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The portable 630-meters QRP kit: loading coil finished.. FINALLY!

– Posted in: 630 Meter General Topics, 630 Meters

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!