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Author Topic: IEM Antenna combiner (when is it necessary?)  (Read 14882 times)

Lyle Williams

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Re: IEM Antenna combiner (when is it necessary?)
« Reply #30 on: January 10, 2016, 02:30:32 pm »

Not really.  The degradation of the RX is in the overload of the front end of the RX before frequency takes part.  If the higher power IEM system is radiating into the RX at a greater power than the Mics which are further away and lower power, the RX will try to protect itself or limit the RF in and therefore make the correct frequency harder to receive.

The different band models should have some front end selectivity.  Otherwise they might have well have made a single radio tuneable across all bands. 

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Pete Erskine

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Re: IEM Antenna combiner (when is it necessary?)
« Reply #31 on: January 10, 2016, 04:52:11 pm »

The different band models should have some front end selectivity.  Otherwise they might have well have made a single radio tuneable across all bands.

The selectivity happens at the first filter stage.  Prior to that most RX have an input protection limiter which prevents overload on a broadband basis.  RF of any frequency if too strong will lower the gain some.
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Mike Devore

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Re: IEM Antenna combiner (when is it necessary?)
« Reply #32 on: January 15, 2016, 10:48:21 am »

You should strongly consider renting an 8 input combiner if you don't have the budget to purchase one now. The time and annoyance factor in running 8 remote antennas to appropriate locations alone will make it worth it, not to mention the cost for the coax runs (don't skimp on the coax; it'll bite you hard), antennas (don't skimp on this either) and mic stands may be a significant contribution toward the price of a combiner.
Thanks for the reply.  Although the whole project is overwhelming. I'm plugging along. I have asked for the combiners but you all know how that goes.  What I have done so far is laid out the antenna's 12" apart and have 5 working. So far No problems. With limited amount of Freq's in the area, no RF interference yet. I wish it was just IEM's being installed on this project.  If a used or great priced combiner shows up on E-bay or such, I will prolly buy it out of my own pocket.  (overwhelmed again)
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Jordan Wolf

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Re: IEM Antenna combiner (when is it necessary?)
« Reply #33 on: January 15, 2016, 12:20:44 pm »

Check out RFVenue's gear; they seem fairly solid.


- Jordan Wolf
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Jordan Wolf
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"We want our sound to go into the soul of the audience, and see if it can awaken some little thing in their minds... Cause there are so many sleeping people." - Jimi Hendrix

Scott Holtzman

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Re: IEM Antenna combiner (when is it necessary?)
« Reply #34 on: February 08, 2016, 11:31:08 pm »

Here is a major artists monitor antenna setup...mics and 16 channels of ears. "It's worked everywhere!"

I will admit that in this venue the furthest musician was 20' away.....

Don't the paddles have RX preamp's in them?  If they do, the amp is before the loss of the cable.  Basically a preamp in the paddle enclosure makes up for cable and splitting losses.

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Scott AKA "Skyking" Holtzman

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Pete Erskine

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Re: IEM Antenna combiner (when is it necessary?)
« Reply #35 on: February 09, 2016, 08:39:55 am »

Don't the paddles have RX preamp's in them?  If they do, the amp is before the loss of the cable.  Basically a preamp in the paddle enclosure makes up for cable and splitting losses.

In that example, quoted the don't.  I always shy away from preamps in antenna cable unless the cable is over 150', particularly in heavy DTV towns and we are outside or in line of sight to the TV towers.  The preamp will just amplify everything, including the high noise floor and often just overload itself and distort the RF.  Shure's UA874 has an interesting "amp".  The options include -6dB.  Also it has an overload light which almost always goes on at the +6dB level so it shows how easily the antenna amp can overload.  If I feel that a long run needs a little boost to match other antennas I use the Shure UA830 and put it at the end of the coax - the RF and noise floor attenuated by the coax lessening the possible overload of the amp but giving the cleanest RF.
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Jens Palm Bacher

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Re: IEM Antenna combiner (when is it necessary?)
« Reply #36 on: February 09, 2016, 02:48:40 pm »

In that example, quoted the don't.  I always shy away from preamps in antenna cable unless the cable is over 150', particularly in heavy DTV towns and we are outside or in line of sight to the TV towers.  The preamp will just amplify everything, including the high noise floor and often just overload itself and distort the RF.  Shure's UA874 has an interesting "amp".  The options include -6dB.  Also it has an overload light which almost always goes on at the +6dB level so it shows how easily the antenna amp can overload.  If I feel that a long run needs a little boost to match other antennas I use the Shure UA830 and put it at the end of the coax - the RF and noise floor attenuated by the coax lessening the possible overload of the amp but giving the cleanest RF.
Hi Pete
Did you know that the UA874 rf amp is "always on", even when the switch is in the "passive" -6 og 0 db position? See this interesting page: http://shure.custhelp.com/app/answers/detail/a_id/4115/~/will-the-shure-ua874-or-ua870-antenna-work-if-dc-power-is-not-supplied%3F
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Pete Erskine

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Re: IEM Antenna combiner (when is it necessary?)
« Reply #37 on: February 09, 2016, 07:24:58 pm »

Hi Pete
Did you know that the UA874 rf amp is "always on", even when the switch is in the "passive" -6 og 0 db position? See this interesting page: http://shure.custhelp.com/app/answers/detail/a_id/4115/~/will-the-shure-ua874-or-ua870-antenna-work-if-dc-power-is-not-supplied%3F

Since it is a software switch the antenna needs power in any setting.
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Pete Erskine
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Scott Holtzman

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Re: IEM Antenna combiner (when is it necessary?)
« Reply #38 on: February 14, 2016, 01:48:45 am »

In that example, quoted the don't.  I always shy away from preamps in antenna cable unless the cable is over 150', particularly in heavy DTV towns and we are outside or in line of sight to the TV towers.  The preamp will just amplify everything, including the high noise floor and often just overload itself and distort the RF.  Shure's UA874 has an interesting "amp".  The options include -6dB.  Also it has an overload light which almost always goes on at the +6dB level so it shows how easily the antenna amp can overload.  If I feel that a long run needs a little boost to match other antennas I use the Shure UA830 and put it at the end of the coax - the RF and noise floor attenuated by the coax lessening the possible overload of the amp but giving the cleanest RF.
Intersting,  if the noise is broadband and in the bandpass of the what you trying to pickup and/or the preamp lacked a preselector filter you could create more harm than good.  It is also dissapointing to hear the front ends of the rx's are that easy to overload.

I was simply quoting a general RF design principle and did not take in account application specific issues.

I will refrain from commenting in the future unless I have direct operational experience with the hardware in question.

My apologies.

Sent from my SM-T800 using Tapatalk

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Scott AKA "Skyking" Holtzman

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Re: IEM Antenna combiner (when is it necessary?)
« Reply #38 on: February 14, 2016, 01:48:45 am »


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