What do I need to change to get my UK 220v AWRC1G to use US 110V power?

You will need a transformer unless your device is rated to use dual voltage - the rating plate sticker on the case will tell you if it's dual voltage - else a simple transformer - match the Wattage of the device with the transformer - have the transformer the same or a little bit higher wattage else you'll put a strain on it.

You will need to arrange appropriate connections -

Transformer to power outlet
Transformer to equipment

You will need a 2:1 step up transformer - takes 110 up to 220
Connect it back to front and it will step down to 55 volts

Do not worry about any odd voltage variation - close enough will do - plus or minus 10 volts will be close enough.

Jumbo
October 2014