I have some times problems with local noise on the lower bands. I find a schematic in the internet for a X-Phase (QRM Eliminator) .
This X-Phase help really a lot!
Thanks to DK9NL for share this project!
Here you can download the schematic for the X-Phase on the website from DK9NL or on the DARC website: http://www.darc.de/distrikte/q/02/projekte/x-phase/