Using ladder line like that often introduces RF into the path.  It might 
help having an external tuner, but here's some other things you can try. 
First, you don't say what rig you are using.

If you are using one of the Kenwoods i.e. TS2000, possibly the TS-570 etc. 
and you haven't modified the mike connector, put a piece of wire from the 
bottom screw of the mike case to the side of the rig where the mobile 
brackets attach.

Second, attach a quarter wavelength counterpoise to your ground and run it 
around the perimeter of your shack.

Third, if you still have RFI look at
hamuniverse.com/ground.html

Steve, K8SP


----- Original Message ----- 
From: "Mike Barnard" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, August 12, 2013 9:41 AM
Subject: RF in my signal:


> I have had this problem quite a lot, I went from a long wire
> antenna, to a 80 meter windam, fed with later line, and a 4 to 1
> balum.  This helped some, and I also now have the heil microphone
> that helped some.  I am using a LDG auto tuner, the kw
> 1000.  Sometimes I can hear it a little when it is bad in the auto
> tuner.  I have thought of getting a manual tuner, but until I get an
> audio box to put in line for SWR I don't want to chance it.
> Last night someone recommen
> Mike Barnard
>
> KD2CDUded a RF isolation box.  I am going to try that.  Any other
> suggestions are welcome.