ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1]   Go Down

Author Topic: Antenna Cable Resistance  (Read 3470 times)

Danny Hazen

  • Newbie
  • *
  • Offline Offline
  • Posts: 2
Antenna Cable Resistance
« on: December 14, 2016, 03:41:27 PM »

I have a handful of Shure PSM300 units (6 total transmitters) 4 of them are on a combiner and the other 2 are not. We're having dropout issues with all of them despite changing frequencies frequently. I was informed that we should move our transmitting antennas further apart and away from the digital snake head also in the same rack.

My question is: Should I purchase 50 Ohm or 75 Ohm cables?

The rack sits in the wing of the stage and there is a hard wall flat directly next to it, so I plan to simply mount the antennas to the top of that flat and space them about 3 ft apart. Any thoughts on that plan would be appreciated as well.
Logged

Keith Broughton

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3667
  • Toronto
Re: Antenna Cable Resistance
« Reply #1 on: December 14, 2016, 03:56:34 PM »

I have a handful of Shure PSM300 units (6 total transmitters) 4 of them are on a combiner and the other 2 are not. We're having dropout issues with all of them despite changing frequencies frequently. I was informed that we should move our transmitting antennas further apart and away from the digital snake head also in the same rack.

My question is: Should I purchase 50 Ohm or 75 Ohm cables?

The rack sits in the wing of the stage and there is a hard wall flat directly next to it, so I plan to simply mount the antennas to the top of that flat and space them about 3 ft apart. Any thoughts on that plan would be appreciated as well.
If you use your full name (as required by forum rules) I'm sure you will get some useful info.
Logged
I don't care enough to be apathetic

Danny Hazen

  • Newbie
  • *
  • Offline Offline
  • Posts: 2
Re: Antenna Cable Resistance
« Reply #2 on: December 14, 2016, 04:17:45 PM »

If you use your full name (as required by forum rules) I'm sure you will get some useful info.

OK... I had registered years ago and haven't logged on in a while. Apparently that's a relatively new rule!
Logged

John Sulek

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 606
  • Toronto Canada
Re: Antenna Cable Resistance
« Reply #3 on: December 14, 2016, 04:46:43 PM »

I have a handful of Shure PSM300 units (6 total transmitters) 4 of them are on a combiner and the other 2 are not. We're having dropout issues with all of them despite changing frequencies frequently. I was informed that we should move our transmitting antennas further apart and away from the digital snake head also in the same rack.

My question is: Should I purchase 50 Ohm or 75 Ohm cables?

The rack sits in the wing of the stage and there is a hard wall flat directly next to it, so I plan to simply mount the antennas to the top of that flat and space them about 3 ft apart. Any thoughts on that plan would be appreciated as well.

You'll want cables with a nominal 50 Ohm IMPEDANCE.
Belden 9913F, Times Microwave LMR-400UltraFlex, Professional Wireless Systems 9046 are examples of high quality, low loss versions.
Logged

Ike Zimbel

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1057
  • I'm not a newbie, I just play one on the internet!
    • Zimbel Audio Productions
Re: Antenna Cable Resistance
« Reply #4 on: December 14, 2016, 07:24:34 PM »

You'll want cables with a nominal 50 Ohm IMPEDANCE.
Belden 9913F, Times Microwave LMR-400UltraFlex, Professional Wireless Systems 9046 are examples of high quality, low loss versions.
All good advice so far...BUT, before you drop a bunch of dough on cables, it sounds like you may have other issues, like:
-Are your frequencies coordinated? At the very least you should be using the same group.
-Are you using other RF devices? If so, they need to be coordinated too.
-What antenna are you using? Sometimes IEM problems come from having too much antenna gain, especially on smaller stages.
Generally, more background info would be helpful. It sounds like you have a fixed installation...somewhere. If you tell us where you are, and what band your PSM-300's are in, someone might roll you a coordination based on your locale.
Logged
~Ike Zimbel~
Wireless frequency coordination specialist and educator.
Manufacturer's Representative (Canada)
Radio Active Designs
Pro Audio equipment repair and upgrades.
~416-720-0887~
ca.linkedin.com/pub/ike-zimbel/48/aa1/266

Mac Kerr

  • Old enough to know better
  • Administrator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 7551
  • Audio Plumber
Re: Antenna Cable Resistance
« Reply #5 on: December 14, 2016, 08:03:25 PM »

OK... I had registered years ago and haven't logged on in a while. Apparently that's a relatively new rule!

You registered in September of this year, the rule has been in effect since the late 1990's. You don't need to use your real name to register, only to post.

Mac
admin
Logged

Karl Winkler

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 548
    • http://www.lectrosonics.com
Re: Antenna Cable Resistance
« Reply #6 on: December 23, 2016, 11:43:48 AM »

I have a handful of Shure PSM300 units (6 total transmitters) 4 of them are on a combiner and the other 2 are not. We're having dropout issues with all of them despite changing frequencies frequently. I was informed that we should move our transmitting antennas further apart and away from the digital snake head also in the same rack.

My question is: Should I purchase 50 Ohm or 75 Ohm cables?

The rack sits in the wing of the stage and there is a hard wall flat directly next to it, so I plan to simply mount the antennas to the top of that flat and space them about 3 ft apart. Any thoughts on that plan would be appreciated as well.

There have already been some good comments and suggestions but I wanted to address some of the other questions Danny asked.

Antenna spacing: generally your receiver antennas should be up about 10 ft. over the deck if possible, to give good line of sight to the transmitters. 3 ft. spacing should probably work OK but greater spacing would give you a slight advantage in diversity reception, say, 10-14 ft apart, if you can do so.

Also, you'll want to keep your IEM transmit antennas as far away from your receive antennas as possible, and use any directionality of either antenna to help further.
Logged
Karl Winkler

Lectrosonics, Inc.

ProSoundWeb Community

Re: Antenna Cable Resistance
« Reply #6 on: December 23, 2016, 11:43:48 AM »


Pages: [1]   Go Up
 



Site Hosted By Ashdown Technologies, Inc.

Page created in 0.048 seconds with 25 queries.