The following pictures tell the story of the system that works quite well for W9HLQ. The High Sierra antenna was installed per recommendations of the manufacturer. I used a trailer hitch to provide a solid mount and hopefully good electrical connection. In addition I have a copper strap between the antenna base and a mounting bolt on the hitch.

With the system shown, I can tune 1835 thru 2000 kHz. This is with a 1:1 SWR, all controlled from the drivers position. With the addition of a capacity hat or more inductance, I am sure I could drop to 1800 kHz.

I use the standard High Sierra model 1800 purchased in Dayton 2002. When it is time to QSY to 160, I must stop and add a large coil to the top of the screwdriver. While there I simply clip a wire at the base to a different base feed coil.

Left is end view of the 285 uH coil.
Right: Notice the screw quick-disconnect. I use lockwasher to prevent loosening.

The top coil was made by Howie, W9NHM from 4 inch PVC pipe. A coil was wound to fit inside. Coil diameter is such that it will fit inside the pipe. Plastic end pieces were turned on a small lathe to fit snugly inside the PVC pipe. These end pieces are held in place by three brass 6-32 1 inch machine screws. Holes were drilled in the end pieces and tapped for the 6-32 screws.

The coil is #14 enamel wire at about 10 to 12 turns per inch. It is close wound, but since it is inside the PVC, there is little chance for the turns to short out. Consider using one of the "Texas Bug Catcher" coils of equivalent inductance in place of making your own coil.

I found the push twist type of quick disconnect connectors for the antenna were not secure enough. Further, the weight of the coil and antenna had a tendency to compress the spring some. I felt that a good bump or shock might cause the coil to pop off the top of the screwdriver. I use the threaded quick connector for the mounting and even these worked loose. I now include a 3/8 inch brass lock washer at the junction of the quick disconnect to prevent it from working loose. I have put many miles with this system and the hand tightened quick disconnects do not work loose.

Left: Toroid coil mounted between thin plastic. Clip attaches to various taps on the coil.
Right: Clip moved to existing coil supplied with the antenna.

The base feed coil is necessary to get a good SWR. The coil supplied with the High Sierra does not have enough inductance for 160 meter operation. I wound a toroid coil consisting of 8 turns on a 2 inch ferrite coil I found in my junk box. I found that about 5 turns yielded about 1 or 2 uH of inductance. I made a tap on the toroid coil at each turn, so I have taps at 3, 4, 5, and 6 turns. I found the tap #4 worked best for my part of 160 - 1935 kHz. I left the original coil in place. I put a clip on a short wire attached to base of the screwdriver antenna. Now I can clip either the original coil or the toroid for 160. It takes just seconds to make this change. Adding the big top coil is time consuming due to the need to remove the whip from the screwdriver, save the lock washer. Then place the 160 meter coil in place, with lock washer, and finally place the whip on top of the 160 meter coil.

Left: Antenna on screwdriver. Top whip not shown
Right: Hand tightened screw "quick disconnect" in place. Don't forget the lockwasher since these tend to loosen

Off we go! I tune the screwdriver for maximum noise to get a ball park adjustment. Then on the Yaesu FT-900, I punch up AM mode, hit the mike key and watch the SWR on the rig's meter. It is touchy, and just a tap is needed to get minimum SWR. The SWR is stable; it stays tuned. Of course, passing by neighborhood trees or trucks on the highway will detune things, but this is normal.

de Brian, W9HLQ email:w9hlq@arrl.net

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