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LINKER IIa REMOTE BASE CONTROLLER
The remote base controller on the Linker IIa uses a new and unique method to control a remote base . Most radios
that have an up input on the microphone that can be used. The Linker IIa controller will allow you to select from
any one of the preset memories in the remote base radio’s memory. The Linker IIa supports from 1 to 250
memories. The Linker IIa remembers what memory the remote base radio is set to. The user only needs to select
which memory he wants to use and the Linker IIa will automatically select that memory on the remote base. This is
a very easy way of selecting remote base memories as the frequencies, offsets and CTCSS – DCS settings are all
preset in the remote base radio. You can choose to only have the receiver active, to have the receiver and transmitter
active or even only the transmitter active on the remote base radio. The commands are easy to setup and to use.
The connection from the remote base radio to the Linker IIa controller is straightforward. First you will need to
determine a way to get a COS signal from your remote base radio. The Linker IIa’s RX 2 COS input can read
voltages from 1 to 9 volts with a positive or negative polarity. While the RX 2 COS input will read from 1 to 9 volts
you can apply a voltage of 0 to 40 volts to it. The COS signal also needs to be able to operate with the Linker IIa’s
approximate input impedance of 100K. The Linker IIa’s COS inputs are preprogrammed to be positive acting and
the CTCSS inputs are also preprogrammed to be positive acting. The COS and CTCSS inputs will both switch at
about 2.5v from the factory. IF (and only if) you need to change the polarity or the switching voltages the Linker IIa
will allow you to do that without adding external circuitry. Please see the SET RX 1 VOLTAGE (Function #79 and
#80) for the repeater inputs (port 1) and the SET RX 2 COS VOLTAGE (Function #81 and #82) for the remote base
/ link (port 2) inputs. You might also want to look at the quick setup guide for the repeater receiver (see index).
The next connection that needs to be made is the remote base / link receiver (port 2) audio. This is fairly simple. If
you are using a regular radio (such as a mobile rig) as a remote base first you should use a resistor that has an
equivalent resistance with a sufficient power rating as the radio’s speaker, as this is the output impedance the radio’s
speaker output was designed for. This resistor should be tied from the audio output to ground. Keep the radio’s
volume as low as possible. You will not need much audio. The audio signal for the RX 2 input on the Linker IIa
can be taken from the signal or non ground side of this resistor. There are other ways to get an audio signal but his
is one easy way to get remote base / link audio. You may also use discriminator audio. The audio from the
discriminator can give you much better sounding audio.
The mike input of the remote base / link radio is the typical connection to the Linker IIa’s TX 2 audio. You may
want to add a resistor (typically 47k) in series with the mike input to match the low output impedance of the
Linker IIa’s RX 2 audio output to a high impedance microphone input of a remote base / link radio’s microphone
input.
If your radio has an “UP” input on its microphone input this can be used to give the Linker IIa control over which
memory to select. The auxiliary 3 output of the Linker IIa is used for this purpose. The “UP” input can be
connected directly to the auxiliary 3 input if the “UP” input is designed to go to ground for it’s activation. The
Linker IIa uses an open collector configuration for this function. If the “UP” input on the remote base radio does not
normally get switched to ground to select the next memory a relay may be connected to the auxiliary 3 output and
appropriate connections to the radio made on the other side of the relay. This is all that is necessary to wire up the
memory selection of your remote base.
The auxiliary 3 output has a programmable timer (see function #116) which times how fast the auxiliary 3 output
goes on and off. This timer can be set to speed up or slow down the rate in which the remote base memories are
selected.
The Linker IIa uses a “home memory” as a reference point. This is the memory in the remote base radio the
Linker IIa will consider memory number 0. The Linker IIa will always return the remote base radio to the home
memory when the remote base is disabled. Memory ‘0’ will always be the first memory to the Linker IIa. The
current memory number is stored in the Linker IIa’s EEPROM memory so the Linker IIa will remember the
currently selected memory the remote base is set to even if the power goes out.
Summary of Contents for Linker IIa
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