[INRAD] FT-1000D roofing filter

[Merv Schweigert]

I installed a FT-1000D roofing filter a few months ago. 
I noticed in the large pile ups for 4O3 that on 20 meters
I had some strange intermod from the pile up 5 khz or
more up the band.   I have never had intemod on 20
meters before.  And due to my location (Hawaii) signals
are not next door so to speak.
I have had the 1000D since they were first out, lived in
ILL with lots of close large signals and never heard this
before.  
Wonder if I am developing a radio problem or there is
a quirk in the roofing filter circuits?  
73  Merv  K9FD/KH6