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Dec. 17, 1946.
J. R. FORD
ULTRA H
IGH FREQUENCY OSCILLATION GENERATOR
Filed Feb. 5, 1944
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2,412,805
2 sheets-sheet 1
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AIV
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INVENTOR.
BY
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Def, A17, 1946.
1R. @RD
2,412,805
lULTRA HIGH FREQUENCY OSCILLATION GENERATOR
Filed Feb. 5, 1944
2 Sheets-Sheet 2
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INVENTOR.
J'aH/l ,9. Paca
BY
Patented Dec. 17, 1946
2,412,805
UNITED -STATES PATENT OFFICE
v,2,412,805
"ULTRA VHIGH FREQUENCY >OSCILLAT'ION
GENERATOR
John R. Ford, 'Narberth, Pa., assignor to Radio
>Corporation
of America, -a-corporation of Dela
Ware
Application vFebruary 5, 1944, Serial No. 521,179
'11 Claims. (Cl. Z50-36)
2
>the
wall grid tubular conductor forming the common
of the two concentric resonators and 'which
Ul
reasonably constant output level over its entire
V"range, in which both feed back and'frequency of
"operation are adjusted simultaneously by Va, single
control.
megacycles and having 'a fre
quency range of vthree or four to one.
A further object is to providean ultra high fre
employing a “lighthouse tube”
llllm'tllbe;
-Fig. 3'is a cross-section of the slider arrange
' ment used in both resonators; and
Figs. 4, 5 “and
6 show, .diagrammatically only,
nators with the sliders in different positions along
the lengths of the conductors. The
Aaverage po
cathode and gan
is graphically illustrated for'the
different slider positions.
Referring `to Fig, 1, there is shown a vacuum
>tube I of generally ¿known “lighthouse” -type,
~ rternal Vcircuit
elements. VIn practice, the anode,
cathode andîgrid electrodes within'the evacuated
glassenvelope are positioned 'very close to each
other. The anode within the tube’forms one en'd
30 lof 'a metallic cylinder which is connected to `the
General Electric type GLI-446 triode. The details
- of this “lighthouse”
tube are now well known in
the art and described in “Electronic Industry,”
September, 1944, page 178; and in “Science News
The cathode
Almere complete description ofthe invention
A'follows in conjunction with drawings, wherein:
Fig. `1 is a view, »partly yin cross-section, of an
ultra high 'frequency oscillator system embodying
the principles of the invention;
Fig. 2
`
is a perspective view of that portion of, '
for the radio frequency energy
flowing between the grid G and conductor 4. The
resonator’formed of conductors 3, ll is tunedïby
means of slider 6 which is a circular aiîairen
gaging the inner surface of 3 and the outer v`sur
face of ll. Conductor 4 is hollow and accommo
dates in its -interior a hollow "cylindrical lcon
'ductor 5 which >is capacitively coupled at one end
2,412,805
now through the vacuum tube II. In the ar
to the anode ring A. The ring A is separated from
the conductor 5 by means of a mica spacer 1 which
comprises part of a by-pass condenser for radio
frequency energy flowing between the anode A
and conductor 5. The inner surface of conductor
rangement shown in Fig. 4, the oscillator pro
duced oscillations at 1500 megacycles, The
voltage curve between anode and cathode for
the desired mode of oscillation is shown in the
l! forms with conductor 5 a concentric line reso
nator which is tuned by means of av circular me
tallic slider 6' engaging both conductors Il and 5.
It should be noted that sliders 6 and 6’ for the
different resonators are staggered in position.
The two sliders B and Iì' are unicontrolled over
links 9 and suitable gearing I5 operated by a
handle H.
Conductor 4 which forms a common conductor
for both resonators is provided at one end with
solid line immediately below the circuit arrange
ment. The arrangement of Fig. 5 shows the slots
8 completely uncovered by the slider 6 which is
now in a position intermediate the ends of the
cathode-grid line resonator. In the arrange
ment of Fig. 5, the oscillator operated at about
900 megacycles, and the average potential across
the slots is shown by the solid curve which slopes
more gradually. The dotted line curve shows the
voltage that would exist between anode and
a plurality of slots 8 for capacitively coupling
both resonators together externally of the tube I.
Slider 5 is adjustable over the entire length of
the slots 8, thus adjusting the effectiveness of
cathode for the three-quarter mode of oscilla
tion. The slots are positioned at a null for this
last voltage. The arrangement of Fig. 5 shows
the sliders in the extreme right position, in which
location the oscillator operated at about 400
megacycles. It should be noted (Fig. 6) that the
these slots. Stated in another way, the slider B is
average potential across the slots between anode
adjustable from a point near the grid electrode
where there would be no capacity coupling
and cathode conductors is close to the maximum
possible, while the slots are positioned near a
through the slots to a point well beyond the slots
null for the voltage that would exist between
where the slots are completely effective.
A grid leak resistor R shunts the condenser 25 anode and cathode for the three-quarter mode of
oscillation. In Figs. 5 and 6, the three-quarter
formed by the grid ring G and the spaced tubu
mode voltage curves are shown dotted, while the
lar grid conductor ll. Anode polarizing potential
desirable one-quarter voltages are shown in solid
is supplied from a source B+ to the anode via a
lines. It will be noted that the oscillator pro
rod II. High energy loss material, such as iron
30 duced its highest frequency at the one-quarter
dust core I2, surrounds the rod II and is in
mode when the cathode-grid line resonator is
sulated from the tubular anode conductor 5 by
shortest, and this is the case with the slots
means of an insulation tube II3 which may be
covered over by the slider 6. Due to the loading
paper. This iron dust core prevents the radio
on the resonators by the Vacuum tube, the maxi
frequency energy from iiowing along rod II. If
mum voltage (EAK) across the slots in the case
desired, the iron dust core can be replaced by
of Figs. 5 and 6 is a greater fraction of the
conducting rubber. The means for keeping the
voltage which would be present with no loading
vacuum tube I in position has not been shown for
the sake of simplifying the drawing, although it
by the vacuum tube than that obtainable in the
will be understood that such means may include 40 case of Fig. 4.
In the practice of the invention, the slots are
suitable springs for exerting pressure on the
so dimensioned and positioned that feed back at
socket of the vacuum tube in the direction of the
the desired frequency of oscillations is consider
line resonators.
ably greater than that for higher frequencies
The construction of the slots in the grid line
corresponding to higher modes of oscillation.
conductor li is illustrated in more detail in Fig. 2.
Because of the greater feed back at the desired
The construction of the sliders Ii and 6’ is illus
trated in Fig. 3 which shows a cross-section of
frequencies, the oscillator is constrained to
>one of these sliders. The effective length of the
generate oscillations at only the desired fre
slider 6 is such that it can substantially com
quency. The slots are preferably located near
pletely cover the slots 8 in the grid line 4 when
or at a voltage (anode-cathode) maximum point
for the desired mode of oscillation, which point
Apositioned. at the extreme left of Fig. 1.
In the operation of the oscillator shown in
is also a voltage minimum for the undesired mode,
Fig. 1, there is always some capacity feed back
thus providing a considerable difference in feed
between the two resonators 3, II and 4, 5 through
back for the two modes. To obtain the Ygreatest
the interelectrode capacities of the tube I. The
benefits of the invention, this difference in feed
slots 8 in tubular conductor ¿i augment this inter- , back between the cases of the desired mode and
electrode capacity coupling to a desired degree.
the undesired mode should be the greatest pos
The slots serve to boost the feed back at the
sible, although the benefits of the invention'can
lower frequencies of operation and also decreases
be achieved so long as there is any appreciably
the tendency for the oscillator to produce oscilla
greater feed back at the desired mode than at
tions at higher modes of oscillation. This is
the undesired mode. The slots should be located
Ashown more clearly by reference to Figs. 4, 5 and
6 which show the sliders 6 and 6’ in three dif
ferent positions along the lengths of the resona
tors, and also s‘now the average potential Ear-Ic
across the slots between anode and cathode con
near the grid electrode, as shown, in order to
ductors 5 and 3, respectively.
sponding to, let us say, the third‘harmonic of the
lowest frequency, then the slots should be posi
-tioned near the end of the grid line farthest
removed from the vacuum tube, and in this posi
tion the greatest feed back will be at the higher
mode (third harmonic) of oscillation, and oscilla
tion will take place only at the higher mode.
The exact position of the slots and their exact
With an oscillator of the type shown in Fig. 1
operating over a frequency range from 400 mega
cycles to 1500 megacycles, the illustration of Fig.
4 shows the arrangement of the sliders 6 at a
point near the grid electrode where the slots Il
are ineffective to provide capacity coupling there
through. The slider 6, it will be seen, covers the
slots and shields the resonators from each other.
The yonly feed back which exists in this case is
obtain a wide range of frequencies by adjusting
the position of the sliders. However, if it is de
sired to obtain only a single frequency corre
dimensions are best determined by experiment
*12,412,805
.higher frequencies.
Y
.sin order to obtain ¿themaximum»eifectfat-fthese
-v utput from‘ithe‘oscillator -maybe .taken from
»coaxial line M.
~ -.-.
¿probe l.I3rconnectedto‘theiinnerconcluctor»of-a
‘.In -one embodiment successfully Ytried `Yout Vin
`
.
A
fianode, vwhereby 'sa-id last two ¿conductors ¿form
‘mon wall with said .ñrst resonator, said coin
'
`
,
Ainon wall having
¥a _ plurality
‘of Aslots
lthere
*feedback between _said two resonators, a'tuning
gpr-actice, thetuned'grid-anode Vline resonator-had
'slider forsaid nrst ‘resonator adjustable'in posi
a 4surge impedance -of forty '-ohms, 7while the
`tion between-.the hollow conductors of said lfirst
tuned grid-cathoderesonator'had'atwentyiohm
--resonator .fand having such aXial length as 'to
,surge impedance. AThese lines Awere about seven 10 ¿control the .coupling between said resonators
:inches long. vThe ~- anode was :byepassed to .the
irad-iotfrequenoy anode conductor 5 by a 150g/lf.
concentric capacitor
`"I‘ egrid was ~connected-by
means of an annular spring to the tubular grid>
through fsaid slots, 'said :slider -in fone .position
iendering `said slots completely ineffective, and
„anotherltunine slider for said other resonator.
~`
An oscillation generator comprising a vac
conductor through an annular three plate `-ca- l5 uum tube having grid, anode and cathode elec
pacitor, the annular spring forming the central
trades, a concentric line resonator having an
`¿plateaof the `capacitor.- ."I'FwdßOS” annular-.mica
outer l:hollow conductor coupled -to vsaid :cathode
„discs .served as :the >:,dielectrlc. One :disc lwas
rand 1an inner ‘hollowf'conductor coupled `to said
¿painted'fa :thinline ofaquadagtomakefai5000
grid, another hollow conductor coaxially rar
`„ohm ggridleak. the :grid l'conductor 4 had ïsix V'20 4ranged within `said last conductor'and coupled
slots »3/8” -wide :starting Yat fthe ¿grid >condenser
to said anode, whereby said last two conductors
.and .running l” away from lthe vacuum tube.
form `another concentric line resonator having
The ‘B+ supply lwas 250 volts positive impressed
-a >common wall with said first resonator, said
`on conductor Il through .;a ¿5600 o
resistor.
common lwall having a plurality of slots there
' e osccillator system vhad ‘a frequency `range :35 through .arranged symmetrically around one por
„fiom 400 mcfto 1200 inc.
on thereof _to enable feed back between said
i» Y atis-clailned is:
wo resonators, a tuning slider for said nist
oscillation generator coinnrising a vac~
resonatoi adlustable in position over the length
uum tube >having grid, anode and cathode elec
of said resonator for controlling the effective
.trodes, sa rc'oncentric line `resonator:coupled be- :l0 ness of said slots, said .slider having-a length
.connecting together rthe .inner 'and outer yicon- 40 concentric line resonator having-an outer hollow
1 2 An oscillation generator compmsing a vacuum tube having grid anode and cathode elec-
Ycoupled
one end forma
to said concentric
anode, whereby
said
last
two at
conductors
line reso
nator having a common wall with said ñrst
tween said grid and cathode, another concentric „o of slots therethrough near the end coupled to
any tuned
desiredtofrequency
at whichwavelength
the resonators
having such axial length as to control the cou- 5U are
be one-quarter
long
pline slots
between
saidso resonators
Said Slots,
electrically
said
being
positioned through
and dimensioned
of
oscillation,is greater than for any higher mode
duce a desired frequency of operation, the volt- 55 uum tube having grid, anode and cathode elec
age across said slots is appreciably greater for
trodes, a concentric line resonator having an
the desired frequency than for any other mode
outer hollow conductor coupled to said cathode
of oscillation.
v
. An oscillation generator comprising aivac-
and an inner hollow conductor coupled to said
grid, another hollow conductor coaxially ar
uum tube having grid, anode and cathode elec- To ranged within said last conductor and coupled
trodes, a concentric line resonator having an
outer hollow conductor coupled to saidfcathode
to said anode, whereby said last two conductors
form another concentric line resonator having
"2,412,805
back between said two resonators, a tuning slider
for said first resonator being adjustable in posi-
-polarizing potential to -said anode, a metallic cy
lindrical tuning slider for each of said resona
tion between the hollow conductors of said first
resonator and having such axial length as to con-
tors, the tuning slider for one of said resonators
being adjustable in position between the hollow
trol the coupling between said resonators through 5 conductors thereof and having such axial length
said slots, said slider in one position rendering
`said slots completely ineffective, and another
tuning slider for said other resonator, a con-
as to control the coupling between said resonators
through said slots, said sliders being in staggered
relation, and unicontrol means for said sliders.
ducting rod coaxially arranged within the inl0. An oscillation generator comprising a vac
nermost hollow conductor of said anode-grid lo uum tube having grid, anode and cathode elec~
resonator for supplying said anode with anode
polarizing potential, and high loss materialk sur-
trodes,aconcentric line resonator having an outer
-hollow conductor coupled to said cathode -and an
inner hollow conductor coupled to said grid, an
other hollow conductor coaxially arranged within
im said last conductor and coupled to said anode,
whereby said last two conductors form another
rounding said rod and insulated from said innermost hollow conductor for absorbing radio íre.quencv energytending to flow along said rod.
'7. An ultra high frequency oscillation generator comprising a vacuum tube having grid, anconcentric line resonator having a common wall
iode and cathode electrodes, a concentric line reswith said ñrst resonator, said common wall hav
onator having an outer cylindrical hollow coning a'pluraltiy of slots therethrough near one end
-ductor coupled at one end to said cathode and 20 thereof to enable feed back between said two res
an inner cylindrical hollow conductor coupled at
onators, a tuning slider for said i'lrst resonator
the same end to said grid, a conductor coaxially
adjustable in position over the length of said res
arranged within said last conductor and also couonator for controlling the effectiveness of said
pled at one end to said anode, whereby said last
slots, said slider having a length which is an ap
two conductors form a concentric line resonator 25 preciable fraction of the length of said slots, said
having a common wall with said first resonator,
slider in one position rendering said slots com
said common wall having a plurality oi slots
pletely ineiiective, and another _tuning slider for
therethrough at one portion to enable feed back
said other resonaton'and means for controlling
between said resonators, a metallic cylindrical
the movement of said sliders simultaneously.v
tuning slider for each of said resonators, the tun- 30
ll. An oscillation generator comprising a vac
ing slider for one of said resonators being adjustuum tube having grid, anode and cathode elec
able in position between the hollow conductors
trodes, a concentric line resonator having an out
thereof and having such axial length as to con-
er hollow conductor coupled at one end to said
trol the coupling between said resonators through
cathode and an inner hollow conductor coupled
said slots, said sliders being in staggered relation, 35 at its adjacent end to said grid, another hollow
and unicontrol means for said sliders.
conductor coaxially arranged within said last
8. A generator in accordance with claim 6,
conductor and coupledat its correspondingly lo
characterized in this that said high loss material
cated end to said anode, whereby said last two
‘is an iron dust core.
'
conductors form another concentric line resona-
9. An ultra high frequency oscillation genera- 40 tor having a common wall with said i’irst resona
tor comprising a vacuum tube having grid, antor, said common wall having near its end which
ode and cathode electrodes, a concentric line
is connected to said vacuum tube a plurality of
resonator having an outer cylindrical hollow con-
slots therethrough to enable feed back between
ductor coupled at one end to said cathode
said two resonators, a tuning slider for said first
and an inner cylindrical hollow conductor cou- "w resonator adjustable-in position over the length
pled at the same end to said grid, another
of said resonator for controlling the effectiveness
cylindrical hollow conductor coaxially arranged
within said last conductor and also coupled
at one end to said anode, whereby said last
two conductors form a concentric line res- oo
of said slots, said slider having a length which is
an appreciable fraction of the length of said
slots, said slider in one position rendering said
slots completely ineffective, and another tuning
onator having a common wall with said ñrst res-
slider for said other resonator, and means for
onator, said common wall having a plurality of
controlling the movement of said sliders simul
slots therethrough at one portion to enable feed
back between said resonators, a conductor within
taneously.
said innermost hollow conductor for supplying
,
JOHN R. FORD.
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