Output transformer question

Ok,first of all,a power transformer is not classified as push pull or single ended.It only supplies power and current handling capabilities.An output transformer is classified that way,and you can tell by the number of wires.It has two wires that go to the plates of the power tubes and a centre tap that goes to a high voltage connection,usually a screen supply that is filtered DC.
You can use a push pull OT on a single ended amp,but it is not recommended because a single ended OT needs to have a larger core gap to handle the current.A single ended amp is conducting current all the time,so it needs to be able to handle the demand placed on it.A push pull OT is handling current half the time so it can have a smaller core gap.
If you use the push pull OT,make sure it has at least a 20 watt rating for a 5 watt single ended amp.

 

So then your saying a SE transformer would only have one wire that goes to the plate of the power tube and one that goes to the High Voltage? I asked Rob to post this as I have a friend that has a RCA chassis he wants to do something with and it has a couple of OT's on them and I wondered if they were SE transformers used on a stereo setup and I wondered what an easy way to tell was. Another thing how do you tell the wattage of an OT that you may find on an old chassis? Any easy way?

 

Many SE hi fi output transformers have a screen tap which means they have the same # of wires as a push pull OT (and often the same red, blue, brown colors).

 

OK so any good way of telling whats what if you do not have a schematic?