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HEWLETT-PACKARD
m f T E C H N I C A L
JOURNAL
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. 6 No. 3-4
[BUSHED BY THE HEWLETT-PACKARD COMPANY, 275 PAGE MILL ROAD, PALO ALTO, CALIFORNIA NOV.-DEC, 1954
New Broadband Microwave Power Amplifiers
Using Helix- Coupled TWTS
' I ^HE Hewlett-Packard laboratories have watts, respectively, into 50 ohms and have
J- developed several new broadband mi gains of 30 and 35 db. They can thus be op
crowave power amplifiers which promise to erated directly from the 1 milliwatt drive
be extremely important in furthering high- available from the -hp- Model 6l6A 1.8-4
frequency development work of many kinds. kmc signal generator to provide high level
The importance of these am signal sources.
plifiers lies in the fact that The 1-watt amplifier is designed as an un
they provide high gains, modulated amplifier, while the 10-milliwatt
high power output, and very unit is designed to be amplitude-modulated
wide 2:1 bandwidths in the microwave re if desired. For modulating purposes very
gion. The development of amplifiers with short pulses of about 25 millimicroseconds
such characteristics at once solves several duration can be used. Both amplifiers will
problems prevalent in high-frequency work. amplify even shorter r-f pulses of the order
These problems include the need for signal of 1 millimicrosecond in duration.
powers much higher than those available A third amplifier, soon to be in produc
from signal generators and the need for the tion, has been designed to operate from 4-8
wide-band amplification device necessary to kmc and provide an output of 10 milliwatts.
development work in any frequency range. Meantime, design work is progressing on
Two of the amplifiers, those in production, higher frequency amplifiers.
operate from 2 to 4 kilomegacycles, provide Engineering-wise, these amplifiers are of
maximum outputs of 1 watt and 10 milli- special interest because they constitute what
is probably the first eco
nomical application of
the wide-band character
istics inherent in the
travel ing- wave tube. To
make use of the poten
tially broadband capa-
pp, bilities of the basic trav-
|H f eling-wave tube, a new
arrangement has been
devised for coupling into
and out of the tube helix.
Fig. (center) used hp- Model 491 A 2-4 kmc Traveling-Wave Tube Amplifier (center) used This coupling arrange
with Ten 616A VHP Signal Generator to form 1 watt signal source. Ten millhcatt
TWT amplifier is similar in appearance to I watt unit sboitn. ment is such that a twt
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 .