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endfed_40m [2022/10/02 12:21] – created tonendfed_40m [2026/02/06 09:39] (current) – external edit 127.0.0.1
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 ======Endfed 40/20/10M====== ======Endfed 40/20/10M======
 \\ \\
 +|Manufacturer|Tonnie ;)| 
 +|Type|End fed with adapting coil, 40M/20M/10M| 
 +|Operating frequency|7MHz, 14MHz, 28MHz| 
 +|Gain|Typical 2.15-5dB|\\
 This endfed was built from scretch, with a 1:49 balun to attach the balanced endfed wire to the unbalanced coax.\\ This endfed was built from scretch, with a 1:49 balun to attach the balanced endfed wire to the unbalanced coax.\\
 The antenna was built using the diagrams from [[https://www.hfkits.nl/beschrijving-mini-aanpassingstrafo-end-fed-antenne/|HFKits]] where I bought the balun kit from.\\ The antenna was built using the diagrams from [[https://www.hfkits.nl/beschrijving-mini-aanpassingstrafo-end-fed-antenne/|HFKits]] where I bought the balun kit from.\\
 +
 +Enough said, measurement time.
 +{{:ef_1-30mhz.png?600|}}\\
 +The antenna resonates but just outside of my intended range, it looks like 7.7MHz, 14.5MHz ans 27.8MHz. Lets take a closer look:\\
 +{{:ef_7-7_2mhz.png?600|}}\\
 +The range for the 40M band is not good, a SWR of 1:5.5 sucks pretty hard.\\
 +{{:ef_14-14_25mhz.png?600|}}\\
 +20M is a bit better, from 2.1 to 1.7 so doable. Still no good, an ATU should be used.\\
 +{{:ef_28-29_7mhz.png?600|}}\\
 +10M is pretty good, starting at 1:1.07 and ending at 1:1.7 so the 10M band is covered as-is.\\
 +\\
 +Some people reccomend a counterpoise, so I modified the balun to accept one and tested again:\\
 +{{:ef_cp_1-30mhz.png?600|}}\\
 +No real shift over the band, just that 10M doesn't dip as deep.\\
 +{{:ef_cp_7-7_2mhz.png?600|}}\\
 +Resonant frequency shifted even further up, so the SWR is even worse than without.\\
 +{{:ef_cp_14-14_25mhz.png?600|}}\\
 +SWR for the 20M went to 1:2 to 1:1.6, a bit better.\\
 +{{:ef_cp_28-29_7mhz.png?600|}}\\
 +10M didn't get any better, but is still OK.\\
 +\\
 +Conclusion must be that the antenna is too short. I'll try lengthening the part after the coil first since that is the part used for 40 and 20 meters, hoping to get it to resonate at least arount 7.1MHz, dead-center 40M hoping that brings the 20m also more in range. 10M is a plus but not enough to care for (Yet) since I think I'll be active on the 40 and 20M bands mostly.
  
endfed_40m.1664713282.txt.gz · Last modified: (external edit)