Category Archives: Antennas, Baluns and EMC

Steve Hunt, G3TXQ – In Memoriam

G3TXQ was well known and respected throughout the technical world of Amateur Radio, through his website and countless postings to a wide range of groups and mailing lists. Always meticulous and deep-thinking, Steve was a fount of good information – and also a very nice guy.

Steve passed away peacefully on 30th December 2018 after a long battle with cancer, which he also recorded in that same meticulous manner.

G3TXQ is known particularly for his optimized versions of the Cobweb and Hexbeam antennas, and for his work on common-mode chokes. His website karinya.net is already archived at https://web.archive.org/web/20180428131952/http://karinya.net/
and if you haven’t already visited, I strongly recommend it. Take the tour, and you will meet the man he was.

Common Mode RF Chokes

G3TXQ-X

In addition to the material on his website about common-mode chokes, in 2015 Steve wrote a stand-alone article for RSGB’s online technical magazine RadCom Plus.  That article is in danger of falling into obscurity, taking with it some new information that has not been published anywhere else, so I am archiving it here in memory of Steve:

Common Mode Chokes: G3TXQ 2015

The article included a new version of Steve’s famous graphic to help in selecting broadband ferrite chokes to cover various HF amateur bands. The best chokes are the ones that cover the required band(s) with both the dark green shading and the black underline. Orange and red shading are to be avoided – the choke may do some good, but may also have problems. (For clarity, I have added a large ‘X‘ across the three chokes at the bottom. As Steve explains, those were included as particularly BAD examples, NOT to be copied.)

Writing this is not the way I’d hoped to begin a New Year’s Morning.
RIP, Steve.

 

VHF-UHF Baluns

This is the talk that I presented at the RSGB Convention in October 2018.

RSGB will eventually release a video of the talk, but in the interest of publishing the technical content as soon as possible, you’re very welcome to download and click through the slideshow.

Even without the voiceover, the important points are clear:

  • Today, “baluns” are about controlling interference, reducing noise
  • Choke baluns are best for doing this.

So we should aim to:

  • Minimize common-mode RF currents on the outside of the coax
    and along the boom.
  • Don’t upset the good feedpoint balance that VHF-UHF Yagis already have.

Comments and discussion, please!  This is new information for VHF-UHF, and certainly not the last words to be said about it. It’s still very much ‘work in progress’.
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Technical slide content © 2018 Ian White, GM3SEK
Slide template © 2018 RSGB
Images as attributed (except where that would be embarrassing).