Göran Krusell <goran.krusell@...>
I think Jerry is right. A 100mV ripple on +100V DC is not the problem in this case. In some cases the ripple enters as a common mode signal and this is never a problem. Of course, if you want to do the experiment and insert an LCL-filter you can do that. Such a filter calls for some calculations but first you need to measure the DC current. It is quite possible to build such a filter using some standard components. But my guess is that you will not see any difference at all.
If you have a substantial rippel on a supply voltage (like 10%) then it would show up as a problem but this is not the case here. The problem is somewhere in the amplifier chain I believe...
On the other hand, what tells you that this ripple has the same frequency as the ripple/noise that you see on the CRT...?