Today I sniped a lot of six devices (three of them are R&S), plus some manuals / schematics and a R&S promotional glass hanger.
I got all of this for ca. 420 Euro.
--snip--
Here are some pictures:
Have you actually verified the unknown variable transformer also contains an isolation transformer? the case doesn't look big enough for both, unless it's very low power.
David
Good observation and question. As it's high voltage output it's unlikely to be isolated. They do make isolated variacs though.
I have a low voltage output one. Basically it's got two windings about 600 turns of fine wire for the input that is fully insulated and then about 50 turns of thicker wire wound over it and the wiper runs on that.
Advantage is its smaller, lighter and possibly cheaper than a mains variac and separate isolation transformer. Disadvantage (for low voltage) is lower voltage resolution as 50 turns only gives 50 voltage steps (there is some interpolation as the brush covers more than one turn).
There is no reason why you could not make an isolated mains variac with two windings, fixed for input and wiper track on the output. Never seen one though.