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Патент USA US2403725

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July 9, 1946.
H. c. LAwRENçE, JR
‘
2,403,725
HIGH FREQUENCY VACUUM TUBE CIRCUIT
Filed Oct. 28, '1945
2 Sheets-Sheet 1
20
A
BY
____
¿é
ATTORNEY
v
July 9, 1.946. .
H. C. LAWRENCE, JR
2,403,725
HIGH FREQUENCY VACUUM TUBE CIRCUIT
Filed Oct. 28, 1945
'TI/T12. .
2 Sheets-Sheet 2
Patented July 9,Y 1946
' *y
2,403,725
_STATES-
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,
` oFFlcEL* ` '1
.CIRCUIT
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Howard C. Lawrence, Jr., Haddoniìeld, NUI., as-l '
signor _toRadioCorporation of America, fa cor-Y f
_ poration 'of Delaware „ Y '
. spp'iicaeonoctoberzs;1943, serial-N0. staats ~
_ 'I'his invention relates Étoßultra' highlfrequency
'oscillatorxcirculta .and particularly", to vacuum
l low= conductors,y I5 lforms ai tunable circuit between
tube oscillatorsv generatin'gïoscillations higher`
Ythan 300r megacyclesp;
'
.
-
l;
~
the cathodes oithe tubes. The >conductors. IVG-.are
directlyconnectedftogether by- ,meansi‘of . a short '
circuitingdisc Il forming ther bottom- partv of 'an '
:Among the ‘objects ofthe present inventionr are :'
To provide Aan yultra high frequency electron dis
operinietallic.can-like«arrangementJß.` The fila-._v
` ments V.Oithe twoltubeslil and fI I >'are supplied
with heating currents through .Wires extending `
ì charge device- oscillator .having anode and cath-V
1; .odel'tuned circuitsV which are shielded fromreach
Within the interiors ofthe hollowy -conductors I6»
and connected Vto-the secondary Winding» .of aV
suitablefilament supply `transformer I9 ¿whose
other Yvili-thin the; device and `individually shielded
externally of the device; toprovide a> grounded
grid-electron discharge device oscillator ofjoult'ra
" prima-ry'winding is connected to .a-flow» frequency
v alternating current> filament heatingi,._sojurce.
’ high frequencies» Whose anode’an'd cathodeelec-A
~ trodeshave separate ’tunable circuits cou'pled'to.V
The anodes of` the two tubes Iiiand I I»v are sup
each other magnetically by means of a selective
plied vvith ga, suitable positiver polarizing. potential
feed back loop; lto providev al grounded grid elec-; Y . from . conductor. 2!)` which» is. connected . to. the up,
tron dischargeoscillator ofj ultra high frequen
cies whoseganode and jcathodes- have separate
shielded-tunable circuits of distributed inductance
per eadjërtcent--` ends of the conductors I4 ofthe
anode tuned circuit. The cathode tuning circuit
is tunable bymoving the can I 8 upor downÁ along
the lengths of the conductors I5 by meansof asl-lit
20. able` rod` connected to pla-te: I1. Thefanode and
and capacity extending .from oppositesides of the
devicefbutcoupled together by means vof a selec
Y' tive feed back circuitçproperly polarized to pro-l
' cathode - tuned'rcireuits . I4 A_and I 6,4v respectively .are
duce oscillations; to >provide a grounded gridvelec
separately shielded by lu_nllovv¿‘metallic~semi-cirF
tron discharge device oscillator of yultra high fre-V
quencies whose `cathodes and annales-“each have`
a shielded tunable circuitv of distributed constants
and oi. a length Whichis a multiple of and greater
thanone- quarter of the length oi."> the communi
cation wave, these tunable anode and cathode‘eir.-Y
cui-ts vbeing coupled togetherby a tunable selec
tive feed back circuit*l v
~
cular sheets represented diagrammatically inulî‘ig->
ure 1 by means of the dash-lines? I.„ It ¿willvzthus
p be seen that »the anode and cathode tuned circuits
are shieldedirom eachy other externallyv ofîthe
vacuumtubesllßaand IfI ¿by sheets 2| 'and also
shielded f from each . other „electrostatic/ally' ...by
,
30
` ` A more detaileddescriptionof the invention fol
can> I8, it should be noted, .is `open at the end `.nearf
lows inl conjunctionvfwith drawings, wherein:
, est the'cathodes.v Can I8` isy separatedby` anair
' `Figure 1 shows a circuit diagram., partly sche
gap fromthe> shield 2l andA is. capacitively coupled
matic and partly _mechanical -ofr-the' ultra >high
totheshield.
frequency ¿oscillation generator of` the invention;
bu
- >Figure 2 shows the essential details of theme
. ,
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In order to provide feed-back between the
anode and cathodecircuits, thereis provideda
selective; feed-back-> circuit in the form» oflan
S-shaped conductor comprising loops r3i] 'and.3I.
chanical construction yofthe ‘oscillation vgenerator
of Figure 1; and
means of- the grounded gridsu which are directly
connected-_tothe metallic disc-,like plate- I2._ The
~
f Figure 3 is a- section along line 3--3 of Figure 2.
It will be seen. that loop 39,;is above the metallic
Referring, to Figure 1 in more detail, there is 40 plate I2 While. the loop 3l .isrbelow the. metallic
platev I2, bothA ofthese loops fbeingconnected-.to
gether .through an aperture 32 in the plate I2.
shown anoultr'a high frequency generator com
prising a pair of vacuum tubes I0 and I I mounted
in andsupporte'd Iby va metallic `plate I2. This
metallicplate is provided Vwithv a pair of¿ apertures
j are» directlygconnectedto „the metallic- plate I2,
The vmidpoint of the feed-back conductor is con-_
nected to the central conductor of a concentric
line 33. The inner and outer conductorsof this
concentric line33 arel adjustable in length by
means Vof a slider 34.v The elîective length of
Whichin turn is grounded.. [It'will thus besseen
that the grid of each tube and associated mount
ing electrostatically shields the anode and cath
coaxial line v33 measuredvbetween slider 34 and
the .midpoint of thevselective feedbackcircuit
39,31 is more than one-quarter of a wavelength
ode and their ’associated circuits from each other.
A tunable' parallel conductor circuit composed of.
hollow conductors I4 connect the anodes of the
at the operating frequencytandvhence acts as a
I3, ~I3 ioraccommodating the envelopes» of the
vacuum tubes.Y The grids ofthe tubes _i0 and -Ii v
capacity reactance for certain frequencies of
operation; f. The> total length of the loops SIland
two tubes ktogether in push-pull relation. The ends
3! is physically less than one-half wavelength;
but by means of the tunable'I capacity reactance
constituted by the coaxial line 33,4 the capacitance
of conductors I4 `at I5 are.. in » telescopic relation
to the otherY portions of the conductors in order
Yto provide adjustment of the lengths `of these con
ductors for tuning purposes.
Putting,ì it in other `
words,.w_e have essentially a collapsible end I5
for tuning the anode circuit. Another pair of hol
60
of this line tunes the feed back circuitto one
half wavelength. While the effective lengthoi
linev 33 -ismentioned as beingsuch that-,it is
capacitative at certain frequencies of operation,
2,403,725
3
it should be understood that it maybe capacitive
or inductive depending upon what is needed to
tune the feed back loop. This would mean that
the stub may be of a length up to one-half wave
length instead of the
one-quarter
wavelength -
The feed back loop may be -f
mentioned above.
longer than one-half wavelength but tuned by`
an inductive reactance to be electrically one-half
wavelength at the operating frequency. The
4
Figure 2 shows a mechanical construction of
the'ultra high frequency oscillation generator of
Figure `1. The oscillator is shown with the two
Vupper halves of the anode circuit shielding sys
tern separated and with one-half Yof the lower
cathode circuit shielding system missing, to sim
plify the drawings. The metallic plate I2 shown
in more detail in Figure 3 is hidden by means
of the rounded’metallic sheet 50;
Sheet 50 is
provided’ with upper and lower shoulders> 5I for
loops 30 and 3I are made in the form of an S 10 accommodating and supporting the semi-cylin
in order to assure the fact that the voltage fed
drical‘shields 2I1,;2I„ The shields for the anode
back to the cathode circuit is 180° -out-of-phase‘
and, cathode tuned circuits each comprise two
relative to the alternating current cathode po
halves which 'are screwed together at the aper
tential. These oppositeV halves of the feed back
tures 52. One-half of the shield for the anode
conductor are 180° out-of-phase insofar as the 15 and 'theïcathode tuned circuitslis shown connected
magnetic field is concerned. The distance be
to the'metallic sheet' 50. The otherfhalf of the
tween the metallic plate I2‘ and each of the short
shield 2| forthe cathode tuned circuitis pro
circuiting conductors I5 and I'I of the anode and
vided in the complete assemblage'but is not shown
cathode tuned circuits is electrically three-quar
ters of a wavelength at the operating frequency. 20 in order not to complicate Vthe drawings. It
should be understood at this time that the paral
The output circuit includes a metallic loop 24
lel transmission line circuit comprising the anode
which is arranged above the plate I2 for cou
conductors I4 is across between a *concentric*
pling to the anode tuned circuit. One end of the
line and a parallel conductor circuit by virtue of'
output loop 24 is connected directly to the plate
I2 while the other end extends down through an 25 the fact that the metallic 'casey'2vI, v2l 'enclosing
this line is an essential part ofthe anode circuit
aperture 35 for connection to the inner conductor
and is not merely a shield. The coaxial line 33
of a concentric transmission line 38. Concentric
>for tuning the selective feedback circuit is shown
transmission line 36, which connects the output
provided with a plunger 53 for vadjusting the po-`
of the slider 34 (note Fig. 1). ’ j l
an antenna, is shown provided with impedance 30 sition
The cathode can-'like slider vI8 kfor ‘tuning the
matching stubs 31, 3T spaced one-quarter of a
cathode circuit is shown provided with 1a metallicl
wavelength apart. A cathode bias resistor 40 is
rod 54 connected to the plate’l'lfor adjusting
connected between ground and that end of the
the position of the. can I8 in tuning the cathodev
cathode conductor I6 farthest removed from the
vacuum tubes. In the operation of the system 35 circuit.> The bottom ends'óf the >conductor ‘IE
of the cathode tuned circuit are connected to
of Figure l, the metallic can I8 for tuning the
gether by means of a'metallic'- plate 55 mounted
loop 24‘to a suitable utilization circuit such' as
cathode tuned circuit serves as one terminal of
in turn upon an insulator board 56. It should
acondenser whose other terminal comprises 'the
be noted that the plate >55 to which the cathode
grounded metallic shield 2l.
conductors I6 are connected is not connected to
40
The lengths of the anode and cathode tuned
the shield 2|. 1t should also be noted that the
circuits, which are here shown to be electrically
can I8 is separated by an air'space ‘from'the
(although not necessarily mechanically) three
shield 2|. v The top of vthe'Í -shield 2I for-*the
quarters of a wavelength long. enable the attend
anode tuned circuit 'is open to enable Éthe circu
ant to tune the circuits at the extremely high
frequencies at which the oscillator is capable of 45 lation of cooling fluid. This ‘cooling fluid in the
form of air from a suitableblower is supplied to
functioning. The use of multiple quarter wave
the interior ofthe shields’ZI both 'above and
length lines isy made possible by the selective fea
below the metallic dividing -plate I2 by means of
ture of the feed back circuit. The selective feed
a rubber conduit 51 and air vents 58.
' ` _,
back circuit comprising the loops 30 and 3I in
The conductors of the anode tunedl circuitare
the form of an S is tuned to the desired oscilla 50
connected to the -anodes-,of the vacuum tubes I0
tion frequency by means of the variable capaci
and II by means of metallic flanges (il).v That
tive reactance comprising the tunable coaxial
portion of each of the conductors I4 of the >anode
line 33, thus controlling the frequency at which
circuit >which is nearest the anode of the tubes
the oscillator functions. Putting it in other
words, oscillations occur at the frequency of the 55 is cut away and provided withV a metallic mesh
like sieve 6IY for enabling air to >flow freely there
feedback circuit only.
The oscillator of Figure 1 can be operated any
The preferred type of vacuum tube to be used
where in the range from 350 to 1400 megacycles
in the invention is one having an anode provided
with anode voltages supplied to lead 20 anywhere
in the range from 300 volts to 15,000 volts. Ob 60 with a multiplicityk of anode fins for cooling pur
poses. It is important- that the grid ofthe tube
viously,A if the circuit of Figure 1 is to be oper
do av good shielding job- b'etween the' cathode and
ated continuously, the anode voltages would be
anode. One such tube which has been used is
somewhere near the 300 volt figure, whereas if
the RCA A-2212 tube shown-,very generally 'in
the oscillation generator of Figure 1 is to be used
Figure 3, which is a cross section of VFigure 2
for pulse operation, for extremely short intervals
along the line 3_3; The anode'fins are shown
of the order of a miscrosecond or so, the anode
as
horizontal metallic rings 62.` The grid, anode
voltage may be in the upper regions near 15,000
and cathode electrodes are arranged concen
volts. By means of the arrangement of Figure l,
trically Within the tube envelope. The grid ex
it is possible when using pulsing methods to ob
tain an output of at least 350 kilowatts employ 70 tends downward and is connected by means of >a
metallic flange 63 to'the plate I2. -,The cathode
ing an anode voltage of around 15,000 volts.
extends below -th'e flange 63 and is vconnected'to
Such pulse operation is obtainable by interrupt
the conductor I6 of the cathode- tuned circuit.
ing the anode voltage supply at the rate at which
through.
itis desired to produce pulses of high frequency
energy.
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Although the anode‘ñns of the vacuum tube have
been shown to be horizontal, it Ashould be under
amarres
nectin‘gv said anodes together, a parallel .conductor
tuned circuit 'of substantially distributed con
stants connecting said cathodes together, a metal
lic shield connecting said grids together, a con
nection from ,said shieldy to ground, means ex
ternal of saidtubes for shielding said tuned cir
cuitsfrom each other, and a selective feedback
circuit coupling said two tuned circuits, said'feed
nal of said‘tùbes for shielding‘said tuned -circuits
from each other, and a selective ‘feedback circuit
couplingsaid two tuned circuits,y said _feedback
circuit including a variable capacitive `~r‘eactance
for> tuning said` feedbackA circuit, said variable
capacitive-reactance being composed offan-~ad-justable. coaxial Yline whose effective length vis
more than one-quarter wavelength at the 'oper
ating frequency.
'
` '
back circuit including a variable reactance for
15. An ultra‘highfrequency oscillator compris
tuning said feedback circuit, said variable re 10
ing a pair of vacuum tubes eachfhaving an anode,
actance comprising an adjustable coaxial line
a cathode and a grid,"a tuned'circuit of substanä
whose eiîective length is less than one-half `wave
tially . distributed constants4 connecting- said
length at the operating frequency.
anodes together, a tuned vcircuit of substantially
ll. An ultra high frequency oscillator compris
ingapair of vacuum tubes each having .an anode, 15 distributed ~constants .connecting said- cathodes
together, means electrostatically- shielding the
'a .cathode and a grid, a tuned circuit of substan
anode and cathode of each tube fromeach other,
tially. .distributed constants connecting said
means external of said tubesv for shieldingA said
anodes together, a vtuned circuit of substantially
tuned circuits from eachother, and a selective
distributed constants connecting said cathodes to
gether, means electrostatically shielding the 20. feedback circuit coupling said two tuned circuits,
said feedback circuit including a variable react
_anode and cathode of each tube from each other,
ance for tuning said feedback circuit, said vari
means external 0f said tubes for shielding said
able reactance comprising an adjustable 'coaxial
tuned circuits from each other, and a selective
line whose effective length is less than one-half
feedback circuit'coupling said two tuned circuits,
‘ " `
saidv feedback circuit including an S-shaped con 25 Wavelength at the operating frequency.
16. A radio frequency Voscillator~ comprising a
ductor oppositehalves of which are 180° out-of
phase for the magnetic field and a variable capac
vacuum tube having a> cathode, an anode and a '
itive reactance connected to the' midpoint of said
grid, individual tuned resonant circuits for said
S-shaped conductor for tuning the selective cir
anode and cathode located -on' opposite sides of
cuit to the frequency at which said oscillator 30 said rtube, a shield intermediate said tuned lcir
cuits and connected to said grid, said shield hav
should function.
E
__ l2. An ultra high frequency oscillator compris
ing an aperture, and a selective feed back extend
ing through said aperture and comprising ari'S'
ing a pair of vacuum tubes each having. an anode,
a cathode and a grid, a parallel conductor tuned
shaped conductor whose oppositeY halves are on
circuit of substantially distributed constants con 35 opposite sides of said shield. »
Y
necting said anodes together, a parallel conductor
1_7. An ultra high frequency oscillator com
tuned circuit of substantially distributed con
prising a pair of vacuum tubes each having an
stants connecting said cathodes together, means
anode, a cathode and a grid, a tuned circuit of
electrostatically shielding the anode and cath
substantially distributed constants connecting
40
ode of each tube from each other, means external
said anodes together, a tuned circuit of substan
of .said tubes for shielding said tuned circuits from
tially distributed constants connecting said cath
each other, and a selective feedback clrcuitcou
odes together, a metallic shield directly connect
pling said two tuned circuits, said feedback cir
ingl said grids together, a direct connection from
cuit including an _Sl-shaped conductor opposite
said shield to ground, means external'of Asaid
halves of whichA are 180° out-of-phase for the 45 tubes for shielding said tune'd circuits from each
magnetic field and _a _variable reactance connected
other, and a selective feed back circuit coupling
to the midpoint of said S-shaped conductor for
said two tuned circuits, said feed back circuit
tuning the selective circuit tothe frequency at
including a' variable reactance for tuning the
which said oscillator should function, said re
same to the frequency at which said oscillator
50
actance comprising ' an adjustable coaxial line
whose effective length is less than one-half wave
length at the operating frequency.`
v ' 13. An ultra high frequency oscillator compris
ing a -vacuum- tube having a cathode, an anode
and a grid, individual tunable resonant circuits
' for said cathode and anode, means external of
said tube for shielding said resonant circuits
from each other, a direct conductive connection
from said shield to said grid, a feedback loop
should function.
’
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18. An ultra high frequency oscillator com
prising a‘vacuum` tube having a cathode,` an
anoder and a grid,..individual'tunable resonant
circuitsfor said cathode and anode, means 'ex
ternal of said tube' for shielding said resonant
circuits from: each other, a direct conductive
connection from said shield to said grid, a tun
able feedback loop magnetically coupling said
tuned
circuits together, and an adjustable'stub
magnetically coupling vsaid tuned circuits to 60
gether, and a variable capacitive reactance for
tuning said loop to the frequency of operation
of
said
oscillator.
v
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tuner connected to the center of said loop.
19. An -ultra high frequency oscillator com
prising a vacuum tube having a cathode, -an
`
anode and aV grid, individual tunable resonant
' 14. An ultra high frequency oscillator compris
ing a pair of vacuum tubes each having an anode, 65. circuits for said cathode and anode, meansex
ternal of said tube for shielding said resonantcir
a cathode and a grid, a parallel conductor tuned
cuits from each other, a direct conductivev con
circuit of substantially distributed constants con
nection from said shield to said grid, aïfeedback
necting said anodes together, a parallel conduc
loop magnetically coupling said tuned circuits to
tor tuned circuit of substantially distributed con
stants-»connecting said cathodes together, means 70 gether, and a reactance circuit coupling» the cen
ter of said loop to said shield.v
electrostatically shielding the`anode and cath
HOWARD C. LAWRENCE, ’Jn '
`ode, of each tube from each other, means exter
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