IF AMP to boost signal along 30 meter cable

al_madhi

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#1
Hi , ppl The length of the coaxial-cable from the LNB to the receiver-end is 30 meters long , I am planning to use an IF Amplifier ( ALCAD ) in order to boost the signal and to compensate for the impedance of the cable .

What is the best way to connect the AMP :-

1 - At the receiver-end
or 2 - At the LNB at the top

Any thought you would have be greatly appreciated

Best Regards
 

PaulR

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#2
Firstly, are you sure that you need the amplifier. If you can do without it then so much the better. Changing the cable for lower loss feed is a better solution.

BUT, if you have to use an amplifier then I believe that in the middle is the best, at the LNB end second best and at the receiver end totally useless.

PS The impedance is fixed and a function of the cable's design. It's the signal loss you're trying to reduce.
 

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#3
Paul is quite correct a better cable will get rid of any insertion loss that the amplifier may have. You do not have a tree or forest problem where you are so why the 30 metre run?????
 
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#4
inline amps are normally used only to boost signal levels on a very long cable run, where input levels become too low for the satellite receiver to work.

Otherwise, note that any added amp will increase bit error rate, ie lower the "signal quality", so your reception will actually get worse!


If bad reception now, the only answer is to improve it, possibly by using a lower noise type lnb. There are also various cable types, some have a lower loss.

Check the lnb connection, this can degrade over time, if necessary replace the f plug on the cable end.

"Compensate for impedence" is gibberish! All lnbs/sat-cables/receivers have the same nominal impedence of 75 Ohms.
 

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#5
If you have to fit an amp, then install it a third of the way down the cable run. But a 30m run of normal quality cable will not need one.
 

al_madhi

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#6
Thanks to all members who reply to my thread .

All agreed that a 30 meter long cable is not that long to insert an AMP to amplify the signal this may distort the signal than to amplify it .

One replied regarding the position of the AMP that it should be in the middle of the cable run is the best choice or at the top at LNB the second choice , But at the receiver -end is the worst . Anyway ,

There is a proverb ( saying ) tells that " Experiment is the best proof "

First I can not put the AMP in the middle of the cable run because it runs throught tunnels built-in in the building , Second when I put it at the top near the LNB there is no change in the signal strength , But when I put it at the receiver-end . The signal level increase from 62% to 78% and the signal quality increased from 74 % to 86% .

As I mentioned in my thread AMP btween two brackets ( ALCAD ) this is the name of the manufacturer of this AMP , It is a TV/SAT Indoor Amplifier .
From the technical leaflet It has one input from the LNB and four outputs for four receivers downstair .
Frequncy Range : Band ( MHz ) For TV ( 47 - 862 ), For SAT( 950-2150)
Gain ( dB ) for TV ( 22 +/- 1 ) , for SAT ( 25 +/- 2)
Adjustable Gain ( dB ) for TV ( 16 ) for SAT ( 13 )
Fixed Equalization ( dB ) For TV ( 3 ) for SAT ( 8 )
Isolation ( dB ) For TV > 13 for SAT > 9
- -
Any comment on this AMP .

Best Regards .
 

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#7
That is a distribution box, not a line amplifier.
 

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#8
FWIW I put an entire 100m drum of cheap B&Q coax lnb & receiver as a test a couple of summers ago. On strong signals (19E) I couldnt see any difference in signal strength between the normal 15-20m runs I use.
 

al_madhi

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#9
Channel Hopper said:
That is a distribution box, not a line amplifier.
To - Channel Hopper , as far it amplifies the signal it is an amplifier , then why ALCAD company designers call it TV/SAT INDOOR AMPLIFIER
 

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#10
al_madhi said:
To - Channel Hopper , as far it amplifies the signal it is an amplifier , then why ALCAD company designers call it TV/SAT INDOOR AMPLIFIER
Since it works to do far more than amplify the signal

'It has one input from the LNB and four outputs for four receivers'....
...Frequncy Range For TV ( 47 - 862 ), For SAT( 950-2150)
Adjustable Gain ( dB ) for TV ( 16 ) for SAT ( 13 )

and also splits the signals out to more than one destination, it is not what is claimed on the box.

How is the gain adjusted anyway ?
 

al_madhi

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#11
Channel Hopper said:
Since it works to do far more than amplify the signal

'It has one input from the LNB and four outputs for four receivers'....
...Frequncy Range For TV ( 47 - 862 ), For SAT( 950-2150)
Adjustable Gain ( dB ) for TV ( 16 ) for SAT ( 13 )

and also splits the signals out to more than one destination, it is not what is claimed on the box.

How is the gain adjusted anyway ?
the AMP is connected to Four receivers , But I use only one receiver at a time , and the other off all receivers are in one room .

There is a hole in the top of the AMP and by using non-metalic screw you can turn it clockwise or anti-clockwise to increase or decrease the gain .
 

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#12
And how big is this box?

Since it has only one input cable, it does seem more like a simple splitter with some components inside that allow attenuation, possibly within a circuit that gives initial amplification to equalise the initial split to four ways
 

al_madhi

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#14
Channel Hopper said:
And how big is this box?

Since it has only one input cable, it does seem more like a simple splitter with some components inside that allow attenuation, possibly within a circuit that gives initial amplification to equalise the initial split to four ways
It is a rectangular box measured 16 cm X 7 cm X 4.5 cm

It has also another input for TV-Antenna with built-in power-supply inside it .
 
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#15
there's an Alcad products catalogue online, so could Al-Madhi give the device product number and/or description, then we can identify what he's using?

Sounds like a multiswitch type product, since there's at least 2 sat outputs!

Adding any sort of satellite amplifier SHOULD increase error rate (ie, lower "signal quality"), not the reverse (!), so it sounds like non-satellite coax cable is being used!
 

al_madhi

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#16
spiney said:
there's an Alcad products catalogue online, so could Al-Madhi give the device product number and/or description, then we can identify what he's using?

Sounds like a multiswitch type product, since there's at least 2 sat outputs!

Adding any sort of satellite amplifier SHOULD increase error rate (ie, lower "signal quality"), not the reverse (!), so it sounds like non-satellite coax cable is being used!
Thanks spiney for reply

Please go back and read again my post # 6 , I mentioned all the technical spec of the AMP , the device product number shown below :-
( ALCAD - CA-220 ) .

I am using Belden Coaxial-cables - 75 ohm for all my satellite connections .

Best Regards
 
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#17
sorry, al mahdi, but you're not giving sufficient information to allow a useful reply!

All tv coax cable is 75 Ohm, but there's 2 sorts. The older type is just for VHF/ UHF tv frequencies, and has solid polythene inner insulation. However, it won't "carry" satellite signals for any appreciable distance!

The newer type will also carry the higher freqency sat signals, between dish lnb antenna and satellite receiver. It should always have a "metal foil" outer conductor, and often - but not necessarily - air spaced inner insulation (holes running through it).

Just saying "Belden" doesn't show which type you're using. Is there an outer foil? Or, is there a type number printed on it?

Also, just describing the Alcad gadget doesn't tell exactly what it is, so can you identify it from the catalogue, at:

http://www.alcad.net/02productos/inicio.php?pulsado=_level0.submenu1.botsubmenu0&idioma=eng ?

(either enter the type number in Alcad's item search, or else look through sections: broadband; tv sat; multiswitches).

Using older type tv cable to distribute satellite signals will give the symptoms you described, ie an extra amplifier improves signal quality instead of worsening it! This isn't "ideal", but if sat reception is now ok, then fair enough! Otherwise, the best thing to do would be to replace the current - presumably old type - tv cable with satellite grade.
 

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#18
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#19
ok, thanks Rolf, in fact looking again al madhi did say there's only 1 lnb input (which I missed, oops!). So, it's just a single wideband amp (in fact 2 amps in parallel!) allowing several tv sets but only 1 sat receiver.
 

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#20
Yes, there are a couple of providers who send all of their channels on two or three transponders in the same band and polarity, so these units work well with four receivers in those circumstances.
 
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