The Splice of Shame

[Disclaimer:  Any misadventures I have had with this antenna were purely my fault and, in no way, reflect on LNR and their excellent product.]

I bought the LNR EFT-10/20/40 trail-friendly end-fed halfwave (EFHW) antenna about a year and a half ago, after seeing one at Field Day.  It’s a great, portable antenna.  It packs up small and weighs hardly anything.  I often use non-resonant antennas because I like to work a variety of bands.  However, I always carry the LNR end-fed in my pack as a backup antenna.  The EFT requires some initial pruning before use.  This is where my misadventures start.

I don’t have enough real estate at home for antenna testing.  Instead, I did the initial pruning of the antenna while setting up for the Skeeter Hunt QRP contest in August of 2015.  Trimming an inch at a time was getting a little tedious for me.  I incorrectly estimated how much I needed to cut to have the antenna favor the CW section of 40 meters.  As you might guess, I screwed up and cut off too much.  Resonance was at about 7.110 MHz and frequencies below 7.023 MHz were outside the 2:1 SWR curve.  20 and 10 meters were fine, however.  I operated in the contest with no issues.

I resolved to correct my mistake and added that task to my “job jar,” where it languished for the next year and a half.  In the meantime, the antenna was used for numerous outings, including a National Parks on the Air (NPOTA) activation of the Appalachian Trail.  I just needed to avoid the bottom end of 40 meters.

Fast-forward to this past weekend.  I finally got around to doing something about the tuning of this antenna.  I had ordered some #26 Poly-STEALTH™ wire from the good folks at Davis RF.  First, I measured the top section of the antenna (from the top of the loading coil to the end of the antenna) in its current state.  Then I cut the wire about a foot or more from the end.  Since the splice wouldn’t fit through the holes in the end insulator, I wanted to keep the splice away from it.  I did this if I would ever want to re-tune the antenna for the phone section of 40 meters.  I next spliced on a piece of Poly-STEALTH™ wire that made the overall length about 2.5 inches longer than before.  After soldering the splice and applying some shrink tubing, I was ready to give it a test in the field.

The Splice of Shame. This is the splice I had to put onto my LNR EFT-10/20/40 EFHW antenna to correct my pruning error.

The Splice of Shame

I was out in central Pennsylvania over the weekend doing some babysitting for my grandson.  As I have done at this location before, I strung the EFT-10/20/40 from a second story window to a Jackite pole strapped to the fence in the backyard.  The antenna was roughly horizontal and up about 25 feet or so.  I wanted to make sure that the range from 7.000 MHz to 7.125 MHz fell within the 2:1 SWR bandwidth.  My antenna analyzer showed that it was just a bit long.

After I lowered the antenna and cut off a half-inch, the SWR was pretty much where I wanted it.  Now it was resonant around 7.040 MHz and the 2:1 SWR bandwidth spanned 7.000 to 7.130 MHz.  On 20 meters, the SWR was less than 1.5:1 across the band.  On 10 meters, the SWR was less than 2:1 across the band.  The SWR indicator on my KX3 confirmed the results.

Final 40M SWR plot for my LNR EFT-10/20/40 antenna. The 2:1 SWR curve covers 7.000 through 7.130 MHz

Final 40M SWR plot for my LNR EFT-10/20/40 antenna. The 2:1 SWR curve covers 7.000 through 7.130 MHz.

At one point, my inner obsessive-compulsive perfectionist said I could cut off another half-inch and make it better.  Fortunately, my practical side was able to resist and leave well enough alone.  As they say, perfect is the enemy of the good.  So, I declared victory and went on to make some nice CW and PSK-31 contacts with my properly tuned antenna.

The antenna works great but that splice will be a constant reminder of what happens when you rush things and try to cut corners.

72, Craig WB3GCK

Facebooktwittergoogle_pluspinterestmail
This entry was posted in Equipment and tagged , . Bookmark the permalink.