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KW7CD USA flag USA

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      I took my first receiver apart (and put it back together) at an early age of six. I've  been a Ham since 1957. Since then, I built many RF systems and made my passion for "radios"-- my life-long profession. I've been an engineer, a scientist, author, and inventor. As an amateur radio operator, I've been known for extensive RF technology articles in magazines such as Ham Radio, Communications Quarterly, RF Design, and QEX. Professionaly, I published two books and over 90 articles and papers on the art of RF design.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.111.6177&rep=rep1&type=pdf

http://www.mikrocontroller.net/attachment/223754/Star10_Part3.pdf

      I am mainly a designer and a builder of equipment rather than an operator. The old and the modern coexist in my station. Most of my equipment is home brewed or designed for manufacturers by me. This includes my home brewed fully synthesized Star-10 transceiver, the MLA-2500 linear amplifier, a directional wattmeter, a high power antenna tuner, a home brewed 2-NT frequency synthsizer, a direct sampling SDR -- spectrum analyzer which displays the entire 30 MHz  bandwidth for propagation (MUF) forcasting and monitoring band activity.

      After experimenting with all digital modes, I returned to the classic CW as the main mode of operation. One of my latest projects has been restoring and integrating an old Drake 2-NT CW transmitter with my home brewed Star-10 and the TS-590 transceivers. The Drake 2-NT transmitter has been one of the best Quartz - crystal controlled Novice designs of the 1960s. But, using a crystal for every frequency on the 80, 40, 20, 15, and 10 meters at today's custom crystal prices would be very expensive. To remedy this problem, I designed a new synthesizer specifically for the 2-NT in order to replace millions of individual crystals with a clean and stable frequency source.

      Another major project was was the design and devlopment of my fully synthesized transceiver, the Star-10 which took five years to complete. Beolw are some pictures of my HB equipment along wit the 2-NT project and synthesizer. 

      Over the years, I had several other calls, YO31143, YO3WK, WN8VUU, WB8BOE and WB3JZO.

73 de KW7CD

 

Project: Restoring the Drake 2-NT transmitter. Designing and developing a home brewed DDS synthesizer to replace the crystals.

 

 

 

Before sandblasting and refinishing the rusted chassis; a tedious preparation.

 

 

 

After restoration

After the sand blasting, the 2-NT chassis was recovered with a special Copper paint and looks like new.

 

 

The reconditioned 2-NT was adjusted and tested. Designing and Implementing a home brewed DDS synthesizer which uses a clever 100 dB isolation RF switch to provide a quiet received environment eventhough the synthesizer remains active and on frequency during receive. This isolation switch is activated by the full break-in capability of the 2-NT transmitter. Synthesizer was designed from scratch by me.

 

 

 

Above is the 2-NT syanthesizer in operation with the transmitter. A multitude of signals can be genrated on each band with the resolution of 1 Hz and a frequency stability of 1x10^-8. The 2-NT T/R switch provides full break in operation on any of the bands covered. The DDS synthesizer gives anew feeling to this old Novice transmitter of the 1960s.

 

 

 

My home brewed 2 elements 20 m beam

 

 

The STAR-10 Transceiver

The dream of any radio amateur was, and still is to build his own radio from scratch. One of my bigger projects which took over five years to complete was designing and building the Star-10 transceiver. See my QEX article:

"The Star-10 Transceiver," QEX, Nov/Dec 2007, Mar/Apr 2008, May/Jun 2008.

http://download.qrz.ru/pub/hamradio/schemes/transceivers/STAR-10.pdf

This was a major undertaking involving all aspects of hardware and software design and development to prove that Hams can build modern equipment competing and outperforming high performance professional equipment.

Shown in the pictures below is the home brewed Star-10 transceiver, a high dynamic range (150 dB Composite LSFDR) unit which is fully synthesized in one band from 1.8 to 30 MHz with a resolution of 10 Hz and a frequency stability of 1x10^-8. Its DDS-driven PLL synthesizer operates at microwave frequencies and is divided down for superb phase noise performance of -140 dBc/Hz at 500 Hz offset. For more information on the design of theStar-10 transceiver please see my QEX article series and my new book (2) listed below.

http://www.amazon.com/Cornell-Drentea/e/B001KIFUWO

The MLA-2500 linear amplifier in my station is the first production prototype (SN 00002) which I designed for Dentron Radio on a consulting assignment in 1975:

http://www.youtube.com/watch?v=QJT1jMuqbTE

The MLA-2500 is the World's smallest (even by today standards) 1.5 KW linear amplifier which includes the power supply and is known for its portability and reliability (over 6000 sold worldwide).

 

About Me:.

Professionally, I have been an accomplished RF technologist, an engineer and a scientist with 50 years of hands-on experience in the aerospace, telecommunications and electronics industry. I have been involved in the design and development of complex RF, Aiborne and Space - Radar, guidance and communications systems at frequencies of up to 100 GHz. I have developed several state-of-the-art RF products including ultra wide band high probability of intercept (HPOI) microwave receivers, complex synthesizers, multi-modulation transmitters as well as Doppler corrected-frequency agile space transceivers.

I received my formal education abroad with continuing studies and experience achieved in the United States. I have presented extensively on RF design topics at technical forums such as IEEE, RF-Expo, Sensors-Expo. 

During my career, I have published over 90 technical papers and articles in professional national and international magazines and I hold five (5) patents. I am the author of two notable books: (1) Radio Communications Receivers, McGraw Hill, ISBN 0-8306-2393-0/ISBN 0-8306-1393-5, 1982 and (2), Modern Communications Receiver Design and Technology, Artech House 2010, ISBN 978-1-59693-309-5

http://www.amazon.com/Cornell-Drentea/e/B001KIFUWO

 

My fully synthesized homebrewed Star-10 Transceiver was a 5 year design and implementation project. Designed from the ground up, the unit is homebrewed.

 

Bottom view of the completed Star-10 transceiver

 

 

 

Top view of the transceiver

 

 

 

The 9 MHz IF assembly uses up to 32 poles of cascaded quartz crystal filters fwed by a ynamic range hproduct detector and digital signal processing (DSP).

 

 

 

The High Dynamic range bilateral Front end assembly features Class A amplifiers, a class 3 H-mode mixer, programmable attenuators and a diplexer. Power consumption for the front end exceeds 15 watts DC. Two brushless miniature fans extract the heat from the assembly

 

 

 

Automatically switched Half Octave filter banks for the transmitter as well as the receiver. Note high power filter banks plug in the PC board via RCA connectors to keep the logic circuits separated from the high power RF. Automatic switching is done from the microprocessor along with the synthesizer commands.

 

 

 

Automatically switched filters assembly cage before instalation in the transceiver

Redesigning the HV power supply for the MLA-2500.

 

 

 

My new book:

For more informationgo to:

http://www.artechhouse.com/

http://www.linkedin.com/pub/cornell-drentea/16/806/169

http://www.rfcafe.com/vendors/services/Cornell-Drentea-Resume-Consultant.htm

 

Testing of the Star-10 transceiver in the KG6NK lab

 

 

 

The newly designed and implemented home brewed PEP wattmeter at KW7CD. The unit measures average and PEP RF power using two independent large LED backlit meters. The power is switchable between 20/200/2000 watts

 

 

 

My 2 element HB 20 meter beam. The boom is 1/10 wavelength (7 feet) while the elements are 16 feet loaded with high Q inductors to keep size to a minimum. This is a very effective beam for its size and competes favorably with much bigger antennas. The height is 25 feet at an altitude of 2650 feet and a water table real ground some 900 feet below surface. All other antennas at KW7CD are full wavelength loops hidden in the roof of the house

 

 

 

My new direct sampling SDR spectrum analyzer system shows activity from near 0 Hz to 30 MHz. Spectrum or water fall are selectable along with filters and numerous other receiver functions. Additional windows focus on the band of interest. The SA is inserted directly in line with the transceiver's antenna and a custom automatic switch over system which provides 105 dB of isolation when transmitting. The SA unit is an Excalibur direct sampling receiver which has been donated by WinRadio

 

 

 

Several other assemblies in the Star-10 transceiver. There are 16 double sided plated through PC boards and assemblies in the transceiver. They have been designed and executed from scratch. The boards are enclosed in aluminum boxes which provide extra shielding and isolation. The synthesizer operates at microwave frequencies and LO output is divided by 10 for improved phase noise performance. A PLXO is used as a master reference. It is locked to a 10 MHz OCXO which in turn is discipined by WWV

 

 

 

Part of the SA system. This is the switch over mechanism which protects the SA in TX. Two RF relays are used in series for 105 dB of isolation. A splitter is used to divide the antenna path into two channels, one for the SA and the other for the TRX receiver

 

 

ARRL reviews Modern Communications Receiver Design and Technology book - Cornell Drentea, Artech House, 2010462 pages

ISBN-13 978-1-59693-309-5

QEX Magazine Review by Bob Allison

Radio amateurs may be familiar with the block diagrams of various superheterodyne receiver types; single conversion, dual or more conversion, or direct conversion. Each block represents a necessary stage with its specific function; mixing, amplifying, tuning and so on. Many of us had to memorize the block diagrams, placing each stage in the proper order, to attain a higher class of Amateur Radio license. Sometimes, we forget all of it, but would like to get reacquainted.

Many years ago, I decided RF was what I wanted to study at the University of Hartford. I quickly felt quite over my head after reading my first receiver design theory book! Yes, the designs were understandable, but the text was often lacking in explanation as to "how" and "why." For instance, how do you pick the best intermediate frequency or frequencies? What makes a good mixer? I got through the course all right and continued my RF courses, going on to what I liked best at the time: transmitters. A few years ago, I became Test Engineer at the ARRL Laboratory, which includes evaluating receiver performance. Now such questions as "what makes a good mixer" is a rather interesting topic to investigate. Fortunately, I recently obtained Cornell Drentea's book, Receiver Design and Technology. This comprehensive and well illustrated text book is a delight to read, unlike my oId college text books. Mind you, the theory is complex, but for anyone wishing to dig deeper into what makes a receiver work and work well, this book will answer all questions the reader is asking. It is quite suitable as a college text book but appropriate for the beginners and old-timers as well.

What made this book special from the very start was the preface. In it, the author tells an autobiographical short story about a nearly six year old boy who wanted to take apart his Dad's radio, "to see what the little people inside looked like." With both parents away from home and with pliers and a screwdriver in hand, little Cornell quickly had the radio totally dismantled. Unexpectedly, the parents returned early, before he was able to re-assemble the radio.

This touching story (with a happy ending) reminded me of the human side of technology; it is our nature as radio amateurs to find out how it all works. The preface also gave me the feeling that a real person, someone I can relate to, is speaking to me and I am about to leam something great.

The first chapter is a brief history lesson on some of the names of the inventors and developers of radio technology. Interestingly, it also poses the question and gives a surprissing answer to, "who invented radio?" I liked the fact that the author mentions, "One must not forget the many dedicated ham radio operators around the world." The following brief chapter describes the history of radio, complete with schematics, from Edouard Branly's Coherer, up to Armstrong's development of the Superheterodyne Receiver. I found the diagram of DeForrest's Audion Receiver interesting since the ARRL has one (with tube) in WlAW's foyer. While I enjoy historical topics, I also enjoy the latest technology topics. As I read through the subsequent chapters I had many eye popping experiences.

Though each chapter is very comprehensive, the mathematics used to describe the various concepts gets right to the point and is not overwhelming, as it can be in other text books. Mathematical proofs are for mathematicians, not for me. The lack of proofs leaves more space for more usable information, and this book has plenty of that.

After an introduction to the superheterodyne receiver, Chapter 4 digs into the implementation of a single conversion receiver and clearly describes the various parts in subchapters. The list of topics in succeeding chapters is too long to list here; topics that include discussions of varieties of superheterodyne receivers, mixers, frequency synthesizers, AGC, digital signal processing, software defined radios, and warfare receivers. Crystal filter design fans will be very pleased too. An added bonus is a chapter on the Arecibo Observatory. In that chapter, the author mentions that with today's technology, useful reception of intelligent signals from a planet 15,000 light years away is possible. That would be pretty good DX.

Readers of QEX may be familiar with Cornell Drentea's three part series on the design and development of his high performance, home brew, Star-10 Transceiver.! The Star-10 transceiver was designed and built as a project with the intent of finding out what could be done to achieve ultimate performance. The author uses this exceptional HF transceiver as an example of receiver design in a few of the chapters. Some of the topography and illustrations seen in QEX are reproduced in Receiver Design and Technology. An example of this is how and why the IF frequencies are chosen. By using an Intermodulation Distortion Web Analysis Tool, the design engineer may quickly find the proper combination of frequencies that will minimize the spurious response of a mixer. The material originally from QEX is very useful. We are lucky to have this gentleman build this complex device from a "laws of physics" point of view, and that he is sharing all of this knowledge with us.

With Cornell Drentea's marvelous style of writing, Receiver Design and Technology will educate, excite, and inspire many. This text book should be used on every college campus that offers such a course. There is a great demand for RF engineers today, and this book will undoubtedly inspire students to become engineers. While I can lament the fact that I didn't have a text book such as this one thirty years ago, I am happy to have this text book today.

Cornell Drentea is an accomplished RF technologist, an engineer and a scientist with fifty years of hands-on experience in the aerospace, telecommunications and electronics industry. He bas been involved in the design and development of complex RF. radar, guidance and communications systems at frequencies up to 100 GHz. He has developed several state-of-the-art products for companies such as Honeywell and Raytheon. This Includes, but is not limited to, ultra wide-band, high probability of intercept microwave receivers, complex synthesizers, and deep-space Doppler agile transceivers. He is known for his scientific and technical publications on the subject of applied RF technology. Cornell has published over 90 technical papers and articles in national and international magazines. He has been a consultant and is currently teaching comprehensive RF design courses to some of the largest international companies. He holds five patents. Cornell holds an Extra class amateur radio license

7657892 Last modified: 2016-10-26 19:34:28, 20711 bytes

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