 |
 |
|
|
|
|
|
|
||||||||||||||||||
|
|
|||||||||||||||||||
|
|
|||||||||||||||||||
|
|||||
 Previous: In Brief |  Next: Nominations Open for the 2003 Philip J. McGan Memorial Silver Antenna Award |
By Anthony A. Luscre, K8ZT
Contributing Editor
December 27, 2002
This installment focuses on the construction side of QRP with projects, kits and homebrewing. We also plan ways to melt some solder to keep warm here in the cold Ohio winter.
The Elecraft K2, a transceiver built from a kit The view inside shows a large number of parts. |
In Amateur Radio's earlier years, before the days of easily available factory-built gear, most hams built their own transmitting and receiving equipment--a process that came to be known as "homebrewing." In the latter decades of the last century, some hams turned to constructing their stations from kits put out by Heath, Johnson, Knight, World Radio Labs and other suppliers. (Who hasn't seen a classic Heathkit--silver and gray in the early years, and, most commonly, two-tone green during its ham radio heyday?)
These days, of course, hardly anyone has a homebrew station, and kits went out when Heath left the Amateur Radio market. Right? Not exactly.
News flash: There are probably more ham radio kit producers now than any time since the early days of broadcast receiver kits in the 1920s, and homebrewing is alive and thriving in the QRP Community. And, at least here in Ohio, winter is a great time to build, and your hands keep warm from the soldering iron.
Let's take a brief tour of some of the "roll-your-own"
radio construction options available.
Step-by-step assembly and detailed instructions ease the K2 construction process. (View a larger copy.) |
If you bemoan the fact that you missed the glory days of kit building, don't worry. Kits are back and many are better than ever. Today's kits can be divided into two categories--commercial kits and kits put together by various QRP and other clubs. Sometimes the line between the two blurs, such as when a club introduces a kit and a commercial vendor later continues its production, sometimes with a few modifications or tweaks. Kits come in a variety of styles: Complete (with all parts, printed circuit board, case, knobs and full documentation necessary to complete the project); Complete minus case (a so-called "board kit" that also may lack knobs, jacks, connectors and other hardware); Partial kits (that include only the harder-to-find parts or parts that require computer preprogramming); and Homebrew-style kits (all the parts and sometimes a printed-circuit board, but with only a schematic diagram and no step-by-step assembly instructions.)
Across the wide variety of above styles, kits can also be divided based on complexity of building, aligning and packaging. A few years back, Doug Hendricks, KI6DS, generated an excellent series of e-mails entitled "What Kit to Build." Although the material is a bit dated, it's still a great read. For a list sampling currently available kits, visit the QRP Community page on my Web site.
Want a little more challenge or just can't find just the right kit for you? You don't need to be an electrical engineer to homebrew. You can find plenty of plans for equipment to build by reading QST and other ham radio magazines.
For more QRP-focused projects, the various QRP club publications are the best source. Yes, this is yet another great reason to join a QRP club or even two or three! There is even a special magazine devoted exclusively to homebrewing and QRP, QRP Homebrewer, published by New Jersey QRP Club. For a wide variety of web resource links on homebrewing you might want to visit DXZone Homebrew Links, Electronic Construction from A to Z, The Homebrewing Zone by VU2MSY, EI9GQ's Homebrew Page, DMOZ's Homebrew section, Dave Metz, WA0AUQ's Twelve Rules to Organize Homebrew Projects, Homebrewing for the Novice, Monty Northrup, N5FC's site, the G-QRP Club site and the NorCal QRP Club site.
One way to differentiate homebrew projects refers to the way the components are connected. Point to point wiring was very popular in the tube days. Components are connected to the pins on the tube sockets, other chassis mounted parts and isolated metal tabs on terminal strips. Point-to-point wiring (sometimes called "ugly style") is often used when prototyping a new project. Two more recent incarnations of point-to-point wiring are "dead bug" and "Manhattan" style.
In dead bug construction integrated circuits (ICs) and transistors are glued upside down on a circuit board and their leads are used to mount other components. Manhattan style uses small "punched out" circles or cut pieces of circuit board glued to the surface of the main circuit board. These pads and the circuit board surface are used to solder parts in place. For examples of Manhattan construction, visit the Web site of James Kortge, K8IQY and that of Jerry Hall, W0PWE.
Perforated insulating board can be used to lay out components. Their leads are then soldered together. For comparisons of various styles of construction methods check out "Building From Schematics--Prototyping Systems Compared," by Russ Carpenter, AA7QU.
Although etched printed circuit boards can make for very neat construction,
the time and effort consumed in making single copies often outweighs the
benefits. Fortunately for fans of printed circuit boards, many authors make
arrangements to have boards "mass produced" for their
projects. One common source for these boards is FAR Circuits.
A simple transmitter kit with a single tube is an easy and quickly assembled kit with a touch of nostalgia and modern construction techniques. |
One of the newest methods of construction is surface mount. Using very small components allows for miniaturization but requires different soldering techniques. Interesting facets of homebrewing are the retro projects using tubes. For resources on tube homebrewing visit Gary Johanson, WD4NKA's Web site, Kenneth Gordon, W7EKB's Glowbugs and DMOZ Boat Anchors Homebrew. For a simple tube kit, try the Glowbug 40 by Dwight Morrison, KG4HSY.
If you want to homebrew and design, this is the route for you. Here is a five-step process to get you started. As a first step I would suggest a good library on electronics and radio theory. Good choices include The ARRL Handbook for Radio Communications, Introduction to Radio Frequency Design by Wes Hayward, W7ZOI, W1FB's Design Notebooks by Doug DeMaw, W1FB, and RF Components and Circuits by Joe Carr, K4IPV.
The second step is to study other's designs. Borrowing portions of circuits from predecessors is an honorable ham radio tradition (think of those names we give circuits, such as Colpitts Oscillator.)
The third step, which I'll call experimentation, requires the acquisition of common values of electronics components (a well-stocked junk box) and a good system for quick, easy prototyping.
The fourth step is testing, sharing your ideas with others for critique and then improving your circuit.
The fifth step is to repeat the first four steps until your project meets
your goals.
An assortment of tools useful in kit building or homebrewing. [Photo by author] |
For our construction project, you will need a few simple tools (and some
fancy ones if you like.) Depending on whether you go the kit route or
homebrew will determine if you will also need to buy electronics
components. For information on acquiring tools and parts visit my previous
columns Hamfests--Shopping for QRP Parts and Supplies
Part-1
and Part-2.
Here is a list for tools.
Tool |
Need |
Notes |
Soldering iron and solder (rosin-core, small diameter) |
B |
Bite the bullet and buy a simple soldering station (preferably with adjustable temperature). You won't be sorry. Although these can be expensive, you don't need to spend hundreds of dollars. You can find them marked down or even on the used market |
Small side cutting pliers (diagonal) |
B |
|
Small needle nose pliers |
B |
|
Assortment of screwdrivers |
B |
|
Volt-Ohm Meter (VOM) |
B |
|
Desoldering tool (solder sucker) |
B |
|
Small "third hand" table clamp or vise |
B |
|
Bright lamp on an adjustable arm |
B |
Makes work with small parts much easier. You can even get fancier ones with magnifying lens, fluorescent and incandescent bulbs. |
Hand ream |
B |
|
Drill bits |
B |
|
Knives (X-Acto type) |
B |
|
Metal files (one flat, one round) |
B |
|
Wire stripper |
B |
|
Wire connector crimping tool |
B |
|
Magnifying headset or lens |
A |
|
Precision miniature screwdrivers |
A |
Get a set with Straight, Phillips and Torx blades |
Drill bits for circuit board holes |
A |
|
Stepper drill bit |
A |
For round holes of various sizes in chassis and cases |
Chassis punches |
A |
For round holes of various sizes in chassis and cases |
Soldering gun or higher-power iron |
A |
For soldering large objects |
Frequency counter |
A |
|
Oscilloscope |
A |
|
Snap Vacuum Solder Popper combines heating element and vacuum system to melt and remove solder from parts that are installed in the wrong holes on a printed circuit board. [Photo by author] |
I hope you all had a good holiday season and received many of the gifts you chose from last month's column. I have received a number of e-mails from QRP Community readers asking about working DX using QRP, so that will be the subject of a future column. If you have any hints for QRP DXing or tales of DXing success with QRP, please e-mail them to me. Share your questions, comments and suggestions for future columns via e-mail too.
On a personal note, I was able to meet the goals of the Flying Pigs QRP Club 2002 WAS/DXCC Challenge. I also was able to meet my personal goal of working 200 DXCC entities during 2002 using QRP. It was a blast to start again from scratch at the beginning of 2002 and rework QRP WAS and DXCC.
So, my New Year's advice to all my readers is to get on the air and "Work some QRP in '03!"
Editor's note: Anthony Luscre, K8ZT, an ARRL member, lives in Stow, Ohio. He has worked in the field of medical microbiology for 18 years and is now a Technology and Computer Coordinator for a local school district. Luscre is an avid QRP operator having earned DXCC, WAS and WAC using no more that 5 W output. Readers are invited to contact the author via e-mail, k8zt@arrl.net or visit his Web site.
| Previous: In Brief | Next: Nominations Open for the 2003 Philip J. McGan Memorial Silver Antenna Award |
