I have a Payne air handler model 517EN036. Need a new transformer. It has 2-05813-1A Foster 15273 on it. Can't seem to find one online. Please let me know where I can purchase a replacement. Thanks

A transformer should have a tag that states input and output voltage. Most are 120 VAC IN and 24 VAC OUT. Any HVAC supplier should be able to match it.

Agreed, any parts supplier in your area, and /or your local dealer