FARALLON SPECIAL ANTENNA SYSTEM
We had "challenging" antenna restrictions for this Island wildlife habitat operation
(especially
for
night use on 40m & 30m). The antenna could not be more than 21 feet high,
had to be placed within a small walled courtyard area adjacent to the small Carpenter
Shop
building on a cliff near the watter, and have no horizontal components. This
eliminated
the
possibilities of my Sigma 40-XKR due to the T-bars. My R-7 and 6BTV verticals
would be too tall, and something was needed that could be errected in high winds
up to 50MPH by one person if necessary.
| Not being a real antenna tech-guru, I started getting up in the middle of the night pouring through the ARRL Antenna Book, ON4UN's Low-Band DXing and other antenna books. I needed to come up with something which would work on both 40m & 30m without having to make any outside physical changes during the night. The courtyard walls were a bit over 4 feet high, so the base of any vertical antenna needed to be at least at or above the wall height. Because of the small allowable land "footprint" we had to work with, regular size 1/4 wave radials were out of the question. From everything I read, it appeared using more shorter 1/10th wave (40m) radials would be the way to go, and permission was obtained that we would be able to drape these over the courtyard walls. Ultimately, they were mostly held in place with rocks and bricks on the Island. I also read that capacity hats were good for "shortened" verticals, and set about the business of putting something together that might work...and provide remote tuning from inside our operating shack (the Carpenter Shop). My good friend Jim, W6SC, had used a High-Sierra HS-1500 on his pickup truck with great success. Several years ago before solar conditions took a real dive, I remembered we sat in his truck after a local radio club meeting and worked a LOT of DX on 15m & 10m with only 100 watts including Europeans. So the idea for what would ultimately become the "Farallon Special" started with a call to Jim Heath at High Sierra Antennas to see about becoming one of our Expedition Sponsors via loan of an HS-1800 PRO. Jim kindly signed on to this rare IOTA project, and in addition to the HS-1800 PRO, also ended up crafting a 6 foot whip into 2 sections with a special coupler, since we were restricted to 4 feet or less in length on anything due to the fact our transportation would be via helicopter. I also picked the brains of fellow NCCC members Dean, N6BV, and Tom, N6BT, who were extremley helpful in answering my antenna "Newbie" questions about radials, whips, etc., since I really didn't know exactly what I was doing at the time. Since any antenna would need to be essentially self-supporting in high winds, and we could not drive any anchors, etc. into the ground, I elected to go with a proven favorite...the Force 12 "X-Base" mounting system. Not knowing exactly the height of the courtyard wall on the Island, I designed several "plug & play" support mast length sections to meet several options, and a custom radial plate all of which Tom at Force 12 kindly fabricated and donated to the cause (in addition to a Sigma 5 Vertical Dipole as one of our raffle prizes). Part of the concept in design was to have the HS-1800 PRO base already affixed to one of the short plug & play mast sections along with the radial plate, and to have all radials pre-attached so there would be no fiddling around to get up and operational once on the Island. What started with 4 radials went to 8 and ultimately 16 short, #14 copper, insulated, 1/10th wavelength insulated on 40m radials. These would simply have to do on 30m, and what turned out to be a use of the antenna on 20m as well. In some of my reading it was mentioned that stainless steel was not as good as conductor as aluminum, so my quest ended up with Steve at DX Engineering who kindly loaned a number of 3 foot and 2 foot aluminum extension shafts as well as two of their "HOT-RODZ" capacity hats. Although horizontal components of rigid aluminum tubing would not be allowed, the thinner, more flexibile nature of the capacity hat rods turned out to be permitted. The primary concern involved potential bird-strikes, (of which there were none as personally anticipated). Budd, W3FF, also donated some parts and one of the Buddipole aluminum arms was used as an extension shaft in the final version of the antenna. Part of my design philosophy was that in the event of real high winds (which we had), if anything above the HS-1800 PRO bent severely or broke off completely, we had immediate replacement shafts and capacity hat parts, etc. to get back in business, and seemed more practical than with trap verticals, etc. as hauling extra traps was not a space luxury we had. Once again, I wasn't quite sure what I was doing with all this. I experimented with different aluminum shaft extension lengths, placement of the capacity hat & rod lengths, as well as whip lengths. Of course, I went through a LOT of AA batteries in my MFJ-259 during this time! I setup the antenna in a flat gravel area next to the driveway, and after every "tweak", would call my Expedition partner, Mike, K9AJ, on the phone to get on the air for another test. In almost every instance, the Farallon Special with the High Sierra HS-1800 PRO as the main component was at least one S-unit better than my HF6-V out in the small vineyard with 4 elevated 1/4 wavelength radials on each band! Always planning for possible "changes" once on the Island, I was mentally prepared to possibly be restricted to a lesser total antenna height, for which the HS-1800 PRO could amply accommodate if necessary. As it turned out, shortly before the trip we obtained approval to operate two 100 watt stations during daylight hours, which added a 20m dimension to the Farallon Special. The final configuration of the Farallon Special ended up with the HS-1800 PRO base at about 4 feet above ground, 8 feet of extension shafts, the capacity hat, and finally a 6 foot whip section (the two 3 foot whip sections with a coupler from Jim Heath). This made the antenna about 17 feet in length, with the top height about 21 feet above ground. The antenna was resonant slightly below 14 Mhz with the HS-1800 PRO fully retracted. An LDG Z-100 tuner took care of this situation, and gave us 20m so we could operate 17m with the small Sigma 5 Vertical Dipole (which had to be taken down at night due to the T-Bars). I had anticipated that 30m would end up being the "Money Band" for us on the Expedition, and had optimized the antenna accordingly. On 10.115 my MFJ-259 read 1.0:1 SWR, 50 Ohms & ZERO reactance. Minimal base loading via the HS-1800 PRO was necessary to make the remote control adjustment from the fully retracted 20m settings. Unfortunately, 30m condx turned out to be a bust, however the antenna also worked great on 40m AND 20m in spite of fairly poor condx. Working some Europerans on 40m from the Island was a thrill. The HS-1800 PRO performed flawlessly with all our remote controlled up and down coil adjustments as needed during band changes. To some, the Farallon Special may seem a bit like a "Rube Goldberg" mish-mash. The setup in my driveway involved just letting the 16 shortened radials "dangle" to the ground. However, as one of the final pre-expedition tests, I called a VU2 on 40m in the afternooon daylight hours with 100 watts and worked him LONG PATH. That was good enough for me...the antenna ROCKED!!! Jim Heath at High Sierra Antennas was great to work with, and I'm pleased to say I've now purchased an HS-1800 PRO so I can continue to put the "Farallon Special" configuration to use in other scenarios. The HS-1800 PRO will most likely end up being used on my SUV in some "unique" type of mobile use as well :-)    
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