On 4 Mar 2012 at 2:09, Stefan Schäfer wrote:
> Am 04.03.2012 02:01, schrieb Graham:
> > Permissible QSY limits for 136
> > Q what is the average Q of a 136 Khz Ae system ? (back
> > garden + larger)
>
> Maybe arround 50.
My very rough tests here suggest that a Q of 50 is about right. My
current reduces to approx 70% at 1.5kHz off the antenna's tuned
frequency. This is a Q of 1.5*2/137 = 46%. It is raining at the
moment and I would expect the Q to rise when it is dry.
The antenna is in a small back garden. It is an inverted-L, with a
14m vertical wire, and five roughly parallel top wires each 14m long.
Lots of trees around help to reduce the Q. Inductive loading is
distributed over several coils, small ones at the bottom and top of
the vertical section, and most inductance some 3m up.
The original question referred to SWR, which in most cases is
irrelevant. In practice, my PA makes worrying noises when the antenna
detunes by only a couple of hundred Hertz.
Mike, G3XDV
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