"Charles Schuler" wrote in message
...
Any iron or steel (but not stainless steel) shield (such as sheet metal)
that you can place between the heater and the TV will help. Iron has much
lower reluctance than air, so the magnetic field from the heater will be
concentrated in the shield. Stainless steel is weird in this regard and
usually won't help even though it can be made up of mostly iron.

Additional information:

"So, in our example of placing a steel plate between the magnet and the area
we desire to shield from the magnetic field, the ends of the steel plate
will have all the flux lines possible trying to get into it, traveling down
to where they must exit to get back to the magnet (the flux channel) and
exiting in a big bunch. Remembering that the more flux lines, the stronger
the field, what we have accomplished with our actions is to make the
magnetic field near the ends of the steel plate stronger (collected flux
lines) and more inhomogeneous (bent more). Both of these points make the
stray magnetic field more of a problem near the ends of the steel plate. One
way to overcome this problem is to make the steel plate much larger that the
desired area to shield. As the dimensions of the steel plate get larger, the
larger the area of the lowest magnetic field behind the steel plate."

It would seem that if the steel plate was large enough, the flux lines at
its edges should be far enough away from the electron guns and the problem
will be solved or at least greatly reduced.

Source: http://www.acornnmr.com/appnotes/shielding.htm