ANTENTOP- 01- 2013 # 017

Modifications for the Multiband UB5UG Antenna

Second step is tuning the ATU on minimum SWR with connected to this one the coaxial going from the TX. SWR- meter is connected between the TX and ATU. By selection of the tap at the inductors the tuning is performed. Then the proper tap is connected to the switch S1A.

Final tuning of the ATU should be made at the working band on the transmitting mode by maximum reading of the MA2 (5- milli-ampere). Inductor (it contains 3-4 turns any wire) connected to the circuit with MA2 placed near main inductor of the ATU. MA1 is a thermo thermocouple HF amperemeter with max scale on 3-A.

Modified antenna (L1= 11.2- meter and with ATU) showed very good results on 40-, 20-, 15- and 10- meter Bands. The antenna works very satisfied on the 80- meter Band.

Later, in Reference 3 there were described the design of the ATU and the data for inductors. ATU made inside a metal box with dimension 280x210x210- mm.

Inductors L1, L2, L3 were sitting on porcelain insulators. MA1, MA2, S1, R1 and C2 are installed on the front panel. Figure 3 shows the schematic of the ATU with taps marked on it. Table 1 shows data for the inductors.

Figure 3 Schematic of the ATU with taps marked on it

Later, in References 4, UA4PA gave some comments about the ATU.

1.     Instead MA1 was installed an usual SWR/Power- meter.

2.     Instead MA2 with the detector circuit was used a neon bulb.

3.     Antenna is disconnected from the "hot" end of the matching inductor and connected with a new added third plate of the S1 to the selected taps of the inductors. It allows match the antenna at the all amateurs HF-Bands, from 10 through 160- meter.

4.    ATU, described here, may be used for matching almost any antenna.

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