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Am effective multi-band antenna for 80m through 10m
I've used this simple antenna from multiple locations to make DX QSOs in CW, RTTY, PSK, and Phone on 80m through 10m; given FT8's superior sensitivity, it should work even better with this relatively new mode.
DJ0IP's web page provides a nice picture and description:
Like DJ0IP, I first learned of this antenna from Lew McCoy W1ICP (SK); I refer to it as a "McCoy Zepp".
For feed-line, I use 300 ohm TV twin-lead from the center of the antenna to a balanced tuner next to my transceiver. Start with ~10 feet more than you need (see below). Keep the feed-line away from metal.
The ends of this antenna can reach high voltages, so use egg insulators. For mechanical robustness, also use an egg insulator in the center.
I use a MFJ-901B tuner, which has "balanced" connectors on its back panel. In my experience, Its internal balun works well.
A classic Johnson Matchbox (often available at flea markets) will work even better.
If you like, you can home-brew a balanced tuner:
You can use a fiberglass pole to support the center of the antenna, but I've generally used a slingshot and fishing sinker to project fishing line over a high tree branch, which I've then used to pull up a rope robust enough to pull up the center of the antenna. Higher is better!
As DJ0IP notes, the ends of the antenna can be similarly raised, or can be closer to the ground in an "inverted Vee" configuration; this antenna can develop high voltages at its endpoints, so keep those endpoints at least 10' off above the ground so they are out of everyone's reach.
After deploying the antenna, connect your tuner to your transceiver's antenna connector with a short length of 50 ohm coax. Reduce your transceiver's RF output power to a few watts, and by trial-and-error find tuner settings for each band that yield an acceptable standing wave ratio (SWR), meaning that most of your transceiver's RF output power is being radiated by the antenna (as opposed to being dissipated by heating in the feed-line!) If your transceiver doesn't include an SWR readout, you'll need an SWR meter.
Often, you'll find more than one set of tuner settings that produce a nice dip in SWR, so don't stop with the first set you encounter than yield an SWR of 2.0 or lower.
When you find optimal settings for a band, gradually increase your transmitter's RF output power to the maximum you plan to use while listening for arcing from the tuner. If arcing occurs, look for another set of tuner settings for that band.
I've generally found settings that yield an SWR of 1.5 or lower on each band, though sometimes this has required cutting 2 feet from the feedline; once, I had to repeat the "remove 2 feet" step twice to get a good match on all bands.
As DJ0IP notes, a half-size version of this antenna (33 foot segments) will work on all bands from 40m to 10m.
Note: there are alternatives to each of the MFJ equipment citations above. I included these citations to provide a representative picture and price range. MFJ tuners and meters have worked well for me. Online reviews of antenna tuners available here:
Some antenna tuners include an SWR meter.
Online reviews of SWR meters are available here:
There's nothing like making QSOs with an antenna that you built with your own two hands!
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