Tektronix DAS9100 User Manual

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Jl6 OPERATING HINTS (CONT.)
trade-off fs a poorer spectral match
to the CIE photopfc response curve.
To correctly zero the J6523/Jl6
combfnatfon, cover the J6523 objective
lens and adjust the J6523 zero on the
XlOOO range. Then change to the XO.l
range and adjust the Jl6 zero. It fs
usually necessary to repeat the
procedure once or twfce as the
adjustments interact. There fs an
incompatabilfty between the J6523 and
very early Jl6's that prevents zeroing
on the XlOOO range. A simple mod kit
fs available to cure ft. The kft P/N
fs 040-0746-00, and applies to the
Jl6's below S/N 8052000.
2) Calf bration--The photopfcally
corrected J16 probes are all initially
calibrated fn the plant usfng 3000 K
tungsten-halogen white light source.
For maximum accuracy with CRT's they
should be calibrated for the
individual phosphors to be measured.
Correction factors up to approximately
101 (higher for the Mfnoltas) may be
necessary to obtain correct data due
to devfatfons from the photopic
response curve. Thfs fs most severe
in the red and blue regions where a
small absolute deviation can be a
large percentage of the actual value
due to it befng on the lower skirts of
the photopfc response curve.
Electrical Standards can provide thfs
calibration service.
· The long tenn calibration of the
probes fs very stable due to the
sflfcon photodfode and glass photopic
correction filters. Sfnce the Jl6
itself fs calibrated usfng only a
simple current source and DVM, ft fs
seldom a source of error unless
incorrectly zeroed.
I rec01111end that the J16's be
recalibrated about once a year. The
probes probably should be recalibrated
every sfx months or so--110stly because
calibration techniques are being
improved with time rather than the
likelihood of the probes themselves
-3-
October, 1883 laaue 31
changing calibration. Routine Jl6 and
probe calibration is handled through
Factory Service while special probe
calibrations are done by Electrical
Standards.
3) J6503 Modifications--As
assem"bled, the J6503 has a plastic
window and shiny blue plastic
front which can cause minor
reflections when placed directly
in contact with a CRT faceplate.
For best accuracy the plastic
window should be discarded, the
probe front painted flat black and
the probe recalibrated.
Some early J6503's had glossy black
paint on the internal baffles and no
inner black shield to reduce internal
reflections. This resulted in side
lobes and a significant difference fn
readings with and without the light
occluder often used for CRT
measurements. These can be modfffed
and recalibrated without too much
df ffi cul ty.
4) 2 1/2 Dflft Jl6's--Early Jl6's
having only 1/2 digits are dffffcult
to read accurately, when the reading
are at •20
11
or so as the +l dfgft
ambfgufty amounts to 51. -Also they
have a 12Hz count rate rather than 6
Hz as fn the 3 1/2 dfgft version.
Thfs causes the display to change
faster than the user can detect a
reading for varying lfght fntensftfes.
Both of these shortcomings were
addressed with major modfffcations at
S/N 8052000.
5) N:. Versus Battery Operatf on--
The Jl6 fs available with an Ar. power
supply installed as Option 3 or ft may
be ordered separately to replace the
battery pack as 119-0404-00. Thf s
overcomes three problems--
I) Battery lffe fs short and
recharging tfme is long,
(ARTICLE CONTINUED ON THE NEXT PAGE)

Tektronix DAS9100 Specifications

General

Brand	Tektronix
Model	DAS9100
Category	Measuring Instruments
Language	English