I've got one of his normal 5/8's here given to me exactly the same as in them photos but without the second length on the top.
It's not base fed as such as it has a stub at the bottom, you make it longer as you lower the freq, however I can tell you it's now swr'ing in and I cannot get 50ohm on it for the life of me.
When I 'attempt' to make a 5/8 I always measure out my 5/8 section and the put a coil at the bottom of it so that electrically it appears to be 3/4 wavelength, this has always matched nicer to 50ohm for me.

That's the right way to do it. I used to make my ⅝-wave job electrically ¾-wave then bend the groundplanes downward to get to a 50Ω resistive match. I experimented with all sorts of groundplane configurations and sizes, but found that the useful minimum for groundplanes that do anything useful is to have three ¼-wave ones, but the ultimate was to have a ¼-wave cone! Plotting the radiation pattern, I found that the gain was closer than ever to its theoretical figure using the cone. However, making and mounting the damn thing was a massive hassle, and wasn't actually worth the extra effort! One interesting thing I tried - partially to prove to an "expert" that the loading coil didn't radiate - I put the loading coil inside the cone, and the results were just the same!

I had endless trouble matching ⅜-wave aerials. These should show significant improvement over a ¼-wave, but because of the matching trouble, they didn't really work for me. Then I found an article in QSL about the .64-wave aerial.....

Matched correctly, a .64 vertical gives the best radiation pattern you can get with a single element. It's only marginally longer than the ⅝-wave, but I was surprised by the increase in the low angle radiation. If you have a really high site, this will give you more low-angle radiation - instead of 23° you get 15°: The results are significant: 4dBd which is a useful power gain without building a bigger PA! It's possible to build these without groundplanes, but you then need a big feed capacitor. I made a sliding-sleeve matcher which worked well, but again was more hassle than it was worth.

You can just use the dimensions for the usual ⅝-wave, then add a bit to the radiator, and remove a turn or two from the matching coil to get it going. I was surprised by the improvement in coverage at distance.

https://www.ebay.co.uk/itm/322430641266

Looks like he's advertising 200w systems as 500w erp. Very misleading to a newbie.

Edit: looks like someone else selling it second hand.


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