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R: Electro-Mavin 2.4 GHz Filter Question



Simply adding a bandpass filter in front of the 13 cm preamp doesn't work.
First,it ruins the preamp's noise figure and attenuation from the filter
adds to the noise figure of the preamp.
Second,it may not solve the problem.
A good idea  to solve the problem of desensitization  and that is amazingly
simple,is to knock the offending signal out using a notch filter on the
front end of the preamplifier wich seems to have no effect on the operation
or noise figure of  the 13 cm preamp and absolutely removes the desense
problem.
This notch filter consists of a series resonant LC network that is tuned to
the frequency of the offending signal.
This network exhibit a low impedance to ground on one frequency only.All
other signals see it as a high impedance and are not effected by it.
If the offending signal is the 70 cm band,the diagram of the notch filter
,how to build  LC circuit and how to tune it is described in the "MODE-S the
Book" ,The complete guide to operating Mode S by Ed Krome, KA9LNV edited by
the AMSAT-NA
The article is " 436 MHz NOTCH FILTER FOR MODE S OPERATION" by : Ed Krome,
KA9LNV ,page-75-77

73 de i8CVS Domenico ( available on AO40 S2 transponder passband CW and
SSB )


----- Original Message -----
From: Joe Leikhim <jleikhim@nettally.com>
To: <amsat-bb@AMSAT.Org>
Sent: Monday, May 14, 2001 4:40 AM
Subject: [amsat-bb] Electro-Mavin 2.4 GHz Filter Question


> Has anybody actually measured the insertion loss of these with any
> accuracy? I know the spec was kind of high for IL. What is it really? Is
> anyone using in front of the LNA to stop L band overload?
>
> --
> Joe Leikhim K4SAT
> Jleikhim@nettally.com
>
> http://www.ibiblio.org/jimmy/mcguinn/9000e.ram
>
> "tv dinner by the pool,
> i'm so glad i finished school" -F.Zappa 1967
>
> "The Revolution will NOT be televised" -Gil Scott Heron
>
> "Whats he building in there?"- Tom Waits
>
> "The large print giveth
>  and the small print taketh away..." Tom Waits.
>
>
> ----
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