The Microair 760 is a very lightweight [0.4 kg] low power
consumption [87 mA receive] panel mounted COMM
The first two sections in the following material are an edited extract from the Microair 760 manual: the full manual can be viewed on the Microair Web site.
1. Priority SwitchThe priority switch is a push down switch designed to activate an emergency frequency. When pushed down briefly, the radio will go into memory mode, and select the frequency the user has stored in the memory 25 position – usually the international aviation distress frequency 121.5 MHz.
2. Volume / On / Squelch KnobThe MA-760 is turned on, by rotating the volume knob. A positive “click” is heard and felt at the start of the rotation to indicate the on/off position. The volume is increased by rotating the knob clockwise, and decreased by rotating counter clockwise.
The squelch is adjusted by rotating the ring behind the volume knob. There is no automatic level set for the squelch, however the ring affords a large manual adjustment to suit all situations. Rotate the ring clockwise to increase the squelch threshold, and counter clockwise to lower the threshold. When the squelch is “broken” (ie the static hiss can be heard), the annunciator light emitting diode [LED] lights green.
Note: This does NOT mean you are receiving a signal on the selected frequency!
3. Receive / Transmit AnnunciatorThe LED operates red or green, and indicates the following states:
4. Mode SwitchThe mode switch is a push down switch. When pushed down briefly the radio will step to the next operating mode. The MA-760 has four operating modes:
5. Frequency Adjust KnobThe standby frequency can be changed by scrolling the frequency adjust knob. Rotate knob to scroll the MHz half of the standby frequency. Press the knob in briefly to move the cursor to the kHz half of the standby frequency. Rotate the knob again to scroll the kHz. After 5 seconds of inactivity the cursor will move back to the MHz side of the standby frequency. Only the standby frequency can be changed directly, the active frequency cannot be directly altered by the frequency adjust knob.
6. Toggle SwitchThe toggle switch is a push down switch. When pushed down briefly, the active and standby frequencies exchange places. Hold the toggle key down for 3 seconds to activate the scan function.
7. Liquid Crystal DisplayTwo lines, each of eight characters of information. In normal operations the active frequency appears in the top line and the standby frequency in the lower line, as shown.
Pilots should monitor 121.5 MHz before engine start and after engine shutdown, to check for transmissions and to ensure that your own distress beacon is not activated.
After starting, the radio can be turned on, and the squelch adjusted so the static hiss can be heard. The LED annunciator will light green while the hiss is heard. Use the hiss tone to adjust the volume to an appropriate level. With the volume set, turn the squelch ring to break the squelch and eliminate the hiss. The LED annunciator light will go clear.
The intercom volume is pre-set, and not affected by the volume knob.
The MA-760 can now be adjusted to the correct active and standby frequencies, by scrolling and pressing the frequency adjust knob.
The MA-760 will transmit when the PTT button is held down. The LED annunciator will light red. When transmitting the user will hear themselves speaking through their own headphones via the sidetone system.
If the transmission lasts longer than 30 seconds, either because you have a lot to say, or because the PTT has stuck, the LED annunciator will flash red. When this happens, check the PTT immediately. If you find no obvious fault, turn the radio off, and then on again. If the LED is still red, turn the radio off and leave it off.
Pre-flight checkThe following check list is applicable to all handheld and fixed panel-mounted transceivers and associated system components:
Interference problemsWhen airborne, continuing excessive background crackle, hum or howling heard in the headset/speaker is usually associated with the components, active wires and ground wires within the electrical system. The engine ignition system may also be a source of RF interference. The identification of the cause, and the fixing of the problem/s, may well be a difficult and protracted process requiring expert help.