G3 300 signal drop out

[jmaudio]

Hi

 

I have 12 radio mics on hire for a run of Grease. 4 sets of G3 300's and 8 sets of G2 300's.

 

I am experiencing issues with one of the G3 300's. The RF level seems to be consistently much lower than all the other sets despite the belt packs being in the same location. This is causing the receiver to mute its self. I have rung the hire company and changed the frequency but although this appeared to work during testing, in a rehearsal situation the problem reoccurred.

 

Originally I had the receivers at FOH, about 20m from the stage, and experienced no issues with the other sets, I have now moved them under the stage (about 10m away tops, but though a wooden floor), but I am still getting drop outs.

 

All the sets are powered though through the Sennheiser 4 way antennae distribution system (so three in total).

 

I've also checked the RF power on the faulty transmitter, and it is on "standard".

 

I'm at a bit of a loss as to what to try next as the first show is tonight!. It maybe a case of only using 11 sets for tonights performance, and get another set sent down for tomorrow. But I thought I might see what the BR had to say!

 

Thanks in advance,

 

Jamie.

[pete10uk]

Have you tried swapping which port on the RF splitter the unit in question is connected too? Also try the beltpack with a different receiver. I would suggest one piece of kit is faulty.

 

it's a process of elimination.

 

In addition to the above, try loosing on of the units known to be working fine and use that frequency, I have had it in the past when using a good number of units the last one can be difficult to get the separation in frequencies.

[adamski1010]

Is the RF signal going straight from the back of the distribution amp into the reciever RF input or is there a RF booster in-line? If you have tried swapping cables/ beltpacks/ freq's etc and it is still dropping out then I suspect you may have a damaged unit and will need a replacement.

 

Cheers

Adam

[Shez]

Is the failing beltpack being worn by someone of a larger build? Some people are like black holes for RF - the pack will work fine when tested but as soon as it's attached to them, down goes the signal strength...

 

In any case, as others have said, follow standard fault finding procedure and eliminate each possible faulty piece of equipment by substitution until you find the problem.

[DrV]

Is the failing beltpack being worn by someone of a larger build? Some people are like black holes for RF - the pack will work fine when tested but as soon as it's attached to them, down goes the signal strength...

 

In a similar vein... A friend of mine had problems with an artiste wearing a costume which contained a lot of metallised thread which was making a very fine RF shield - worth checking

[peza2010]

This won't be of much help, but I had this problem on one of my sets from new, it happened got about a week from new, no matter how close the mice were to the receivers and no matter how you set it up.

 

However after the first week, it has NEVER happe again (Been used on about 200 shows since) and I have never been able to re create the problem.

 

How strange!

[AndyL]

Hi

 

I have 12 radio mics on hire for a run of Grease. 4 sets of G3 300's and 8 sets of G2 300's.

 

I am experiencing issues with one of the G3 300's. The RF level seems to be consistently much lower than all the other sets despite the belt packs being in the same location. This is causing the receiver to mute its self. I have rung the hire company and changed the frequency but although this appeared to work during testing, in a rehearsal situation the problem reoccurred.

 

Originally I had the receivers at FOH, about 20m from the stage, and experienced no issues with the other sets, I have now moved them under the stage (about 10m away tops, but though a wooden floor), but I am still getting drop outs.

 

All the sets are powered though through the Sennheiser 4 way antennae distribution system (so three in total).

 

I've also checked the RF power on the faulty transmitter, and it is on "standard".

 

I'm at a bit of a loss as to what to try next as the first show is tonight!. It maybe a case of only using 11 sets for tonights performance, and get another set sent down for tomorrow. But I thought I might see what the BR had to say!

 

Thanks in advance,

 

Jamie.

 

To eliminate the transmitter from the equation, tune the offending receiver to the same frequency as a 'known good' transmitter (TX), switch all the other transmitters off. If you can find no difference in performance between the two receivers repeat the exercise this time using the suspect transmitter pack; make sure you turn the 'known good' one off first! Using the suspect one on the 'known good' frequency for this test eliminates the operating frequency as a variable.

 

To help replicate body absorption do your walk test with the body pack antenna squashed under your armpit. If it doesn't drop out like that then your system is in good shape.

 

Assuming that you've done the above and it isn't the TX pack....

 

1) Check the routing of the RF connections from the splitter (hopefully it is an ASA 1) to the receivers. Make sure that each receiver is getting a feed of two different antennas, not two feeds of the same antenna as you will then not have any diversity.

 

2) Almost all problems of this type end up being down to RF cables in one way or another. Once you have checked point 1 above, if that wasn't the problem, try swapping the RF connections of the offending receiver with the ones from a known good receiver (RX) at the receiver end of the BNC cables. If the problem stays with the same RX then that would point to the RX being the problem. If not then try swapping the actual BNC leads in turn keeping careful track of the ones which started out as the known good system and the ones under suspicion. Make sure that all the BNC leads are 50 ohm coax not 75 ohm video cable and check for physical damage of any sort all along the length of each cable in the system and for daft things like missing centre pins on the BNC plugs.