Welcome to the Homebrew Challenge!
Every year the editors of QST magazine issue a challenge to your technical creativity. We invite you to participate in a tradition that dates back to the very beginning of Amateur Radio -- homebrewing, designing a building a device purely on the basis of your imagination.
Homebrew Challenge winners will not only be published in QST, cash prizes are offered as well! See the current Challenge rules and prior Challenge winners below.
Rules and Winners
The ARRL has sponsored two Homebrew Challenges in the past, designed to test our members’ design and construction skills by making useful amateur gear at low cost — and sharing their results with our members. Our first ARRL Homebrew Challenge, announced in QST for August 2006, required the construction of a 40 meter, 5 W, voice and CW transceiver built for less than $50 of new parts. The second, announced in February 2009, resulted in a number of creative designs of low cost 50 W linear amplifiers to follow the transceiver, two for about $30, and a multiband amplifier with many features for somewhat more.
This time we announce a challenge to build a transceiver in celebration of the (slow) return of sunspots. This challenge will be in two parts, and readers can enter into either or both:
♦ A single band, 25 W, SSB and CW transceiver for 10 or 6 meters (Option 1), prize $200, and
♦ A 25 W, SSB and CW transceiver that can be switched between 10 and 6 meters, using one or two switches, (Option 2), prize $300.
In addition to the cash prize, the winners of these challenges will have articles describing their designs in QST, and will receive our usual page rate for the published articles. Additional entrants who meet the minimum requirements, and have interesting design features may also be considered for QST or ARRL Web articles.
Instead of challenging entrants to make the transceiver at the lowest cost, this time we will challenge builders to provide the highest quality, best performance and most features within the cost target of $150 for Option 1 and $200 for Option 2.
Entrants for either option must be received at ARRL Headquarters no later than November 1, 2011. To be considered, each entrant must submit a working transceiver, suitable for testing in the ARRL Lab, and on the air judging by the ARRL staff judges. Documentation required includes a priced parts list indicating the source and purchase price of each part, an article draft including a design description, construction hints, alignment instruction, block and schematic diagrams. Photographs may be provides, but final magazine photos will be taken by ARRL staff.
Rule Change December 1, 2010 — Clarification of microprocessor options.
1. Embedded, standard, available and readily programmed microprocessors (including PICs) are allowed as long as the cost of chip is included in the price, and the firmware is provided to be put on the ARRL Web.
2. The chip needs to be programmable via a straightforward processor programmer of the type described in a few recent QST articles or equivalent. The cost of the programmer does not need to be covered in the priced parts count.
3. Any PC software needed to drive the programmer must be readily available at no cost, or the cost must be included.
4. If you made programmed chips available at a nominal fee, that would be considered a service to our readers and would be up to you, independent of the above.
Original Rules — November 2010 (also see Questions and Answers)
There are general requirements, listed below, similar to those in the other challenges as to what is and isn’t included in the cost calculation. For this challenge, some specific requirements are provided as follows:
♦ Frequency coverage;
10 meters, 28.0 through 28.6 MHz or greater;
6 meters, 50.0 through 50.25 MHz or greater.
♦ Frequency readout (mechanical or electronic) resolution: less than 1 kHz.
♦ Receiver noise figure: 10 meters, less than 8 dB; 6 meters, less than 5 dB.
♦ Receiver selectivity maximum: 3 kHz at 6 dB.
♦ Receiver audio output: minimum; 0.5 W minimum with less than 10% distortion.
♦ Transmitter must meet all FCC requirements. Note that for HF, spurious signals need to be down 43 dB below the carrier, while they must be down 60 dB on 6 meters.
♦ TR switching; CW, semi or full break-in operation; Voice, VOX or push-to-talk
♦ Mic sensitivity; Adjustable, with full 25 W output from standard low impedance dynamic mic or equivalent.
♦ Output of 25 W into 50 W load with up to 2:1 SWR for at least 30 seconds. No damage driving open or short at antenna jack for 30 seconds.
♦ Power required: either 120 V ac, 60 Hz mains or nominal 13.8 V dc supply.
Transceivers that meet all the cost and specific performance requirements will be evaluated by ARRL staff members based on the following criteria:
1. Elegance and originality of design, craftsmanship (10%).
2. Receiver laboratory performance (25%).
Dynamic performance; (blocking gain compression and two-tone, third-order IMD)
Image and spurious rejection
Sensitivity and selectivity
3. Transmit lab performance (25%).
Audio response and distortion
4. Operating convenience (25%).
Intuitiveness of controls and functions
Ease of tuning CW and SSB signals
Frequency accuracy and calibration
AGC action smoothness
Mechanical and thermal stability
4. Ease of duplication, adjustment and calibration (15%).
The evaluation will be conducted by vote of the judges and will be final.
The cost target of $150 for Option 1 and $200 for Option 2 must include the retail cost of all parts required to assemble the transceiver. The following definitions of cost elements are intended to assist builders in understanding what needs to be included.
●Parts must be readily available either from local retailers or by mail order. No “flea market specials” allowed.
●Any test equipment other than a multimeter, RF power meter and communications receiver must either be constructed as part of the project or purchased as part of the budget. A personal computer and standard office software may be used in the design process, as well as any specialized freeware. Software requiring the purchase of a special license, must have the license cost included as part of the total cost.
●The full cost of parts purchased must be included in the above targets. That means that parts should be purchased for single unit price, unless multiple parts of the same type are used. For example, if seven 0.01 µF capacitors are used and it makes sense to purchase 10, the total price for 10 can be apportioned over the seven, if that is less than the single unit cost. If any “free sample” parts are used, they must be priced at their regular retail cost.
●To equalize purchase options, parts cost need not include shipping, handling or sales tax.
●Cost of usual construction consumables such as wire, solder, tape, PC etchant and similar items need not be included. If a PC board is used, the cost of the raw board must be included as well as any costs incurred in board layout (software based board provider charges, for example).
Each entrant must submit a sample of the station with documentation indicating the source and price of each part used in the construction. A draft QST article will also be provided including a discussion of the design with schematic diagram and description of the construction, test and alignment steps. All portions of the entry must be received at ARRL Headquarters before Nov 1, 2012.
●The station will first be evaluated by the ARRL Laboratory in a manner similar to a Product Review of HF transceivers. Entries determined by the Lab to be acceptable on the basis of FCC spectral purity requirements will be evaluated by the QST Technical Editorial Staff based on the listed requirements.
Questions and Answers
Q1. Please clarify the costing requirements for Challenge III. The rules state that any test equipment other than basic equipment and basic software must be included in the cost of the project. Does this refer to the construction of the project by other individuals or does it refer to the designing of the rig? In other words, can I use my spectrum analyzer and ECAD software to help me design the project or must these costs be included in the calculations. Or, is it referring to the instructions I include on how to align the rig as it is being built by another person? The same question applies to the PC layout. Can I utlize my autorouter program, or must the cost of the program be included?
A1. This set of costs refer to the actual duplication of the transceiver by our readers, not it’s development. This assumes that any results, such as PC board artwork resulting from the use of the tools be available for readers to copy and duplicate in their shop.
Q2. What if the radio requires embedded software (for a microcontroller or DSP)? If the software is available free, does that add to the cost? How do you make the software available, and program it into the radio? If I made the software available for free, and sold programmed parts at the cost of the raw part, is that allowed, or is that not a "standard available part" by mail order? What if a PC with serial port were required to program the software into the radio?
A2. Embedded, standard, available and readily programmed PICs or microprocessors are allowed as long as the cost of chip is included in the price, and the firmware is provided so we can make it available on the ARRL website.
The chip needs to be programmable via a straightforward processor programmer of the type described in a few recent QST articles or equivalent. The cost of such a programmer does not need to be covered in the parts count.
Any PC software needed to drive the programmer must be readily available at no cost, or the cost must be included.
If you choose to make programmed chips available at a nominal fee, that would be considered a service to our readers and would be up to you. The firmware would still have to be provided so readers could program their own, as described above.
Q3. Does the total cost of for the Homebrew Challenge III transceiver(s) include the microphone and key?
A3. The mic and key costs do not need to be included in the cost calculation, however, the transceiver needs to operate with a standard low-Z mic. You are welcome to submit a mic with the unit for our evaluation — if not please use some standard connector for both mic and key.
Q4. Can a partial kit assembly (such as a DDS VFO board) be used in the station as long as the total cost of the kit and documentation is included in the cost calculation?
A4. A generally available kit can be used, just as can an IC, for example. It should be considered at the advertised single unit retail price, without postage — as any other part.
Q5. If for a crystal filter, for example, I purchase a large number (say 100) crystals and then use the radio itself to match their motional parameters, I'll likely be left over with 95 crystals. Do I need to include the full cost of however many crystals it takes me to get a matched set of five, or because I have good info on those crystals and can possibly use them in other projects, can I just include the cost of the five, or do I have to use the cost of 100?
Q5. The defining principle is still the same. The price used should reflect what a builder would have to do if he were to just build this transceiver and never make another project.
Keep in mind that there are two possible outcomes here:
1. Design and development process: If you need to buy 100 crystals in order to understand the details of what the crystal manufacturer offers, or to refine your design, that would not necessarily make it so that a builder would have buy all the same pieces. Hopefully your purchase would result in a determination of which five need to be ordered and thus the builder would only need to buy those and that would be the price you would use.
2. On the other hand, if you find that the tolerances are such that it is necessary to buy 100 in order to find five suitable units, then presumably each builder would also need to and the cost of all would need to be included.
Q6. Can I use a PC to run software for a software defined radio, without including it in the cost of our homebrew challenge.
A6. The intent was that this be a transceiver that could operate with parts that can be purchased for the listed maximum cost. Thus the cost of a PC that is part of the operating platform would have to be included.
Note that PC use is permitted as part of the development process:
"A personal computer and standard office software may be used in the design process, as well as any specialized freeware.”"
However, that equipment is not required for someone to duplicate the transceiver and put a station on the air.