gamma scientific G-3 Manuale di istruzioni - Pagina 9
Sfoglia online o scarica il pdf Manuale di istruzioni per Strumenti di misura gamma scientific G-3. gamma scientific G-3 13. Photomultiplier photometer
Stampa la pagina7. If the meter pointer is not within the 0-100 range on the scale, the intensity
of the input is too high. To bring the pointer between 0-100, attenuate the in-
put by means of the neutral density filter in the shutter (full cw - open, increasing
to closed - full ccw).
8. Adjust, as necessary, the "Sensitivity Control" in a cw direction (increasing
the high voltage applied to the photomultiplier) to obtain the desired reading, for
instance, 100.
9. Turn shutter to closed (full ccw).
10. Adjust the "Zero Control" for 0 (zero) on the meter. NOTE: Each time the
"Sensitivity Control" is adjusted (either cw or ccw), the zero should be checked
and adjusted if necessary. Remember, by turning the "Range" control to "0-20",
a more sensitive 0 (zero) adjustment can be made. When the unit is adjusted
for 0 (zero) on the "0-20" range, it will also be adjusted on the "0-100" range.
When 0 (zero) is adjusted on the "0-100" range, it may or may not be exactly 0
(zero) on the "0-20" range. Hence it is always the best procedure to adjust zero
in the 0-20 position of the meter range switch.
11. Turn shutter to open (full ccw) or to desired attenuation position (see Step
7).
12. Readjust, if necessary, the "Sensitivity Control" for the desired reading,
i. e., 100.
13. Repeat Steps 9, 10, 11 and 12 as necessary to obtain the desired "Relative
Intensity" reading and proper 0 (zero) reading.
Use
The G-3 Photometer is now ready to be used to measure the relative intensity of
the unknown source or surface. Allow 15 minutes warm-up time (to stabilize the
electrometer amplifier) before taking any measurement data. When the meter
pointer is reading 20 or below on the 0-100 scale ("Range" control in "0-100"),
the "Range" control may be turned to the "0-20" range, thus producing a full scale
reading of 20 decreasing down to 0.
NOTE: As the "Sensitivity Control" is turned cw (increasing high voltage), the
noise, inherent in the photomultiplier tube, will become evident and show as
minor fluctuation on the meter pointer. This fluctuation is normal operation of
the G-3 when operated near its maximum sensitivity.
External Output Jack
The external output jack has an impedance of 1.5K ohms. The output circuit is
capable of driving any high impedance accessory instrumentation.
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