Solution for quick & easy POTA activations
In 2022 Wolf River Coils introduced their Sporty Forty coil. This product is designed to be used at the base of their 213-inch Collapsible Whip.
click to enlarge
The concept is simple:
• Use the whip alone for 20m and higher bands
• Add the coil at the base for 40m
I've calculated the Sporty Forty is about 9.5 µH to resonate at 7.0 MHz with an overall antenna length of 18.25 feet using a 213" whip and adding 6" for the coil.
Not surprisingly, it works well and is a reasonably cost-effective solution for POTA. You will still need a decent counterpoise, but you won't have to fiddle with the tuning ring that's on WRC's regular products. While an antenna analyzer can make the tuning process go a little faster, it isn't as necessary as with their Silver Bullet 1000 or SB Mini which can drive a person batshit crazy tuning up without one.
I do have several suggestions which will save you LOTS of time and frustration:
• Make sure your whip is long enough. As my friend Michael (KB9VBR) found out, Chameleon's 17-foot (204") whip isn't quite long enough, even for SSB. With the Sporty 40 you need 213" for the CW/Data lower end of the 40m band and a few inches less for SSB.
• Carry a spare whip. I'm not a huge fan of telescoping whips because they do not work well (if at all) when bent which can happen after being blown over a couple times. For that reason, I use a brass sectional military-style whip with my Wolf River Coil. But, you can't use a mil whip with the Sporty Forty because it doesn't collapse for tuning.
• Carry a short jumper with alligator clips on both ends to bypass the coil. This way you can switch from 40m to 20m just by adding the jumper instead of having to remove the coil. It's both simple and fast. Remember, this jumper will be part of the 20m antenna's overall length, so you will have to adjust the whip a little shorter than when using the whip alone without the jumpered coil.
Sporty Forty Deployed
UPDATE: Chameleon Antenna also sells a 40m coil, but the cost is more than twice WRC’s for similar CW & SSB power ratings.
UPDATE: Michael, KB9VBR, offers a video on his YouTube channel showing how to make your own coil for 40m. If you are handy, this would be an economical solution for adding a very useful band to your telescopic whip.
If you're handy, and happen to have a bunch of tent poles stashed in your camping gear, you can make my Tent Pole Vertical. It is basically the same antenna, but was FREE and fun to build. |
