Radio Microphones

We have just come back from a church who were having problems with their radio microphones - one did not appear to be working. It turned out that adjusting the settings on the back of the microphone fixed the problem, but we know that many churches do not understand the settings on the back of their radio microphone receiver, so here goes for an explanation...

There are generally two controls on the back of a radio microphone receiver - the first is called Gain or Volume and the second called Mute or Squelch. What do they do???

The gain control adjusts the output level from the radio microphone receiver, so that it can match the input of the mixer/amplifier which it is driving. This can be very useful as you will see...

The Problem : we found that the church had the level controls on the mixer set to around 1.5 out of 10 for the radio microphone channels. This meant that there was very little room for adjustment when there was a loud speaker using the radio microphone - even the slightest touch turned off the channel or worse still made it far too loud!

The Solution : by reducing the output level from the receiver, using the Gain control, we were then able to turn up the level on the mixer input. Carefully, we were able to set a nice sound level where the mixer control was half way, i.e. 5 out of 10. This therefore meant that the operator had lots of upward and downward movement to compensate for different speakers.

The Mute control sets a threshold where the receiver decides that incoming radio signals must be rubbish, or interference. When the radio signal level is below this threshold, the receiver automatically mutes its output. This is great for ensuring that you do not pick up transmissions from local taxi firms, airports and such like. However it has a downside...

The Problem : it appeared that one of the radio microphone receivers was not working - or that the transmitter had stopped transmitting. Whichever, it seemed that there was no radio signal and therefore no audio coming from the microphone.

The Solution : on closer investigation, we found that the Mute control had been turned up to maximum. This meant that the radio microphone was muting out (removing) all signals, including the valid signal from the radio microphone transmitter. This gave the impression that the system was not working. By simply reducing the mute level we made the receiver "work" again. However, it is worth listening to the system with the transmitter off for a while to make sure that you don't then start picking up the local disco again.....

Well, thats it for this time.

Tim.

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