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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | Emtron DX-1b Help

Reviews Summary for Emtron DX-1b
Emtron DX-1b Reviews: 6 Average rating: 5.0/5 MSRP: $(missing—add MSRP)
Description: 800 Watt Linear Amplifier
Product is in production.
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VK5KLT Rating: 5/5 Sep 13, 2010 22:23 Send this review to a friend
Sweet little gem of an amplifier  Time owned: more than 12 months

I have owned my DX-1 amplifier (purchased second-hand) for over 1 year now and during that time it has performed flawlessly. Its previous owner had kept the amp in mint condition. The DX-1 works impeccably well, is stable and predictable in its behaviour, and teams well with my various exciter rigs and has become entrenched as my station work-horse that's now used more often than my bigger DX-2SP linear amplifier.

Does precisely what a high-end amplifier should do; transparently and cleanly increase the transceiver's power level without adding any extraneous and deleterious signal products. Never fails to receive excellent signal quality reports completely free of any tell-tail intermod spectral artefacts.

The well conceived and proportioned DX-1 model has a compact desktop footprint with nice back-illuminated analog panel meters. The amp effortlessly delivers its output power with finesse and happily runs all day long barely getting warm.

Consistent with on-air signal quality reports, the amplifier measures spectrally very clean on lab-bench tests with typical IM3 circa -40 dB down from PEP on two-tone testing, the higher order IMD products are very low; an increasingly important factor and consideration for use with some of the latest generation high-end transceivers and SDR rigs with their clean pure Class-A bias exciter stages with excellent IMD performance.

In common with its DX-2SP bigger brother, the professionally executed DX-1 has exceptional build quality and superb craftsmanship. It's in a unique class all of its own and its internal construction is a wonderful sight to behold, with the heavy high-current ceramic band switch, the heavily silver plated tank components, and weighty dual loop C-core power transformer with Emtron’s unique phase controlled triac based soft-start circuit to control inrush current and bring the HV power supply and tube filaments up slowly and gently.

The bullet-proof external metal anode fin / ceramic Russian military GU-74B / 4CX800A tetrode tube is conservatively cooled by a quiet temperature controlled centrifugal squirrel cage turbine blower.

The amp's 1 kW PEP output power is more than ample for use here in VK land with plenty in quietly understated reserve power. At the more moderate 400 to 500 Watt power level the amp just loafs along very conservatively and cleanly with lots of spare dynamic range and headroom. It has impressively low IMD / IM3 IM5 + high-order products when driven at this level. To moderate back the drive I run a Weinschel / Narda 6 dB 50W power attenuator pad between the exciter rig and amp; which also helps keep my Yaesu FT-2000 exciter in its optimally clean IMD "sweet-spot" region. This external attenuator pad also removes any risk of accidental overdrive of the high gain GU-74B tetrode by the exciter. Due to poor commercial transceiver PA and ALC design in some rigs I don’t use any linearity / spectral purity compromising ALC on my linear amplifiers.

As this great amplifier just keeps on keeping on, I expect the DX-1 and the tough GU-74B tube will likely outlive its owner! The Russian miltary surplus NOS tubes are low cost and easily found. I have acquired a few spares for a rainy day but suspect I'll never need them. I believe the rugged GU-74B tetrode is one of the best HF SSB linear amp tubes ever made, and the Emtron DX-1 amplifier competently and reliably extracts outstanding performance from it.



AE7AE Rating: 5/5 Aug 21, 2006 06:36 Send this review to a friend
Great value for money  Time owned: more than 12 months
After 1-year of owning a second-hand DX1 (not the'b') I can report that it is truely a fool-proof, rugged, reasonably quiet 800w linear. It was used by the VI9NI DXpedition for 30-days non-stop operation, and helped me work 300+ countries from the home QTH. No TVI has been reported either! I like the feature of having air intake on the side of the covers instead of the top. That way I can stack my MFJ Antenna tuner on top. Even at 800w output on RTTY, the case never gets more than a little 'warm'. The designer deserves a lot of credit for his thoughtfulness and foolproof features. I have a spare 4CX800 tube, but don't think I will ever need it! I will keep using this amplifier until I'm "SK". On the slightly 'negative' side, the fan is noisey, but, I guess you can't get high volume airflow without some noise! I can not comment on customer service from Rudy and his team, as I have never had a reason to contact them.
VK2GWK Rating: 5/5 Feb 18, 2004 07:44 Send this review to a friend
Very Good!  Time owned: 0 to 3 months
Very robust and easy to tune. Everybody is impressed with the good audio.... so no clipping or overdrive or distortion. I break through pile ups I never dreamed of breaking..... Highly recommended.
WV4R Rating: 5/5 Dec 6, 2003 21:57 Send this review to a friend
Fantastic, Awesome, Incredible, Amazing... did I say Good?  Time owned: 0 to 3 months
The ham radio adventure continues with the new Mini-Wombat at WV4R… Big Brown pulled up yesterday afternoon with a big brown box containing my first ham radio Christmas present of the season.

Excitedly, I opened the heavy box, peeled away the bubble wrap and plastic bagging to reveal the shiny new EMTRON DX1b. Removing the 4 machine screws, I lifted up the heavy epoxy-painted dark gray cover. I carefully pulled out the heavy foam protecting the single Russian GU-74B, ceramic/metal tetrode and gazed upon a true work of wiring artistry. All the beefy looking components were exposed to my curious eye. A brief scan of all the wiring revealed NO Glaring problems.

After anxiously reading the well-written manual, wiring the provided Modular power cord, and getting all the cables heading the right way, I was building to the dreaded ‘smoke test’. I sat back, sipped more coffee and smiled as I looked at the classically attractive styling of the dark gray epoxy painted front panel with white stenciling. Selecting 20m with the heavy duty bandswitch, holding my breath, I hit the crisp-feeling Power ON switch for the first time... 1-2-3-4-5 seconds as the soft-start initialized, the tube timer started, and the constant speed turbine cranked up. About 3-minutes later the ‘Ready’ lite came on. Tuning was a breeze, albeit different than typical triode tune-up. 35 watts IN yielded a Texas kilowatt OUT with no objectionable heat increase in the exhaust air… a real cool cucumber fer sure.

Cautiously I called ‘CQ’ and started collecting ‘audio quality’ reports with special emphasis on the performance of the proprietary two-stage ‘zero-bias’ operation. Whew… a clean bill of health from every station. Soon a pileup started building with hams from all over wondering what this Australian Mini Wombat was all about and complimenting it's Quietness.

Although this is only Day Two, I find myself drawn to add this 24-hour Product Review for all to ponder. Four year transferable warranty, quality materials, quality engineering, Very reasonably priced Russian copy of a 4CX800 tube, 9-position beefy band switch for 160-10m, combo of L.E.D.s and very nice studio VU style meters, 800 watt Continuous Output with no transformer Groan, QSK, Terrific response and personal service from BOTH Factory & U.S. Distributor in Virginia - NT4I/Vince Cammarata, did I mention Four Year Warranty? And more earn this unit the WV4R 5-star rating.

I promise to Update this Emtron DX-1b product review after six months or if it catches fire! 73 es God bless, murf/wv4r.
VK3DOU Rating: 5/5 Feb 5, 2003 20:24 Send this review to a friend
Impressive  Time owned: more than 12 months
I've been running this amp for over two years now and although I did have a problem with the bias circuit and the switch-on timer, these issues were resolved in a satisfactory manner. The amp has been designed so as the user has very little chance of overdriving it. The 400w VK power limit is easily attained and one feels the amp would run forever at this pace. The build quality is exceptional and the price is competitive.
WP3HW Rating: 5/5 May 17, 2002 12:41 Send this review to a friend
Excellent  Time owned: 3 to 6 months
Exquisite build quality, excellent performance, easy to tune, impossible to overdrive, very reasonable price for such a refined product. Extremely happy with this purchase. Cannot comment on after sales service since I haven't had a single problem with it.
Pepe, WP3HW

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