Hi Len,
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You want your HO track voltage to be about 14 - 14.4V.
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Definitely use an RRampmeter to measure the track voltage.? DCC voltages usually cannot be read accurately with a meter that was not specifically designed with DCC in mind.
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Also measure it with a load on the track.? If you measure it without a load, it will read higher.? I'm guessing you got 16.5V with no load on your booster or not much of one.
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The manufacturer of your decoder in your locomotive will tell you the maximum track voltage it take without damage.? Sometimes this can be over 20V.? Since you are reading under 19V, go ahead and use a locomotive as a load to measure your booster voltage.? HO decoders can take take this at least long enough for you to make a measurement.
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Besides the obvious that the decoder's electronics cannot take "high" voltages, higher voltages can overheat decoders.? So if you are getting 16.5V with a locomotive load, review your SB5 documentation and see if it can be dialed down a bit.
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Allan Gartner
Wiring for DCC
