Elecraft K2 Internal 4:1 balun

March 8th, 2009 by m0rgb

Whilst looking around at the various mods done to K2's I discovered the following balun.

It is a small efficient QRP balun designed some time ago by Charles Greene W1CG. see www.njqrp.org for further details, including full building instructions.

My K2 is setup on internal batteries with it's main goal to be a portable radio. As I use mainly doublets through a 4:1 balun I thought building this inside the K2 would suit my needs perfectly.

I purchased the toriods from www.qrpproject.de you can buy these ready made but I wanted to build it! The toriods purchase were Amidon FT82-43.

Main components used

Main components used

As I had already performed a mod to add a separate charging socket to my K2 I knew I would have to move this to allow me to add the balun.

The balun consists of two toriods wound with 6 turns on way, a cross over and 6 turns the other way. Then wired together to give 4:1

Winding was pretty easy compared to the many toroids in the K2 :-)

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Dipole Centres

January 12th, 2009 by g0vgs

As we are essentially a portable group, we are constantly trying to improve our techniques and equipment.  We were thinking about how to improve the way we use wire aerials and out of this discussion, Frank g8bme came up with this solution.


The one on the left in the above photograph is designed for use with a vertical.  The top bolt takes the vertical radiator and the side bolts take the radials.  The one on the right takes a standard dipole and both of them are really light.


The bottom of each box has a SO-239 for easy connection.  We have plans to improve the design at some time in the future.  We also have a dipole version with a wider white bar which can support 3 dipoles in a fan formation.  We used all these centres to really good use during our Jura dxpedition.

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