As you're considering what to build during occasional stormy days, remember that there is often a rainbow at the end of a storm ... and the NJQRP Club is offering a Rainbow Tuner Kit to help you through it all.
We are proud to bring back the Rainbow Tuner and Bridge Kit. The Rainbow Tuner was first introduced in 1997 as a QRP design from QRP Hall of Famer Joe Everhart, N2CX. His design was the co-winner of the NorCal Design Competition that year. The Rainbow Tuner is a very lightweight, compact, combination half-wave antenna tuner and a built-in automatic SWR bridge.
The Rainbow Tuner Kit was originally intended as a companion to the popular 40-9er, a complete 40 meter QRP transceiver that fits inside an Altoids mint tin. Similarly, the Rainbow consists of simple tuner *and* LED display SWR bridge on a 2x3 inch printed circuit board that can be built in a another Altoids tin. A complete QRP station except for the key and a 67 foot antenna wire fits inside two Altoids tins!
And as a bonus, the Rainbow is the perfect companion to the 38 Special, the other Design Competition winner. With a 30 meter half-wave end fed wire, it will tune the 30 meter band with no added components.
The Rainbow SWR Bridge is also useful even without the tuner. It automatically turns itself on when RF is applied and turns off when the RF disappears. It uses four multicolor LEDS in a bar graph display that give relative SWR readings *and* accurate absolute SWR indication. Simpler two-LED SWR bridges only give you the relative indication. It senses both forward and reverse power and automatically tracks over a range of 150 mW (or less) to 4 W so that there are absolutely no adjustments.
Complete details on the Rainbow Tuner Kit are given in articles appearing in the December 1996 QRPp, January 1997 issue of QRP Quarterly, and QRP Homebrewer issue #7.
The Rainbow Tuner Kit is available from the NJQRP. It consists of a high quality printed circuit board, all board-mounted parts including the tuner parts and the Rainbow display and a detailed construction and usage manual. You need supply only three coaxial connectors of your choice and a 6 to 12 volt power source. Directions are included in the manual on how to install a low-cost N-sized battery right on the pc board. An Altoids mint tin is included in the kit, de to its ideal service as an enclosure.
The cost of the Rainbow as described is $25.00 each plus $3.00 for shipping ($5.00 outside USA). Please make checks payable to "George Heron, N2APB" and send to George Heron, N2APB, 2419 Feather Mae Ct, Forest Hill, MD 21050. You may instead pay through the PayPal services, sending funds to firstname.lastname@example.org.