Fluke 6060B - Option -132 Medium-Stability Reference

Option
-132
Medium-Stability
Reference
132-1.
INTRODUCTION
The Medium-Stability Reference, Option -132, provides the
Generator with a medium-
stability frequency reference.
132-2.
OPERATION
The Medium-Stability Reference is selected
as
as
the Generator’s reference when
the
Generator’s
rear
panel REF
INT/EXT switch is
set
to INT.
NOTE
The
Mediurn'^Stability Reference
does not have standby power nor
is
its oven
kept warm during external reference operation. Therefore,
each time the
Medium-Stability Reference is selected,
a warm-up time is required to meet
specifications. The warm-up time is typically 5 to JO
minutes.
(See the
specifications
for
details.)
132-3.
CIRCUIT DESCRIPTION
The Medium-Stability Reference
printed circuit assembly (PCA A5A1)
consists of an
evened
oscillator
(Yl)
and an ac-to-TTL converter. The PCA is
field repairable and is
also available under the Module Exchange Program.
The
ovened oscillator (Yl) is
not
field repairable and is not described here.
The
PCA is
mounted on the left side rail. The PCA is
connected to the +5V power
supply
and to control signals via cable W25. The
output is connected to the
Synthesizer PCA
(A2A1) through cable
W24.
Two NAND gates of U1 are used to
convert the oscillator’s ac-coupled
output
to a TTL
signal. Another NAND gate of U1 and transistor
Q
1 control the
power
for the oven and
oscillator circuit of Yl.
When the REF INT/EXT switch is set to EXT for
external
reference operation,
the
control line EXREFL is set low. This
disables
the oven and oscillator
circuit
of Yl and
also disables
the
ac-to-TTL converter to prevent it from
oscillating
spuriously.
132-4.
ADJUSTMENT
This procedure
is used to adjust
the frequency of the Medium-Stability
Reference. For
the best results, the Generator should be warmed up
at room temperature before
proceeding
with the
adjustment procedure (see step
1,
below).
132-1