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RA-20A-1 Remote Antenna Switch | Radioaficion Ham Radio

RA-20A-1 Remote Antenna Switch


RA-20A-1 Remote Antenna SwitchRA-20A-1 Remote Antenna Switch

The HF ANTENNA switch is a single pole 6 position rotary.  For antenna selections 1, 2, 3 and 4 it provides 12VDC to the appropriate control wire and to K105 control wire.  This energizes both the selected relay and K105 which in turn will disconnect antenna 5 and connect the selected antenna.

This feature ensures that antenna 5 will be connected to the feed line if all power and/or control is lost to the remote assembly.  If antenna 5 is selected by the control assembly then all relays are de-energized.  To disconnect all antenna ports, power is supplied to only K105.

A 20 Watt, 12 V halogen bulb provides current limiting.  The filament's cold resistance is very low and causes very little voltage drop due to the relay currents.  However, for a short on one of the control lines it will light and the hot filament current will be less than 1.75 Amps.


•  The RA-20A-1 is designed to remotely switch five 50  unbalanced antenna ports to a single RF feed line using a weather resistant, tower mounted assembly.

•  Port five is connected to the RF feed line by default and a control signal must be present to disconnect it.  This ensures the antenna connected to port five is available even if all communication is lost between the remote switch and the control assembly.

•  Control cable requires 7 low current conductors, such as CAT 5 computer cable.
•  Control signals are current limited to prevent wiring or equipment damage.
•  Port to port isolation and insertion loss are excellent up through 150 MHz.

•  Control assembly includes an HF (five port switch) as well as a VHF/UHF ( two port switch) to operate a single 2M and 70 CM relay that is not included in the remote assembly .

•  Power handling exceeds 800 W as designed but could operate at 2 KW with ceramic relays.
•  Power requirement from the station power supply is 12 VDC at 0.25 Amp.

•  Green LED indicates power present and non-shorted control lines.  20 Watt 12V halogen lamp provides current limit and visual indication of shorted control lines. Applications

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