snubber capacitor help - halogen lights

I just bought 3 low voltage halogen pendant lights. Inside the canopy, each
light has a small transformer with 120VAC primary and a 12VAC secondary. The
lights cause a tremendous amount of interference on AM radio in the kitchen
and makes it so you can hardly listen to anything except the strongest
stations. I am no electronics expert, but I have some RIFA PMR 210 snubber
capacitors I was thinking of trying across the primary, secondary or both.
My knowledge is very limited and I have only used these capacitors in my job
to solve some problems across relay coils.
From looking around, this seems to be a "X" capacitor (line to line).
However, I noticed that the interference gets worse when the ground touches
the shield of the light cable which is connected to one side of the
secondary. So I am concerned I need a "Y" type (line to ground). Anyway, I
plan to try the capacitors that I have. Does anyone have experience with
this problem? Any suggestions on the type / value of capacitors I should be
using? Is there another way to solve the problem?
Thank you.