[Elecraft] Broadcast band interference [KX3}]

[Igor Sokolov]

Gary,
Direct detection of AM signals is inherent  problem with zero IF SDR. The 
best solution is  the use of RX SHIFT.
You can possibly use high Q filter at the input of the radio if you know the 
frequency of the interfering AM station and if it is only one such a 
station. But it is hardly practical solution. When RX shift is enabled you 
do lose narrow roofing but 15 kHz roofing is still in place. Without roofing 
filter the radio still has more then 90 db  of IMD dynamic range which is 
more then enough in 99.9% of cases. Think of those using Yaesu and Icom rigs 
with DR of less then 80db and still winning contests.
More valuable feature which is lost with RX shift engaged is DUAL RX.  Yet 
Wayne promised, we will get DUAL RX with RX SHIFT  in future firmware 
releases.

73, Igor UA9CDC
----- Original Message ----- 
From: "Gary Auchard" <w0mna74 at gmail.com>
To: <Elecraft at mailman.qth.net>
Sent: Wednesday, January 09, 2013 9:15 PM
Subject: Re: [Elecraft] Broadcast band interference [KX3}]


>I posted a question concerning an issue with broadcast band interference on
> my KX3 and received several good replys.  Here's more info on this
> issue.....there is a local AM broadcast station about 8 miles away but 
> that
> is not the one I'm hearing.  It's sounding like a Shortwave AM broadcast
> from some religious station.  Using the RX SHFT as suggested by one person
> replying is not a viable option.  When you do that it disables the Roofing
> Filter option which I need usually for copying CW signals where I'm having
> the problem.
>
> I do have the antenna tuner installed and tuned to the band where I'm
> working but I'm still getting the problem.  The signal does vary up and
> down in strength so I'm sure it's a Shortwave signal causing the problem.
>
> I can live with the problem most of the time but I would hope Elecraft
> could provide an answer to this issue.  How about it Eric or Wayne?  Any
> comments from your end?  My KX3 is SN. 564 built by me in June of 2012.
>
> Gary A. - W0MNA
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