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From: Jef verborgt
Date: 28 Mar 2002
Time: 23:53:34
Remote Name: 152.163.197.76
Just had a look at the Barret website and from the looks one can see that there must be quite a big coil in the base of the antenna.They claim an active network so there must be some relais and capacitors as well. Have a look as well at the moonraker ( australian as well) web site and the Wimo antennes website. They sell ferrite fixed ratio transformers with a whip length of 6,3 meters and that seems to cover most of the ham bands with an acceptable SWR, usually below 3. So there are no moving parts here but there is also no black magic required to explain how they work.I have been experimentng with different ferrite materials and came up with some very promising results and a very flat SWR. This is a most interesting field to experiment and lots of things still can be discovered or optimalized. Some years ago I did buy a unit from " Match all " It worked reasonably well but the signal was down and when I opened it up it did contain a ferrite core and a 300 ohm precision resistor. I guess that the balun was a six to one ratio balun and that the antenna wire was connected straight to the resistor. I think that you can do a lot better with some experimenting. Adding a resistor is of course not the way to go.