Voltage Drop in ZW-C

My guess is you're getting a one volt voltage drop somewhere within the electronics board in the transformer. 17.2 volts at the track is fine. It might even prolong the life of a few light bulbs.

Well thats the only thing I could come up with, all the circuit boards and circuitry inside the ZW must be eating that 1 volt.

Most electronic controls such as the ZW-C or a TPC will drop some voltage on the way through.  Since they're simply electronically switching the voltage, there are losses in the process.  The losses show up as heat, which is why there's a rather large heatsink inside the ZW-C.

Although there is some voltage drop across the output transistors in the ZW, with no load that drop is quite small.

BUT the Lionel phase control power controllers such as the ZW and the Powermaster reserve a small portion of the AC sinewave for generating the DC offsets for the horn/whistle and bell.  The waveform pictures at the end of
http://www.trainfacts.com/trainfacts/?p=180 show how these offsets are created.

If you checked your voltage around the loop without any current load on the track, your voltage measurements around the loop are useless.  If there are any high-resistance points in the loop, there will only be a voltage drop when a current is flowing through that bad joint.  A typical voltmeter draws almost no current and therefore won't register any drop in a bad joint.

We tested with a train running on the loop. The voltage on the track was the same everywhere we checked, also the same reading as coming out of the ZW on the A post. So it seems that everything is working normally, as intended. thanks for the replies