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The orion has a front microphone connector as well a rear din connector which can be used as well.

Both connectors can be controlled with a menu setting. The front connector is designed to be used with a directly connected microphone and includes a microphone amplifier within the audio path. Through the menu one can set a hardware gain as well a software gain for the front connected microphone.

The rear connector expects line level audio and like the front connector is unbalanced. With a menu setting one can switch between the audio source mic, aux or both.

The rear connector does not include a microphone amplifier and hence connecting a microphone would require an external device to amplify the mic audio to line level.

Audio and shielding

It is recommended to use shielded audio cables where shield is independent from the audio signals and the audio wires reside within the shield. At Orion the shield should connect to the orion chassis. This way the shield of the audio cables become one with the orion chassis.

The use of ferrite

Often using a ferrite helps reducing RF feedback. Its recommended to investigate the root cause of the RF feedback instead of attempting reducing symptoms. Proper shielding of audio cables should be suffient.

Balanced versus unbalanced

Using a balanced audio setup reduces noise and improves common mode rejection. Because the rear connector expects line level audio it is good to have a balanced setup. Keep in mind that at the din connector an unbalanced audio connection is expected.

Known issue rear din connector

Reported by Peter oz1pif and later confirmed by many others the rear din connector has a design error. The audio input pin also has a 5 volt dc voltage and when using an audio transformer you need to include a decoupling capacitor to avoid transformer saturation.

Transformer and ground shield

I am not sure what the best approach is. For some audio transformers there is no additional earth pin. I believe the audio shield should be connected to the Orion in all cases. The transformer isolates the mic - and mic + wires from the other side of the transformer. Providing electrical isolation for the actual audio signal and thats good. The transformer does not provide other isolation and based on this I believe the audio shield should be connected to the Orion shield pin. It has nothing to do with the actual audio but it is responsible for reducing / preventing RF entering the audio path.

Connecting a microphone to front connector

Use a good quality audio cable with two wires which are isolated from but reside within a common shield.

Taking above into account all you need to ensure is that the body of the microphone is connected to the orion chassis by using the audio cable shield. The actuall mic - and mic + wires should reside within the cable shield and not use the cable shield as means to pass audio.

At the Orion front panel ensure mic - and mic + are connected to pin 1 and pin 2. Last but not least connect the shield to the body of the plug. Latter to ensure the shield becomes part of the Orion chassis.

Optionally if PTT is also provided by the microphone ensure that the PTT wires resides outside the audio cable shield.

Connecting your audio gear to the rear din connector

One can use a audio transformer but this is not mandatory. When using an audio transformer keep in mind the recommendation above. Include a decoupling capacitor as well ensure the audio shield is starting at the Orion chassis way up to the actuall microphone body.

When connecting the rear connector directly to the microphone amplifier please ensure the amplifier can run in unbalanced mode. Some equipment recognizes balanced / unbalanced connection automatically and some require additional configuration. Furthermore just like all other configurations ensure the audio shield is starting at the orion chassis all the way up to the actual microphone body.

Microphone body

Most microphone bodies are made from some conductive material such as aluminium. Without exception all my Heil microphones were nicely painted however the paint acted as isolation as well. Hence the shielding was compromised and after removing some of the paint the whole mic body was part of the shielding.

Line level and its actual level

In most cases the aux level has to be set to a low level of around 8. Adding a 20-30dB attenuator at the din connector provides a better match. I have used 30 dB and the aux level was set to around 50 if I recall correctly providing better resolution. The attenuator can also be used to move from balanced to unbalanced at the same time.

Hope this helps and regards Onno pa1ap


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