Buildathon 2008

For the past five years, various clubs have sponsored a "Buildathon" as part of FDIM. This is an opportunity for people that may not have access to an Elmer, yet want to try their hand at building a piece of station equipment. The "Buildathon" gives people a chance to construct something with the help of experienced builders (at the FDIM Buildathon, there is 1 Elmer for each 4 or 5 builders). The hope is that the experience will give confidence such that participants will try building other projects when they return home.

Buildathon 2008 is designed to give the builder a useful addition to the QRP shack. Did you build the SP-1 transmitter at last year's Buildathon? If so, this year we will build an HF BJT amplifier that will add a little umph to that transmitter. Actually, we will be building a 5 watt plus amplifier that can be used either as the last stage in a transmitter like the SP-1 or of one's own design. It can also be used as a standalone amp with popular QRP rigs like the NorCal 40A, SW40, Green Mountain 20, etc. The amplifier will have the option of including an RF actuated TX/RX switch. The design of the amplifier will be the subject of one of Thursday's FDIM QRP forum presentations. Buildathon 2008 will allow participants to immediately put the theory and techniques learned in the presentation into practice by constructing a working unit. This amplifier uses a popular bipolar junction transistor that loafs at 5W, providing a clean stable signal for your CW rig. (With the appropriate drive level, this amplifier is capable of more than 10 watts output at 13.6 VDC.) Although the Buildathon kit is designed specifically as a Class C amplifier, the PCB board is laid out to
accept biasing to convert it to a Class AB linear amp for your QRP SSB and/or PSK exciter. The kit is optimized for 40 meters but you can easily put it on other HF bands.

The Buildathon kit is built on a single printed circuit board. All on board parts, including those for the RF actuated TR switch, plus an untapped heat sink are included. The builder will need to supply their own case, switch(es), power connector and RF connectors. The output low-pass filter is also not part of the actual Buildathon kit; however design specifics will be provided so you can roll your own or you can use one of Diz's RF Toolkit filters. There will be test equipment available at the Buildathon to test the completed amplifiers.

The Buildathon activity is scheduled for Friday, May 16th, at the FDIM host hotel from 1:00 PM til 5:00 PM. Cost of the kit is $40.00 US. We will be limiting the number of Buildathon participants to 25. So, if you are interested, please register now. You may register through PayPal by sending the appropriate fee to This e-mail address is being protected from spam bots, you need JavaScript enabled to view it . Please indicate your name and call with the payment so we can have it posted on the FDIM website. You can also send payment to K8IKE's call book address as found on QRZ.com. If you mail payment, you probably should contact Jim at the above address to confirm that slots are still available. Once we have 25 confirmed participants we will announce on this page that registration is closed.

While the sponsors will attempt to provide appropriate soldering equipment and other tools, participants are encouraged to bring their own equipment, if they can.

Jim, K8IKE, and Jay, K4ZLE