What the hell am i missing here ?

[Transwarp]

Well running a few more tests it seems like its providing a lot of isolation. If i touch the coax where it enters the choke i get SWR variations. Touching it where it leaves the choke the SWR is rock solid indicating common mode on the line and that's with a bought choke installed just down from the feed point. When i get time and a dry day i'll install it near the feed point and see how it performs

Home made - 1 : shop bought - 0

So what you can do now is go and buy a load of ferrite rings, cable etc and start making decent 1:1 baluns / chokes and flog em'

A new hobby for ya and a bit of side hustle to boot

[Transwarp]

If mounting the choke in a sealed box for outside use drill a hole in the bottom of the box that faces down and glue a piece of fine mesh over it to allow moisture to get out and stop bugs getting in. Biggest issue with is corrosion of the wire, rain is a bugger.

[Buick Mackane]

Well now i know the choke is effective Ive ordered more suitable wire to rewind it with. The mains cable is a bit of a tight fit with some turns not fully seated against the core. With the correct wire it should perform even better..

[Buick Mackane]

I placed the choke near the feed point of the end fed just as test. It doesn't half reduce my noise floor. Because the internal coax is no longer radiating and picking up stray RF from inside the house. Although it has put the SWR up on the higher bands now that the coax isn't part of the antenna with the choke in place. Will see how it performs when properly wound with the correct wire

[Transwarp]

You can put one near the feed point and one in the shack also. Just beware of over-choking though, an overwound ferrite for instance is no good at all, and different winding techniques produce different results just the same as wire / cable types do.

[Buick Mackane]

Just added a compensation coil to pull the harmonic bands down as they were way too high. That's done the trick. But annoyingly i'm still waiting on the wire to wind the choke. Was hoping to wrap things up today

[Buick Mackane]

What a stinking infuriatingly frustrating job that was rewinding the choke. No joke. Right i ordered and wound it with 20 AWG silicon wire. Rated at 600 volts and 200c temp. If anybody reading this makes one be careful of the wire gauge you choose. Too thick you won't be able fit enough turns on. Too thin it will break and won't handle the current load.. The wire i used is OD 1.9mm

Youtuber TRX lab has lots of great videos about chokes / baluns. He uses 18 AWG PTFE wire. But wire can differ according to the thickness of the insulation. A few times i thought i'd cracked it only to discover a crossover in one of the turns. So had to start again. Then when you only have a few turns to go you realise they won't fit. And yup had to start again keeping the windings tighter to give me more space. Ball bursting!!!

On a dummy load its 1.1 from 160m to 6m. Here is the SWR readings with it installed..

20m - 1.05 to 1.24
15m - 1.48 to 1.33
40m - 1.12 to 1.37

No tune on 10m (Lowest 2.0)

But my commercial transformer never did tune on 10m. SWR on the other bands is rock solid. Doesn't vary when i touch the coax so zero common mode

The 'Harmonic Resonator' coil done the job of bringing the high bands into range. The insulation on Silicon wire is fragile and found the cores edges were cutting into it so covered the core in self amalgamating tape. Not ideal but all i had. Should be plumbers tape. I don't run high power levels so not concerned

Like i say be careful of the wire Gauge you choose if you build one of these

[Transwarp]

Looks fine, good job, and does what its supposed too. Worth the effort and time imo

[Buick Mackane]

Its not as neat as some ive seen. But i found it a right pig to wind. Likely due to arthritis in my hands. Main thing is it works

[Transwarp]

Its not as neat as some ive seen. But i found it a right pig to wind. Likely due to arthritis in my hands. Main thing is it works

Aye, they're a fiddle to wind with wire, twin wire more so, coax of course is easier. From my understanding though the best results / performance seems to be from using wire instead of coax and your own tests and results suggest that's the case.

I guess using enameled wire makes it a bit easier for winding, however the fact you mentioned having to make the windings tight - by pulling wire tight - thus rough edges of the core potentially breaching the insulation of by doing so, makes me think same could happen to enameled wire, although it's pretty tough coating.

I'm thinking why ferrites arent't made like a doughnut instead so as to eliminate rough edges.

[Buick Mackane]

Maybe something to do with the way they work. Inductance etc. Its also knocked an S point or 2 off my noise floor. At least i know what wire etc to use if i ever build one again. Hard to believe hams pay upwards of £50 for these. Luckily i already had the core and enclosure