July 24, 2019





Coming from a previous solid amps owned like the SPE Expert 1.3K and the PalStar 1KA, I can tell the builtin of these amps are more professional.
I actually own the Mercury II that work from 160 to 6M making 1100W easily with just 20W IN. There is no way to destroy these kits, besides to be used a very rugedized single LDMOS, its own protection against antenna high SWR over 2 to 1, against excessive input power and against wrong band selector position.
I checked personally with a professional spectrum analyzer the IM distortion been as low as any other imported amp or built within the US, my test showed always not less than 35db in most cases 37db and the reports received from other stations using professional panadapters were that my transmissions at full power was very clean and narrow banded.
To put together these kits is very simple. It will come preassembled and you only need to complete the installation of cables and plugs between boards
The model II that I am using is discontinued now and the actual model III in production will be more elaborated using RF sensing to save a band switch and fast band switching with just pressing the radio PTT.
One very attractive thing this new kit has is its price been very affordable for hams wishing to have a very good HF amp.



 Я не большой дока в писании. Видео снять не могу, фото сделал с
горем пополам, его и посылаю.
   Впечатление о работе усилителя положительное. Отрегулировал ALC на
1000 вт выхода, теперь более не выдает. При испытании без ALC усилитель
выдал 1200 вт. Работаю всеми видами модуляции. При интенсивной работе
температура не превысила 55 градусов. С таким транзисторным усилителем
ранее никогда не работал. Пока очень радует. Набираюсь опыта. Все
друзья одобрили приобретение (UA1CT, R1MA, UA1AHZ, UA1B, R1AJ,
R1AC…). Если будут какие рекомендации, с удовольствием приму.
   73! Игорь, UA1ABO



Добрый вечер Александр!
Пытался снять видео, но что-то не очень.
Сделал несколько фото, выбрал кажется наиболее отражающие суть.
Напишите от моего имени KM3KM, что я брал его усилитель конкретно под Flex-6400.
Мой выбор пал на него естественно после ваших публикаций и поначалу я считал,
что это ваша конструкция и производство. Сейчас я понял что, автор идеи KM3KM,
но ваша рука тут видна тоже.
Учитывая, что кроме CW и DIGI я особо нигде не блещу, мой К3 вместе с KPA500
только для CW, а Flex-6400 только для DIGI. 100W маловато будет и благодаря вам
теперь образовался отличный тандем Flex-6400 + Mercury III. Использую этот тандем
на полную катушку, т.е. от 500W и выше. Мало того, стал даже работать и SSB и
на 80, 40 и 20 с полной отдачей мощности. Честно говоря, фантастика. Температура
не поднималась выше 50. Отсутствие тюнера никак не сказывается на работоспособности
усилителя. Диапазоны определяет от поданного 1 вата. Одним словом раздаю
направо налево фото усилителя и отправляю всех интересующихся к вам, наверно

Напишите автору мои благодарности за хорошую конструкцию.

73! С уважением Геннадий RA3AL.




I am a very happy owner of an kit amplifier made by Kenny, Km3Km, it is an unbelievable piece of equipment that every Ham radio must have in his or her shack. It is completely automatic,and recognizes the band you are using, and gives a big punch to the transmission. It is all transistorized, no vacuum tubes, it gives an steady signal with no variation.
Just to say that the day that it was delivery and installed in my shack, by coincidence there was an station in 40 meters, in 7,150 MHz in Moscow m, Rusia that gave me a report of 20 decibels. The ham radio in Rusia was surprised in how nice my transmission was from Miami Florida, he mention to me that my signal was the best he was receiving at that moment, and there were many stations trying to contacts him.
I, myself was very happily surprised.
With no hesitation I sincerely recommend this amplifier to my fellow Ham Radios.


After 9 months of use, I am very happy and satisfied with my Mercury I amp.

Kenny Martinez [km3km], make my dream of having a solid-state amp come thru. After seeing the home-made Vhf and Uhf repeaters that he made; his knowledge in Electronics Engineer and attention to details and working long and hard to achieve perfection; I don’t I had any doubts that Kenny will do an excellent job constructing a solid-state amp, and when the firsts one was available, I don’t hesitate to be one of the firths to buy the amp.

The construction, functionality and performance are comparable or equal to any of the Europeans amps in the market, costing the double or more to this one. I sold my Heathkit SB-220, and never look back.

The kit was very easy to put together, all the hard work was already done, no smd or
others components to solder or calibrated.

The almost instant power on and ready to transmit, with no tuning required and all the protections available, plus low stan-by consumption, no warn on period, the fast change of bands, are some of the characteristics of this amp that made me no to think twice to buy one.

The low noise of the fans is a super plus for me and the adaptability of the power supply included with the unit, to work really well using 220v and with a simple change of plug is working without any trouble using 120v, for those that don’t have 220v easily available.

The characteristics and ruggedness of the LDMOS Ampleon BLF188XR transistor, all the quality parts, construction and attention to details, assure me of my good purchase and investment at the time to pay to this one, allow me for the price to enjoy this amp for many, many years without any problem or concern.

Ramon V Jimenez
Miami, FL USA.


Assembling my new toy, Arduino and power supply on the way, I’m eager to try this version


I am very satisfied and pleased with the quality and modernization of my new “Mercury I” fabricated by KM3KM.

I upgraded from Heathkit SB200 to this amplifier with zero hesitation. The “Mercury I” amplifier offers great protection for the Antenna. The Amplifier doesn’t heat up, it offers indicators on the screen which display the potency, temperature





Fantastic amplifier, I was waiting for this equipment for many years. I really like the amplifiers, it is part of our radio shack, I always wanted to have a solid state, but I never imagined having the opportunity to have this sophisticated, small, lightweight device at such a good price.


It is very easy to assemble, you just need to follow the instructions, everything is very well explained and pre-adjusted. It was my first experience with arduino, I loaded the small program and in the blink of an eye I had it already working.
The instrument for measuring power and SWR is extremely accurate. The design of printed circuits is very professional, with high quality components. Convenient connectors for easy assembly, a few interconnection tapes and everything is finished, there is no minute where you are in doubt if you are doing well.
   The screen shows the necessary information, is a touch screen and has a very attractive design, goes very well with all modern equipment today.
on the rear panel of the amplifier you have 3 antenna connectors, very convenient …. one less problem of having a horrible mechanical switch (mostly with false contact) with several cables.
 At the top of the display there is a port for SD Card to update the firmware
I am surprised at the powerful source of power it has, I have a hard time believing that it delivers that savage current at 50V, with such a compact size and as if that were not enough it is auto volt, it works in 125v as well as the 240v, impressive !!

Now I have a powerful amplifier for many many years, I will not have to worry more about the painful adjustment of the plate and the load and useful life of the vacuum tubes. I will no longer have a lost DX, with all its protections I am not afraid to make a mistake. Finally, there are no reasons not to have one of these, the most beautiful and cheap amplifier on the market, I recommend them.



The mercury lll has a good performance  and is very easy to operate in all bands. I like it’s design and I am very happy with my new amplifier. 


MERCURY lll es un excelente lineal , puedo asegurar que se trata de un amplificador automático, sintoniza de acuerdo a la banda que se use en el HF, fácil de conectar no requiere calentar para usar,  recomiendo a cualquier persona interesada que lo adquiera sin ningún riesgo.


MERCURY lll is an excellent linear . I can assure you that it is an automatic amplifier, it tunes according to the band used in the HF, easy to connect does not require heating to use, I recommend to anyone interested to acquire it without any risk.

Francisco A. Rodriguez