[bars] Torroid

[Leandra MacLennan]

Kristie:

Not a problem. The glued double toroids will work fine. The two toroids do not need to physically touch each other, they just need to be close to each other.

You’re building a toroid transformer. Transformers work by changing electrical energy to magnetic energy then back to electrical energy. The toroids do a very good job of coupling the magnetic energy from one winding to the other winding. Magnetic energy can jump over small physical gaps, so your double glued toroid, from a magnetic point of view, will look like a single large toroid that is double the size of each of the two glued toroids.

For magnetic energy, think of a toroid or any ferrite material as if it were copper wire for electrical current. Magnetic energy travels well through a ferrite material.
For magnetic energy, traveling through air is like electrical current going through a very high resistance resistor. Magnetic energy will travel through air, but not very well. I don’t have the exact figure for the magnetic “resistance”, but think of it as the equivalent of “X ohms per inch” (I think for magnetic energy traveling through air the “resistance” increases as a squared or cubed value of distance – it goes up very fast).
You have tiny air gap between the toroids. Yes it is an air (glue) gap, but a very short distance, so the magnetic “resistance” between the toroids will be a very small number, and effectively the two glued toroids will look like a larger one.

The only issues you may have would be thermal. The ferrite material will get warm from the energy that is passing through it, so there could be some physical expansion of the toroids, which could break the glue bonds.
Or, if the toroids get very hot they could melt the glue. You could wrap your windings tightly so even if the glue breaks the two toroids will remain close to each other.

To prevent overheating the toroids, do not use high power for high SWR conditions. The double toriods should be able to handle 100 watts for normal SWR less than 3:1. If you try to use the antenna on a band it is not designed for, be very conservative with the power you send to the antenna. If you use a tuner to use the antenna on a band it was not designed for, my recommendation is to limit your power to less than 25 watts continuous for SWR greater than 3:1.

   -Leandra  AF1R

From: bars <bars-bounces at w1hh.org> On Behalf Of Kristie Connolly via bars
Sent: Sunday, February 2, 2025 8:58 PM
To: W1hh <bars at w1hh.org>
Subject: [bars] Torroid

This is my post  i wanted to ask the same question here if I may
[Inline image]



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