It's a bit of an animal - actually, it's a lot of an animal - A 1:1 Balun for use on HF (1.8-30MHz) that easily handles 400w RF power (full-duty cycle). Ideal for Dipoles at the home QTH. We don't cut corners: This balun is wound on an FT240-31 ferrite core offering resistive performance 3.5MHz up to 30MHz so a perfect companion for your resonant HF aerial or fan-dipole. At resonance, this balun is good for around 1kW CW/Datamodes.
160m/80m : If you intend to use this Choke mostly below 15MHz, we can supply it with 12 turns instead of the usual 8. This gives improved choking performance on the lower bands but it can still be used across the whole of HF. Please note that this is a custom option and will add 24 hours to the delivery time.
USE WITH : Resonant Dipole
We also have a Doublet/G5RV Choke, using the same internal configuration, but with the terminals at the top of the box.
Baluns - What/Why?
It's good practice to put a Bal(anced)Un(balanced) where coax meets aerial or balanced-feeder. A Balun will help prevent "common-mode current" on the outer of the coaxial braid - This is vital to ensure that RF does not flow down the coax, turn it into part of the antenna system and give you "RF in the Shack". Using a 1:1 Current Balun at the junction of balanced-feeder+coax is also recommended.
We do not advise the use of "ugly chokes" (air-cored coils of coax) for use at HF - these do not offer a consistent choking impedance and, in some cases, can actually increase common-mode current! Simply put - Use a 43 or 31 mix ferrite toroid and a coax of a suitable power rating. At VHF, a few turns of coax is perfectly adequate - for 50MHz/70MHz, Aerial Parts of Colchester offer a ready-made choke for a yagi.