[TowerTalk] Matching the BB3

[Dave Jordan]

Hi Folks,

Now that it's warm enough outside (103 degrees) I thought I'd spend the
afternoon on the concrete
driveway and fool around with matching the input to the BB3 mobile
antenna.  Found some scape
2.5 inch airdux, cut off a 14 turn hunk. Connected one end of the coil
to the antenna input and the other to ground. Tapped the coil with the
center conductor from the coax...couldn't get a good match.  Moved the
ground sideup the coil with a ground jumper.  Ended up with using four
turns of coil with the coax tap at the feed point of the BB3 and the
ground strap located 4 turn below.  I set the antenna to resonate at
7.225mhz before I started  this exercise.

The measurement/results were are follows:

Frequency            R            X            SWR
7.185                    100        21            2.0
7.210                     69          0              1.3
7.232                     53          0              1.0
7.251                     43          10            1.2
7.265                     39          18            1.6
7.281                     34          25             2.0

SO, does it look about right?

HAVE FUN,
dave
WA3GIN


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