FT240-43 Torriod based on the W1JR design


Email for availability

 W1JR-FT240-43-Balun.jpg  mounting_kit.jpg

 Balun With Out Mounting Kit £55.00

 Balun With Mounting Kit £62.50


FT240-43 Torriod based on the W1JR design

This form of choke is referred to as an Inline-Isolation Balun. Design is quite simple. 70cm of RG-142 high power coax coiled 8 times round a FT240-43 Toroid housed in a waterproof box and potted with Polyester resin. Termination is a chassis-mount SO-239 on opposite ends of the box.

Balun is tested with full UK power limit due to power restrictions; under perfect 1:1 SWR conditions the FT-240 can handle 1KW of power.

In-line Isolation Balun consists of

  • 10cm x 10cm x 5cm UV resistant Box
  • 1 x FT240-43 Torriod core
  • RG-142 high power Teflon Coax or similar
  • 2 x SO-239 Chassis Mounted Sockets
  • All fixing hardware stainless steel
  • Potted for 100% WX proofing
  • Feed at lowest band, E.G. 20m


Make your own balun

1:1 Balun Options

Steve G3TXQ has done a lot of research on the use of different types of cores and air cored ferrites, the results can be seen on the chart below. For a link direct to his page please click here

The two types I refer to within this site are the 8T RG58 on FT240-43 but substituting the RG58 for RG142. Also the 6 x FB-31-1020 on RG213. There are many other ways listed on Steve's list below and more info can be found on his site.






Contact Us

Contact Ant MW0JZE

Manufacturing Hexbeams Since July 2009

G3TXQ Hexbeams Trading as Hexbeam UK since 31st March 2013

45 Amanwy Bryn Llanelli SA14 9AH

+44 (0)1554 785 002

Connect With Us



Payment Methods

payment methods

Joomla! Debug Console


Profile Information

Memory Usage

Database Queries