Building a better End Fed Half Wave Antenna for Ham Radio?

Son, you're making my head hurt! Glad there are smart peeps out there to figure this stuff out; appreciate you're showing the process!

You're the one giving me wisdom. I like your deduction that your NanoVA wasn't providing sufficient current for inductive coupling. 73, KF0NNQ.

Looking foward to the revisit of this after testing

Well it might have to get a field test

It's all about the pronunciation. 😂 (Now all kidding aside...compare the image at 9:20 with the schematic of the Johnson Matchbox, and you'll see why this is the CORRECT placement of the capacitor.) Nye Viking knew exactly what they were doing. This is also why it is important to fact check designs against proven ones from decades ago. I can't tell you how many times I've seen schematics copied incorrectly and used that way in publication after publication. Always "trust but verify". PS, this UNUN can also be modeled in SimSmith for those who wish to take it to the next level. 7

That twisted primary is where they get you!

Impedence matching. When matched you have maximum energy transfer. Look at the impedence on the VNA, and not so much the SWR. The transformer-cap--reactors--are the transmission between the radio engine and the rear wheels antenna. Get a thermal camera and "see" where the RF power gets used up-hot cores- indicate poor matching and or improper core material composition.

You're such a great buddy, buddy!

Looking forward to what you find. Cool design.

That is some fine material to digest. I think you are correct that you are not getting enough current through the system for the coupling to take place. I would think with the capacitor across the secondary it should bring the high bands closer in VSWR to the lower bands. Really cool discussion. This is why the CaRH folks and their best teaching channels out there. Bravo

That looks a bit like the unun design that is described by the guys at ocfmasters as well... I've built one and just haven't got it hung up yet to test 😁

Great topic. Hallelujah, where's the Tylenol

Snow blowing will have to wait for now. Time to go the bench and slap on some caps on the secondary’s and have some fun. Thanks ape for the fun and practical videos.

It will be interesting to see the test under load results. I had forgotten about AA5TB's site. Lots of good information there!

NanoVNA output power is somewhere around -9dBm. The bigger commercial benchtop units are around 0-15 dBm. You might need to step up to one of the big boys now 😜

This is what I call an "isolation transformer", you get extreme amounts of common mode rejection. I use 5 turns : 5 turns to couple signals into my SDR this way, it is very lossy but can do good things for your receive. This transformer is similar to the LoG antenna transformer. I'll build one of these up and post the results on discord.

Yes I played with this type of windings. It seemed to tune up very easily 80 -10m with some very low swr in the right places but would get fairly warm at just 50 watts

I have built several of the efhw antennas without adding a capacitor (there is probably some inevitable capacitance created by wraps of the coils). It doesn't seem to make a lot of difference from what I've seen. Thanks for sharing! 73- AA4K

Fuchin good video.

Interesting and informative on the detail you guys put into your products. MM0OPX has a good design, and I’m keen to try your one. Bit of an antenna farm going on around my property now.