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 Previous: In Brief |  Next: NTIA Heaves Potential Monkey Wrench into 5-MHz Band Proposal |
By Anthony A. Luscre, K8ZT
Contributing Editor
September 5, 2002
In this installment, we continue shopping for QRP goodies at hamfests, explore other sources of QRP-related items and clean up that newly acquired hamfest find.
In case you missed it, you can view the first part of the column, "QRP Community: Shopping for QRP Items and Supplies" elsewhere on the ARRL Web site. As we noted earlier, many of these suggestions can apply to non-QRP hamfesters as well.
We continue our quest for QRP equipment, parts and supplies with the search for electronics parts. Whether we need parts for a new project, to repair a specific piece of equipment or just to develop a supply of commonly needed parts, we need to start with a list of desired parts. A little homework in preparing a list before the hamfest can prevent the frustration of forgetting to get necessary part(s) or buying the wrong value part.
Last time, I recommended The Electronic Data Book for Homebrewers and QRPers by Paul Harden, NA5N, to help in electronic parts selection. Another very useful tool is a part number cross-reference guide. Parts often are listed under multiple numbers or have similar electronic specifications. Manufacturers frequently have data sheets available that describe both electronic and physical characteristics of components and may even provide sample circuits for their use. You can find these cross-references, substitution guides and data sheets in both printed form and online resources. Here are a few of those sources: Daniel Burke's The Data Bookshelf links to many manufacturers' data sheets, Quest Link/Chip Centers (requires free registration), NTE QuickCross, Electronics Tutorials Links and Source Research Inc's Cross Reference Guide Both the Weber State University Physics Department-Electronics home page and the Radio Shoppers.com site have a good selection of links to data sheet sources, component cross references and parts vendors.
For more general information on components, you may want to visit these sites: Basic Electronics.com, Internet Guide to Electronics' Online Resistor Color Code Calculator, The EE Compendium and Component Database Server from Penn State University.
Once we know what we want to buy, the question is where to find it. Hamfest shopping often can yield very common components (connectors, capacitors, resistors, etc) in small volumes. For a wider selection or larger volume purchases, we might need to go the mail order route.
One inexpensive source of components that is often overlooked is old or discarded equipment. A good way to build up your junk box supply of parts (of sometimes dubious quality and questionable component value--Ed) is to cannibalize old equipment, including TVs, VCRs, stereos and CBs. While these are great sources for resistors, capacitors, diodes, transformers and other electronic components, don't overlook the other goodies such as bolts, nuts, knobs, battery holders, gobs of hook-up wire and a wide variety of switches.
An especially good source of low-profile project cases is old external modems. Some older equipment can yield ready-to-use sub-assemblies, such as 12-V power supplies. Recently one of the ham magazines ran an article about using old computer power supplies to provide 12 and/or 5 V for ham use.
Tools can vary from new top-of-the-line quality to bottom-of-the-barrel. Low-quality, cheap, imported (but serviceable) and used commercial-quality tools (at greatly reduced prices) often are sold. Watch for excessive wear or damage when purchasing used tools.
Reference materials include books, magazines, parts catalogs, callbooks and CD ROM collections. Both new (often discounted) and used books at bargain prices can be consistently found at most hamfests. Often if you are patient and stay late, older magazines and books often go down significantly in price (and sometimes are given away at the end of the show).
Although some hams complain about the volume of computer equipment at hamfests, most hams (at least the wise readers of this column) use computers directly or indirectly in their ham radio activities. Hamfests can be a good source of inexpensive used and new computers and equipment, but for the first-time buyer it can be difficult to find the right computer and price. Here is where a computer savvy friend can be invaluable.
Hamfests are a great place to meet old friends and make new ones, to learn more about the hobby and, well, to just have a good time. Don't be afraid to start up a conversation with a fellow hamfester. You might make a new friend, learn a few hints and tricks of ham radio or find that piece of equipment that you have been searching for. As my wife Linda, KA8ODP, pointed out to me at Dayton Hamvention, where else can you stand in a long line waiting to get in a restaurant with a bunch of total strangers all chatting with each other?
Many hamfests have forums on various topics, guest dignitaries (ARRL section and division officers, FCC officials, famous hams, etc) and/or club booths where you can become a member. Most hamfests also have prize drawings, so be sure you get your ticket stub properly filled out and into the prize drum. Sometimes, the prizes are pretty impressive.
Once you get all your hamfest bargains safely home, a few minutes of preparation can save hours of repairs or totally ruined equipment. I have a short checklist I like to run through with any new equipment I bring home:
Check all power cables and power supplies closely. Make sure they are the correct ones for that piece of equipment, that polarity is correct, that there are no shorts or other damage to cables. For items without their own power supplies a well-regulated bench power supply with voltage and current meters can be very useful.
If you have a manual for the equipment at least read the basic setup information.
Double check that cables are plugged into proper jacks and in the proper orientation. Plugging 12 V of power into a key or accessory jack can have a very bad outcome.
Before powering up the equipment, make sure all controls are set properly. Pay special attention to transmitting settings including VOX, transmit switch, and mike settings. You don't want to power it up in transmit mode!
If there is any chance that the equipment has been subjected to moisture, excessive dust or other foreign material, check carefully inside before applying power. (I always give a gentle shake and listen for loose hardware and parts, too.)
Once you have your equipment operating, a few more minutes spent doing a little cleaning and preventive maintenance can improve not only the appearance but also future performance. Here are some tips on cleaning and preventive maintenance.
Gather your supplies. Tools include an old toothbrush, soft cloth rags, vacuum cleaner and/or canned air, fine steel wool (to clean aluminum antennas) and a sheet of heavy construction paper or a contact burnisher (to clean keys and other contacts). Cleaners include household cleaning sprays such as Fantastic or Formula 401, mild soap and warm water solution, toothpaste (a substitute for fine rubbing compounds), Goo Gone or WD-40 (adhesive tape and tag removers), lubricant and contact cleaning chemicals. Caig Laboratories offers a good selection of specialized chemicals.
Before you start any cleaning, always remember that line from the Hippocratic Oath: "First, do no harm." Read the labels on all cleaners and sprays. Always spot check any chemicals on an out-of-the-way part of the surface to see if they cause damage. Warning! Collectable items require very special care beyond the scope of this column, and your well-intended cleaning efforts may greatly decrease the item's resale value.
My cleaning, especially on items with cooling fans, begins with opening them and clearing out dust, hair and dirt. I suggest using canned air or a vacuum cleaner set to blow air (to avoid static electricity and physical damage by contact with a plastic vacuuming tool.) Next, after a visual inspection of the interior, I carefully use contact cleaners and lubricants only where needed. The exterior is cleaned and the trick here is to be as gentle as possible. Mild soaps or cleaners should be used in moderation. For stubborn adhesive residue, a careful use of Goo Gone or WD-40 can work wonders. For stubborn dirt and grime, use a soft old toothbrush and mild degreasing product (orange or citrus based). For light scratches on plastics use toothpaste as a fine polishing compound (there are specialty products available for very valuable equipment.)
I have a little more homework for you. After you get a few hamfests under your belt, volunteer to give your local radio club a talk on hamfesting. To make it easy for you, I have posted an outline that I previously used for a talk to my local club, on The QRP Community Page on my Web site. When you are done, invite them to accompany you to the next hamfest.
The Small Wonder Labs' "Rock Mite" (actual size 2 x 2.5 inches). [Small Wonders Lab Photo] |
The buzz in July on all the QRP mailing lists was about a mystery rig. It seems the attendees at this July's Lobstercon got a little extra surprise--the "Rock Mite." The Rock Mite is a miniature 40-meter transceiver from Dave Benson, K1SWL, Small Wonders Lab. The Rock Mite is a simple to assemble 7040 MHz CW rig with lots of features but a low price, and it fits into an Altoids tin. The Rock Mite Files, a builder resources and modifications page is already on Web for this little gem.
Thank you for all the very positive comments on last month's Hamfesting (Part 1) column. Next month's topic is QRP Contesting, and I would like to hear from you about your experiences and contesting tips. Please share your questions and comments and suggestions for future columns via e-mail to k8zt@arrl.net.
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 or visit his Web site.
| Previous: In Brief | Next: NTIA Heaves Potential Monkey Wrench into 5-MHz Band Proposal |
