So I need to build a bulb tester for testing Eiko 1820 bulbs. They require 28v AC, 0.1A and consume about 3W. Any ideas on how I can do this?

 

Just use a continuity meter, surely?
Or are you wanting to test how bright they will be? In which case, get yourself a 28V ac power supply and a bulb holder!

 

All you really need is a 120 to 28 volt step down transformer

 

I definitely need to check them at 28V so that I can confirm their brightness. I've done some searching for a step down transformer... but I can't seem to find a match. Any links to some good sites that would carry one?

 

Are you planning on just eyeballing the brightness level? Unless you do side-by-side against a reference, it could be tough to make a judgement.

 

655-4900-8028RC62 at www.mouser.com
$8.40 plus shipping

 

just get an off the shelf 24V DC power supply

Or here http://www.mpja.com/24VAC-40VA-Plug-Transformer/productinfo/12637+PA/