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HEWLETT-PACKARD
JOURNAL
T E C H N I C A L I N F O R M A T I O N F R O M T H E - h p - L A B O R A T O R I E S
VOL. 3 No. 5-6
'UBLISHED BY THE HEWLETT-PACKARD COMPANY, 395 PAGE MILL ROAD, PALO ALTO, CALIFORNIA JAN.-FEB., 1952
Simplified Microwave Frequency Measurements
Using the 10-MC Frequency Counter
>T"~ JL was designed as a new type of secondary interesting applications both for measure
frequency standard capable of measuring ments within its direct-reading range as well
frequencies up to 10 megacycles directly and as at frequencies well above its nominal 10-
automatically. The instrument differs from megacycle limit. Many of these applications
conventional frequency standards in that make use of frequency dividers to divide the
the measured frequency is displayed on a unknown frequency down into the range of
direct-reading system on the Model 524A. In one application in the
SEE ALSO A DISCUS
SION ON PAGE 2 OF the front panel and in -hp- plant, the Model 524A is used in a some
THE "PERFECT LOAD"
AND THE NULL SHIFT
that the instrument is what different way. This application makes
complete in itself, requir- use of the Model 524A to permit precise fre
ing no external associated equipment. The quency settings of an oscillator in the 10-
indicating system identifies frequencies as megacycle region. The output of the oscilla
high as 10 megacycles to eight significant tor is then multiplied up to the microwave
figures so that a 10-megacycle unknown can region for comparison purposes.
be read to one-tenth of a cycle. Readings are In the -hp- plant the Model 5 24 A is used
accurate within approximately 2 parts per to calibrate the -hp- Model 530A waveguide
million ±0.1 cycle. Simplicity of operating frequency meters over a range from 5850 to
the instrument is such that even the most in 12,400 megacycles. The set-up for this work
experienced can make frequency measure is diagrammed in Fig. 2. The frequency
ments accurately and rapidly, for it is only meter to be calibrated is inserted between
necessary to connect the unknown and to the signal source and the waveguide tee.
record the reading displayed by the indi One arm of the tee connects to an -hp- Model
cating system. 485B detector mount which provides a rec
tified signal for presentation on
the oscilloscope. The second arm
of the tee connects to a multi
plier chain driven by the vari
able oscillator. The oscillator is
provided with a high-ratio gear
drive that varies the frequency
over a range of a few hundred
kilocycles on each side of 10
'
Fig. 1. Set-up j or calibrating waveguide frequency meters using
megacycles. The harmonic-gen
erating system provides marker
frequencies throughout the de
Model 524 A Frequency Counter. sired SHF range.
P R I N T E D I N U . S . A .
C O P Y R I G H T 1 9 5 2 H E W L E T T - P A C K A R D C O .