With the weather trying to warm up a bit, I have found myself wanting to be outside more. As a result, I have been thinking about how to put together a small, very portable HF station. The goal is to assemble a rig that can fit entirely – everything from Morse key to antenna – in a small day pack that I can carry comfortably down a hiking trail. I also wanted to be able to set everything up and be operating within 20 minutes, and similarly be able to break it all down and pack up in short order. I think I’ve been successful, although being a ham, I am always finding ways to tweak my system.
My end-fed half wave antenna and mast
The antenna for this kit consists of a 40m end fed half wave wire, based on a design by Michael, GØPOT. It has a 9:1 unun to bring the high impedance at the end of the antenna into line with the 50 ohms expected by most transceivers. I put a small 20m trap in the middle of the wire to make it a dual band antenna. I purchased a SOTABeams Carbon 6 20-foot collapsible mast from DX Engineering to raise the antenna into an inverted V. One of the advantages of an end-fed antenna is that you can eliminate the need for a feedline by plugging the end directly into the radio. The unun on my antenna has a BNC connector that I can attach directly to the antenna port of my transceiver.
The radios I’ve been using lately are single-band QRP CW kits from QRP Labs. The QCX is quite a capable little radio that includes its own RF testing and alignment tools built in. It also has a CW decoder built in, and can be used as a WSPR beacon for propagation testing as well. I have built a 40m version and a 20m version. I power the radios with a 12-volt, 4.5 amp-hour LiFePO4 battery from Bioenneo Power. These batteries are small and lightweight, and for QRP operation, provide plenty of power for a day out.
Finally, I can’t forget my Morse paddle. I have a Vibroplex Square Racer iambic paddle, which is probably the heaviest piece of gear in the kit. I am thinking about building an Arduino-based touch-sensitive paddle instead, which will reduce the weight (but possibly increase the complexity and opportunities for equipment failure). There are, of course, a few other bits that go along with all of this: guy lines and stakes for the antenna mast, headphones, a notebook and pencil for logging, bug spray, water bottle, sunscreen, and anything else you might take out on a day hike.
I took this rig out for a bit to Cuivre River State Park (KFF-1753) a couple of weeks ago. I was able to set it up in about 15 minutes. In a little over an hour of operating, I made nine QSOs from California to Connecticut, on both 20m and 40m. I was able to pack it all up in a similar amount of time and was on my way back to the car. It was a successful test run, and I hope to carry out more extensive operations over the coming weeks.