[MilCom] Intermod / Antenna Problems

[YoCuz at comcast.net]

Have a question for the knowledgeable people for the list(s).

I have recently installed an Antenna Warehouse Log Periodic antenna on 
my roof.  I am getting terrible intermod (I believe its called this) 
across both of the scanners I attach to the antenna...  A BC 250D and 
BC 780xlt... The intermod signals comes across the worse in the vhf 
marine band 156 - 160 mhz and especially the 220- 320 mhz range what I 
would call Mil Air Range....

I think I have tracked the source down from the 929.15 929.39 and some 
938 mhz spots....  It's really driving me nuts... Because I live in a 
row home in Philadelphia and monitor in my basement (its the only room 
in the house that I can claim as my own) There is no signal what so 
ever down here... An external was a must...  On the roof about 5' away 
from the antenna is a direct tv dish.  If this makes a difference...

Anyway I figured that someone out there might have experienced this or 
has the knowledge to help me out....

Thanks in advance....

Dennis Moore