Classical
Matching Unit with taps
You can see that C3 is isolated from metal cabinet of the ATU. It is
not convenient for practical design of an ATU, so amateurs often
use Classical Matching Unit with taps.
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Fig. 4 shows such MU with asymmetrical
output, Fig. 5 shows Classical
Matching Unit with taps with symmetrical output. These schemes
(Fig. 4 and 5) cannot give such careful matching,
as shown in Fig. 2 or Fig. 3 have provided.
But in case if it is need to minimize dimensions of
an ATU the schemes can be used.
Multi-range
Matching Unit with taps
So, if you want to build an ATU having minimum sizes and parts try the
schematic shown in Fig. 6. However, the Matching Unit has not high efficiency
at upper amateur ranges because of lowering of the Q-factor of
L2 and because of not optimal selection of taps from L2. But usage
of such simplified multi- range Matching Unit at amateur HF -
ranges 1,8- 10-MHz is quite acceptable.
T
- Matching Unit
Classical Matching Unit is very effective in the work. However, among
radio amateurs and military T- Matching Unit has more popularity
then one shown in Fig. 2.
It takes place because T- Matching Unit have high efficiency at
very wide frequency ranges and T- Matching Unit allows to do easy
automatic tuning (that very likely to the military!). Also, T-
Matching Unit works very well with for asymmetrical coaxial cables
feeding modern antennas. Fig. 7 shows schematic of T- Matching Unit. The
MU has rather good parameters. It is possible to do matching a
50- Ohms transmitter to 10- 1000-Ohms antenna. It is possible
overlap all HF- amateur bands from 3,5 up to 30 MHz using only
one variable inductor at 0.5-30-μH
and two variable capacitor at 10- 250-pF. The MU does matching
at 1.8-MHz if to bridge C1 and C2 to connect fixed capacitors
at 200-pF.
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