User's Manual

A channel with a receive frequency programmed into it should be selected. The correct local oscillator will
be displayed on the programmer channel box. The frequency on the counter should be observed and the
RX Frequency Trim value adjusted for least error. Because of the very low local oscillator level at the
antenna terminals, the frequency counter may not be able to read the frequency. If so, perform the TX
Frequency Trim adjustment detailed later and set the RX Frequency Trim value to match that of the proper
TX Frequency Trim value.
10.2.2 AUX OUT GAIN
To set the AUX OUT gain, an RF signal generator must be connected to the DTX module. Its frequency
should be set to that of a programmed channel. The generator should be modulated at the desired
deviation, typically 60 % of maximum, with a 1 kHz tone. The RF output level is not critical, but should be
above any squelch threshold which may have been set. –70 dBm should be sufficient. If not, squelch can
be disabled via the settings menu of the programmer for this procedure.
With an oscilloscope connected to the AUX OUT output, the AUX OUT Gain setting should be set to value
which produces the desired output level. Note that the output impedance of the AUX OUT is about 600
ohms. If the load impedance of the load that will be connected to this output is less than 10 k or so, a
resistor of a value equal to the load impedance should be connected to the AUX OUT output when making
the adjustment.
10.2.3 AUDIO PA GAIN
To set the Audio PA gain, an RF signal generator must be connected to the DTX module. Its frequency
should be set to that of a programmed channel. The generator should be modulated at the desired
deviation, typically 60 % of maximum, with a 1 kHz tone. The RF output level is not critical, but should be
above any squelch threshold which may have been set. A –70 dBm level should be sufficient. If not,
squelch operation can be disabled via the settings menu of the programmer.
With an oscilloscope connected to the AUDIO OUT output, the AUDIO OUT Gain setting should be set to
value which produces the desired output level.
10.2.4 CARRIER DETECT ON AND CARRIER DETECT OFF
The Carrier Detect On and Carrier Detect Off settings control the RF level (or Signal-to-noise ratio) at
which the DCD output goes true and what level at which it goes false. To prevent chattering on noise,
these two settings are not normally the same. 3 to 5 dB of hysteresis is usually provided i.e. if the RF
signal level is increased from zero, at some point, the DCD output will go from false to true. The RF level
may then have to be decreased by several dB before the DCD output goes false again. This prevents
chattering with signal levels near the carrier detect level. If squelch is enabled, the receive audio muting
will follow the DCD output. The desired carrier detect levels can be directly entered via the alignment
screen in dBm and then fine tuned with a high quality signal generator, if necessary.
To determine the state of the DCD output, connect a DC coupled oscilloscope or DVM to the DCD output.
It may help to disable the squelch via the Monitor input or Monitor button on the programmer so that the
receive audio signal can be continuously observed i.e. not squelched when DCD is false.
10.2.5 TX LOW POWER AND HIGH POWER
The transmitter output power level can be programmed on a per channel basis via the alignment page of the
programmer. If RNet Compatibility has not been programmed on the settings page, both the low and high
power levels can be set. If RNet Compatibility has been programmed, only high power can be set. The TX
High Power and TX Low Power settings in the TX Power box act to select a common value for all
channels. Individual values for each channel can be entered in the per channel boxes at the bottom of the
screen. Power is set in watts with a resolution of 0.1 watt. The power level can be confirmed and fine
tuned, if desired, by connecting the radio to an accurate wattmeter.
10.2.6 AUX IN GAIN
To set the Aux In gain, an audio oscillator or appropriate signal source (e.g. modem) should be connected
to the Aux In input at the desired input level. An FM deviation meter should be connected to the antenna
connector through a suitable attenuator or coupler. The unit should be keyed for transmit and the Aux In
gain should be adjusted for the desired deviation, typically 60 % of rated deviation.