Re: 135ft flat-top with K2, KAT2, BL2, and 450 ohm feedline

Posted by Geoffrey Mackenzie-Kennedy-2 on Oct 01, 2006; 7:21pm
URL: http://elecraft.85.s1.nabble.com/135ft-flat-top-with-K2-KAT2-BL2-and-450-ohm-feedline-tp394239p394251.html

Perhaps Elecraft might like to consider adding an 'old fashioned' type of
balanced antenna tuner to their product range, with a balun at the
transmitter connection, to make it easier to match some types of antenna
system to the transmitter?  One that could be used outside and be remotely
controlled would be useful.

73,
Geoff
GM4ESD


Stephen W. Kercel AA4AK wrote:

> I'm guessing that the configuration that you propose could run you into
> all sorts of trouble on 80 M. The problem is that the 135 ft flat top
> would have low impedance, about 50 Ohms. The transmission line is
> disturbingly close to a quarter wavelength. A 450 Ohm line with an exact
> electrical quarter wavelength and a 50 Ohm load would have 4050 Ohms
> impedance at the transmitter end, and the KAT-2 would see it as an SWR of
> about 80:1. Even if your line is not an exact quarter wavelength, if it is
> within a few feet either way, the impedance that your KAT2 will see is
> very high.

<snip>



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