Questions tagged [toroid]

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5
votes
1answer
954 views

How to build a balun transformer for 2m RX with low insertion loss

I'm looking into ways to match a 137MHz RX dipole antenna to an unbalanced coax + amplifier. I know there are several types of baluns which can be categorized under magnetic baluns (where there are ...
5
votes
1answer
339 views

How do I evaluate and use a toroidial core for my HF double-balanced mixer?

Last year, I planned to make a double-balanced mixer covering the entire 3-30 MHz band as an upconverter for my RTL-SDR receiver, mainly for learning RF circuits and ham radio. Naturally, it requires ...
23
votes
3answers
33k views

Why are some 1:1 current baluns twice as complicated as others?

I would like to add a balun/choke to my dipole for the reasons outlined in Using a balun with a resonant dipole. In the spirit of continued kit and/or DIY building for my ham shack, I set out to ...
9
votes
2answers
4k views

Does a balun need to be made with coax?

The short version My understanding is that one of the main reasons to use a balun with coax is to prevent the outside of the shield from becoming part of your antenna system. If that's the case, won'...
3
votes
2answers
340 views

Why don't baluns require precise conductor spacing as in twin-lead?

This is a follow up to another recent question of mine: Does a balun need to be made with coax? In that question, we establish that a choke balun doesn't actually work by protecting the "third ...
8
votes
1answer
881 views

What's this “crossover” toroid winding called and what is its purpose?

I am winding an EFHW matchbox and many of the designs I've found (including the diagram provided with the kit I bought) include a sort of "twist" when winding them: (Image taken from this post and ...