[ACARS] Filter & amplifier

Mon, 26 May 2003 13:06:31 +0300

Hello
Marinus's explanation makes sense in this case.=20
However, in general the amplifier should be located as close to the =
antenna as possible. Preferably right there next to the antenna in the =
mast. This way the noise that is amplified is at its minimum level. If =
you insert the amplifier in the lower end of the cable, between the =
filter and the radio, there is a lot of additional attenuation from the =
cable itself and from the filter (its insertion loss). This attenuation =
"makes" noise (S/N) and thus the noise gets amplified.=20

-Sami

> -----Original Message-----
> From: ext Jacobs Marinus-TCA001 [mailto:[email protected]]
> Sent: 26 May, 2003 12:50
> To: [email protected]
> Subject: RE: [ACARS] Filter & amplifier
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> Hi Carlos,
> To get the best results is to connect the filter between the=20
> antenna and the amplifier. This is done for the following reason:
> Right next to the VHF air band (which is from 108...136 MHz)=20
> is the FM broadcast band (88...108 MHz). Aircraft usually=20
> transmit between 10 and 25 Watts of power, while the FM=20
> broadcast band transmitters have output power ranging from 1=20
> kW and up (often you'll find 100 kW of power). The filter=20
> between the antenna and the amplifier prevents overloading,=20
> which causes all kinds of spurious and other unwanted signals.
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> A good example is at my location:=20
> I use an Icom discone antenna, a FM broadcast band filter and=20
> an Icom IC-R7000. At about 3 km there is a transmitter site,=20
> which has several high power FM broadcast stations (up to 100 kW erp)!
> With the filter installed I can listen to airport signals=20
> from an airport at about 30 km from here. When I remove the=20
> filter I don't hear anything anymore (due to front end overload).
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> I don't know your location, so the results might not be so=20
> drastic, but it is worth trying it this way!
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> 73,
> Marinus
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> -----Original Message-----
> From: Carlos Abreu [mailto:[email protected]]
> Sent: Monday, May 26, 2003 11:29
> To: [email protected]
> Subject: [ACARS] Filter & amplifier
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> Hi List
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> I have a question that I would like to ear your opinion:
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> I use for my ACARS listening a WATSON WRP-125 Pre Amplifier=20
> instaled after
> the antenna and before a AOR ABF 125 filter, is  this the=20
> most correct way
> to plug in ?
> Or I must install the filter after the antenna and than the=20
> Pre Amplifier ?
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> How are your results for each situation ?
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> Brgds
> Carlos
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> _____________________________________________
> Acars info and Aircraft ID answers go to:=20
> http://www.acarsonline.co.uk =20
> [email protected]
> http://mailman.qth.net/mailman/listinfo/acars
> _____________________________________________
> Acars info and Aircraft ID answers go to:=20
> http://www.acarsonline.co.uk =20
> [email protected]
> http://mailman.qth.net/mailman/listinfo/acars
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