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Part 1: Background
 n the fall of 1999, at a weekly PARC Repeater Committee work session, an idea was planted in the minds of those present (K7RUN, N7RX, NO7V, KD7CTF and KC7MBN) by W7PR. Envisioning a 160 meter club test station using a very tall vertical, the idea was to use a commercial AM broadcast tower, along with high power, to see what the
combination might produce in terms of generating a big signal on the "Top Band". Just for fun. The
transmitter site I had in mind was, of course, the one managed by K7RUN, and it is safe to assume John had been thinking the same thing since taking on the job of maintaining that site. The tower had intriguing possibilities.
Skip ahead to the Fall of 2000,
following Field Day. A plan began to come together to do a test operation at the site during the ARRL November Sweepstakes, on
SSB. The concept proposed by PARC President and HF contester N7RX, and K7RUN, was to use the station competitively in the winter 160 meter contests. K7RUN quickly designed a matching network and we assembled it. Mounted on
plywood, the three inductor unit would be adjusted to match the base fed tower to our first test radio, W7PR's TS-690SAT. The week before Sweepstakes found K7RUN and W7PR at the site late one evening. When the AM station shut down at 2200 hours, the new network was installed at the base of the tower, jumpered in place of the existing broadcast circuit.
Careful adjustment by K7RUN produced an acceptable load to the 2¼ inch Heliax feedline going to the transmitter building, some 200 feet away. An SO239 connector was installed at the inside antenna switch and a length of RG8X coax was run to the 160 meter radio.
The 160 meter matching network for the base fed tower. Note that the floor tiles are 12 inch square for
reference
Running 100 watts to the big tower allowed us to
easily work the few stations heard in the Puget Sound and Spokane areas, receiving excellent signal reports. When a station in the group asked what we were using, our answer was "100 watts to a 300 foot, 5/8 wave
vertical". John and I grinned at each other. After an extended pause, the other operator's reply was "that is
quite an antenna!". We quickly found we could work anything we could hear, but on a late weeknight evening the band was fairly quiet, so we shut down the test station. In a few short days W7LT would be on the air for the Sweepstakes.
- W7PR
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