Tuesday, August 30, 2011

ARRL Homebrew 3 Challenge update: all modules mounted inside chassis

Have mounted all of the RF modules into the chassis.  From the top; photo of the driver, PA, and low pass filter; photo of the front panel with digital display mounted; photo of the bottom with the front-end, IF, product detector, audio/AGC board.

Next step:  wire it together then trouble-shoot system level problems.

Sunday, August 28, 2011

ARRL Homebrew 3 Challenge update: front panel of the chassis is complete!

The front panel of my ARRL Homebrew III challenge radio is complete. This radio is designed for both 10m and 6m operation SSB and CW modes.

It features 100 watts transmit power (or more), a digital display, and provides 1 Hz tuning resolution (digital display to be mounted in black box on upper right of front panel).

Looking forward to putting this rig on the air soon!

Tuesday, August 23, 2011

IEEE AP-S Boston Chapter: August 26, 6pm Marta Martinez-Vazquez from IMST Gm...

Everyone is welcome to the

IEEE AP-S Boston Chapter: August 26, 6pm Marta Martinez-Vazquez from IMST Gm...: We are pleased to announce that Marta Martinez-Vazquez is flying out from Germany to speak to a joint meeting of AP-S, WIE, AES, and GRSS so...

Be sure to register (registration is free) by following the directions. Hope to see you there!

Sunday, August 21, 2011

ARRL Homebrew 3 Challenge update: chassis machining completed

I've completed the front panel machining on the chassis for my homebrew 3 challenge radio. Shown above is the completed chassis, below is the chassis before machining.

I am recycling an old Nemes Clarke receiver chassis for this project because it is a good size allowing room to work. It is also 'green' to re-use old chassis like this rather than throwing them away. Chassis like this one, of approximately the same size, are readily available at almost any hamfest.

Friday, August 19, 2011

MIT Opencourseware Site is now up: Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar Imaging

A radar signal image superimposed on an overhead photo of a large steel scultpure, plus a photo of a student-built radar system.

Now you too can teach yourself how to

Build a Small Radar System Capable of Sensing Range, Doppler, and Synthetic Aperture Radar Imaging

Goto the MIT Opencourseware site for this class to view all lecture slides, read the how-to instructions on the coffee can radar kit, and see results from the doppler, ranging, and SAR imaging experiments.

Stay tuned to OCW because periodic updates to this site will include samples of data acquired from a coffee can radar and additional resources.

Tuesday, August 16, 2011

Very happy to report that i am now a Senior Member of the IEEE

I found out today that i've been elevated to Senior Member of the IEEE. I am very excited about this news and thankful for those who wrote recommendation letters on my behalf.

Looking forward to serving on the IEEE Boston Section Executive Committee in 2012 as a Member at Large and working on lining up more awesome speakers at the Boston Chapter of the Antennas and Propagation Society.

The IEEE is an excellent organization and i encourage anyone who is passionate about engineering to join. Hang out with like-minded individuals, work together to setup talks, conferences, write, communicate, and have a great time while doing it.

Monday, August 15, 2011

Why Your Dad’s 30-Year-Old Stereo System Sounds Better than Your new One

"If you fashion yourself as an audiophile and just threw down a decent wad of cash on a new A/V receiver, you probably won't like hearing that the receivers of yesteryearproduce comparable sound. Why is that? Technological advancement, ironically."

Saturday, August 13, 2011

from the ARRL: A Simple Regen Radio for Beginners

I found this simple single-transistor regenerative receiver design while reading through the QRZ.com forums.

1 transistor and 1 LM386 audio amplifier lets you listen to short wave and amateur stations.

This is a great little radio for those who want to start learning about receivers! I am posting it here because i was in fact thinking about designing such a radio, fortunately it already exists.

Thursday, August 11, 2011

ARRL Homebrew Challenge 3 radio update: front panel layout on re-used chassis

One of the most important parts of building anything in your basement laboratory is a good front-panel layout.

Re-using old parts and equipment is tricky. As can be seen above, there are many 'extra' holes in this chassis that i must either use or cover up. At the same time, i want the layout of knobs, toggles, buttons, displays, etc to look nice and be ergonomic for the end user.

To do this i un-bolted the front rack mount panel and placed the necessary controls and connectors on the front panel in various configurations until i found one that i really liked (shown above).

Now i am looking forward to machining out the front panel, it should have that 1950's cold war vintage look that i try to give all of my projects.

Tuesday, August 9, 2011

ARRL Homebrew Challenge 3 radio update: re-use of an old radio chassis

I picked up this old Nemes Clarke receiver at a local hamfest. It is a VHF FM tube receiver.

I then salvaged the chassis of this receiver, removing all internal components and saving those for a later date for re-use in other projects.

Some of these salvaged components included a nice power supply transformer for tube gear, two chokes, and a pair of 10 uF oil capacitors. A number of tubes were pulled out including a few 12AU7's, a full-wave rectifier, and a voltage regulator. Sounds like the beginnings of another vacuum tube audio power amplifier to me....

I plan to use this rack-mount chassis for my homebrew challenge 3 radio. Chassis like these are readily available at local hamfests at very low cost, therefore i believe that it is a valid part to use. Furthermore i believe that we homebrew radio enthusiasts should recycle this legacy equipment instead of throwing it in the trash, sending it over seas to be recycled, or letting it sit on the shelf for decades without use.

Saturday, August 6, 2011

update on the MIT Prof Ed 1-week radar course: SAR image of Kresge auditorium

Student results from the final day of the MIT Professional Education 1-week radar course, where everyone learns about radar, then makes one, then uses it in a series of field tests.

Shown here is a SAR image using the student-built radar kit of the outside of Kresge auditorium. The railing around the underground garage entrance shows up really well, as does the edge of Kresge itself.

An excellent image for a radar built out of coffee cans.

Thursday, August 4, 2011

update on the MIT Prof Ed 1-week radar course: RTI plot of Longfellow Bridge

Student results from day 3/5 of the MIT Professional Ed. 1-week radar course.

Range time intensity plot of vehicles crossing the Longfellow bridge from Cambridge to Boston. This plot shows both the remarkable range of the coffee cantenna radar kit and this student's ability to make a small radar and use it to acquire real measurements.

Wednesday, August 3, 2011

update on the MIT Prof Ed 1-week radar course: DTI plot of an exercise bike

Student results from Day 2/5 of the MIT Professional Ed. radar course:

A first in the history of Radar engineering and measurement: a doppler time intensity (DIT) plot of an exercise bike!

Monday, August 1, 2011

MIT prof ed 1-week radar short course update: 35 cantenna radar kits

Here they are, 35 cantenna radar kits prior to distribution as part of the 1-week MIT professional education radar course. Shown on the top figure are the 70 cantennas. Second photo shows the bags of parts for each kit.

Each kit contains 6 uwave modules, solderless breadboards, a piece of plywood, 50 ft tape measurer, a handfull of analog parts, and 8 AA batteries, plus other stuff.

Welcome to our 1-week radar short course, where we learn about radar systems by actually making one and using it in the field

I want to welcome our students to this week's radar short course at MIT!

This week we will learn about radar systems by everyone actually making their own and using it in the field.

This will be a fun and challenging week for us all. Thank you for signing up to our course and we hope that you have a wonderful time this week.

This course is completely full with 30 students attending and one or more on a waiting list.

I will post updates to the blog as things progress.


Date: August 1-5, 2011 | Tuition: $3,400 | Continuing Education Units (CEUs): 3.0
Application Deadline »


Are you interested in learning about radar by building and testing your own imaging radar system?

MIT Professional Education is offering a course in the design, fabrication, and test of a laptop-based radar sensor capable of measuring Doppler and range and forming synthetic aperture radar (SAR) imagery. Lectures will be presented on the topics of applied electromagnetics, antennas, RF design, analog circuits, and digital signal processing while at the same time you build your own radar system and perform field experiments. Each student will receive a radar kit, designed by MIT Lincoln Laboratory staff, and a course pack.

This course will appeal to those who want to learn radar systems engineering or SAR imaging, use radar technology in a product or experiment, or make components or sub-systems.

You do not have to be a radar engineer but it helps if you have at least a bachelor’s degree in electrical engineering or physics and are interested in any of the following: electronics, electromagnetics, signal processing, physics, or amateur radio. It is recommended that you have some familiarity with MATLAB. Each student is required to bring a laptop (with a stereo audio input) with MATLAB because this will be used for data acquisition and signal processing.

During the course you will bring your radar kit into the field and perform experiments such as measuring the speed of passing cars or plotting the range of moving targets. A SAR imaging competition will test your ability to form a SAR image of a target scene of your choice from around campus.