NJDTechnologies

Radio: it's not just a hobby, it's a way of life

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OFF AIR - but back tonight after dark for more CW

HF Pedestrian mobile at Cedar Hill State Park!

– Posted in: QRP

This is my first post in the QRP section of this site and it will be brief so hopefully pictures really are worth a 1000 words (pics courtesy of Dr. Fred Harris, N5VDQ).

Pedestrian mobile (/PM) is the act of hiking around while actively making QSO’s from a self contained system.  That may be easy at VHF and UHF but gets a little more complicated at HF.  The operator is literally a “one-man band”.

2John Langridge, KB5NJD, (back to camera) and Steve Parks, KF5RYI, suiting up for a hike.

3Battery pack and feed point for John’s system is shown above.  The antenna is a helically-wound  vertical on a fiber glass fishing pole and fed with a 9:1 end fed transformer.  The windings equate to almost a half wavelength of wire on 17 meters and works very well on 10-12-15-17 and 20 meters..  This design was chosen to avoid the need for a traditional drag counterpoise wire, however, a secondary feed point is included for  30 and 40 meters, which would represent a low impedance and require a counterpoise.  This secondary feed point has not been thoroughly evaluated at this time.

5Close up of both feed point options.  The battery in the pack is a 12v 10Ah sealed lead acid battery and weights about 7 pounds.

6Elecraft KX3 sitting in the front waist pack.  Grommets were added after holes were melted into each side for RF, keying, power, and ear bud cables.

downloadHere I am working someone.  I worked several stations  by calling CQ near the traditional QRP CW frequencies on 12 and 15 meters.  Several QSOs were QRP to QRP with stations in the north-east.  All were solid QSO’s.   Our party hiked about 3 miles that day and while we got a lot weird looks, we all concede that this is not a hot look, but it sure was fun.  After spending 25 years in the shack running mostly QRO, this was a really great experience and I look forward to doing it a lot more… Kayak mobile (/KM) is in my future.