K3JZD's Pages

The QCX QRP Transceiver is available as a kit from QRP-Labs. [Update: It is now the QCX+, which is the same radio but with a larger, reconfigured circuit board]. The QCX is a Single-Band, CW Only QRP Transceiver. I built mine for 40 meters. Since it is a light radio, one of the places that I use it is during a monthly event called the Spartan Sprint. The Spartan Sprint is unique in that your score is based on (Number of Contacts) / (Weight of Station in Pounds). The 'Station' is everything that you are using, up to your antenna connection.

Complete QCX Station. My goal was to be as light as possible. The total weight of the components shown here is 9.1 ounces, which is 0.569 pounds. So, if I make 5 QSOs, my score is (5) / (0.569) or 8.79. The Naked QCX is 5.0 oz. The ear buds and 3D Printed Key are 0.4 oz and 0.8 oz. The difficult thing is finding a light weight battery that will last a while. I settled on building a pack of ten 2/3 AAA NiMH batteries. That battery pack weighs 2.9 oz. I am able to run 3 watts with this particular setup. Here are the results from two of the Spartan Sprint events where I used this station :

This event does not have a real big following. And not everyone who works it submits their score. W5ACM has a rather unique station. He is in a class by himself with a station that light. But, if he has a really bad night I can be competitive. But either way, it is all in fun, just trying to do the best you can with a small lightweight station.

Trying to get a little lighter with my QCX Station, I tried some small 3.6v LiPo batteries that were made for use in a small quad copter. The pack of four weighs 2.48 oz, making my total station weight 8.66 oz or 0.541 pounds. (I keep using Power Pole connectors out of convenience - If I was trying to be even more competitive, I would eliminate that 'extra weight'). I was hoping to get more than 3 watts with this LiPo battery pack that has a higher voltage than my NiMH battery pack has. But I do not - they must be current limiting. But 3 watts gets the job done. The four LiPo batteries are wired in series.

After the QCX and QCX+, QRP Labs then produced a QCX-Mini kit. Like the QCX, it was a Single Band QRP CW transceiver. Only smaller and lighter. I built QCX-Minis for 80m, 40m, and 20m. I purpose built them for the Spartan Sprint by swapping some parts out to make them even lighter. My Total Station Weight for a single band QCX-Mini operation was 0.439 pounds. I tpyically just use 40m. When I do want to work an additional band, I use the same User Interface Board, and just plug it into a different RF Board. That way working an additinal band will only add 0.113 Pounds to my Total Station Weight.