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Re: [TowerTalk] 2m intermod filter placement

To: towertalk@contesting.com
Subject: Re: [TowerTalk] 2m intermod filter placement
From: Jim Lux <jimlux@earthlink.net>
Date: Sun, 11 May 2014 13:16:21 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 5/11/14, 12:01 PM, Joe Subich, W4TV wrote:

It depends on whether the preamp is generating the intermod or the
IC-9100 is generating the intermod.  If the intermod is due to mixing
in the IC-9100's internal preamp, put the notch filter between the
LNA and IC-9100 so it does not impact the system noise figure.


worth trying for a quick initial test. The filter in front of the LNA will degrade the noise figure a bit (or a lot.. what's the loss of the filter at 144 MHz?)

 But I'm going to bet that the odds are that the intermod is in the LNA;
if the signals are strong enough that he's getting intermod in the 9100, he doesn't need the LNA, or it has too much gain (and then, put a pad in series between lna and rx)



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