Phil Hobbs wrote:

You can get Barkhausen oscillations in light bulbs, as I said. If you
have a spectrum analyzer, you can find out pretty fast.

I do have one (of course, I'd say). My radio reception (hamradio bands) has
never been disturbed by incandescent lights though (and it's about
the only electric thing that doesn't make any RF nowadays).
In the next days (as I find time) I'll try to run the transient suppressor
with a small dc current and see if it oscillates (and at what frequency).

Thanks
Frank IZ8DWF