I recently changed antennas from a ladder line fed doublet to a base fed inverted L. The L is 100' long, 50' vertical and 50' horizontal. I have a remote tuner at the base of the L, and 75' of LMR-400 from the tuner to the shack. The antenna has a ground rod and roughly 40-50 radials of varying length (length is limited in some directions by topography). The longest radials are 120' long the shortest are maybe 30' long. I am getting RF in the shack when I run at 100 watts on SSB phone. Interestingly, when I run at 30 watts on PSK31, I don't seem to get any RF, or at least it is not noticeable. I am finding that the RF is messing with my computer, and I lose CAT control after I transmit the first time on phone. I am going to put a common mode choke on the system (something like an MFJ-915). The question I have is do I put the check at the entry to the shack or at remote tuner? Or both?