is definitely the IMD weak link in the Tx chain. This external attenuator pad also removes any risk of accidental overdrive of the high gain GU-84B tetrode by the exciter. Due to poor commercial transceiver design I don’t use any linearity / spectral purity compromising ALC on my linear amplifiers.

As the amplifier just keeps on keeping on, I expect the DX-2SP and the tough tube will outlive its owner!



RFEXPERT Rating: 3/5 Sep 19, 2009 22:56 Send this review to a friend
Poor Support  Time owned: 6 to 12 months
I bought my DX2SP second hand in pieces from someone who was waiting for a new blower and controller board. He had been waiting for 6 months.

I assembled it and had further problems. I contacted Rudi who said the best option was a replacement board. I indicated that I would be happy to pay all freight costs by Fedex. I waited almost 8 months for the board and a new blower. The total wait between the original owner and myself was over 14 months!

I got mine working and its a great amp when it works. I dont even want to think about fixing it again since the support is so poor.

The only issue that I have with this AMP is its poor EBS and ALC system which causes leading edge splatter and RF on the audio. This is very apparent when you want to run the amp at less output power. I would suggest not using any ALC and turning the EBS off.

Every Emtron DX2SP that I hear on the air has leading edge splatter problems and sounds like it has RF on the audio. RF activated EBS is a recipe for bad splatter and bringing attention to yourself which nobody wants!

I fixed this splatter problems by installing 3 db attenuators in the grid circuit. I used RFPower Labs attenuators available from Henry Radio. They are quite cheap. I installed 2 X 3db attenuators giving me the ability to reduce drive power by 3 or 6db. I used reed relays from Measures AG6K to do the switching.

The blame for this problem is not entirely Emtrons. Just about all of the Japanese radio models have ALC overshoot problems, especially when you reduce power for low drive amps like the Emtron. Appplying a variable -5 volts to the ALC port on your radio might also help reducing this leading edge splatter problem

I Always run the radio at full 100 watts of output power and use the attenuators to reduce the drive. With no ALC or EBS activated the DX2Sp puts out a perfectly clean signal.

I have measured the suppression of IMD products at 5, 10,15 and 20khz and they are well over 70 db down at 20khz. I no longer send buckshot up the bands like I used to do. My life on the air is a lot easier now that I dont cause problems HI!
At least it does not sound like I am running a class C CB amp!

The only minus for the future of this amplifier is the lack of availability of good tubes. The GU84 is getting as rare as hens teeth. There is no equivalent available from anyone. The new DX2 uses 2 X 4cx1000's which are tubes not really designed for linear SSB service. A better choice would have been 4cx1500B's

If you can get one of these AMPS cheap it would be a great buy. If you looking for something new with good service I would be looking at the OM Power amplifiers. They are of the same or better quality and certainly offer much better product support.

WV4R Rating: 5/5 Jan 13, 2007 07:10 Send this review to a friend
DX2sp "2001model" Keeps on Ticking!  Time owned: more than 12 months
DX2sp From 2001 & Keeps on Ticking!

Update #3 from August 2002

A lot of water has passed over the dam since 2001 but my Emtron DX2sp keeps on Ticking. I use my “Beeg Wombat” mostly on 75m & 20m where 25w or less Input still puts Out 1500w P.E.P. unlike some amps requiring you to drive the snot out of your ‘exciter’ to achieve the ‘Legal Limit’. No “IMD” problemos with my station cuz all is running well Below the max! I do like the high quality paint job and great front panel look.

Unlike a lotta hams I work, I turn my Beeg Wombat ON when I sit down at the Main Operating Console & turn it OFF when I git up so ‘3-minute warm up time’ is Not a factor for me.

This Emtron DX2sp is now pushing six years old & is my favorite of Three H.F. amps. I appreciate the very quick-acting LCD wattmeter which Rudi tells me is Peak Reading on voice peaks. Compared to my Mirage MP-1 & Bird Peak-Reading Watt Meters, it is spot-on.

Did I say I still like it’s Good Looks?

Tuning is quite predictable with the veneer tuning… almost set and forget.

I do Not use the provided Outboard 220vac muffin exhaust fan which sounds like a jet airliner taking off. An engineer told me you need a “3X” air volume increase to achieve cooling advantage. I use a remotely located 4-inch 750cfm FanTech fan which is perfectly matched to the required ‘quiet’ cooling for the monster GU-84b tube which is the Russky copy of an Eimac 4CX2500U.

The factory QSK option is still doing it’s thang.

Like other world-class amps, it sounds the same in Standby or Full Power modes… only the terrific signal reports give it away. Like other high dollar amps, it looks like the real deal Inside as well.

I hear the new DX2sp has a beeger cabinet and a beeger exhaust but I like my ole ‘compact’ unit.

Design, Reliability, Readability, inexpensive single tube replacement cost, did I say good looks? Continue to earn my DX2sp the WV4R ‘FIVE STAR’ rating. 73 es God bless, murf/wv4r.
VK3PA Rating: 5/5 Nov 18, 2005 20:46 Send this review to a friend
DX-2sp Great amp  Time owned: more than 12 months
DX-2sp now over 12 months and still de best amp I have ever owned,(sb220,sb200,fl2100b,MLA2500,h/b 4-1000) use mainly 80/75m ssb/ up to 220 DXCC comfirmed/262 wked in 3 years.. speaks for its self tu Rudy
K9XK Rating: 5/5 Mar 25, 2005 11:14 Send this review to a friend
Check it Out  Time owned: 0 to 3 months
I was one of those people that didn't even know this company existed until a friend came across this amp. I bought mine used, and although it is not very old, I am pretty sure that this unit was well-tested by the previous owner. That's okay - the price was right.

I think the metering is great because you can see all parameters at once. Some amps that are less sophisticated make you switch between functions and that just means extra tune-up time.

That said, I am not crazy about LEDs, in spite of their cool-factor, because the resolution is not great. I am not knocking this amp, though, because LEDs are the only way to display all of this info at a reasonable price with high reliability.

The step-start circuit works great, and the amp is built with LOTS of overhead in the key areas:

1) it loafs along at full legal power with about 30w drive. It will easily do 2500W into a dummy load.

2) it has cooling power to spare, if you have one of the more recent ones with a muffin fan on top. All that cooling comes at a price, though - this is not a whisper-quiet amp, like the L-7 I used to have was. I replaced that with the IC-PW1 and that is sort of loud, I thought, until I got the Emtron. In any case, fans make noise, and you need fans, so just wear headphones and forget about it. (And keep your mike gain down while you're at it.)

3) there is a lot of circuitry to babysit you and make sure that no matter what you do, you won't blow up the amp. I would be hard-pressed to think of a way to destroy this thing other than to have it slightly mis-tuned and run it that way every day for 20 years. And even then you will probably just have to spring for a new tube, which is quite inexpensive. I have seen new ones for 150 bucks.

Geography is an issue for purchasers of an Emtron unit, and hopefully they can get some U.S. distribution. That said, I have had a question or two and Rudi was quick with an answer.
IK3ERN Rating: 0/5 Feb 1, 2005 06:28 Send this review to a friend
Warranty and assistance  Time owned: more than 12 months
Two years ago on counsel of a amateur radio friend has acquired an Emtron amplifier
DX-2sp by internet from Emona Electronic.
Once open the package has noticed the handle grip " Load " are broken . In any manner
it I have systematized.
I have written and phoned to Rudy but the handle grip in substitution has not ever
A five months ago the grid of the tube GU 54b has gone in loss.
Sincerely I have always worked at 70 % of the potentiality of the tube and not for many
weekly hours.
I have asked to Rudy where it was the center assistance in europa or Italy, no precise
answer an only email with a reference in Slovenia country, has asked him explanations
by email like substitute the tube....... no answer !!!!!!!!.
I in these last six months have done a many ..ten of fax and of email .
For answare have receiver two email , with nothing specific explanations .
I have known Italians amateur radio that have had the same treatment .
He is not proper and correct this behavior.

73 de IK3ERN Mauro Zanco
W4VOL Rating: 5/5 Nov 4, 2004 19:22 Send this review to a friend
Superb Amplifier  Time owned: 0 to 3 months
The Emtron DX2sp is a superb amplifier. Absolutely no distortion at full output. Key down 1500W out continuous. Excellent craftsmanship in every respect. When I call CQ I always get an answer, even though antenna is a random wire only up about 20 feet in the trees. (N4XM XMatch Antenna Tuner) Excellent customer service from Rudi et al. Shipped on time when promised. Arrived in perfect condition. I have a Bose Wave Radio sitting on top of the amp and there is no interference to the Bose Wave Radio on any frequency even at full output from the Emtron. No intereference to 500-watt per channel stereo upstairs either. One setting of Tune and Load is all that is needed for any band. No RFI or TVI whatsoever with this amp, as contrasted to another amp I had with the number 1500 in it! This amp runs cool and quiet and is solid as a rock. I highly recommend Rudi and Emtron. I definitely would do business with them again.
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