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Патент USA US2115877

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May 3, 1938.
2,115,877
Y. ROCARD
ELECTRONIC OSCILLATOR TUBQE
Filed Nov. 15, 1935
INVENTOR‘
YVZROCARD
- v
M
ATTORNEY._ ‘
Patented May 3’ 1938
.
UNITED STATES
2,115,877
PATENT OFFICE
2,115,87 7
ELECTRONIC OSCILLATOR TUBE
Yves Rocard, Paris, France, assignor to. Com
pagnie Generale de Telegraphic Sans Fil, a cor;
poration of France
Application November 15, 1935‘, Serial No. 49,886
In France November 24, 1934,
4 Claims. (Cl. 250—36)
The present invention represents an improve
ent from the strictly accurate solution indicated
ment upon the disclosure of my copending appli
in the present invention and which consists in
cation'Serial No, 11,905, ?led March 20, 1935, giving the circuits the number of parameters,
wherein it is stated that if pg and p are the inter—
5, nal grid and-plate resistances of the tube sup
posed to be constant in ?rst approximation, then
desired and to choose the same in such a fashion
that there will be:
I
the equation which determines the angular
(cyclic) frequency w 'of the'oscillator has this
form:
while for the particular case where the oscillator
has its resonant circuit included in the plate cir
cuit, means have beensuggested in order that
1,5‘ there may be realized the following conditions:
there being taken into consideration in the cal
culations the“‘natural” resistance inhering in the
0,), coils and (possibly) in the condenser. If these
‘ conditions are ful?lled, the angular frequency w
is given by the equation A(w)=0 which has a
solution independent of p and pa and this means
a frequency stabilized in reference to the resist
ances of the grid and the plate.
The object of the present invention is to dis
close ways and means adapted to insure stabiliza
tion which will hold good even if the tuned cir
cult of the oscillator is not included in the plate
3Q circuit of the tube, to improve the stabilizing
means indicated to be effective or efficient by ele
mentary theory taking into consideration the har
monics introduced by the curvature (knee) of the
characteristics of the tube, and augment and en
hance the effectiveness of the said ways and
means by the adoption of stabilizing means and
maintaining a value constant 'at the limit of sus
tenance of oscillations or oscillatory state of the
tube and this stabilizes the proportion of har
40- monics generated and precludes frequency varia
tions which might arise if the said proportion of
harmonics were to vary.
In order that the nature of this invention may
be better understood, it may be recalled here that
45 the. arrangement of impedances Z, 21 in series
there being duly included all of the resistance
exterior to the tube.
oscillator of ‘thekind previously considered by
Fromy (only with the radio frequency circuits).
The solution suggested with a view to stabilization '
by the said author consists in regulating the 153
capacities C1 and C2 in resonance with the in
ductances L1 and L2, respectively, to the pulsation
1
w
which then becomes the natural period of the
oscillator. By resuming this line of investigation
it will be found that this solution is only effective
if 1'1 and T2 are of zero value.
There is no reason‘
for taking into consideration the resistance 7' any
more than the others, their in?uence upon the
frequency being entirely similar and comparable.
If, therefore, according to this invention, the
complete solution is adopted, it is found that as
a general rule the following conditions must be 30
satis?ed, to wit:
35
Moreover, the coefficients of mutual induction
M1 and M2 should be alike, in absolute values.
Under these conditions (and this is ful?llable by
means of individual setting or regulation of C1
and C2, and then'of M1 and M2) the angular fre
quency w is strictly equal to
1/611
with the plate and the grid of the oscillating tube,
with a View to insuring stabilization of frequency,
is known from the research of Fromy (L’Onde
Electrique, 1925) and of F. B. Llewellyn (Bell
50' System Technical Journal, January, 1932, p. 6'7)
and other investigators. However, what is dise
regarded in these studies either partly (Fromy) or
totally (by the other author) is the resistance
residing in the impedances exterior to the tube,
55' and this leads to solutions that are totally di?‘er
.
The situation shall be illustrated by reference
to an example shown in Fig, 1, which shows an
if the situation is kept very close to the oscillating
limit, and this regardless of what may be r, n,
7'2, and p, pg.
It will be noted that, for this oscillator repre
sented in Fig. 1, it is necessary to have three
parameters in order to neutralize at one and the
same-time 3(a)), C(w) and D(w), whereas in the
oscillator disclosed in the above-mentioned co
pending patent application No. 11,905, two pa
2
2,115,877
rameters are sufficient in order that the identical
result may be obtained, whence it follows that
the stabilization of the latter oscillator is easier,
less expensive, and more convenient to regulate
and insure. The oscillator comprising a tuned
circuit disposed in the plate circuit, or, more gen
erally and broadly speaking, in the circuit of an
electrode which does not control the resistance
of the oscillating grid, is by virtue of the said
corresponding to the amplitude of a typical over
tone (say the third harmonic). This voltage is
used for an anti-fading effect maintaining the
oscillator in a stationary state, for instance, by
an additional control grid ‘I provided for this pur
pose ‘in the oscillating tube 8.
It will be noticed that circuits I and 2 result
ing in zero impedance in the plate circuit for
the main harmonics exercise by themselves 'a
fact a preferred form of construction and em
bodiment of this invention.
Con?ning the following description to the case
of an oscillator comprising a tuned circuit in the
plate, novel ways and means for frequency sta
15 bilization shall be disclosed in which the har
monies are duly taken into consideration which
will inevitably arise because of the curvature or
knee in the characteristic of the tube.
If by way of calculation the state of oscillation
20 of the triode presenting characteristics similar
to the general curves, is ascertained, which is sus
ceptible of giving a grid current ig related to the
grid voltage Vg by this condition ig=j(Vg) there
results a system of simultaneous differential
25 equations, hence those in which the characteris
tics of the tube play a part and which are non
linear in nature. It will therefore be noted that
the oscillation is not possible without the ap
pearance of harmonics, and that these harmonics
in the currents or the voltages act in two differ
ent ways upon the frequency, to wit: Because
of lack of linearity of the characteristics, the
frequency depending, in second approximation,
upon the proportion of harmonics resulting from
35 the adopted regulation, said proportion being it
self a function of the characteristics of the tube
and being thus in need of stabilization; general
ly these harmonics exercise a marked effect upon
the phase of the voltages which reach the elec
40. trodes and being, to a certain extent, equivalent
to a “detuning” of the stabilizing circuits, which
results from the elementary study wherein p and
pg have been treated as constants.
Now, according to this invention, the frequency
is protected against ?uctuations in the “rate” of
the harmonics by maintaining the proportion
thereof at a constant value by an action which
comprises an ampli?cation of these harmonics,
detection and automatic regularization of the
oscillation.
50
In the drawing, Fig. 1 is given to illustrate
the principles of the invention, and shows a
known circuit arrangement as modi?ed by appli
cant by the inclusion of resistances, and Figs. 2
I to 5 illustrate different embodiments of the in
vention.
By way of example, Fig. 2 shows the ways and
means comprising a multi-tube circuit arrange
ment adapted to the said end as applied to an
stabilizing effect by preventing the harmonics 10
of the plate circuit from circulating through the
oscillating circuit and setting up harmonics in
the grid voltage. However, since the existence of
a grid current is itself generative of harmonics
for the grid potential, it will be seen that this
stabilizer effect is not sufficient.
One thus comes to the question of the means
adapted to preserve the phase of the voltages ar
riving at the grid from the influence of the har
monics. For this purpose it is necessary to estab- _
lish resonance of the grid circuit properly so
called not only for the fundamental wave, as
pointed out in the co-pending patent applica-,
tion above referred to, but also for all of the
troublesome harmonics.
Fig. 3, by way of example, shows a single tube
circuit arrangement adopted for this last pur-v
pose. In scries with the coupling inductance L1
in the grid circuit of the oscillator tube 9, there
are arranged as many parallel branches as there 30
are undesirable harmonics to be eliminated, each
of the said branches containing an inductance
coil and a capacity in series L2 C2, L3 Ca, etc.,
save one branch ?nally which comprises only a
capacity C1. All of these quantities are deter
UI
mined in a way so as to result in resonance of
the assembly L1 C1 L2 C2 L3 C3, etc., with the
fundamental and all of the harmonics of the cur
rent. If this is realized, conditions will be so
that the control potential at the grid is simply 40
given by the term
‘
di
{"5
where i is the current in the inductance of the
oscillation circuit just as if the oscillator were
free from grid current.
If, for instance, it is deemed that only the sec
ond harmonic ‘is undesirable, L3 C3 may be dis
pensed with, while making C1 of the value
a _C
50
L w/f),
C2 of the value
l. sgjE-nc
Ll
2J5
and L2 of the value
L
2
In this way the impedance of the grid circuit 60
for the fundamental and the second harmonic
of a four electrode oscillator tube is shunted by has been eliminated, and an oscillator is obtained
a parallel tuned circuit I forming a stopper in whose stability is entirely satisfactory, even with
reference to the fundamental frequency, followed out the additional stabilization of frequency in
by two series circuits 2 in parallel with respect to sured by maintaining the proportion of bar (13
each other, such that the combination of circuit monies constant being really necessary.
It may be noted here that the oscillator shown
I and circuits 2 wil1 be resonant to the frequencies
of the chief harmonics (such as the second and in Fig. 3 offers already the property of reducing
third harmonics); at a point indicated by 3 in at the ration 1/11, the amplitude of the harmonic
one of the circuits 2 there is taken off a potential of nth order which would arise in the conven TI)
which will be almost entirely due to the third tional type of oscillator where the inductance L
harmonic, for-instance; ampli?cation is effected in series with the oscillation circuit would be ab~
in ampli?er tube 1 and detection in a diode valve sent.
60 oscillator of the kind dealt with in patent appli
cation No. 11,905, and in which the plate circuit
5 in order to make available across a resistance
6 in the output of the diode a negative voltage‘
Fig. 4 shows an oscillator circuit which com
prises'the combination of all of the stabilizing,
2,115,877
means disclosed in this invention, and more par
ticularly illustrated in Figs. 2 and 3. In this ?g
me, which shows amulti-tube circuit compris
ing an oscillator 8, an'ampli?er 4- and a diode rec
ti?er 5, the oscillator tube 8 is shown with a sta
bilizing ‘grid 1 separated by a screen from the
other electrodes. The oscillating plate may like
wise be separated by means of a screen from the
oscillating grid.
10
Fig. 5 shows another oscillation circuit com
prising a combination of all the stabilizing means
of the invention. This circuit is a combination
of the features of Figs. 1, 2, and 3, and will be
obvious from what has been set forth above in
15 connection with the various ?gures.
After the descriptions hereinbefore given it
may now be necessary to set forth What is dis
closed in and claimed by the invention in a gen
eral way.
20
Assuming the characteristics of the tube to be
linear, there is ?rst insured stabilization accord
ing to the principles that have been indicated and
consisting in making to strictly equal to
25
1/c_L
regardless of what may be the plate and the grid
resistances of the tube and the resistances of the
30 outside circuits. This stabilization presupposes
regulation at the oscillating limit and necessitates
the fundamental frequency generated independ
ent of internal resistances of the tube and of
ohmic resistances of the- external circuits, the 20
said means comprising a ?rst predetermined im
pedance in the grid circuit and a second predeter
mined impedance in the anode circuit, means
connected to- the anode circuit for stopping the
fundamental frequency and for passing predeter 25
mined harmonics, means for amplifying and de
teoting one of the said harmonics, and means
comprising a detected current controlled electrode
in the tube for maintaining constant ratio be
tween the amplitudes of the said harmonics and 80
of the fundamental frequency.
one thereof in the grid circuit and the other
one in the plate circuit, there being moreover one
condition to be ful?lled as regards the couplings,
comprising a mu-lti-electrode tube having cathode,
grid and anode electrodes, said grid electrode
where the oscillation circuit is connected in series
with the circuit of an electrode which does not
produce any appreciable control action upon the
oscillating grid or grids.
Next the frequency is stabilized as regards the
in?uence of the variations at the oscillating limit
by the agency of automatic means of control of
the proportion of the harmonics generated.
The stabilizing circuits ?nally are designed so
45 that the potential at the control electrodes (grids)
will not depend upon the harmonics, and that the
harmonics of the current of the control elec
trodes will not get up electromotive forces in the
oscillation circuit properly so-called.
50
Preferably the means here disclosed and claimed
are used in combination, though it will be under
stood that the use individually or separately of
some of these means may be susceptible of insur
ing results that will be quite satisfactory.
55
anode electrode each connected to a circuit-con
taining a de?nite ohmic resistance and coupling
said anode and grid electrodes to the cathode of
said tube, an oscillating circuit containing an 10
ohmic resistance and coupled at the same time
with said grid and anode circuits, the coupling
degree between said oscillating circuit and said
grid and anode circuits being so adjusted that
the tube is maintained at oscillation entertaining 15
limit, a fundamental frequency and its har
monics being thus generated, means for making
the provision of two supplementary impedances,
35 though this condition is non-existent in a case
40
there being a predetermined ratio‘ of couplings
between the oscillating circuit and‘the said anode
and grid. circuits‘ respectively.
2. In combination, 'an oscillation generator
comprising a multi-electrode tube‘ having cathode,
gridand anode electrodes, said grid electrode and
What I claim is:
1. In combination, an oscillation generator
comprising a multi-electrode tube having a cath
ode, a grid electrode and an anode electrode, said
grid electrode and anode electrode each con
60 nected to a circuit containing a de?nite ohmic re
sistance and coupling said anode and grid elec
trodes to- the cathode of said tube, an oscillat
ing circuit containing an ohmic resistance and
coupled at the same time with said grid and
65 anode circuits without being inserted in series in
any of said circuits, the coupling degree be
tween said oscillating circuit and said grid and
anode circuits being so adjusted that the tube
is maintained at oscillation entertaining limit,
70 and means for making the frequency generated
3. In combination, an oscillation generator
and anode electrode each connected to a circuit 35
containing a de?nite ohmic resistance and cou
pling said anode and grid electrodes to the oath
ode of said tube, an oscillating circuit contain
ing an ohmic resistance and coupled at the same‘
time with said grid and anode circuits, the cou
pling degree between said oscillating circuit and
said grid and anode circuits being so adjusted
that the tube is maintained at oscillation enter
taining limit, a fundamental frequency and its
harmonics being thus generated, means for mak 45
ing the fundamental frequency generated inde
pendent of internal resistances of the tube and of
ohmic resistances of the external circuits, the
said means comprising a ?rst predetermined im
pedance in the grid circuit and a second predeter 50
mined impedance in the anode circuit, the said
?rst impedance comprising an inductance-ca
pacity assembly so dimensioned that the grid
circuit is resonant to the fundamental fre
quency and to the desired harmonics.
in U!
4. In combination, an oscillation. generator
comprising a multi-electrode tube having cathode,
grid and anode electrodes, said grid electrode
and anode electrode each connected to a circuit
containing a de?nite ohmic resistance and cou
pling said anode and grid electrodes to‘ the oath
ode of said tube, an oscillating circuit containing
an ohmic resistance and coupled at the same time
with said grid and anode circuits, the coupling
degree between said oscillating circuit and said 65
grid and anode circuits being so adjusted that
the tube is maintained at oscillation entertain
ing limit, a fundamental frequency and its har
monics being thus generated, means for making
independent of internal resistances of the tube
the fundamental frequency generated independ 70
and of ohmic resistances of the external cir
cuits, the said means comprising a ?rst predeter
mined impedance in the grid circuit a second
means comprising a ?rst predetermined imped
75 predetermined impedance in the anode circuit,
ent of internal resistances of the tube and of
ohmic resistances of external circuits, the said
ance in the grid circuit and a second predeter
mined impedance in the anode circuit, the said 75
4
2,115,877
?rst impedance comprising an inductance-ca
pacity assembly so dimensioned that the grid
circuit is resonant to the fundamental frequency
and to the desired harmonics, means-connected
to the anode circuit for stopping the fundamental
frequency and for passing predetermined har
monies, means for amplifying and detecting one
of the said-harmonics, and means comprising a
detected current controlled electrode in the tube
for maintaining constant ratio between the am
plitudes of the said harmonics and of the funda
mental
frequency;
‘
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.YVES ROCARD.
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