from 8, 12, 13 and 14- turns from ends of the inductors (see Figure 2).
The five taps were enough to tune antenna at all amateur’s bands
(including WARC). Taps of the inductor L1 placed at the other
side of the dielectric plate.
used a three – plate rotary switch at the ATU. It allowed used
the ATU at high power – up to 500- Wtts.
Take a look to the Figure 2.
Taps for upper bands for L2- 1 and L2- 2 are connected to one
plate (near the inductor) of the rotary switch. Taps for lower
bands for L2- 1 and L2- are connected to separate plates (one
plate for one inductor) of the rotary switch.
C1 is 500- pF air capacitor from old tube receiver. Capacitor
C2 should be high quality high voltage capacitor with maxima 150-
pF. For 150- Wtts
going to the Symmetrical ATU it would be enough to install air
capacitor with 2… 3 mm gap between plates. However when I used
the Symmetrical ATU with such capacitor connected to my amplifier
FL-2100 it is happened sparking between plates of the C2. Vacuum
variable capacitor (as seen on Figure 2) installed in the ATU resolved the problem.
W.: Das DARC Antennenbuch.