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Патент USA US2407861

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Sept; 17, 1946.
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L. J. ‘WOLF
'
2,407,860
COMMUNICATION SYSTEM FOR ULTRA HIGH FREQUENCY
Filed April 22,. 1942
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Imventor
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attorney
Patented Sept. 17, 1946
2,407,860
UNITED STATES PATENT OFFICE
2,407,860
I
‘
COMMUNICATION SYSTEM FOR ULTRA
HIGH FREQUENCIES
Lester J. Wolf, Audubon, N. J ., assignor to Radio
Corporation of America, a corporation of Dela
ware
1
Application April 22, 1942, Serial No. 439,964
4 Claims. (Cl. 179-1715)
This invention relates generally to radio
transmitters and particularly to ultra-high fre
quency pulse transmitters modulated by voice or
other signal frequencies.
It has long been recognized that considerable
difficulty is experienced in generating ultra-high
frequencies with transmitting tubes of high power
rating. At present, high power telephone com
munication at frequencies of the order of 100
megacycles or higher is limited in the transmitter
because of the dif?culty in constructing vacuum
tubes to handle large amounts of radio frequency
power at these frequencies. This difficulty is
seemingly inherent because of the interelectrode
2
.
cuits, consisting of tuned transmission lines, is
shown in combination with a modulator having
a conventional input circuit. The oscillator tubes '
l and 2 have 'a balanced anode circuit compris
ing the resonant lines 3 and 4 tuned by the
shorting bar 6. The shorting bar 5 is connected
to a source of anode potential which may be of
the order of at least ten times the normal volt
age rating for the tubes. The shorting bar 5 is
also connected to the anode of the modulator
tube l3. The grids of the oscillator tubes l and
2 are connected respectively to the tuned .resonant 7
lines 6 and ‘l which are tunedby the shorting
bar 8. The cathodes of the oscillator tubes l
capacity and transit-time losses in conventional 15 and 2 are connected respectively to the resonant
high power transmitting tubes. In a similar
lines 9 and [0 which are tuned by the shorting
manner communication at these frequencies is
bar It. A capacitor 12 is connected between the
limited in the receiver because of noise level due
shorting bars 8 and H. The shorting ‘bar 8 is
to static, ignition noises, etc., and to transit-time
also connected to the cathode of the modulator
losses and reduced ampli?cation. One solution 20 tube l3.
.
to this problem is the use of a pulse transmitter
,The grid circuit of the modulator I3 includes
in which extremely short pulses having high peak
power are radiated from the transmitter.
It is
perfectly practical under these conditions to
the secondary of a modulation transformer M
and an adjustable source of grid potential 15.
The primary of the modulation transformer M
radiate a peak output of as much as 100 times 25 is supplied with modulating potential applied to
the continuous power rating of a transmitting.
tube designed for operation at the frequencies
previously mentioned.
Among the objects of the invention are to pro
vide improved methods and means for generat
ing and modulating ultra-high frequency pulses
of radio frequency energy having peak power
many times greater than the continuous power
the input terminals IS. The negative terminal of
the high potential anode power supply is con
nected to the shorting bar I l.
'
In operation the modulator tube acts as a grid
30 leak of very high resistance for the grid capacitor
l 2 in the oscillator circuit. When the high anode
voltage is applied to the oscillator tubes l and 2,
they commence to oscillate very abruptly, and a
high peak power radio frequency current is gen
is to provide an improved method and means for
The resultant‘ high grid current in the
modulating ultra-high frequency pulses of radio 35 erated.
oscillator circuit rapidly charges the small con-'
frequency energy by controlling the blocking and
denser l2, and the bias on the oscillator tubes
unblocking of an oscillator circuit in response to
rises to a blocking value within a few microsec
modulation potentials. Another object is to pro
onds. The oscillator tubes l and. 2 will remain
vide improved means for blocking an oscillator 40 blocked until the condenser I2 can discharge _
circuit and unblocking the circuit through a leak
through the leakage path provided by the anode
age path through a modulator tube circuit.
circuit of the modulator tube l3.
The invention will be described by reference to
The bias potential onthe grid of the modulator \
the drawing of which Figure 1 is 'a schematic
tube [3 is adjusted to the value which will provide
circuit diagram of one modi?cation of the in 45 an anode resistance of a predetermined value for
vention; Figure 2 is a graph showing the operat
pulsing the oscillator. circuit at any desired fre
ing characteristics of the circuit; and Figure 3
quency. Modulation potential applied to the
is a block diagram of a receiver for signals from
terminals I 6 of the modulation transformer I4
the system to be described. It should be under
will vary the grid potential of the modulator l3,
stood that the invention will be adaptable to 50 which in turn will vary the anode resistance of
any standard transmitter circuits and that the
the modulator. Any change in the anode re
circuit described and illustrated is merely one
sistance of the modulator l3 will vary the dis
embodiment of the invention.
charge time of the capacitor I2 in the grid cir
Referring to Fig. 1, a push-pull oscillator cir
cuit of the oscillators l and 2. Variations of the
cuit utilizing tuned anode, grid, and cathode cir 55 discharge time of the capacitor I2 will vary the
rating of the transmitting tubes. Another object
2,407,866
3
interval between successive pulses of radio fre
quency power in the oscillator circuit, and may
possibly vary the shape of the individual pulses.
4i
lator anode and control electrode circuits for
varying the time‘ intervals between pulses gener
ated by said oscillator in accordance with said
modulator anode circuit variations.
The use of the extremely high anode voltage on
2. A pulse transmitter including a pair of oscil
the oscillators and modulator will also tend to $1
lator tubes having push-pull tuned anode and
reduce the transit-time losses in these circuits.
control electrode circuits coupled to provide oscil
Fig. 2 shows the variation in time interval be
lations, a capacitor in said control electrode cir
tween successive radio time frequency pulses
cuit connected to effectively block said oscilla
resulting from a variation in the resistance of
the leakage path through the tube i3 for the 10 tions, a modulator having control electrode and
capacitor l2.
Fig. 3 is a block diagram of a receiver which
will provide satisfactory reception of the signals
anode circuits, means for applying modulating
potentials to said modulator control electrode
circuit to vary the resistance of said modulator
anode circuit, and means connecting said modu
radiated from the transmitter of Fig. '1. The
receiver may be of any conventional design such 15 lator anode circuit between said oscillator anode
and control electrode circuits for varying the time
as a radio frequency ampli?er 3| followed by a
intervals between pulses generated by said oscil
detector-A, V. C. circuit 32, and an audio ampli
lator in "accordance with said modulator'anode
?er 33 connected to a reproducer 34. The .auto
circuit variations.
‘
matic volume control circuit is shown connected
3. A pulse transmitter including a pair of
to the radio frequency ampli?er by the line 35, 20
oscillator tubes having push-pull tuned anode,
so as to bias off all but the peak portion of the
control electrode and cathode circuits coupled to
received’ pulses as shown by the pulse peaks 22
provide oscillations, a capacitor connected be
above the dash line 2% in Fig. 2. The average
tween
said control electrode and said cathode
noise level‘indicated by the curve 2| in Fig. 2
ordinarily will be considerably lower than the 25 circuits to effectively block said oscillator tubes,
a modulator tube having a variable resistance
A. V. C. limiting value 20 and will, therefore,
anode circuit, means for varying said anode re
provide substantially noiseless reception. It
sistance of said modulator as a function of modu
should be understood that this limiting feature
lating potentials applied to said modulator,- and
may be applied to any conventional radio receiver
by this or other well known methods.
I claim as my invention:
1. A pulse transmitter including an oscillator
having tuned anode and control electrode circuits
coupled to provide oscillations, a capacitor in said
control electrode circuit connected to effectively
block said oscillations, a modulator having control
electrode and anode circuits, means for applying
modulating potentials to said modulator control
electrode circuit to vary the resistance of said
modulator anode circuit, and means connecting 40
said modulator‘ anode circuit between said oscil
means connecting said modulator anode circuit
between said oscillator anode and control elec
trode circuits for varying the time intervals be
tween pulses generated by said oscillator in ac
cordance with said modulator anode circuit varia
tions.
.
4. Apparatus of the type described in claim 2
including variable means in said modulator circuit
for adjusting said modulator anode circuit re
sistance.
_
~
LESTER J. WOLF. '
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