What
Balun / Ferrite ?
We're often asked what type of Balun or UnUn is
required for a given situation along with questions about Ferrite Toroids,
their mix-types and how many turns are needed.
Much of this information can be found on the respective
product pages although this selection page serves as a quick+simple way to get
to the best solution for your needs.
Build vs Buy - Why?
Amateur Radio is, after all, a technical hobby that encourages construction
where possible - but this isn't always practical with some projects. You
may have to purchase more materials than you need to make it cost-effective, you
may not have the suitable tools, space or equipment required to build+test.
Winding 8-12 turns (especially RG142 coax) around a toroid is more of a physical
skill than a technical one - and you'll know exactly how after you try it for
the first time!
Just what is inside that box? Does it say? Does the seller know? One size doesn't always fit all solutions - and this is why we have a few Balun options plus this page to help you decide.
Baluns and UnUns
My aerial is a coax-fed Dipole for
a single band (but I might use an ATU on other bands) with up to 100-watts
100-watt 1:1 Balun
My aerial is a coax-fed Dipole for a single
band (but I might use an ATU on other bands) and I'm using more than 100-watts
400-watt
Dipole Balun
My aerial is a Doublet (fed with balanced
line) or is a G5RV - I'll be using up to 100-watts across the whole of HF
100-watt 1:1 Balun
My aerial is a Doublet (fed with balanced
line) or is a G5RV - I'll be using up to 1000-watts and/or
operating mostly below 15MHz
400-watt
Choke Balun for ATU/G5RV
My aerial is an off-centre-fed Dipole
4:1 Current Balun
My aerial is a full-wave loop
2:1 Loop Balun
/ 4:1 Current Balun
My aerial is a random end-fed wire which
I'll use an ATU to deal with - max 250-watts
9:1 UnUn
My aerial is a half-wave wire or I have
a 20m/40m of garden - max
250-watts
End-Fed
Halfwave Coupler
Ferrite Toroids
Home-brew is a great way to get exactly what
you want from a project as well as learning along the way.
We sell a range
of ferrite toroids than can be wound with either
RG316,
RG142, RG58,
Mini8 etc to form a Choke Balun.
Frequency | Power |
Application |
Solution - best for QRP |
1.8-30MHz | 25-watts |
Balun or Choke |
FT68-43 / FT114-31, 8-turns |
Frequency | Power |
Application |
Solution |
1.8-30MHz | 100-watts |
Balun or Choke |
FT114-31, 8-turns |
Frequency | Power |
Application |
Solution |
5-30MHz | 100-watts |
Balun or Choke |
FT140-43, 8-turns |
Frequency | Power |
Application |
Solution - best for <10MHz |
1.8-10MHz |
100-watts 1000-watts |
Balun or Choke |
FT240-75, 8-turns 2x FT240-75, 8-turns |
Frequency | Power |
Application |
Solution - best "all rounder" |
3.5-30MHz 1.8-30MHz |
1000-watts |
Balun or Choke |
FT240-31, 8-turns FT240-31, 12-turns |
Frequency | Power |
Application |
Solution |
5-30MHz | 1000-watts |
Balun or Choke |
FT240-43, 8-turns |
Frequency | Power |
Application |
Solution |
1.8-30MHz |
250-watts 1000-watts |
End-Fed Coupler |
FT240-43 FT240-43 |
Frequency | Power |
Application |
Solution |
3.5-30MHz 1.8-30MHz |
250-watts 500-watts |
UnUn |
FT240-61 2x FT240-61 |
Our Ferrite Toroid comparison chart may also help you decide:
Here's a line-graph we made using data from Fair-Rite based on a single ferrite bead. This outlines the typical Resistance of each type of Ferrite mix over a range of frequencies. This data serves as a simple visual guide rather than a definitive answer to "What type do I need?"...
Although this is quite a basic plot, a longer look will show that a 31-mix offers the best "all-round" solution unless you have a specific frequency range in mind. Bear in mind that with 2.4" ferrites, the Resistance will (hopefully) be >1500-ohms and differences between ferrite types will be greater than the few Ohms you see here!
[this page was last updated Thursday September 21, 2023]