Axino FM transmitter
Operators Manual

Placement

On receipt of the equipment, carefully unpack and check for damage. The transmitter should be placed in a secure area which is clean and dry. Positioning should allow access to the rear for connections. Nothing should be placed on top of the transmitter and in particular the ventilation fan inlet on top should be unobstructed.

Connections

Antenna

Your antenna should be an FM dipole or ground plane monopole designed for the frequency of use. It should be safely installed in a location where it will provide the necessary coverage. It should be matched to 50 ohms and connected to the transmitter by 50 ohm coaxial cable. The transmitter has an N-type connector for the antenna. Adaptors may be supplied as part of the contract. The minimum safe distance for public to the antenna is only 0.6 metres, however you should ensure that your location does prevent the public coming any closer than that to the antenna.

Programme input

The Axino FM transmitter has a variety of connection possibilities. The various inputs are selected by a rotary switch. One of the input modes is a test mode, which allows, for example, test tone, advertising material, introduction and identification messages, or music to be played and repeat if required. The material is pre-programmed onto a micro-SD card within the transmitter. The card is not accessible to the hirer and material in the form of .wav files must be supplied to Axino-tech for programming.

Following are the descriptions of each input on the transmitter. Connect whichever suits your source/playout equipment.

Input 1: Balanced Audio
XLR male connectors at rear. +2.2dBu (1.0V) required for full deviation.
Input 2: Unbalanced Audio
RCA connectors at rear. 0dBu (0.775V) required for full deviation.
Input 3: Digital Audio
Optical OR Coax SPIDF at front. -0.5dBFS required for full deviation.
Input 4: PC Audio USB
USB (type A) at front for pc source. -3dBFS required for full deviation.
Input 5: SD card playback (test source)
Front panel button start/stop playback.
Input 6: Silence
No input.

The above are selected manually by 6-way switch on the front panel. A level control allows for attenuation if required. The levels quoted above are correct when the level control is at maximum. When your source is connected to the transmitter, you will be able to check your levels are correct by using the L+R/L-R meter positions on the meter selector. The RF ENABLE switch does not have to be on for the metering to be active.

Operating

The diagram of the front panel controls follows:

panel label

Initially, ensure the RF ENABLE switch is OFF, then connect AC (or 12Vdc) power. Application of power will activate the low level parts of the transmitter, including the metering, but no signal will be radiated until RF ENABLE is on.

  1. Use the Input Source switch at right to select your chosen input source. Make sure the level control is near maximum.
  2. Put the function selector to the L+R position to see your programme level. Reset the level control until the meter occasionally hits orange.
  3. If you have only mono material, put the Stereo/Mono switch to mono. Coverage will be better in mono.
  4. If you have stereo material, then some reading will also show on the L-R position, but probably won't be near top of the meter range.
  5. Check the DC 12V meter position and the reading should be in the orange zone.
  6. When you are ready to go on air, put RF ENABLE to 'ON'. The indicator at bottom left should be green. You are on air.
  7. Check the FWD power reading. The number of LEDs depends on power; this will be pre-set for you; the expected reading will be noted.
  8. Check the REFL power reading. The lower the reading the better. This depends on how good your antenna is. A poor antenna will give a high reading, and the transmitter may turn off as will be shown by the green LED becoming red.

Pre-programme tests

Once the transmitter and antenna are installed, you can check coverage before your audio programme source is ready to go. Select the Test Source position and press the go button below the source selector. This will play material from the internal SD card. The SD card player will have been set before despatch with material, if you have requested this. If you have not requested or supplied specific files, the player will have some test tones and short music segments. It can be optionally set to start playing as soon as power is turned on, or only when the button is pushed.

Troubleshooting

I connected it up but nothing shows on the L+R position or the MPX level position

Ensure the level control is up and near maximum. Is the input selector in the proper position? Failing that, check your cabling.

There is a high reading on the REFL PWR position.

Your antenna or coax cable is poor. If the TX fault light is not red, then you will still be radiating something. However if the coverage seems particularly poor, then the problem is more likely with the coax than the antenna.

The clip light is always flashing.

This means the audio level is too high. Usually the limiting bar at left will be lighting up as well. Reduce the audio level until only the 1dB or at most the 2dB LED on the four segment bar at left lights up now and then. Occasional clipping will be no problem but constant clipping will sound distorted.

Everything appears to be working but there is a loud hum on my programme.

This could happen if you are using the unbalanced audio input mode. If you wish to continue using unbalanced audio, can you put the transmitter AC supply to the same outlet as your programme source? Failing that, connect an earth wire between the transmitter and your pc, mixer or player. The earth wire should be connected to the black terminal at the rear of the transmitter. If that does not solve the problem, you may have to use balanced audio or a digital audio option.

I connected power but the dc 12V meter shows nothing and the fan doesn't go.

That looks like a fault in the power supply. Check that mains is arriving at the transmitter; if so then check the fuse within the mains socket assembly. If AC is present and the fuse is OK, there is an internal power fault. If you have 12V available, you could connect that to the red/black terminals at the rear instead of AC power. Failing all that, the transmitter should be returned for repair.

Contact info

Axino-Tech Contact Page. For assistance, Axino-Tech will be available during reasonable hours. Ph 0274496967.
Go to the gory technical details of the transmitter.