20
Having run all the wires we will now terminate them. First connect the power cable to a 14-
volt or 28-volt source. It is advisable to run this via a circuit breaker or fuse (2-amp max).
NOTE
The FL-760 has an internal 10 amp fusible link which is not field replaceable. If the radio
fails it must be returned to a Polmar approved repair facility.
RED is POSITIVE! (Pins 9 and 10) GROUND (Pins 11 and 12)
It is advisable to connect the power cable through a radio master switch and not direct to
the battery. Solder the PTT cable to the J001 with the shield connected to ground and the
center conductor to pin 7.
The other end of the cable should be connected to the common and normally open contact
on the push button switch.
If using two switches simply wire them in parallel. Now solder the microphone cable center
conductor to pin 3 or 1 (both if two mics are used) on the J001 socket and the shield to
ground (Pin2).
You can now connect the microphone. If using an electret mic please check that the red
wire is connected to the center conductor as these are polarity sensed and reverse polarity
will severely damage the mic.
If using two microphones then wire to the 2 separate inputs. NOTE both mics are active
on transmit. For pilot/copilot isolation order the optional relay board.
Now connect the backlight switch using two wires, one to ground and the other to pin 8.
You can use volume instead of backlight switch (for brightness adjustment). The switch
(volume) is wired center conductor to common and the other side to ground.
THIS IS NOT A MOMENTARY SWITCH, it needs to be switched on or off.
For Motor Glider and Ultralights install the following intercom switch wiring. Wire the center
conductor to PIN 5 and the shield to ground. The switch is the same as for the backlight
switch described previously or when the switch is not used, you can use voice operation
(VOX function).
Memory toggle center conductor to PIN 13 and the shield to ground. The memory toggle
switch is momentary type with the center conductor to common and the shield to normally
open.
You may have noted that nearly all switch connections are to ground, this was done to
simplify wiring and avoid any possible shorts to positive voltages.
5.7 Antenna Installation
The following section refers to proper antenna installation.
Note: In certified aircraft approved antennas must be used.
5.8 Tuning
Before any tuning can be attempted you must have a VSWR meter which can measure
the antenna’s reflected power. The lower the SWR reading the higher the output and the
radiated signal. High SWR degrades performance and can cause damage.
An SWR of <1.5:1 is desirable.
5.9 On air testing
Before transmitting check all connections and switch on. Operate controls as per section 6.
A simple on air test for audio quality on transmit and receive should be done.
