Paradan Antenna Disconnect

Paradan Antenna Disconnect


Reduce the chance of station damage from lightning.

The Antenna Disconnect is made up of the Actuator and, if needed, the Radio ON Sensor.

The Actuator automatically disconnects the antenna from your radio and grounds the antenna. It prevents voltage surges from static-discharges and lightning strikes from damaging your radio and associated equipment. The Actuator is installed at the output from your transceiver, power amplifier, or antenna tuner in line with the antenna’s feedline. Power for the Actuator comes from the transceiver, the power supply, or from the Radio ON Sensor.

When the transceiver is turned OFF, the antenna’s signal and ground are shorted together and grounded, and are totally disconnected from the radio. When the transceiver is powered ON, the Actuator re-connects the antenna for normal operating. Note that the Actuator also contains a gas discharge tube (GDT) for reasonable lightning surge protection while operating.


Antenna Disconnect Actuator

The Actuator is placed at the output of the transceiver, amplifier, or the antenna tuner. The Actuator requires a connection to an effective ground via its %-inch stud. The device may be placed close to the radio, outside the radio shack, or near or on the antenna or tower. Note that the Actuator is in a water-proof enclosure.

Grounding is extremely important. Use a number 10 wire, or heavy braided strap. Connect to a water pipe, an outside power ground (green wire buss), or to a copper pipe that is driven a few feet into the earth. Connecting to the transceiver’s ground strap system is not recommended, because this line may offer some impedance above true ground and present some danger from lightning induced transients.

The Actuator power wire requires 10 to 18 volts to switch the relays. There are three connection methods to apply this voltage when powering up your station for operating:

1. For radios that have an accessory 12 volt jack, just plug in the wire from the Actuator (Figure 1A). When the radio is turned ON, 12 volts appears on this jack. Most radios use an RCA-phono plug. If you need another connector, wire the RED lead to plus, and the BLACK to common.

2. For radios that do not have an accessory 12 volt jack, you can connect the Actuator’s wire to the power supply. The red lead is plus 13.8 volts and the black lead is common (Figure 1B). Then when you turn ON the power supply, the Actuator connects the antenna for transmitting.

3. For radios that do not have an accessory 12 volt jack, and you want to leave the power supply ON, then must use the Radio ON Sensor (Figure 1C).

Radio ON Sensor

PARADAN Antenna Disconnect Radio ON SensorThe Radio ON Sensor provides the power for the Actuator whenever the radio transceiver is turned ON. The Sensor is placed in series with the radio’s 12 volt (13.8 V) power wire. The input wire connects to the power supply, and the output connects to the radio’s power lead. There’s a socket to plug in the phono-plug from the Actuator.

The Sensor’s input wire comes with a Powerpole connector intended to plug directly into a power strip. When using barrier strips, wire nuts, or push terminals simply cut off the Powerpoles and strip the wires. Two ring terminals may be crimped on for good connection to the appropriate power supply. Remember the RED wire is PLUS, and the BLACK wire is NEGATIVE (or Ground). DO NOT REVERSE ! CHECK IT TWICE !

The Sensor’s output wire is a 4-way binding post. Connect the radio’s power lead to it. This binding post accepts stripped wire, ring terminals, and banana plugs. Connect the radio’s PLUS wire to the RED post, and the NEGATIVE wire to the

BLACK post. DO NOT REVERSE CHECK IT TWICE. Use the Powerpole extension

wire if the radio’s power wire has Powerpoles installed.

Note that the Sensor uses the fuse as a current-sensing resistor. Install the 40 Amp fuse for 200 watt radios, the 20 Amp fuse for 100 watt radios, and the 10 Amp Fuse for 50 watt or less radios.

Paradan Antenna Disconnect

Operating the Antenna Disconnect

The Antenna Disconnect Actuator is in the protection mode whenever the Radio’s power is OFF; the antenna is disconnected and the feedline is grounded. When the radio is powered ON, the antenna is reconnected and the green LEDs on both the Actuator and the Sensor (if used) illuminate.

If you are using the radio’s 12 volt accessory output to drive the Actuator, simply unplug the connector while listening to a station. Just observe that the station went silent (or very low). This confirms that the antenna properly disconnects.

If you are using the ON-Sensor, depress the pushbutton while listening to a staion. Confirm that the station went silent (or very low).

If the Actuator is powered from the radio’s dc power supply, you must unplug the power wire to hear the station go from loud to soft. This confirms performance.

Because the Actuator is in series with your antenna, it is very important that you see the green LED light up when you turn ON the radio. Also listen to the radio to confirm that the antenna is connected. As always, check the SWR before transmitting.


Specifications: Actuator:

1. Operating Voltage: 10-18 Volts dc

2. Current: 60 mA when turned ON to connect antenna

3. LED: Illuminates green when relays connect the antenna

4. Relays: Two relays with 15 Amp contacts, protected for reverse spikes

5. Case: Grounded to the antenna’s coax connector

Isolated from the radio’s coaxial connector

Connected to the radio’s coaxial connector ground when actuated.

6. Control Wire: Two-conductor AWG 18 with RCA phono plug

This wire may be lengthened: RED wire goes to center pin, BLACK wire goes to shell on the RCA plug

7. Control Input: Diode protected against reverse polarity. RF filtered.

8. Active Lightning Protection: Gas Discharge Tube on antenna coax input

9. Case Ground Stud: One-quarter inch with washers, lock washer and nut

10. Case: Die-cast aluminum, black powder coat, white print, water resistant

11. Size: 4.8 x 2.6 x 1.6 in., mtg. tabs w/4 holes @ 5.25 and 1.5 in. centers

12. Weight: 13 oz., 360 grams Sensor:

1. Operating Voltage: 10 to 18 Volts dc

2. Current: 10 mA Quiescent, 60 mA when Activator is powered ON

3. Current Sensing Resistor: Fuse, 10, 20, or 40 Amp ATCO fuse

4. Maximum Pass Current: 40 Amperes for 40 Amp fuse

5. Input Connector: #12 AWG Wire with Powerpoles

May be changed to % inch Ring Terminals or Stripped Wires RED wire is POSITIVE, BLACK wire is NEGATIVE

6. Output Connector: 4-way 30 A binding Posts (wires, banana plugs, % inch

ring or spade terminals). RED terminal POSITIVE, BLACK terminal is NEGATIVE. Included: 1′ jumper #12 AWG wire w/Powerpoles.

7. Activator Connector: RCA Phono socket

8. LED: Illuminates green when supplying power for switching Actuator.

9. Case: Aluminum, painted black, white screen printing

10. Size: 4 x 3 x 1 in., four mounting holes @ 4.5 and 2.5 centers

11. Weight: 6.5 oz., 200 grams

Warrantee: The Auto Antenna Disconnect Actuator and Radio ON Sensor are warranted against failure due to defects in workmanship or materials for one year after the purchase date. This does not cover damage by abuse or incorrect installation or use. If failure occurs, please return the items to Paradan, LLC., with an explanation of the problem.

Disclaimer: We do not know the effects of nor have we tested the Antenna Disconnect with a direct lightning strike. We do know that fewer lightning related surge damages to radio equipment, such as static buildup and discharge, “Saint Elmo’s Fire”, and other corona discharges, occur when antenna feedlines are grounded, and radios are disconnected. This product is intended to provide this aforementioned known measure of protection against effects of lightning strikes. When the radio is turned on, the Gas Discharge Tube offers additional documented lightning protection. The Actuator may not be sufficiently robust to provide an intact conduction path to ground during a direct lightning strike, such as may occur with a commercial lightning rod installation.

The Antenna Disconnect Actuator and Radio ON Sensors are manufactured in the USA by Paradan, LLC, 50A Sinawoy Road, Cos Cob, CT 06807. The devices are “patent pending”.

You might also be interested in: Lightning protection is a safe investment for any station.

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