GENERAL INFORMATION
This manual contains directions for use that
apply to
a number ofmodels. In order to simplify
references
to
certain
models,
the
follow-
ing designation system is used throughout the
manual:
PM6681
stands
for PM6681, PM6681R and PM6681R/676/AF
PM668 1 R
stands
for PM668 1 R and PM668 1
R/676/AF
The PM6681R/676/AF is
a model
supplied
with the following features:
-
PM6681R base model
-
Prescaler PM9624
(2.7
GHz)
-
Rackmount
kit
PM9622
-
Reference output option PM9671B
Refer to the
respective
type
nunibers
in the Operators
Manual
for specifications
and other infomiation not
found in this manual.
New options
and deviations
from
the
original design are collectively treated
in
Chapter
9,
Appendix. Below is a summary of the
changes:
Unit
1
The main printed-circuit board (Unit
1)
has recently
been redesigned due to obsolescence ofa number of
integrated
circuits. Designa-
tions found in circuit descriptions, schematic
diagrams
and parts lists in the first eight chapters refer to the original design. The func-
tional descriptions are correct on the
whole,
if you make a few substitutions. Anew set of schematic diagrams and a new replacement
parts list are added in Chapter
9,
Appendix.
-
Instruments having serial numbers >784919
belong to the new generation.
-
The model
PM6681R/676/AF has
only been produced with the new Unit 1 board,
so
the serial number is irrelevant.
Model PM6681R
The model PM6681R introduces an ultra-stable rubidium
atomic clock reference.
Option PM9671B
Reference output unit offering six buffered
1
Vrms
outputs
with four different standard frequencies: 3x10 MHz, 1x5 MHz, 1 xl MDHz
and 1 X 0.1 MHz.
New OCXOs
The
PM9691
has
been redesigned,
and
a version with very high stability
,
the
PM9692,
has been
introduced.
Ill
To Next Page
Loading...
