Category Archive: Uncategorized


The very popular SONOMO-500 Series.   These amps are specifically designed for neuromodulation.   Small, efficient and effective.

We offer a 10W and 20W version.Sonomo-500-20

WPTC in London

E&I had an excellent time at the WPTC in London!  Very exciting progress being made in wireless power transfer.   Notice the nice blue amp in the pic?

Posted by: Jeff Keller, July 2, 2019

E&I Exhibited at the IEEE IUS Conference

E&I exhibited at the IEEE IUS conference again this year.  The conference was held in Kobe, Japan and there were approximately 1,400 attendees many of whom stopped by our booth to see our new S-Series product and to discuss their applications.  It is always great to meet with potential new customers and visit with our current customers. We are looking forward to exhibiting at the conference next year which will be held in Glasgow, Scotland.  

As always, E&I can help with all your RF power needs, especially with regards to ultrasound!

The Mad Scientist


We often hear tales of the experiments that are conducted by scientists. Behind closed doors, in their laboratories in the depth of night. Bunsen burners heating flasks of overflowing foam as test tubes containing varying concoctions are added. A Van De Graff generator in the background is driving the voltage of a couple of parallel plates to breakdown and sparks fly across them sizzling and piercing the silence. The crazy scientist wearing a well-worn and chemical-stained lab coat looks on with wild scary glazed eyes. Rapidly recording notes into an overstuffed lab book, their hair all standing on end, with a smile reminiscent of Mona Lisa.

However, if you meet Jessica Foley, the Chief Scientific Officer at the Focused Ultrasound Foundation, you will find, on first impression at least, that she does not live up to the caricature at all. She is very engaging and she and her colleagues were very generous with their time as we discussed E&I and where our amplifiers fit into the FUS environment.

Then just as we were about to leave, she said “I must tell you of an experiment that I did with one of your amplifiers, whilst I was at the University of Washington.” (Oh yeah; here we go I thought.) “Late one afternoon” she said “myself and some other researchers locked the door of the lab and using one of your high power amplifiers decided to try some acoustic cooking. We immersed salmon, vegetables and steak into water and then applied several hundred watts of RF power to the transducers and cooked all the food with ultrasonic energy.” She went on to tell us that it all tasted wonderful, though she herself avoided the steak that was well done in the middle and rare on the outside!

So it is true that you never know what crazy scientists will cook up!



Written by Tony Harris, October 5, 2017

Car Sound Systems

Written by Tony Harris, September 22, 2017


Don’t you think the quality of car sound systems today is quite phenomenal? They are very compact units and capable of high volume and low distortion. How do they do it? You’d think you’d have to lug a trailer on the back full of amplifiers to get that type of sound quality.

The fundamental components that are doing the work in today’s amplifiers are transistors. The transistor gets its name from the combination of ‘resistor’ and ‘trans’. Basically it is just a resistor that we can vary. We can vary it from a short circuit to an open circuit. If you recall from some science or physics class years ago, you will know that the loss in a resistor is I2R: where I is the current in Amps and R is the resistance in Ohms. So if the resistance is 0 then the loss is the current squared times zero, so it’s zero loss. Now if the resistance is open (infinite) then no current can flow so again the loss is zero. So if we use a transistor in only two states; open or short, there is no loss and therefore, very efficient.

Car sound systems use a type of sampling technique, whereby they sample the input signal and effectively digitize it. Then they amplify it, but because they are now amplifying a digital signal it is either full on or full off – very efficient. After it is amplified they use a filter to reconstruct the analogue signal. The end result is it sounds great, but is very efficient so doesn’t dissipate a lot of heat and can be very small.

So why don’t we use this technique for high frequency amplifiers for ultrasonic and communication applications? The difficulty with this technique is that you have to switch the amplifier much faster than the frequency of the signal that you are amplifying. For audio signals this is not a problem but as we move into the high KHz and MHz region this pushes the state of the art of the capability of the transistors.

However, here at E&I using fast devices and interleaving techniques, we are pushing the frequencies higher and higher. We have our 1000S04 which is capable of 1000 watts of instantaneous power from 10 KHz up to 400 KHz. We also have 500S06 which is capable of 500 Watts 20 KHz to 600 KHz.

Before the end of June we will be at 1 MHz and then go beyond.

E&I is the leader in this technology, which will become the standard for ultrasound systems.


The Secret of the S-Series

Written by Tony Harris,  2nd September 2017


Someone was asking me the other day; how we are able to get such high switching rates on the large Fets that we use in our S-Series to enable us to achieve 1000 watts over a 600 KHz bandwidth. It is a good question, if you look at the performance of linearity, bandwidth and flatness you think that we were switching at over 3 MHz.  Actually, in the 1000S04 we only switch at 1.6 MHz. But, then we use the technique, common in switch mode power supply design, to interleave the two halves of the H bridge. This enables us to mimic the performance that one would expect by from switching at 3.2 MHz.



So that’s the secret. We are looking to interleave in quadrature and so further push the frequency while maintain the excellent linearity and harmonic performance.


Old Documents

Written by Tony Harris, February 8, 2017



The value of note taking and retention of documents is severely reduced if one is unable to locate the information at a later date.  We are lazy these days, I fear. With the advent of “search” applications we just type a few words into our PC and hit enter. Seemingly, miraculously, relevant documents are unearthed.  And so our filing systems have become all but redundant. I have pieces of paper that collect upon my desk and when they have reached an amount that I find annoying, I file them. I do this by sorting them into two groups. The first I unceremoniously dump into the shredder, and the second I simply stuff into a manila folder – mark it “Important and Confidential” and shove it into a filing cabinet in my office. This works very well for the retention of documents. But it leaves a lot to be desired with respect to the retrieval aspect and so calls into question the value of the whole activity in the first place. Of course, as I file said documents, I am convinced that I shall remember where they are. But then in actuality, when I try to find something, the fact that I know of their existence only increases my frustration. I get incensed as I randomly and fruitlessly pull out filing drawers, folders and documents and then vacillate between the scanning and perusal of page after page.

But I did take refuge in the belief that this was a universal problem with varying solutions all based on the effort and time that one puts into maintaining a system. Jan, my wife, for example files all the required documents for taxes, insurance, appliance operating manuals and is able to locate them as required. Although I do not have the necessary skill set to perform this task, it is a fairly simple set theory problem, with well defined labels.

The other day, I was asked a question by a customer in Australia as to the IMD performance of E&I amplifiers with 12 tones at 2 watts per channel. I was fairly sure that I did not have any information on how to glean this data from our test records and after a quick Google search left me empty-handed I decided to ask Serge Juhel, an old colleague of mine for help. I say old colleague as I have known him for a long time and he is old. Serge came to the rescue with the calculation of PEP and the recommended CW power required. In addition to attaching a document delineating the test procedure, he also copied an old colleague of ours, John Pritiskutch (yes; we’ve known him for a long time and he’s old) and asked him to verify the calculations and check the formulae. John kindly did this but noted his surprise that we were having this discussion as Serge had previously authored a document which I was copied on, that explains the calculations in detail. John had thoughtfully attached a copy of this document to his e-mail.

The document that John attached was a scan of a print out of an e-mail that Serge had sent me in 1992.

This is 2017! What sort of archival system does John have?  The question was about multi-tone IMD performance v two-tone measurement. What can you file that under and be able to retrieve it??? Remember, this is a paper system. The document he sent me was scan of a print out. The print out was from a “dot matrix’ printer!

So in conclusion; I’d say, if you are looking for the answer to an RF question ask Serge Juhel; he probably can answer it without looking for notes. Or ask John Pritiskutch, he also can probably answer without looking for notes, but if he needs to – he has them!



E&I OEM Solutions

Written by Tony Harris, November 17, 2016


Anyone involved in RF design or testing in the field of ultrasound, telemetry activation, HF, VHF or UHF applications knows E&I®. Over the last 13 years, picking up where ENI® left off, we have been supplying the industry with rugged and reliable broadband power amplifiers.

They will not be the lightest piece of test equipment on your bench, nor indeed the quietest. They will probably be your bluest and also the most rugged and reliable piece of gear. They are indeed known throughout the industry as the stalwart solution for your RF testing needs.

About six years ago, at the behest of several customers, we began supplying RF modules. This enabled our customers to utilize our superior technology and proven designs as an integral part of their systems. Working with these customers we have found that to in order to provide the optimum RF solution, it preferable to begin working with them, as an extension of their design team, early on in the OEM project.

We have therefore launched a new division; called the E&I OEM Solutions Division. The charter of this new group is to work with clients to define their RF needs and assist in architecting the clients system, to bring the RF issues to the forefront and so avoid wasted time and effort in unnecessary design cycles. Then, utilizing the technology and expertise of E&I’s engineering group provide an optimum OEM solution.

To learn more about E&I’s OEM Solutions Division and how you can utilize the group as an extension of your design team, give me a call or drop me an e-mail.


Tony Harris (November 17, 2016)