Great optical improvements are readily apparent when you sight a target for the first time. The BC-27BR/CR charger supplied with the gun is a 'smart charger,' which means you can take advantage of a refreshing cycle to completely drain the battery before it goes into its normal charging cycle. You have really got to work hard to run out of battery with all these options. There are three battery chargers to choose from, as well as an auto-converter, the AC-5, and an automobile power outlet charger, the BC-9. A 1.8ah capacity, the BT-3Q, and a 6.0ah, the BT-3L, can still be plugged into a receptacle in the base of the gun. Topcon has an entire battery system that can be purchased for the 6000 series. We have three of them and got into the third one when operating on cold windy winter days. Two batteries will normally get you through an average day in the summer and most of the shorter winter days. The BT-50Q is a 2.7ah Ni-MH battery that is rated at 14 hours for angle reading only, and at 2.7 hours of continuous measurement time.

Our GPT-6001C came with two BT-50Q, on board batteries. It can be plugged into the base of the instrument for those extra long summer days. One of the neat things about the GTS-3 series is the ability to power the gun with a supplemental square battery.

(Our crew carries an electronic altimeter/barometer and temperature unit to take readings of the current temperature and site barometric pressure to set our PPMs correctly for the environmental conditions we are working in.) Additional spaces are provided for accessories that you may wish to carry. Molded compartments comprise the balance of the case, with spaces for everything, including the battery charger and the spare battery. The hinge system is designed to be very secure in order to prevent accidental opening of the instrument case when in transit.

The instrument case is the typical clamshell design with a rubber gasket seal between the two halves. GPT-6001C, serial number WS0124, owned and used by Trans Associates, appears to be well-steeped in the tradition of the 1984-vintage Topcon GTS-3 total station. Such is the case with the Topcon GPT-6001C, a one-second reflectorless total station.

From time to time, some of the instruments that I review in this column are not demonstrators, but rather instruments that are in regular service.

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