This weekend, the sun finally poked out so baby Isabella and I were out for a walk. As babies do, she took a nap (we were at a noisy ball field, so a long walk around the back end of park was a lot quieter for both of us.) Also on the back of the All Terrain Baby Carriage was my FT-817 and a MFJ-1899T with a counterpoise.
The MFJ-1899T, is is a fascinating mini-antenna for on-the-spot HF'ing. It is made by Waters and Stanton of the UK and imported to the US by MFJ Enterprises, I got mine at HRO.
This multiband rig is similar to a miniature Outbacker, with band taps along its lower helical winding section, a jumper lead for selecting bands (wander wand), and a top mounted pull-up whip. The base is fitted with a BNC connector to mate with the FT-817’s front socket.
The MFJ-1899T “Walkabout” antenna covers 80 through 2 meters in a single “break apart and carry anywhere” package. Fully extended, it measures 63 inches in height. Retracted and separated, the helical base section is 12 inches long and the pull-up whip is 7 inches long. Adding a BNC-to-PL-259 plus a right angle PL-259 adapter and connecting it to the stronger SO-239 socket of the FT-817 relieves strain. That same idea also works for adapting the MFJ “Walkabout” to other transceivers (FT-857). But dial it down the output below the antenna’s limit of 25 watts.
It is the counterpoise, that is the key to making this little antenna perform. -- The instruction sheet suggests it need not be 1/4 wave long. In fact, the info sheet suggests using the formula 180/F(in MHz) = Length (in feet) of the counterpoise. I use a 16ft section for 40m & 20m and seems to work well enough, I used stainless steel cable covered in Teflon available at HOME DEPOT.
Isabella, slept for a little over an hour and half. When she awoke, we walked back to where the rest of the family was enjoying the ball games. She was rested and I was very happy to have worked a few stations on 20m QRP.
NOTE: I also listened for k4ESA on 10m, but did not hear anybody local, just lots and lots of South American stations calling, 10m is working well in the afternoon.
Monday, March 22, 2010
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