On 80 meters, the loop becomes a 1/8 wave and the input impedance is now
only 2.249 ohm and the transformer turns ratio is approximately (4.5 to
1) this is 9 turns to 2.
Because of the extremely low input
impedance at the 160 mtr or 1/16, wave loop, the input
impedance is only (0.2278 ohms) the number of turns on the primary
is 20 turns.
Therefore the primary of the transformer consists of
20 turns tapped at three turns and again at nine turns which means
that the input to the transformer has four wires.- 1,= start. 2,=
three turn tap. 3, = nine turn tap. and no4,= twenty turns.
will then match the 50 ohms of the transceiver to the input impedance
of the loop at 1/4, 1/8, and 1/16 wave.
This means that you can switch
through 40, 80, and 160, by using a suitable switch to the primary
of the transformer.
As can be seen in the pictures the loop support is a fishing pole with a
cross member at the top. The pole is pivoted on a four-legged support.
There is an extension at the bottom of the pole that overhangs the
pivot, to this is attached a cord that runs through to the inside of the
van where it can be used to pull the loop into position when required.
The loop element (coax or flexible wire) is attached to the top spreader
and the ends bought down to pass through into the roof of the van and
there connected to the Tuning and matching unit.