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Author Topic: Extending BTR antennas to get more coverage  (Read 4838 times)

Pete Erskine

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Extending BTR antennas to get more coverage
« on: February 22, 2016, 03:19:26 pm »

I have had several people ask this question off line.
I created this page to explain how I have done it.

http://www.bestaudio.com/s/BTR_antenna_extend.pdf

Info on splitters - there are many others but this is what's in my case

                            at 500 MHz      
Splitters   Part no     Loss/port   Isolation/port   Link
1X2   ZAPD-21+             3.2           22            http://www.minicircuits.com/pdfs/ZAPD-21+.pdf
1X3   ZB3PD1-222+     5.2             18            http://www.minicircuits.com/pdfs/ZB3PD1-222+.pdf
1X4   ZFSC - 4 -175W+ 6.5             30            http://www.minicircuits.com/pdfs/ZFSC-4-175W+.pdf
1X6   ZB5CS-920-10W-N 7.5     28            https://www.minicircuits.com/pdfs/ZB5CS-920-10W.pdf

DIRECTIONAL TAP
ZGDC10-362HP+                                        http://www.minicircuits.com/pages/npa/ZGDC10-362HP+_NPA.pdf
<1dB insertion in to out
>12dB loss on tap
used to fet a low level feed off of an rf antenna for the Fiber input of RFOF.
« Last Edit: February 22, 2016, 03:57:09 pm by Pete Erskine »
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Pete Erskine
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Jerome Malsack

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Re: Extending BTR antennas to get more coverage
« Reply #1 on: February 23, 2016, 11:19:07 am »

Thanks Pete, 

This is a good diagram on what I was asking on recently.   The verification that the passive combining the two antennae is a big help for the two or more areas of reception.
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Keith Broughton

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Re: Extending BTR antennas to get more coverage
« Reply #2 on: February 23, 2016, 11:52:33 am »

Quote
put the RF amp at the end of the coax


I presume you mean the antenna end of the coax.
Great info! Thanks for posting :)
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Pete Erskine

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Re: Extending BTR antennas to get more coverage
« Reply #3 on: February 23, 2016, 01:11:35 pm »


I presume you mean the antenna end of the coax.
Great info! Thanks for posting :)

No- I mean the end at the RX.  The point I was making was that in a high BG rf noise location such as on 34th street below the Empire State putting the RF amp at the antenna probably will overload it.  Moving it to the RX end uses the Coax as protection.  Either way it works.  There is no inherent advantage to putting it at the antenna unless your coax is so leakly that it picks up noise itself.
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Jens Palm Bacher

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Re: Extending BTR antennas to get more coverage
« Reply #4 on: February 23, 2016, 02:47:35 pm »

No- I mean the end at the RX.  The point I was making was that in a high BG rf noise location such as on 34th street below the Empire State putting the RF amp at the antenna probably will overload it.
-Or get an RF amp with a good bandpass filter and learn to tune it. The old trusty Sennheiser AB 1036 can be tuned very easily with  spectrum analyzer with tracking generator and a small screwdriver. The new AB 9000 will also do the trick.
« Last Edit: February 23, 2016, 02:53:32 pm by Jens Palm Bacher »
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Keith Broughton

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Re: Extending BTR antennas to get more coverage
« Reply #5 on: February 23, 2016, 02:57:07 pm »

No- I mean the end at the RX.  The point I was making was that in a high BG rf noise location such as on 34th street below the Empire State putting the RF amp at the antenna probably will overload it.  Moving it to the RX end uses the Coax as protection.  Either way it works.  There is no inherent advantage to putting it at the antenna unless your coax is so leakly that it picks up noise itself.
Ahhhhh...got it!
I'm used to putting amps before a long run of coax back to the receiver to make up for cable loss before the fact.
I can see that in a very high noise RF environment, the amp may get overloaded.
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Pete Erskine

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Re: Extending BTR antennas to get more coverage
« Reply #6 on: February 23, 2016, 03:03:55 pm »

-Or get an RF amp with a good bandpass filter and learn to tune it. The old trusty Sennheiser AB 1036 can be tuned very easily with  spectrum analyzer with tracking generator and a small screwdriver. The new AB 9000 will also do the trick.

Can the AB9000 be used stand alone?  is there software?

The online info on the AB1036 doesn't say anything about filtering except in specs with the note "adjustable" Is there a more complete manual?
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Jens Palm Bacher

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Re: Extending BTR antennas to get more coverage
« Reply #7 on: February 23, 2016, 03:43:32 pm »

Can the AB9000 be used stand alone?  is there software?

The online info on the AB1036 doesn't say anything about filtering except in specs with the note "adjustable" Is there a more complete manual?
AB 9000 filtering range can be set with a rotary switch when not connected to a 9000 mainframe. The gain is fixed at 17dB, but it would be easy to put in a Mini Circuits NAT-10DC+ to bring it down to 7dB if needed.
The AB 1036 is probably too old for a pdf manual ;-), but it includes a bandpass filter that can be tuned to around 5-40 MHz bandwith. Needs a screwdriver and somebody that knows how a spectrum analyzer works, so not exactly plug and play.
« Last Edit: February 23, 2016, 03:47:49 pm by Jens Palm Bacher »
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Ross Goldman (2)

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Re: Extending BTR antennas to get more coverage
« Reply #8 on: March 01, 2016, 11:07:34 am »

Thanks for this! What is the benefit of having separate TX1 and TX2 outputs from a BTR base station, only to combine them again? (Especially since this requires a modification to the unit.)
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Mac Kerr

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Re: Extending BTR antennas to get more coverage
« Reply #9 on: March 01, 2016, 11:17:42 am »

Thanks for this! What is the benefit of having separate TX1 and TX2 outputs from a BTR base station, only to combine them again? (Especially since this requires a modification to the unit.)

When you are combining more than 1 BTR you want all the transmits separate into the combiner to minimize the intermods created. You never want to amplify an RF signal that has more than 1 carrier. Inside the IEM combiner the signals are amplified first, then combined.

Mac
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Re: Extending BTR antennas to get more coverage
« Reply #9 on: March 01, 2016, 11:17:42 am »


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