I previously posted this message under Surger Suppressors but it is also appropriate in this thread:
I have two of the ABC1200-11 units that I use for my HT system. I bought both of these units on EBAY; $201.05 & $219.95 including shipping.
I also did some research on these units before purchasing and on isolation transformers in general. A good analysis of the benefits, myths, and pitfalls of using isolation transformers can be found at
http://www.blackmagic.com/ses/bruceg...solatrans.html. If properly designed, isolation transformers can provide a good degree of common mode and normal mode noise reduction. The efficacy of the Powervar unit in this regard is shown in their test results using an ANSI/IEEE specified noise pulse applied to the input.
In my application, I have the secondary neutrals connected together, the secondary ground leads connected to a cold water pipe, and my equipment load roughly divided between the two Powervar units.
Though I can make no claims about improved system performance, my intent has been that by providing clean power to my equipment I am eliminating another possible source performance degradation.