[Amps] Filtering Negative SIde of PS

[Peter Chadwick]

KV5I said:
>Could I get some recommendations on literature of Pros, Cons, and How to's?<
There's a bit on it in the older ARRL Handbooks in the Power Supplies section..
I've been doing it for over 20 years. I tune the choke slightly HF, so it looks like a bigger inductor - I don't believe that you want it actually resonant at twice line frequency, because of the voltages involved. Advantages include the fact that the choke insulation requirements are reduced. Disadvantage is that if the choke opens, it gets the full HV across it, so a spark gap or some other sort of protection across it is a reasonable idea. But one that can handle the energy! If tuning the choke, bear in mind the AC current rating needed in the capacitor. I use 3 paralleled 0.1 mFd wartime paper caps meant for radar modulators. The best method of tuning the choke is to use an audio sig gen and scope, rather than tweaking things with the HV on. Bear in mind that you'll get a lower frequency under such test conditions, because you won't have the DC bleed current flowing, which will reduce the inductance. Actual resonance is to be avoided - W8JI can tell you about that - he has a real horror story from his experience. 
The SG supply for my amp also uses negative lead filtering. Here, I cheat a bit, because I rectify the AC across the choke to get a negative bias supply. This has been working for 20 years, too.
73
Peter G3RZP