[Elecraft] K2 ATU question

[Trevor Day]

In message <20040914182246.GA11103 at trixie.musoftware.de>, Ullrich von 
Bassewitz <elecraft at musoftware.de> writes

Surely this doesn't matter.  Once the ATU in the K2 has been tuned once, 
then it won't attempt to correct for any mismatch (caused by tuning the 
mag loop) until you press the tune button again.

Trev G3ZYY

>Unfortunately, it's not that easy. Matching a combined feeder/antenna system
>with a tuner so that the PA sees 50 ohms doesn't mean that the antenna is
>actually working. What you say is true, provided that the antenna is resonant,
>and has 50 ohms with no imaginary part. But if you don't know that for sure,
>for example if you're experimenting, or because the antenna has a very low
>bandwidth (see below), just matching it with the ATU won't help.
>
>A mag loop is special, because it has a very narrow bandwidth (often 10khz or
>less), so changing frequency means retuning the antenna. But to tune the
>antenna, one needs to know the real SWR. And this is the point where the ATU
>needs to be switched off, because it will just correct the SWR as far as the
>PA is concerned, but it will not make the antenna resonant.
>
>Regards
>
>
>        Uz
>
>

-- 
Trevor Day
SIP: 84411998 at voiptalk.org