Calibration
General
Calibration is guaranteed as in the specification. The Manufacturers provide a re-calibration
service, as do most of their agents overseas. Where owners wish to carry out re-calibration
themselves, this should only be done by skilled personnel with access to precision equipment
working in conjunction with the service manual which may be purchased directly from the
Manufacturers or their agents overseas.
Zero Calibration
An automatic zero calibration of the basic DC measurement circuitry is performed every time that
the instrument is switched on. If the meter has been stored at a temperature outside the specified
operating range, and is switched on before it has fully acclimatised to the working environment,
meter accuracy may be affected as the meter’s temperature changes. To ensure optimum
accuracy the zero calibration can be repeated when the meter has acclimatised by using the Null
key as follows:
Press the Null key and continue to hold it down until nULL shows in the main display (about 3
seconds later). nULL continues to show whilst the auto-zero is being performed (typically 5
seconds); on completion the display returns to its previous mode.
DC zero calibration affects all measurement ranges, but ac measurements, resistance and
capacitance have additional zero adjustments which are only made during the full calibration
routine. However, if there is a small residual offset on the most sensitive ranges, it can always be
nulled out using the Null or Ohms Null facilities, see appropriate sections.
50Hz/60Hz Rejection
The analogue-to-digital converter operation can, by software adjustment, be optimised for either
50Hz or 60Hz ac line rejection; the NMR and CMR figures given in the Specification assume that
the appropriate frequency rejection has been set, as described below.
To check or change the ac line rejection setting press Shift followed by Address (the shifted
function of FUNCTION) and then depress the Cal switch (accessible through the front panel Cal
hole) with a small tool until it clicks on. The main display will show REJ and the secondary display
will show either 50 or 60. Press the Range Up/Range Down keys to toggle between 50 and 60Hz
rejection. When the correct frequency has been selected (to suit the local ac supply) release the
Cal switch by depressing it again with a small tool and then press Run; the display should return
to normal measurement mode.
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Telemeter Electronic GmbH | Joseph-Gaensler-Str. 10 | Phone +49 906 70693-0 | Fax +49 906 70693-50 | www.telemeter.info 28
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