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Re: Where to place passband filter in signal chain?



Andre,
Try the AMSAT mode J Desense filter at:
http://www.amsat.org/amsat/articles/w6shp/jfilter.html
I haven't tried it personally, but it is designed specifically to solve the problem you are experiencing.

Others have reported success using diplexers to combine the rig's signals onto a single coax and then again to seperate it for the V and U antennas.  If you have any of these laying around this might be worth a try first.

73,
John, KJ6HZ
___________________________________
At 09:54 PM 12/8/2003 +0100, you wrote:
>Hi all,
>
>I'm experiencing some serious desense problems in mode-J.
>At the moment I'm using an FT-847 with 70cm X-Quad + SSB preamp and
>2m X-Quad + SSB preamp (pictures and schematic are on my website).
>
>I'm researching for some good designs for passband filters now.
>Two questions:
>
>- What is the best place to insert the passband filter?
>   (2m or 70cm or both? should it be between antenna and preamp or can
>    it be installed inside the shack?)
>
>- Links to good filter designs to build are welcome
>
>Thanks,
>
>
>Andre PE1OIG
>-----------------------------------------
>pe1oig at pe1oig dot net - www.pe1oig.net
>

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