[R-390] filters

[KK4XO Gmail]

Yes....Bob is right.
I was going to say that it may sound crazy but not all black IC foam are the 
same.  Although you might think they should be made of insulated material, 
I've run into at least one that was conductive - that is, all pins of the IC 
chip were grounded by the material.  If you use this kind of foam, make sure 
that it is not of the conductive type.
Bill, KK4XO