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6.
MEASURING CONSIDERATIONS
6 - 1
Use of attenuator
The input impedance ( 1 . 2 M e g a o h m , and 4 0 p F or
less) of the C H A N N E L A juck is not
through manipulation of A T T x 10 switch @ .
The circuit load can be reduced by the attenuator
probe to the C H A N N E L A input juck. Set the
attenuator probe to the x 10 position to reduce the
circuit load.
Note 1 : Sf 10 ; 1 attenuator probe is used, v e r i f y
that the- amplitude of the s i g n a l , input to the
counter s a t i s f i e s the following condition :
M i n i m u m
^
signal level
Note 2 : Sf the prescale input is used, does not
use the 10 : 1 attenuator probe. T h i s attenuation
circuit is designed based on the input impedance of
1 Megaohm. The prescale input juck is
w i t h the resistance of 50 ohm. A s a result, the
attenuation circuit w i l l function a s the 180,000: 1
if used together w i t h the prescale input juck. Please
keep it in mind.
26
probe
affected
Attenuated
input
signal level
terminated
6 - 2
Change in measurement mode and resolution
A new measurement operation is started each time
when a measurement mode or resolution value is
changed. The measurement display d a t a on Display
(I) is not updated until the new measurement
cycle is completed.
Even if decimal point place and leading zeroes are
corrected, and a new measurement value then
appears on the L E D display, it may be inaccurate
due to display delay. Please keep it in mind.
8—3
Self check mode
The self check mode is provided to check the
internal general functions of the F C - 7 5 8
functional frequency counter for a short time.
(Operational Procedure)
(1)
Select the C H E C K / 1 0 MHz mode w i t h F U N C
s w i t c h
@ .
When the frequency counter enters this mode, the
counter input is logically connected to the time
base oscillator.
V e r i f y that the output results agree to those
listed below.
m u l t i -
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