OK so this is really part two of a project I have been working on far too long. A few weeks back I reported on building the GW3UEP QRP QTX into Altoids tins – one for the signal generator/VFO, one for the PA, and one for the reflectometer. Clip-lead tests with a short wire draped around the ham shack yielded some really interesting results including one test where I could copy my CW a little over a mile a way on my Sangean SWL receiver inside my Prius. That, in itself, is a worthwhile achievement. And yes, the master antenna here at WG2XIQ was detuned while I was running the test so this is not a simple matter of resonant re-radiation.
I examined a number of methods of loading a short, probably random antenna on 630-meters in the field. One method included winding a coil on the ever-functional fiberglass hiking pole, still another involved what I perceived to be much more efficient, that is, winding a coil on a cardboard container used for oatmeal. Because of the size and how compact it would be to transport, I was interested in using ferrite but many consultations suggested that it might introduce inefficiencies that a 1-watt QRP might not be able to afford. While I don’t doubt that one bit, what I ended up with did use a ferrite rod from an old AM radio and the listening results so far in close proximity were quite good. For a limited QRP CW operation and proof of concept, this might just work well. I can always reinvent the wheel later.
What I have here is a piece of phenolic with an AM ferrite rod rewound with #22 enamel, tapped and mounted. Simple as that. The output of the PA connect via BNC and the appropriate output tap, per the measurements from the reflectometer couples the clip-lead antenna to the system. While it worked during my initial clip-lead test, the loading coil has not been tested in this “finished” form but at the moment I have no reason to think it will be a problem.
One question that I was asked was about how the hardware would be transported in the field. While all of these components are generally pretty durable, rolling around loose in a backpack might be a problem. As luck would have it I found an old metal case with a gasketted lid that originally contained a first aid kit. While I still need to work on the packing configuration and cut some foam to stabilize the contents, I think this will work just fine.
The next installment will be from the field with a real on air CW test attempting to complete a very short distance 2-way QSO. Stay tuned!