ADS Antenna-Disconnect-Switch Installation and operating instructions

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ADS
Antenna-Disconnect-Switch
To protect your radio equipment from damage due to surge voltages
Assembly and Operation Manual
Table of Content
Introduction..............................................................................................................................2
Functional diagram....................................................................................................................2
Electrical characteristics ............................................................................................................2
FUNCTIONAL DESCRIPTION AND OPERATING GUIDELINES..........................................................3
Power Supply............................................................................................................................3
“REMOTE OFF“ Input.................................................................................................................3
Installation................................................................................................................................4
Earth ground connection ...........................................................................................................4
Circuit Diagram .........................................................................................................................4
Connections ..............................................................................................................................5
ASSEMBLY INSTRUCTIONS .........................................................................................................5
Component layout diagram .......................................................................................................5
Activation Methods...................................................................................................................8
Measurements undertaken –Transmission loss and Reflexion loss.............................................8
Disclaimer.................................................................................................................................9
Copyright ..................................................................................................................................9
Parts List .................................................................................................................................10

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Introduction
The ADS is a remote controlled switch, that completely disconnects the antenna from your radio and
grounds the antenna. It is designed to prevent transient overvoltage due to lightning and atmospheric
surge effects damaging your radio equipment. The Antenna Disconnect Switch is installed at the output
from your transceiver, power amplifier, or antenna tuner in line with the antenna’s coaxial feedline.
When the Power is turned OFF, the antenna’s coax signal wire and shield are shorted together and
grounded, and both the coax center and coax shield are disconnected from the radio. When the ADS
gets powered ON, it re-connects the antenna for normal operating. It and can handle 1.5 kW RF Peak
Power up to 50 MHz. With reduced power it is possible to use the ADS even at higher frequencies.
Important notice: For maximum protection a good earth ground connection is essential. See chapter
“ground earth connection” for details.
Functional diagram
Electrical characteristics
Supply/activation voltage DC 10-18 Volt
Operating current typ. 75 mA when activated/connected (at 12V Supply voltage)
RF-Connectors: female SO239/UHF coaxial socket
Antenna Socket fully isolated against case, RX/TX socket - braid connected to case
Supply connector: 2-pole screw terminal, twin core flexible lead
Case -aluminum diecast, dimension: 112 x 60 x 42 mm
Earth ground connection through a ground screw connected with the metal enclosure, or
Earth ground connection via the box flange-cover mounted on a metal plate connected to Earth
Transmission loss <0.05 dB up to 30 MHz, <0.12 dB up to 70 MHz, return-loss > 26dB
Max. Power: 1,5 KW PEP ( up to 30 MHz, 50% Duty Cycle, Load SWR <2)
Antenna through-connection is activated when Power applied
Remote controlled “OFF”, activated by manual or open collector switching
Connected/Activated condition is indicated by a green LED
Gas-Discharge Tube to provide supplementary surge protection during operation
relay-contacts shown in condition
“deactivated” (Supply Voltage „OFF“)

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FUNCTIONAL DESCRIPTION AND OPERATING GUIDELINES
With Power turned OFF the ADS is in protection mode, the antenna’s coax signal and shield are shorted
together and the antenna is connected to ground. The antenna line is completely disconnected from the
radio equipment. With Power turned ON, the “TO ANTENNA” connector is connected to the “TO RADIO”
jack and ready for operation.
Power for the ADS antenna switch comes either from the transceiver’s external accessory output or
directly from a power supply. In case the ADS is powered via the transceiver accessory output, the ADS
disconnects, when the transceiver is switched OFF. When the transceiver is powered ON, the ADS re-
connects the antenna’s coax for normal operating.
The ADS needs a supply voltage in the range between 10V und 18V. A green LED indicates when the ADS
is activated and the antenna is connected to the radio.
The “Remote OFF” Input is an additional feature of the ADS that allows to disconnect the antenna
remotely despite power is applied. With a manual switch or an open collector connected to the “Remote
OFF” RCA/Cinch jack an “active low” level deactivates the ADS and the antenna becomes disconnected
from the radio.
Operating conditions:
ON –Connected Antenna is connected to the radio equipment, green LED is illuminated.
OFF –Protection ADS is in protection mode. Coaxial Line to Radio equipment is disconnected.
Feedline from Antenna is connected to the grounded metal case. Green LED
display ist off.
Learn more about the various operating conditions in Chapter „Activation Methods“.
Transmit operation: Under specific conditions with highly mismatched antennas and high VSWR,
standing wave voltage maxima could be high enough to trigger the Gas-Discharge-Tube. This may occur
only when using high power and non-resonant antennas with extreme VSWR.
Power Supply
The Relays in the ADS are operated with a smoothed or stabilized DC supply voltage in the range of 10 to
18V. The relays need a current of 60 mA for safe switching. At 12V, the typical operating current is 70
mA, at 13.8 V the current is 85 mA. The operating power can be taken out of a DC-Power Supply or from
the external accessories output of the radio. When the radio is turned ON, 12 volts appears on this
output and the actuator is switched ON. Most radios use an RCA/Cinch plug. Wire the red wire of the
twin core flat litz to plus and the black wire to minus. A Plus and Minus sign is printed on the pcb at the
screw-terminal inside the ADS box.
“REMOTE OFF“ Input
The “Remote OFF” Input is intended to remotely disconnect the antenna despite power is applied to the
ADS. With zero voltage contacts or an open collector Transistor switch connected to the “Remote OFF”
RCA/Cinch jack, a “low” level deactivates the ADS and the antenna becomes disconnected from the
radio. The “Remote Off” Input ist a RCA/Cinch Socket internally wired to a 2-pole Pin Header (K4) on the
PCB. If you shortcut the inner conductor of the RCA socket with the outer conductor, a MOSFET brakes
the supply of the relays and the ADS disconnects. The Voltage at the inner conductor of the jack is

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positive and the same as the supply voltage. The internal pullup resistor is 47kΩ. The “Remote OFF”
socket is isolated from the aluminum case.
„Remote OFF“ can be used to activate/deactivate the ADS for example by CAT Interfaces (e.g.
Stationmaster or similar)
Installation
The ADS is placed at the output of the receiver, transceiver, amplifier, or the antenna tuner. The device
may be placed close to the radio or outside the shack. Best protection is achieved when installed and
properly earthed before the feedline from the Antenna enters the building. Note that the ADS box is not
waterproof and need to get housed in a waterproof enclosure.
-Note: If a remote power supply over the coaxial cable is used to supply e.g. an active antenna or masthead
amplifiers, make sure that the ADS ist installed in the DC-free leg between Radio and Bias-Tee and not
between Antenna and Bias-Tee, else the remote supply voltage will be short circuited to ground.
Earth ground connection
To provide effective protection the ADS requires a direct conduction path with sufficient diameter to an
suitable earth ground point. Earth ground is tied either to the ground-stud of the ADS or via the flange
cover of the box mounted on a thick metal plate, which needs to wired to the ground earth system. An
effective station ground bonds the chassis of all equipment together with low impedance conductors
und ties into a good earth ground. Use a heavy conductor (copper, diameter 4mm, AWG #6) and
connect as short and as direct as possible.
The coaxial braid of the feedline, metal-water pipes or the protection earth of the domestic power
distribution are not adequate as earth ground connection for an antenna. Minimum requirement for an
earth ground point is one or more ground rods at least1,5m (8 inch) long driven into the earth. The ground
rod should be solid copper or clad steel with 20mm (3/8 inch) in diameter. Earth Ground must be in
accordance to the national electrical codes and standards for antennas applicable in your country.
Circuit Diagram

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Connections
ASSEMBLY INSTRUCTIONS
Component layout diagram
Distances given in mm (25,4 mm = 1 inch)
TO ANTENNA
FROM RADIO
„Remote OFF“
earth ground
stud
DC-supply
cable (10…18V)

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Mounting of the pcb in the aluminum box
Note: The SO259 bulkhead socket „TO ANTENNA“ and the RCA Phono Plug “REMOTE OFF” must be
mounted completely isolated against the metal box. For this purpose a specific set of isolation washer
and busher is needed.
Resistor R4 (1MΩ/1KV) is optional and no part of the bill of material. If necessary, it may retrofitted in
order to discharge static electricity from wire antennas. The resistor must be able to handle high
voltages (>1kV).
First step is to mount the fitted printed circuit board into the previously drilled aluminum enclosure and
fix it with two 2mm/AWG #16 bolts and nuts. Use two 6mm (3/16 inch) long metallic spacer sleeves
suited for the screws to provide sufficient clearance between pcb and the bottom of the metal box. The
nuts and bolt connection builds the main conductive path between the ground layer of the printed
circuit board and the grounded aluminum case.
Wiring of the connectors
To wire the rf-connectors to the corresponding pads on the pcb use bare or silver plated copper wire
with a diameter of 1,4mm (AWG #16).
The „TO RADIO“ rf-socket must
completely be isolated against the metal
box. Use the isolation washers and the
soldering tag to assemble the bulkhead
connector in the box. Wire and solder the
soldering tag of the outer conductor with
the corresponding pad K2 on the pcb
(yellow arrow).
Next step: wire and solder the core
conductor with K1 (red arrow). Put the

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wire from K1 in the opening of the rf-bulkhead socket’s core conductor. Fill the hole with solder.
Hint: Screw a PL259 Plug at the outside to avoid deformation of the socket’s insulation caused by the
soldering heat.
Attention: when inserting and soldering the wires into the the pcb pad make sure to avoid a shortcut of
the wire ends with the bottom of the metal box.
The outer conductor of the „TO ANTENNA“
SO259 Socket is firmly screwed and connected
with the metal box. Wire and solder the core
conductor of the SO259 jack with Pad K5 on the
pcb.
The connection between the isolated „Remote
OFF“RCA Phono-Plug and the pcb is done by a
2-pole pin header (K4). Use short pieces of
red/black litz wire to connect the RCA Socket
with the 2-pole female connector and plug it to
the pin header (K4). Take care of the correct
polarity: plus (red) should connect to the inner
conductor and minus (black) must connect to
the braid/outer conductor.
For the DC supply cable you are best advised to use red/black colored twin strand wire. Feed the cable
through the rubber bushing. Connect the cable with the 2-pole screw terminal (K3). Take care of the
correct polarity: connect the red wire of the cable with the Plus clamp and the black wire with the minus
clamp. DC supply voltage is 12V nominal (10V –18V possible).
.

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Activation Methods
For radios that have a supply output for external accessories, connect the
supply cable from the ADS to this output. When the radio turned ON, supply
voltage appears on this output, and the ADS gets switched ON. Wire the RED
wire to plus, and the BLACK to common.
For radios that do not have an accessory supply output, connect the ADS Supply
cable directly to the power supply. When the Power Supply is turned ON the
ADS connects the antenna to the radio equipment
The„Remote OFF” switching input remotely deactivates the ADS despite during
DC-supply is powered. The function can triggered manually or by an automated
device. Closing contact at the Input disconnects the ADS, opening - reconnects.

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Measurements undertaken –Transmission loss and Reflexion loss
Scale: Transmission (blue) –1dB/Div
Reflexion (red) 10dB/Div
Frequency (horizontal Axis) 5kHz to 150MHz, 15MHz/Div
Disclaimer
The ADS Antenna-Disconnect-Switch is a supplementary protection device to
protect the station against high-voltage events that are induced by nearby
lightning strikes. It may not be sufficient to act as a lightning arrestor during a
direct lightning strike. It does not replace a professional antenna lightning
protection system as required in the national electrical codes and standards
applicable in your country. Each operator or owner of a station is fully
responsible on its own to comply with his country specific rules for antenna
lightning protection and safety earth. Any liability in this context is explicit
excluded.
Copyright
©2018, Guenter Fred Mandel, all rights reserved

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Parts List
Pos.
qty
component nr.
value / type
description
1
1
C1
100nF, ceramic capacitor
labelled as 104
2
1
C2
10nF, ceramic capacitor
labelled as 103
3
1
C3
4,7 pF ceramic capacitor
high voltage type, 3KV,
RM5mm
labelled as 4.7pF 3KV
4
2
D1,D2
Diode 1N4007
5
1
D3
LED, green 5mm
6
4
K1,K2,K5,K6
Solder-Pad on PCB
No component, pad on pcb
7
1
K3
Screw terminal 2-pol
Pitch 5mm
8
1
K4
2-pol Pin-Header
set with plug and cable
9
1
R1
47K
10
1
R2
2,7K
11
1
R3
2,7K
12
2
RLY1,RLY2
Relay 12V
Finder 41.61.9.12V
13
1
T1
MOSFET BS170
14
1
X1
Gas discharge tube, GDT
Bourns 2049-600

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15
1
Coaxial socket
SO239 female socket
16
1
Bulkhead connector
SO239
Bulkhead connector with
ground soldering tag
17
1
Rubber grommet
5mm
18
1m
Power Cable
Twin core flexible lead
red - black
19
1
Buchse
„Remote OFF“
RCA/Cinch
for isolated assembly
20
Miscellaneous mechanical
parts
Screws and washers
M4 (USA: #8 UNC)
6mm distance sleeves
21
Antenna Socket Isolation
Set
PE washer , bushing
insulator
22
1
Ground stud
23
1
Throug Hole Plated
Printed Circuit Board
24
1
Aluminum die-cast box,
flanged
Hammond 1590BSFL

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