On the heels of the Wolf River Coil DIY tripod rebuild, comes the Spider Antenna. Invented and patented at the time by Fred Smitka, K6AQI, out of California, the Spider Antenna was created and sold in the early 80’s. It is by design a mobile antenna designed to take advantage of the ground plane a vehicle can provide. But since I had just reworked my tripod for the WRC, I made a few adjustments so that I could also connect the Spider Antenna and take advantage of the radials I had already created for the WRC. And it works! Sort of. More on that in a moment…
Where the WRC is a bottom loaded vertical, the Spider Antenna is a top loaded vertical. This blast from the past was picked up in a Craigslist buy several years ago. I was looking to upgrade a dipole from my then G5RV Jr. When I arrived to purchase a DC-CC fan dipole I was greeted with a pile of various antennas. There were a couple of wire dipoles, a rigid Cushcraft D3 20-15-10 rotatable dipole, what looked like at least a pair of “chimney sweep” MFJ antennas with all manner of missing parts, and maybe one other antenna worth of parts I never did figure out. But, there was also a cardboard tube that contained this odd looking antenna system that is known as a Spider Antenna. The seller was more than happy to see the entire pile leave. Their trash became my treasure.
So what is this thing? In simple terms, the Spider antenna is a top loaded vertical. Unlike the coil antennas we are accustomed to seeing, where you have 1 coil, and then you tap the coil for the band you wish to operate on, the Spider Antenna has a 5′ metal mast, with a fitting at the top for up to 4 individual coils. There is a separate coil for each band. The coils come in bands 80-10. The one catch is that 80, and 40, can only go on top. So you cannot for instance have 40 and 80 on at the same time. But you could do 40, 20, 17, and 15 if you like, or whatever combo you wish. What was really cool about this find was that it was a complete set of coils for 80-10 meters. bands!
To tune the antenna, over each coil is a ferrite that you slide up or down the coil until it is resonant where you want it within the band. As the bandwidth can be a bit narrow on 40/80, you will have to adjust to which end of the band. What is also remarkable is that after 36 years, this antenna still seems just fine. The antenna is rated to easily be able to handle 200 watts. And I even found a review online from Gordan West that claims he ran a Magnus 800 watt amplifier through the Spider Antenna and it worked just fine.
The entire antenna is of quite high quality construction. Normally, as we have experienced, plastic coatings break down over time. The materials on the Spider Antenna have held up very well. Each coil is of rigid fiberglass construction.
Setting it up in the back yard and using my Nano VNA, I was able to bring adjust each coil in just a few minutes. I hooked up my KX3, but was only on battery so output power was quite low, but I was able to receive quite well. I will have to connect to the TS-440 and do an A/B test and post an update.