ANTENTOP- 01- 2018 # 022

Antenna Switching Units

Antenna Switching Units

By Igor Grigorov, VA3ZNW, Canada

Oh, it was very good times long ago. I had one antenna on the roof and one home-made transceiver in the shack. My antenna was connected to transmitter without even using an RF-connector. Coaxial cable from the antenna just was soldered to transmitter's PA. These are the times that every radio amateur remembers as being the best in one's radio amateur life.

But in due course, new antennas were installed, to first home made transceiver was added a commercial made second one then an old military third... Antenna connectors on these transceivers were differed from each other. That situation caused to use RF adapters and special coaxial cables to alter the arrangement of rigs and antennas.

There came a time when I entangled in antennas, receivers, transceivers, and the methods of switching to alternate antennas and change from one rig to another.

Solution was clear- it should be used clear marked an Antenna Switching Unit (ASU).

So to make life easy I made several experimental Antenna Switching Units that some of them are described below.

Universal ASU

A schematic diagram for universal ASU is shown in Figure 1. The unit provides connection of 3 transceivers and two receivers (or transceivers) to one of four antennas or to a dummy load 50 or 75 Ohm (in the USSR some commercial made transmitters have 75- Ohm output). It is useful to connect a small bulb in series with the dummy load that allows estimate power level of the used transceiver.

Figure 1 Universal ASU

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