While it's easy to make your own x-rays, I think I've got to agree with
the guy who pointed out that making the efficiently enough to provide
the energy density (Watts/area) necessary to erase an eprom might be well
beyond amateur capabilities, even if it were possible to erase them that
way.  I think this number (W/cm^2) is published somewhere, and I can't
think of any particular reason why the number would be smaller for xrays
than for UV.  We all know that it takes pretty intense UV to do the erasing.
If you've got a little 4W quartz tube, your chip has be be very close to
erase in reasonable time...

BillW