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Патент USA US2409459

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Patented Oct. 15, 1946
2,409,457
UNITEDl STATESl PÀTENT OFFICE4N
George L. Usselman, Port JelïersomN. Y., assign
’
or to Radio Corporation of America, a corpo
ration of Delaware
Application February 21, 1944, serial No. 523,232
9 Claims.
1
(Cl. 179-1715)
2
.
This application Concerns timing modulation
capacitive branch on the other side of the said
point at which the tank circuit is grounded. The
cathode of Vl is grounded, and thus the connec
tions are such as to operate’ the anode and grid
at opposed radio frequency potentials to make use
of regeneration in the production of oscillations
systems and more exactly systems for generat
ing wave energy and controlling or modulating
the ¿timing of the generated wave energy as de
sire
.
"
Many systems for‘this purpose are known in
the radio art, and the general object of this
when the electrodes are provided with operating Y
application is improved `wave Vgeneration and
wave length control.
‘
î
`
potentials.
`
.
The anode I4 and grid I6 are coupled in a
`
A more speciñc object of the present inven
10
tion is to provide a more simplified and more
efficient arrangement for generating wave en
ergy and controlling the Wave length thereof,
similar 4manner to the inductive branch LI of
the tank circuit. This coupling includes direct
’current blocking and`~coupling condenser `-I8.
Here again,- for reasons‘pointed out above in con
which arrangement uses a relatively small num
ber oi tubes and circuit elements. I
nection with tube VI, oscillations are generated
in the tube V2 Whenfoperating potentials are sup-'
An additional object of this invention is an
arrangement as described in thepreceding par
plied tothe tube electrodes.
_
`
"
Anode potential is supplied to the tube‘Vl
agraph such that theA generated wave energy is .
through choking inductance CH and to the tube
controlled as to timing through a considerable
range without causing undue undesired amplitude
V2 through a part of the inductance LI. Biasing
potential Vis supplied to the control grids I0 and
I6 byïv'irtue of current (due to‘grid rectifica
modulation
thereof.
`
`
»
`
‘
‘
‘
The manner in which the Vabove objects and
other objects, which, appear hereinafter, are at-.»
tained will be >apparent from the description
which follows and therefrom when read <in con-1 25
tion) in resistances Rl and R2 or the same sup
nection with the attached drawing.
both branches ofthe tuned circuit and at the
same time ï‘ prevent split tuning of the tank cir
cuit. That is‘to prevent the upper and the lower
halves ofthe circuit `from tuning separately.
,
l
.l
`
Figs. 1 and` 2 each illustrate diagrammatically
by‘circuit connections the essential elements of
a timing modulation systemarranged in accord
plemented by potentialfrom the source B. The
purpose of resistor R3 'is to make it possible to
provide an RL‘fF, ground for the> center pointfof
ance with my invention. The two embodiments 30
The anodes of tubes VI and V2 are both con
are substantially the same, except that in the 'em
nected to `the tank circuit on the same side of
bodiment of Fig. l triode tubes are used ingthe
the ground connection, as are the grids of these
circuits, Whereas in the embodiment >of Fig. 2
tubes, so that the tubes operate in parallel using
multi-grid tubes-are used.- `In the embodiment
the same tank circuit.
‘
oi Fig. 1 the control of thegtimîng of the gen 35 y'I'he oscillation generating tubes Vl and V2 also
erated oscillations is by way of control grid elec
have as a functionimodulation or control of the
trodes, Wlfiereas` other grid electrodesare used for
timing of the oscillations generated. The imped-`
this purpose inFig.2.
„
ance between the anode and cathode of tube VI
In Fig. 1 of the drawing, the tank-.circuit com
prising an inductive branch LI and a capacitive
branch Ci,»C2,.C3, is connected in an oscilla
f
v
f «j
` '„
isv connected‘across Cl and constitutes a variable
resistance `tapped across this condenser Cl, which
tion generating circuit-includinggtwo tubes Vl
and V2. In `the embodiment shown, the tubes
and determines in part the frequency of the oscil- '
may be considered as inl parallel in4 the oscil
The tube V2 has its output impedance coupled
lation generating circuits, and the arrangement
is also such that each-of the tubesper se may
is a portion of the total tank capacitive reactanoe.
lations generated.
_
45 across a’ portion of the inductive branch Ll of
the tank‘circuit so that this> tube output imped
be considered as a separate generator having l
ance constitutes avariable’resistance tapped
as a tank circuit Ll, Cl, JC2,and C3... However,
the tank circuit is common,„so ‘that `the tubes
tapped across" al portion of the total tank induc-V
across a part` ofA Ll which is equivalent to being
50
tive rèactance which also determines in part _the
frequency' “of the 'oscillations generated.
It is _known that if a resistance istapped across
a portion of any reactance the total effective reac
a coupling?` and blockingfoondensera I2f`tofthel 55
also produces a variation in the total reactance.
operate
.In theinarrangement,
unison.
the
> anode
l _
8 of VI
` isg cou
pled tothe capacitive leg at a point on one side
of the point at which the tank circuit is grounded.
The control grid VIll of this tube is coupled by
tance is changed. A variation of this resistance1
2,409,457
4
3
Where the reactance is used in an oscillation gen
capacitive reactance between the control grid 6
erator circuit as is the case here, this causes a
and the cathode in tube VI. L3 serves a similar
purpose in connection with tube V3. L4 is of a
value such as to balance out the capacitive reac
change in frequency of the oscillations generated.
In my arrangement I have the variable re
sistances, i. e., the outputs of V! and V2 tapped Cl tance between the anode and cathode of tube VI.
across a portion of the reactance in each leg or
Inductance L5 serves a similar purpose in the cir
side of the parallely tuned tank circuit. 'I’hat is,
cuits. of tube V2'. The advantage of cancelling the
‘tube capacities at thegoperating frequencies is
that there remains only the resistive component
one tube’s loutput is tapped acrossa portion of
the capacitive reactance and the other tube’s
output is tapped across a portion of the inductive'
reactance of the tuned circuit. If bothpfthese
vof the tube impedance which is the one I vary to
produce the frequency modulation. The tube
capacitive reactance does not vary and therefore
lproduces no'useful modulation. It may cause dis
tube resistances are alike and are tapped" across
the same proportion of the totalgreactance of the
two branches of the tank circuit, the :frequency
to which the tank circuit is tuned is not changed.
This is because the increase in capacitive reac
tance is accompanied by a decrease in inductive
reactance and vice versa, so that in general-the
tuning of the circuit is unchanged. As long as
these resistances remain equal, though they be
'tortio-n4 by lunbalancing the modulator circuit.
Thereforeit is Wi'seito cancel it out.
In the embodiment of Fig. 2, the control grids
8 and IB are biased by the potential drop in re
sistances Rl and R2 caused by current flowing in
the grid circuit due to grid rectification. The in
20 ductances L4 and L5y serve as anode direct cur
varied, the tuning of the circuit remains un
rent'Y supply circuits for the tubes VI and V2,
changed. However, if _one resistance be changed,
while the inductances L2’ and L3 supply the bias
forexampleby changing the current in one tube,
potentials to the grids of tubes VI and V2.
In both embodiments the reference character
or ifboth tube resistances be changed in oppo
site=sense,.for example, by changing-the currents
in both tubes in oppositesense, then the tuning
BP has beenapplied to radio frequency bypassing
condensers, the function and connection of which
frequency of the tank circuit is changed.
'll-he arrangement including tubes Vi.- -andV2
and thejtank circuit is, as'stated above, an> oscil
are so well. known in the art as> tol hardly need
discussion herein. In Fig. 2, 24 and 25 are high
frequency coupling and direct current blocking
_lation generator. Since thetube output imped
condensers.
ances are connected» across portions of the tank
reactance as explained.v in detail above, and are
guency bypass condenser.
2`8- is a modulation potential fre
_arranged for differential individual amplituue
In both embodiments the connections between
the tank- circuit andthe anode and grid of either
modulation-*the timing of the oscillations gener
ated is modulated and the arrangement is a timing
point at which the tankcircuit is ground or neu
modulation System,
v
»
'
tube Vi, V2, maybe reversed with respect to the
tral withoutl changing the operation of the fre
quency'modulation. This is obvious because the
,
_» =If-thetubes Vl andVZ aresimilar andare _sym
tube arrangements would still be such as to pro
metrically tapped onzthe reactive legs the timing
vide'r regeneration therein. The oscillator tubes
modulation» »characteristic isV 5 symmetrical ' above
and'k below ai mean carrier frequency. Both tubes 40 might then be considered as being `coupled dif~
Viaud; V2 deliver their generated energy to the
ferentially tothe tank circuit.
Same tank-circuit `and the fact that both ytubes
In thepmodiñcation of. Fig. 2, a frequency shift
of'255'kc. was. obtained at a carrier frequency of
arediiïerentially modulated in amplitude assures
that amplitudefmodulation is balancedfout of the
45
output signal'. „Y
3188 kc.
I
».
¿the embodiment of Fig. 1, the tube output
resistancesand currents are varied by differen
claim:
`
'
v
Y
Y 1. In a wave-generating and- Wavel length mod
ulating system, a capacitive element and an in
tiallyV varyingl the tube grid potentials. A change
ingridpotential'in the positive direction increases
ductive element, a `discharge device having an
anode', aV control grid and acathode,y connections
the .anode .current andthereby decreases the tube «
resistance. The „effect of this on say the capaci
regeneratively coupling the anode, control grid,
tive'branchisrto increase thecapacity. The effect
including atïleast a part of one of said elements
and-cathode of `-said- device in ay circuit for the
of this on the inductive branch is to decrease the
production of oscillations,ïthe arrangement be
inductance;v Conversely, a change inthe grid
potential -in a lnegative direction decreases the
ing ’such that a part at least of said one element
is4 shunted by the impedance between the anode
and-'cathode of said one device, a second electron
discharge device having an anode, a'cathode and
anodecurrent, therebyincreasing the tube output
impedance. - Theeiîect of this on say the capaci
tive 'branch is _to- ,decreasethe‘ capacity and on
a control ' grid,` connections including at least
theinductive ’branch -to_ increase ythe inductance.
a part of the> other of said elements regenera
This therefore. requires that the modulation or 60 tively coupling the anode, control grid and cath
control potentials are.applied‘differentially
ode of the seconddevice in a circuit for the pro
In the embodiment illustrated; the control po
ductionof oscillations of substantially the same
tentials are A„supplied from source A through a
frequency, the arrangement being such that the
transformer'T differentially to the control grids.
impedance between the anode and cathode of
~1The`embodiment of Fig. ’2 is essentially the
same as ._tlieiembodiment of Fig. 1.V In Fig. 2,
however, the tubes Vl and V2' have additional
gri'dsîß .andîZiiito-_which themodulationis applied
diiîerentially. .by-transformerfl‘. > ' These . grids are
shown as _operating at positive potentials and may
be considered screen grids.
_
y -
'
' said.. second; device isin. shunt toa-part at least
of said other-element, and a source of- modulat
ing .potentialscoupled -diiîerentiallybetween cor
responding electrodes-foffsaid devices.vvvv
»
2. In a wave generating and wave vlength vmod
ulating system, acapacitive elementand anin
ductiveelement; a pair ofdischarge deviceseach
The inductance coils L2', L3, L4 andL5 are
usedtofbalance out or cancel the effect of capaci
havingY an anode„a,controligrid, and a cathode,
tive >reactance between» the tubeelectrodes. For
» elements¿regeneratively*coupling the anodes„control grids, and cathodes of said devices in a re
example, L2' compensates or cancels out the
connections including at leastì afportion of said
2,409,457
5
generative circuit for the production of oscilla
tions, the arrangement being such that a por
tion of one of said elements is shunted by the
impedance between the anode and cathode of
one device, anda portion of the other of said
elements iS shunted by the impedance between
the anode and cathode ci the other device, and
a source ci modulating potentials coupled difier
entially between corresponding electrodes of said
devices.
p
3. In a wave generating and wave length mod
ulating system, a capacitive element, an induc
tive element in parallel with the capacitive ele~
ment, a pair of discharge devices each having
an anode, a control grid, and a cathode, con
nections including said elements regeneratively
coupling the anodes, control grids, and cathodes
of said devices in a regenerative circuit for the
production of oscillations, the arrangement be
6
5. In a Wave generating and Wave length mod
ulating system, a tank circuit having a capacitive
branch and an inductive branch, a first discharge
device having an anode, a control grid, and a
cathode, connections coupling the anode and
control grid of said device to spaced points on
the capacitive branch of said circuit, and cou
pling the cathode of said device to a point on
the capacitive branch intermediate said spaced
points, thereby coupling the impedance between
the anode and cathode of said device -in shunt
to capacity of said capacitive branch, a second
electron discharge device having a cathode, an
anode, and a control grid, connections coupling
the anode and control grid of the second device
to spaced points on the inductive branch of said
tank circuit, and the cathode of the second_de
vice to a point intermediate said spaced points
on said inductive branch, the arrangement being
ing such that a portion of one of said elements 20 such that the anode to cathode impedance of
said second device is in shunt to inductance of
is shunted by the impedance between the anode
and cathode of one device, and a portion of the
other of said elements is shunted by the imped
ance between the anode and cathode of the other
device, and a source of modulating potentials 25
coupled diiîerentially between corresponding
electrodes of said devices.
4. In a signalling system, a capacitive element,
said inductive branch and the said electrodes
of both devices are regeneratively coupled by
said tank circuit for the production of oscilla
tions in said tank‘circuit and a source of mod
ulating potentials coupled differentially between
corresponding electrodes of said devices.
6. A system as recited in claim 1 wherein said
corresponding electrodes are the control' grids of
pacitive element, two discharge devices each hav 30 the ñrst and second discharge devices.
ing an anode, a control grid, and a cathode,l
7. A system as recited in claim 2 wherein said
connections including said parallel elements re
discharge devices each include a screen grid elec-'
generatively coupling `the anode, control grid,
trode, and wherein said screen grid electrodes
and cathode of each of said devices in an oscil
are the corresponding electrodes to which the
lation circuit for the production of oscillations, 35 source of modulating potentials is differentially
the arrangement being such that a portion of one
coupled.
of said elements is shunted by the impedance
8. A system as recited in claim 5 wherein said
between the anode and cathode of one device,
corresponding electrodes of the devices are the
and a portion of the other of said elements is
control grids of the devices.
shunted by the impedance between the anode 40 9. A system as recited in claim 5 wherein said
and cathode of the other device, and a source
devices each have an additional grid-like elec
of modulating potentials coupled diiïerentially
trode, and wherein said corresponding electrodes
between corresponding electrodes of said de
are said additional grid-like electrodes.
an inductive element in parallel with the ca
VÍCES.
‘
GEORGE L. USSESLMAN.
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