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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. 5 No. 5-6
IBLISHED 1954 THE HEWLETT-PACKARD COMPANY, 395 PAGE MILL ROAD, PALO ALTO, CALIFORNIA JAN. -FEB., 1954
A New Signal Generator for the
7,000 to 11,000 MC Range
>~pHE new -hp- Model 620 A SHF Signal Gen- source in this frequency region. For radar work
JL erator operates over the frequency range and other pulse type applications, the modu
from 7,000 to 1 1,000 megacycles and incorpo lation system includes a pulser so that any r-f
rates all of the features that have given an un pulse width is obtainable from '/z to 10 micro
usual measure of popularity to the other -hp- seconds at any repetition rate from 40 to 4,000
high- frequency generators. For example, the pps. Both the pulse width and pulse repetition
new 620A is direct-reading in frequency and rate are selected by direct-reading controls.
For applications such as slotted line work,
in power output, provides a maximum of ap
the modulation system provides for a square-
proximately 1 milliwatt over most of its fre
wave modulated r-f output which is adjustable
quency range, has an accurate continuously-
over a range from 40 to 4,000 cps. The repe
adjustable output attenuator to provide output
levels as low as 0.1 microvolt, and has a flexible tition frequency of the square-wave modula
tion is selected by the same direct-reading con
modulation system that provides for both in
trols that select the repetition frequency for
ternal and external modulation.
pulse modulation.
The flexibility of the modulation system is
such as to enable the generator to be used for The modulator further provides two syn
chronizing pulses of at least 25 volts peak am
nearly any application desired for a signal
plitude into 1,000 ohms. One of these pulses
begins approximately concurrently with the
start of the pulsed r-f output. The other sync
pulse is adjustable over a range from 3 to 300
microseconds ahead of the r-f output in order
to position the sync pulse suitably for external
triggering purposes. The rise time of the sync
pulses is less than 1 microsecond. The modu
lation system can also be synchronized with ex
ternal sine or pulse voltages of either polarity
and as low as 5 volts amplitude.
A third type of internal modulation avail
able is sawtooth f-m. The repetition frequency
of the sawtooth is adjustable from 40 to 4,000
cps, while the r-f deviation is adjustable up to
at least ±3 me. Both the external synchroniza
tion feature and the sync out pulse feature are
Fig. 1. New -hp- Model 620A SHF Signal Generator pro- available for use when internal sawtooth mod
fides for cw, pulse, square-wave or f-m output orer 7 to
1 1 kmc range. ulation is used.
P R I N T E D I N U . S . A . C O P Y R I G H T 1 9 5 4 H E W L E T T - P A C K A R D C O .