49:1 vs 64:1 Unun

[Buick Mackane]

Was thinking of trying out a 64:1 unun, Currently using a 49:1, Any benefits of using a 64:1 unun verses a 49:1 ?



Cheers

[ch25]

No one knows what ratio wire you are using needs.
Measure it with 49:1 and than you will know which one would do better job.

Basically for antennas hanging lower than 5m 64:1 should be better, especially below 10MHz.

[Buick Mackane]

No one knows what ratio wire you are using needs.
Measure it and than you will know which one would do better job.

Was thinking of buying one lemmy, Don't have any info regarding it, Wire / core type etc

[ch25]

Sure thing:
https://squashpractice.com/2021/07/20/e ... d-antenna/
https://squashpractice.com/2021/06/23/p ... nsformers/

What would be max transmitted power through that?

[Buick Mackane]

Sure thing:
https://squashpractice.com/2021/07/20/e ... d-antenna/
https://squashpractice.com/2021/06/23/p ... nsformers/

What would be max transmitted power through that?

Cheers for the links

50w max power

[Buick Mackane]

Basically for antennas hanging lower than 5m 64:1 should be better, especially below 10MHz.

It's approximately 5m high

[ch25]

If you are on stage of choosing antenna, I suggest to try Windom instead.

[Buick Mackane]

I'm just experimenting lemmy, Was going to buy a pre-made transformer, But i'll just make one for a fraction of the price, I'll report back with my findings

[Buick Mackane]

Got the transformer wound, Toroid is a FT-140-43, I only run 50 watts, Here it is under a bench test with approx 3.400 ohms on the output, Looks good to me, Waiting on the enclosure, Will get it set up over the weekend.

[Buick Mackane]

Well that turned out to be a waste of the best part of a day Everything that could have gone wrong did go wrong, You know the kind of job you wish you hadn't started, Ended up having to take the antenna down to swap the transformer,

The 64.1 unun tuned fine on 40m & 15m, on 10m and 20m was slightly over a 2:1 SWR, Sometimes if things work leave well alone, Anyhow swapped back over to the 49:1 unun and i'm good on all bands again,

I'll probably end up rewinding it to a 49:1 and keep it as a spare

[Whisky1]

Nothing worse than spending a day and not getting out of the starting blocks mate, I don't know why we do that

[Alan Pilot]

I count 16 turns in that picture ??.

[Buick Mackane]

I count 16 turns in that picture ??.

You certainly do

[paulears]

Surely the entire point of these things is to take the physics and use it to improve something that needs improving? The skill of learning the measurement system you have available, them repeated adjustments to maximise performance and solve your problem. What I mean is that they are problem solvers. You have an issue that needs fixing. You identify what is is, then you make exactly the right thing. If it doesn’t do what you expect, you tweak it. Maybe taking a turn off or adding one, testing and responding. Nipping a pair of wires up, or gently pulling them apart. Many people have less good construction skills, but antennas are mechanical so it’s something to learn on, with bigger soldering irons and drills, not micro heat irons and microscopes. Buying something, trying it, returning it, buying another etc etc is not the way to do it, in my humble view because without a few different ones sitting there, how can you even test? Waiting for the postman and a different day different atmospheric conditions and even different weather wrecks your judgement.

It’s like buying a car quarter wave you had the supplier pre-cut, and then buying another a bit shorter or longer from a different dealer. What are we talking about here? A transformer? I bet if you buy three the same, they all measure differently. Impedance has components that change depending on so many things. Add turns and things happen. Look at the images of turns on a core. Some are closer than others. Would evening them up change things much? Probably!