(Now a bi-weekly program)

Next episode ... May 7

On Component Testing

(See the table below containing the whiteboards and podcast files of all previous episodes.)

Every other Tuesday evening at 8pm Eastern (0000z), N2APB and N2CX co-host a live audio conferencing session called “Chat With The Designers". Often joined by designers of other projects as well, we gather around this technical watering hole to discuss various topics that are of interest to us all.  Whether you seek information about your latest project on the bench or just wish to listen in on the various designers discussing some new chip or product/kit solution they are currently working on, this is the place to be.

For a little more than an hour, or as long as the discussion is lively, N2APB and N2CX run the session in "net control"-like fashion, guiding the discussion and passing the mic in an orderly way among those wishing to contribute.  Augmented by a very useful "text chat window" at the bottom of the screen, everyone is able to post text comments, links and other information when the urge strikes.  We record the audio from each session, as well as save the text chat window great reference later on.

We’re using “Teamspeak 3” (TS3), an Internet-based multi-client audio conferencing system. TS3 is available to run on just about every operating system ... Windows, Mac, Linux, and even the mobile platforms like Android and iOS 5 (Apple)!   It's free, presents no spam or “friend” sign-ups, and is easily downloadable and configurable.  See our Teamspeak Instructions page for downloading and installing TS3.
Once you install the client onto your computer, launch the client and connect to the TS3 server, click on the QRP Homebrewing channel, and you will see a list of all the people that are signed in, as well as your own name and callsign. A little button lights up when pressing the “PTT switch” (a key you set up on your keyboard for when you wish to talk) and you then hear that person speak. You reply by doing the same when you see that nobody else’s PTT light is on. Pretty easy and really enjoyable to use.

New!  Check out the Tips for listening in on CWTD for each episode.

CWTD Project Room
Here are the projects we have discussed, designed and analyzed during one or more of our bi-weekly programs throughout the year.  In some cases, a special offer of a parts kit is made to help you more easily follow along with the principles and replicate the project on your own.  Most of these projects are "limited run" ... but even if you miss out on getting a parts kit, the project is easily homebrewed from the information supplied.  Have fun!

Now available for sale (quantities are limited) ...
2x16 Character LCD

(One per customer)

$7 ...


(follow link to order)

Retro SWR

(follow link to order)

N2CX Choke Balun

(follow link to order)

"In progress", not yet ready  ...

SIC RF Input Card

Signal Quality Meter

Step Attenuator

Rainbow Tuner

Electronics Bench Reference

Growler SWR Bridge



Previous Episodes:                                                             (RSS feed:  https://dl.dropbox.com/u/3549602/cwtd.rss)

Date     Episode Description
April 23 Whiteboard Podcast

52a) Remote 7-segment LED Display for the Precision Arduino Clock -- This installment of the Clock project combines the XBee RF link topic from last time with a 4-digit,7-segment multiplexed LED module to provide remote display of time for the radio shack.
52bTools for the Homebrewer's Workbench and Workshop -- This collection of "essential tools" for the homebrewing workbench will turn you and your projects into a star!  Seriously, they are mostly inexpensive and every good homebrewer should outfit his shop with these basic items.  
52c) Cool Product of the Month --  A new regular segment is added to our bi-weekly program, describing a cool new product for us homebrewers ... this time it's the Si4707 Weather Band and SAME Data Receiver.  Just think of the cool thinks we can do with this little board in out Ham Station Mesh Network ! ;-)

April 9 Whiteboard Podcast 51) XBee RF Data Link for Ham Station Mesh Networking (Part 1) and Arduino Clock Synchronization & 7-Segment Display
We first start an interesting group project that will lead in several episodes to the creation of a functional, useful and indeed valuable "mesh network" for data and control within our ham stations.  We begin by using a couple of XBee modules to set up a remote terminal modem capability. Then we reconfigure the standalone remote node to read a temperature sensor and send data over the RF link to the XBee receiver on the base Arduino for display in the serial console. 
Our second focus
deals with the addition of a 7-segment, 4-digit multiplexed LED module to provide time and temperature readouts (soon) on our Precision Arduino Clock project.
Mar 26 Whiteboard Podcast 50) Two topics this time! ... AM Mode and RTC Software for the Precision Arduino Clock Project
We first consider a venerable operating mode that many of Old Timers grew up using: Amplitude Modulation. We take a brief look at the technology and construct of AM operation, as well as how it is implemented in even one of the most modern SDR rigs today: the SDR Cube Transceiver.
Our second focus is on our continuing group project: the Precision Arduino Clock. This time we implement the software for a key element for moving forward: the Real-Time Clock. Surprisingly, the Arduino sketch (software) is vastly simplified and we have the stage set now for making the Arduino and our CWTD shield (hardware) a very useful addition to anyone's shack.
Feb 26 Whiteboard Podcast 49) Time & Time Again ... Adding a Real-Time Clock Chip to the CWTD Precision Arduino Clock Project
In this week's episode we take our basic “phase 0” Arduino clock and advance the project to the phase 1 milestone with the addition of a Real Time Clock chip (the DS1307). With this hardware addition, our “CWTD Arduino Clock” can be set with accurate time and retain it when power is removed. Then we take a close, step-by-step look at the initial sketch (software) used on the Arduino last time, and show the construct and way that it works. You won’t need to become an expert on sketch design, but it’s always good for a homebrewer to at least have a feel for what makes this project tick.
Feb 5 Whiteboard Podcast 48) Precision Time Display & Synchronization with the Arduino
Time … you can’t beat it, make it, save it, store it, replay it or out run it.  But we amateurs can measure time using a number of techniques for our benefit in the shack, in our rigs, in our QSOs, and more.  In this session we overview the sometimes-esoteric world of timekeeping and time synchronization available to us (WWV, CHU, GPS, Rubidium, Cesium, etc.) and then spend a good amount of time on a unique Arduino-based project that can grow and be useful to each of us.
Jan 22 Whiteboard Podcast 47) Arduino Design Tactics
Okay, so who hasn't heard of the Arduino in the last couple of years? It's actually been pretty hard to avoid. But have you given it a try yet for a project on the bench? Perhaps a VFO controller, or maybe a dedicated voltmeter, antenna rotor controller, code practice oscillator ... the list goes on! The Arduino is designed for use by non-techie users: artists to add lights and sound to their works, musicians to add new dimensions to their instruments, hobbyists building robots and R/C vehicles, homeowners to make custom home automation, and tinkerers to make unique alarm systems. The functional modules are simple to use and require only basic electronic and software skills.
Jan 8 Whiteboard Podcast 46) Analyze This!  Flexible Signal Source
A signal source can be extremely helpful on the homebrewer's bench ... and even more so when "flexible", with a Fractional-N Synthesizer/PLL, programmable gain+attenuation stage, and TFT graphic display.
Dec 11 Whiteboard Podcast 45) Decibels and the Hombrewer
Decibels (dB, dBm, dBW, dBc, dBu) are useful concepts for homebrewing hams to be comfortable with. When these terms come up in magazines and equipment measurement/evaluation articles, we sometimes have trouble focusing on the real issue if we are busy wondering whether 3 dB means a factor of 2 or 4 (or something else). And when it comes to measuring your homebrew creation on the bench, the dB readings become the universal language describing performance: sensitivity, MDS, IMD, gain, LPF rolloff, and more.
Nov 27 Whiteboard Podcast 44) Emergency Preparedness: Before, During and After
In this episode #44 of CWTD, we have noted author and long-time columnist in QRP and ARRL circles: Rich Arland, K7SZ joining with N2APB and N2CX to discuss the equipment, practices and techniques of preparing for emergency communications.  Whether your focus is preparing in the calm warmth of your home, or being directly involved in the disaster relief operations with other hams and response organization, this week’s session of CWTD is bound to be of interest to many.
Nov 13 Whiteboard Podcast 43) RFI Detective
We discuss the topic of finding and eliminating local sources of noise that interfere with signal reception and trying to mitigate them. The basic process is to first try to characterize what the noise characteristics are then to use fairly standard troubleshooting techniques to identify the source(s) and to describe the measures that can be taken to lessen or eliminate the noise. And per usual, we have a great set of references for further study, and a "project" that you can build and use in the shack or around the home to locate troublesome interference.
Oct 16 Whiteboard Podcast 42) Homebrewing VHF/UHF Antennas
We discuss and illustrate examples of getting on the air with 6m, 2m and 70cm (440 MHz).  Most of us know the "mechanics" of HF operation, but VHF and UHF throw some interesting curves at us as far as propagation, feedlines and losses, antenna polarization, power levels, terrestrial impediments, and more.
Oct 2 Whiteboard Podcast 41) Morse Code ... Dying Art or Thriving Specialty?
We explore a bit of the background, overview the various equipment out there for CW operation, and then hunker down on what makes a CW operator tick.  What his tips and tricks are.  If you've never considered using CW mode and Morse code, or if you've let your fist drift away over the years, or even if you are currently active and in the A1 Operator club, we think you'll find the discussion of the "original mode" interesting and eye-opening. 
Sept 18 Whiteboard Podcast 40) Analyze This! ... The Desert Ratt Regenerative Radio Receiver
One of the easiest and best performing receivers to build, the "regen" offers a unique and incomparable operating experience. Once you hear the characteristics whistles and pops when tuning in a station, you'll think of your grandfather's radio in his den while you lay listening to the 1939 Yanks pounding the Philadelphia Athletics. And you'll also hear dynamic range and crystal clarity that is hard to duplicate with others receivers ... even today!!
Sept 11 Whiteboard Podcast 39) Assembling a QRP Station for Field Operation
It's always good to consider what it takes to get a station together for field use.  We'll discuss some things that maybe you hadn't yet considered ... or some important aspects that you should be aware of.
Sept 4 Whiteboard Podcast 38) Analyze This!: The PFR-3A
This time we study the PFR-3A, the KD1JV-designed QRP CW transceiver
Aug 28 Whiteboard Podcast 37) Troubleshooting Techniques, Part 2
Basic guidance on troubleshooting circuits that should be working ... but are not.
Aug 21 Whiteboard Podcast 36) Troubleshooting Techniques, Part 1
Basic guidance on troubleshooting circuits that should be working ... but are not.
Aug 14 Whiteboard Podcast 35) Analyze This!: The 8640-Jr Signal Source
Dissecting and analyzing the 8640-Jr Signal Source
Aug 7 Whiteboard Podcast

34) Toroids ... Selection, Construction and Use
Are you a bit fearful, or at least hesitant, when it comes to dealing with toroids in your homebrew circuits?  If so, this week's episode is made just for you!

Jul 31 Whiteboard Podcast 33) Resistance is Futile
Selecting the correct resistor for RF, DC, audio, power, size, SMT or leaded, package, vendors and more.
Jul 24 Whiteboard Podcast 32) Component Selection
Tips for selecting the right components when you are trying to adapt or modify a project for your own usage.
Jul 17 Whiteboard Podcast 31) Mid-Year Project Recap
Review of the 30 technical topics and 15 projects covered during the first half of this year & status of each!
Jun 26 Whiteboard Podcast 30) GPS Applications in QRP Communications
Using GPS to enhance our communications: digital modes, frequency standards, stability, and more!
Jun 19 Whiteboard Podcast 29) Oscilloscope Applications
Building on the o'scope basics covered earlier in our Apr 10th episode, we now delve into the many productive uses of the 'scope with our projects, with guest host and expert lecturer Alan Wolke W2AEW.
Jun 12 Whiteboard Podcast 28) QRO Power Supplies
Armed with basic principles and components, you can design just the right solution for your needs!
Jun 5 Whiteboard Podcast 27) Retro SWR
Analysis, design and construction of a simple & useful SWR meter from yesteryear!
May 29 Whiteboard Podcast 26) Feedline Frenzy
Which feedline should you use?  How to measure?  Tips & Tricks
May 22 Whiteboard Podcast 25) Antenna Tuners (ATUs)
Impedance matching in a world of mis-matches
May 15 Whiteboard Podcast 24) Remote Control Techniques for Hams
A review of basic principles and "transports" (RF, IR, wired) and an experimenter's platform
May 8 Whiteboard Podcast 23) Homebrewing Techniques
Some ideas for closing the loop on how to get your next new project built up
May 1 Whiteboard Podcast 22) Harmonics & Spurs & Parasitics ("Oh My!")
How to see/measure the various spectra that comes with the generation of the fundamental.
April 24 Whiteboard Podcast 21) Magnetic Loop Design Cookbook
Design guidelines and critical factors for homebrewing an "STL" mag loop ... and a novel example!
Apr 17 Apr 17 Podcast 20) Erecting a Vertical Antenna
Erecting a Vertical Antenna: base, grounding, feedline, tuning, ...
Apr 10 Apr 10 Podcast 19) Oscilloscope Basics
Wondering about how to use an o'scope for your homebrew project?  This session is for you!
Apr 3 Whiteboard Podcast 18) Soldering 101
A guide to the science and art of melting solder
Mar 20 Whiteboard Podcast 17) Simple & Accurate Power Measurement
Homebrew some simple building blocks to extend the range of accurate lab-grade power meters
Mar 13 Whiteboard Podcast 16) Intro to the Digital Modes
Discussion of the many strange-sounding digital mode signals heard on the bands
Mar 6 Whiteboard Podcast

15) Return of the Rainbow Tuner
Multiband end-fed half-wave antenna tuner and multispectral SWR bridge

Feb 28 Whiteboard Podcast 14) Anatomy of a PICAXE SWR Meter
How to control things with a simple, inexpensive BASIC controller
Feb 21 Whiteboard Podcast

13) Circuit Simulation
Spice Up Your Circuits!  A Homebrewer's Overview of Circuit Simulation"

Feb 14 Whiteboard Podcast 12) Schematic Capture and PCB Layout
Tools and techniques used to get a design from the napkin stage to having a pcb on the bench
Jan 31 Whiteboard Podcast 11) Homebrew Battery Chargers
Considerations and cautions in buying, building and using the right kind of chargers.
Jan 24 Whiteboard Podcast 10) Grounding 101
Different approaches, techniques, tool, products and benefits of doing a good job at grounding.
Jan 17 Whiteboard Podcast 9) What is the BEST Antenna?
Discussion of the most common antennas, their relative benefits and drawbacks
Jan 10 Whiteboard Podcast 8) LPF Design mini-tutorial, Part 3
Measuring the filter and comparing to expected results
Jan 3 Whiteboard Podcast 7) LPF Design mini-tutorial, Part 2
Designing the filter, selecting components and building the circuit
Dec 27 Whiteboard Podcast 6) LPF Design mini-tutorial, Part 1
Overview of the Low Pass Filter, specifying the important design goals and parameters
Dec 20 Whiteboard Podcast 5) Best QRP References
The online sites, books, publications, magazines, people, ...
Dec 13 Whiteboard Podcast 4) Favorite Parts & Kit Suppliers
Where do you get your parts from?  Best deals?  Best service?  Best kits?
Dec 6 Whiteboard Podcast 3) Best Kits
What are the best kits on your bench?  Most useful?  Best bang for the buck?
Nov 29 Whiteboard N/A 2) Technology Round Robin
What technology floats your boat?  Microcontroller? PMO or DDS?  SMT or thru-hole?
Nov 22 Whiteboard Podcast 1) RF Power Measurement for QRPers
What techniques, products and parts are around for us homebrewing QRPs to use?