Racal Instruments 9916 Workshop Manual page 22

INTRO DUCT
10
N
1.1 The 9916 is an eight digit frequency counter with a measl:Jrement capability of
over 520 MHz and containing a number of advanced operational features. The
instrument operates from a.c. supplies or an optional internal battery pack. Built in battery
charging fa<;:il ities are provided.
1.2 Four gate times of .01,0.1, 1 and 10 seconds are provided. The switch
positions are marked with the resolution of the display.
A
GATE!CHARGI NG
lamp lights when measurement is in progress. An OVERFLOW!STANDBY lamp lights when
the display is over-filled or when the instrument is in the Standby mode. The display and
all indicator lamps are I.e.d.ls (light-emitting diodes).
INPUTS
1.3 Two input channels are provided. Input
'B'
is a directly gated, high impedance
c hanne
I
for frequencies up to 60
MHz
wi th a. g. c. Input'
A
I
is a 50 ohm
channel covering the range 40
MHz
to 520
MHz,
prescaled by ten and with a.g.c.,
automatic overload protection and I.e.d. overload indicator.
SPECIAL FEATURES
Larae Scale Intearation
~ ~
1.4 The heart of the instrument is an integrated circuit element IC4 which performs
all the measuring functions of an 8-digit 60
MHz
counter.
'Burst' Measurement
1.5 This facil ity is provided for measurements on signals which occur in short bursts
at irregular intervals. The minimum burst duration for the
'A-'
and 'B' input
channels is 40 ms plus the gate time.
Battery Economy (Standby) Facil ity
1.6 When the optional battery pack is fitted and continuous readout is not required,
a significant increase in battery operating time can be obtained by switching to
STANDBY. The instrument is then 'off' except for the internal frequency standard.
If the
RESET button is depressed the instrument will operate normally for approximately one minute,
after which it reverts to the standby conditions. This operation may be repeated as required.
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9916 Vol. 2