[Boatanchors] Designing Isolation Xfmr; Need Advice

[Ken Woodside, WB8EQO]

Hi To All-

I have several B.A.'s I want to check out... I would like to build an Isolation Transformer for safety. I need some ideas & have a few questions.

I assume that there are two levels of such devices:
1. Testing receivers or tranceivers in receive mode. (low amp draw)and 
2. Transmitters or transceivers transmitting (may be high amp draw)

I wud like to build the former to start and to control costs.

I understand I can use 2 back-to-back transformers that are equal, wired secondary side to secondary side.

Wud I be better with: two 12 volt 5 amp transformers or two 24 volt 5 amp transformers (as an example)?

Ideas on fusing?  Minimum Transformer size? Other guidelines?

Many thanks to all.

Happy Holidays!

Ken AA8EE
former call sign WB8EQO