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Re: [LPFM] The problem of having such an efficient dipole antennae.   Message List  
Reply | Forward Message #4237 of 6098 |
You can build an attenuator circuit using resistors which is fairly simple and much cheaper.  You would need a tiny piece of circuit board and a simple diagram showing what goes where.  There is bound to be an example somewhere on the net.
 
I think someone on this list will know how to build one.
 
Ross.
----- Original Message -----
From: Michael
Sent: Friday, January 06, 2006 3:27 PM
Subject: [LPFM] The problem of having such an efficient dipole antennae...

By my calculations, with a 3.7dBi stacked dipole, I need to only feed
it 217mW to get an EIRP of 500mW.... so with a 1 watt transmitter,
this means 40 metres of RG-58A cable to come in under the legal limit,
and at $1.80/metre... that's $72 worth of cable.

Is there an ever crappier, lossier cable type I could use? Or a
special way to attenuate the signal further?


Fri Jan 6, 2006 2:56 am

rosslevis
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You can build an attenuator circuit using resistors which is fairly simple and much cheaper. You would need a tiny piece of circuit board and a simple diagram...
Ross Levis
rosslevis
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Jan 6, 2006
2:56 am

I just found this page. http://www.radio-electronics.com/info/circuits/resistor_attenuator/resistor_attenuator.php Only 3 resistors are required. Use 1 watt...
Ross Levis
rosslevis
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Jan 6, 2006
3:26 am

... http://www.radio-electronics.com/info/circuits/resistor_attenuator/resistor_attenuator.php ... away without a circuit board and just solder them together....
Michael
exparrotnz
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Jan 6, 2006
4:22 am

I'm guessing I want to build this inside a metal box to prevent RF interference? -Michael ... ...
Michael
exparrotnz
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Jan 6, 2006
5:49 am

RG178 has very high loss figures but don't ask me where to get hold of any. Best just build an attenuator Adam...
Pirate FM 88.1
arubie2000
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Jan 6, 2006
5:48 am

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