Spark,
The Load impedance of a transformer's secondary is reflected back to the primary by the square of the turns ratio. Let's take an example of a 12V, 10A transformer. It should have a 10:1 turns ratio if the primary is 120V. To get a 10A current flow in the secondary, the load resistamce/reactance has to be 1.2 ohms. 1.2 ohms load impedance X 10^2 = 120 ohms reflected back to the primary. 120 V/120 ohms = 1A. The numbers work out and all is good in the neighborhood.
Experience tells us that if you have your TX plugged in, unloaded, and only get 12 volts out, it probably is not considered a 12 volt TX. The voltage out should be what it puts out at rated load.
Joe
[This message has been edited by JoeTestingEngr (edited 12-21-2005).]
