Cutting out: bad antenna?

Uncle Dirtnap

Active Member
Hey all- have some Shure Slx bodypacks that are cutting out. I have ordered some new microphones, but they are getting here the day before opening night (Doh!).

When the cut outs happen, the antenna signal on the receiver will switch to the other antenna and stop showing an input, which makes me think it is not a mic issue. I see there are replacement antennas available- any way to test if that is my problem?
 

Brenden Friedel

Active Member
Hey all- have some Shure Slx bodypacks that are cutting out. I have ordered some new microphones, but they are getting here the day before opening night (Doh!).

When the cut outs happen, the antenna signal on the receiver will switch to the other antenna and stop showing an input, which makes me think it is not a mic issue. I see there are replacement antennas available- any way to test if that is my problem?
Cycle through various frequencies. What model are the Shure Receivers
 

MRW Lights

Well-Known Member
Basic troubleshooting includes...

How does RF look on the receiver with the TX powered off?

How does the RF compare with the matching transmitter powered on?

How does the RF look as you add more transmitters to the space?

If you manipulate the mic does the problem persist or get worse?

If you move the mic to another transmitter does the problem follow the mic?

Do you have a known good mic to try on the suspected bad transmitter?

Where are the TX located on the body?

Where are the antennas in relation to the TX?

When did the problem start, how many tx's are experiencing the issue and what changed when the problem/s started to occur? (Keep in mind neighbors particularly construction or demolition)
 

Uncle Dirtnap

Active Member
Thank you - I should finally have a known good mic today and can narrow things down a bit.

Some background - small community theatre with a huge gap in institutional knowledge. I was told that they used to have mics but didn't anymore - I eventually found all the transmitters and found a handful mics. The majority of the mics had internal wire breaks (those shure ear loops with the little triangular nodule behind the ear - broken in the strain relief). I found 4 lavalier-type shure mics that were not obvious broken (wiggling cable, gently fussing along the length, etc) but not above suspicion.

We would still get some crackly cut outs, more rare, but they would still happen. On the receiver, it would show no signal and a switch to the other antenna. With no mic packs on, there is nothing on the 5-bar signal meter on the shure receivers.

Most of the testing has been simply holding the mic and pack on the stage 20' from the receiver and walking around while talking-
 

Uncle Dirtnap

Active Member
okay, after a hour trying a bunch of things, it seems that there are 2 packs that cut out as there are rotated. upside down they will cut out, one of them cuts out when you pinch the end of the antenna.
 

Brenden Friedel

Active Member
okay, after a hour trying a bunch of things, it seems that there are 2 packs that cut out as there are rotated. upside down they will cut out, one of them cuts out when you pinch the end of the antenna.
If you attach your zip code as well as your wireless microphone inventory, I can generate some frequencies for you that shouldn’t have any issues.
 

Uncle Dirtnap

Active Member
Sure - the theatre is at 28027. We only have those 6 slx combos in the 494-518 Mhz range. Unfortunately its impossible to manually set the frequency. We will probably end up borowing/renting for this show.

On the 2 packs that had an obvious physical issue, I replaced the antenna with a similar guage wire of identical length. It seemed to work, but some of the others had similar issues that didnt come out in my quick tests. I will attempt an antennaectomy on them today.
 

Ben Stiegler

Well-Known Member
seeing the antenna switch from one to the other tells you there's an RF problem - perhaps in addition to the mic cable problems. Assuming you are standing still with the transmitters under test and not in a tricky null behind the antenna, you should not see the antenna choice hopping from one to the other - that happens only when 1 RF signal input is degraded in sterngth or S/N ratio. So you might have more than 1 thing to iron out.
 

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