Low power Guanella 1:1 tuner balun using a pair of Fair-rite 2643625102 suppression sleeves

A reader of Low power Guanella 1:1 tuner balun using a pair of Jaycar LF1260 suppression sleeves asked whether there is an equivalent Fair-rite core for the project.

Fair-rite part 2643625102 (~$4 each from Element14) is of similar size and also medium µ, but slightly different characteristic to the LF1260. Continue reading Low power Guanella 1:1 tuner balun using a pair of Fair-rite 2643625102 suppression sleeves

Baluns – show me the numbers

Hams talk at length about baluns but rarely in quantitative terms.

A quotation from Lord Kelvin is most appropriate: When you can measure what you are speaking about, and express it in numbers, you know something about it. But when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. It may be the beginning of knowledge but you have scarcely in your thoughts advanced to the state of science. Continue reading Baluns – show me the numbers

Why the preference for Guanella 1:1 current baluns for HF wire antennas

I am often asked why I recommend a Guanella 1:1 balun with high choking impedance for most HF wire antennas over voltage baluns and 4:1 current baluns. This article explores the topic using SPICE models for a voltage balun, 1:1 current balun, and 4:1 current balun. Continue reading Why the preference for Guanella 1:1 current baluns for HF wire antennas

Spoiling balun action with ‘shielded twin’

In a QST column in 2008, a correspondent asked the question

… I have the ladder line terminated to double coaxes that run about 12′ (4m) inside the house to an antenna tuner. Should this pair of coaxes be grounded at one end or both ends?

ShieldedTwin

The Doctor gave a detailed diagram (above) and his advice was… Continue reading Spoiling balun action with ‘shielded twin’

OCF dipoles

Off centre fed (OCF) dipoles are very popular with Hams on HF.

Many claims are made for variations of the theme, but the essential common feature is that the offset feed point provides a feed point impedance that is not too unsuited to 50Ω coaxial feed line at the fundamental resonance of the dipole and half wave harmonics. Continue reading OCF dipoles