[Fwd: LF: First kite tests]

[Andre Kesteloot]

Peter Martinez wrote:

> >From Peter Martinez G3PLX Kendal Cumbria:
>
> Weather conditions were ideal today (Sunday 29th March) for the
> first RF tests on the Mk 2 kite. I had prepared 100m of wire and got
> it aloft and steady, but had no real idea of what would be needed to
> tune it. A quick test with the existing 4.3mH coil as used for the
> 330pF longwire, showed resonance at 101.6 kHz. This meant that
> the 100m kite wire was 567pF and would need 2.4mH to tune it to
> 136kHz. Knowing it would take me several hours to construct such
> a coil, and in order to get some RF out before the wind vanished, I
> reeled in wire, hanking it round two fence-posts, until it resonated at
> 135 kHz with the existing coil. I later measured the length of wire
> which was flying at 47.5m. That's interesting, because that's almost
> exactly the same as the length of the longwire: I think I would have
> expected less capacitance with a wire going straight up compared
> to one going horizontally at 20ft high. The wire on the fence may
> have had a significant capacitance.
>
> The kite was flying at 70 degrees to the horizontal, with the wind
> from the east coming up a sloping meadow. After some beaconing I
> put out some CQ calls to no avail, then phoned John G4GVC, who
> reported that I was about 6dB up on the longwire. I would have
> expected a bit more, but realised that the 20dB I had estimated last
> week for the full 200ft height was wrong: the longwire is 20ft high and
> that's it's effective height, whereas the 200ft vertical has an effective
> height of 100ft, so the increase should be 14dB for the full height.
> John's report of 6dB is perhaps 2-3dB down on the revised
> expectations, but the poor result might be due to the improvised
> hanking of 50m of excess wire around two damp wooden fence
> posts.
>
> The next part is to build a 2.4mH coil, probably adjustable and with
> integral 50 ohm reverse power meter, and arrange suitable anchor
> points at various points around the cottage, each with access to the
> earth system.
>
> If anyone heard me sending "DE G3PLX 200FT KITE QSA?" that
> afternoon, I would be grateful for a signal report, especially if you
> heard my signal previously.
>
> 73
> Peter G3PLX