Streamer Loading

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Original poster: "S&JY" <youngsters@xxxxxxxxxxxxxxx>

Here's a way to quite accurately tune your primary to your secondary, taking
into account the extra capacitance from streamer loading.  From your toroid,
horizontally suspend a wire starting at the toroid, with the other end
attached to some string to hold it horzontally.  The length of the wire
should be the same as your typical streamer length.  Now measure the
secondary frequency.  Then disconnect the toroid from the secondary, and
tune the primary to the secondary frequency.  Your tuning should be very
close to optimum - within a couple tenths of a primary turn.  (Remember to
reconnect the toroid).

Here is an example of the effect of a "wire streamer" on Fsec for a 7"
diameter by 27 inch center to center toroid:

Fsec (KHz)    Wire streamer length (ft)
143.3                0 (bare toroid)
139.8                2
138.4                2.5
137.3                3
136                    3.5
134.7                4

For the 4 ft case, the primary is tuned about 6.4% lower for my coil.

I used a home-built dip-meter with six foot leads to the sensor coil so I
could be away from the coil and not significantly influence it's resonant
frequency.  I measured the dip-meter frequency with a digital counter.  But
using a Terry Tuner would work as well - just keep yourself as far away from
the secondary as you can.

Happy tuning,
--Steve Y.