Hi Mike, There are a few topics in the post which will be spread over several posts, if that's ok. DC blocker The main problem in selecting the diodes for the DC blocker which cannot under any circumstances fail, is how to determine the peak current due to the inrush of the Transformer. Gut feeling, the Topaz is 'not too bad' as far as inrush is concerned, with a a disclaimer, have not measured. However a 120/60 1000VA toroid measures 10 times load current around 80A. Diodes are rated with continuous as well as peak values, which needs usually a lit larger diode. Please check the peak rating of the DC blocker. Formula Peak current (amps) = n x VA/V n = 10 for power toroid, less for Topaz, but will measure my 1000VA on the weekend. The caps in DC blockers also need some thought, usually voltage rating and how much shift above the zero is needed. A little bit to consider! Did you know..... During a short circuit the voltage has a DC offset for AC waveform, the higher the voltage, the more current.