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Oct. 8, 1946.
A. H. TURNER
2,408,895
ULTRA HIGH FREQUENCY TUNER
Filed March 31, 1943
2 Sheets-Sheet 1
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ULTRA HIGH FREQuE?cY TUNER
' Filed March 31,_ \l943
- 2 Sheets-Sheet 2
3noentor
Patented Oct. 8, 1946
2,408,895
UNITED STATES PATENT OFFICE
2,408,895
ULTRA HIGH FREQUENCY TUNER
Alfred H. Turner, Collingswood, N. J., assignor
to Radio Corporation of America, a corporation
of Delaware
Application March 31, 1943, Serial No. 481,215
12 Claims.
(Cl. 250-40)
1
2
This invention relates generally to ultra high
frequency apparatus and particularly to an im
proved apparatus for tuning e?iciently over a
relatively wide band of ultra high frequencies.
One of the conventional methods of tuning at
ultra high frequencies is to employ a resonant
be arranged to rotate with them. The effective
inductance of the inductive element is of the
order of that employed for one of the resonant
lines. It should be understood that two or more
tuning units of the type described may be con
nected to di?erent utilization circuits, such as,
line of suitable design across one end of which
is connected a variable capacitor having a rela
tively high maximum capacity. Such an ar
rangement provides a theoretical limit of 1 to 2 10
for example, the input and output circuits of the
between minimum and maximum frequency ad
justments. In practice, the theoretical limit is
not attainable because of distributed resistances
convenient mechanical arrangement.
The second modi?cation of the invention to be
same or diiierent thermionic tubes.
It should
also be understood that the rotating capacitive
elements may be suitably ganged by means of any
described in detail hereinafter comprises a con
and impedances throughout the circuit. In ad
centric line section of the order of one half wave
dition, the loading e?ect of the device to which 15 length at the operating frequency, having one
the tuner is connected reduces the practicable
tuning frequency band.
The instant invention contemplates the use of
a resonant line connected at one end to a suit
able utilization circuit.
end of each of the conductors connected to the
utilization device. 'The center conductor of the
concentric line is interrupted at a point of the
order of one half of the shortest operating Wave
The opposite ends of 20 length from the end connected to the utilization
the line are connected together through one or
circuit. The remaining quarter wave section in
cludes at its extremity remote from the utiliza
more variable capacitors and an inductive ele
ment having an inductance of the order of that
tion circuit a conductive element in close ca
of one of the lines. The resulting circuit com
pacitive relation with the other concentric con
prises a parallel-tuned circuit including the uti 25 ductor. This conductive element and the inner
lization device and the resonant lines, having a
conductor portion connected thereto‘ is provided
series-tuned circuit including the capacitive and
with a suitable control element such as, for ex
the inductive element connected across the ends
ample, a shaft and a control knob, whereby the
of the lines remote from the utilization device.
gap between the :two portions of the center con
Adjustment of the capacitive reactance of the 30 ductor may be varied to provide a variable series
series capacitors therefore effectively provides
capacitor between said portions. It will be un
simultaneous adjustment of both the capacitive
derstood that the capacitance between the con
and inductive reactances of the circuit. Such
ductive element which terminates the inner con-,
an arrangement provides a theoretical limit of
ductor portion and the outer line conductor will
remain substantially constant as the capacitance
one to three between the minimum and maxi
mum tuning frequency limits. Of course, the
between the inner line portions is varied. Vary
theoretical limit may not be attainable in actual
ing the capacitance between the portions of the
practice, but the practical limits substantially
inner line will vary effectively the capacitive
exceed those possible with the conventional tun
coupling between the quarter wave line connected
ing arrangement described heretofore.
to the utilization device and the quarter wave
line remote therefrom. ‘In operation, the effect
Two modi?cations of this novel and ef?cient
tuning system will be described in detail here
is similar to that described for the ?rst modi?
inafter. One means comprises a pair of reso
cation of the invention, since the effective result
is to simultaneously vary the series inductive and
nant lines of the order of one quarter to one
half wave length at the operating frequency
capacitive reactance of the circuit.
Among the objects of the invention are to pro
which terminate at one end in the utilization
vide an improved method of and means for tun
device and at the other end in ?xed capacitor
ing an ultra high frequency circuit. Another ob
electrodes. Two movable capacitor electrodes are
ject is to provide an improved method of and
disposed in variable capacitive relation to sep
arate ones of the ?xed capacitive elements and 50 means for varying simultaneously the inductive
arranged to vary simultaneously the capacity
and capacitive reactance of an ultra high fre
quency circuit. A further object of the invention
between each ?xed and movable electrode. A
is to provide an improved method of and means
lumped inductive element, such as, for example,
for tuning an ultra high frequency circuit over a
a relatively small helix is connected directly be
tween the movable capacitive elements, and may 55 relatively wide band of frequencies. Another ob
52,408,895
3
means for varying simultaneously the series in
ductive and capacitive reactance in a plurality
of ultra high frequency tuned circuits.
?rst inner conductor 4 will vary the capacitive
coupling between the inner conductors, thereby
A still
further object of the invention is to provide an
improved method of and means for tuning a con
4
slightly less than one quarter wave length at the
highest operating frequency. Moving the second
inner conductor l0 axially with respect to the
iect is to provide an improved method of and
61
effectively varying the series capacitive and in
ductive reactances in the circuit, as explained
centric ultra high frequency line by adjusting
heretofore. It should be understood that any
suitable mechanical arrangement may be pro
tive reactances connected to said line.
vided for moving the control shaft I4 axially with
The invention will be described in greater de
respect to the inner conductor 4.
tail by reference to the accompanying drawings
Referring to Figure 4, an ultra high frequency
of which Figure 1 is a schematic circuit diagram
circuit comprising an ultra high frequency am
thereof; Figures 2 and 3 are cross-sectional views
pli?er, an ultra high frequency oscillator and an
of one embodiment thereof; Figure 4 is a’ sche
ultra high frequency mixer or ?rst detector, is
matic circuit diagram of a second embodiment
shown in combination with tuning circuits of the
thereof and Figure 5 is an elevational view of the
general type illustrated in Figure 1 and described
tuning elements illustrated in Figure 4. Figure
in detail heretofore. A concentric transmission
5 includes a fragmentary cross-sectional portion
line 2| connected to, for example, a suitable re
to illustrate better the construction thereof.
Similar reference numerals are applied to similar 20 ceiving antenna, not shown, is connected to one
end of an input coupling loop 22. The remaining
elements throughout the drawings.
end of the input coupling loop 22 is connected to
Referring to Figure 1, a utilization circuit com
ground through a variable tuning capacitor 23.
prising the anode circuits of tubes I and 2, and
An ultra high frequency balanced ampli?er
having an inherent capacitance 3, is connected
to one end of a ?rst resonant line represented by 25 such as, for example, a double pentode tube 24,
simultaneously the series inductive and ‘capaci
an inductance 4 and to one end of a ‘second res
is self-biased by means of a conventional cathode
o'nant line repreesnted by a second inductance 5.
The remaining terminals of the lines 4 and 5 ter
are connected between the cathode and ground.
mi'n'ate respectively in ?xed capacitive elements
The control grids of each of the tube pentode
5 and ‘I. A ?rst movable capacitive element 8
is disposed in variable capacitive relation with
the ?rst ?xed capacitive element 6. A second
movable capacitive element 9 is disposed in simi
lar variable capacitive relation to the second ?xed
capacitive element 1. A third inductive element
I0, which, vfor example, may be a small substan
tially rigid helix, having an inductance of the
order of the inductance of one of the resonant
lines, is connected between the ?rst and second
movable capacitive elements 8 and 9. The third
inductive element 10 may, if desired, be rotated
simultaneously with the movable capacitive ele
sections are connected to the ends of separate
ones of a ?rst pair of resonant lines 4, 5 which
resistor 25 and cathode bypass capacitor 28 which
are of the order of one quarter to one half wave
length at the operating frequency. The remain~
ing ends of the resonant lines 4 and 5 terminate
respectively in ?rst and second ?xed capacitive
elements 6 and 1. A grounded center-tapped re
sistor network 21, 28 is connected between the
?xed capacitive elements 6, 1 to provide a D.-C.
grid return circuit.
The movable capacitive elements 8 and 9,
which are in capacitive relation respectively with
the ?xed capacitive elements 6, and ‘I, are con
nected together through a compact bunched in
ments 8 and 9, these movable elementsmay be in
dividually or interdependently rotated.
ductive element I'D of the type described hereto
Referring to Figures 2 and 3, there is provided 45 fore. The screen electrodes of the two pentodes
of the tube 24 are connected together and by
an arrangement employing a concentric line to
passed to ground by means of a screen capacitor
replace the lines 4 and 5 of Figure 1. The device
29. Operating potentials for the screen electrodes
includes an inner conductor 4, surrounded by a
and the anodes of the two pentodes are provided
concentrically disposed outer cylindrical conduc
tor~5, both connected to a utilization device such 50 from any suitable source, not shown, and applied
to the respective electrodes through suitable iso
as a tube H5. The length of the inner conductor
lating resistors 30, 3| and 32.
4 is of the order of one half wave length at the
The anodes of the two pentodes are each con
highest operating frequency, while that of the
nected to one end of a second pair of resonant
outer conductor 5 is substantially greater than
three quarter wave length at the highest operat 55 lines 34, 35 terminate in a similar tuning unit 5’,
ing frequency. A second inner conductor H] in
cludes a conductive element II which provides
close capacitive coupling between the second in
ner conductor [0 and the outer conductor 5. This
1’, 8', 9’, l0’. In order to match the two tuned
circuits, a matching capacitor 33 may be con
nected between the anode terminals of the lines
Such movement might be facilitated by means
of a control shaft I4 connected to the conductive
ratus described heretofore.
34, 35. Similarly, separate ?xed capacitors 0 may
coupling may be maintained substantially con (30 be connected selectively by means of switches 8,
across each group of resonant lines adjacent the
stant by means of an insulated ring [2 forming
utilization circuits connected thereto, to provide
a spacer between the conductive element H and
a tuner having a plurality of tuning frequency
the outer conductor 5. The two inner conductors
4 and ID are disposed coaxially and separated by
ranges.
Suitable coupling between the input loop 22
a gap I3. The width of the gap l3 may be in
and either of the ?rst resonant lines 4, 5 may be
creased or decreased by moving the second inner
provided by spacing the conductors to provide
conductor l0, and the conductive element H at
desired mutual inductance between them. A
tached thereto, axially within the outer conduc
shield 36 preferably surrounds all of the app'a
tor 5.
element l l coaxially with the inner conductor
Ill. The control shaft l4 may include a control
knob l5 attached thereto. The effective length
of the second inner conductor l0 should also be 75
A second shield 31
separates the ?rst resonant lines 4, 5, and their
associated tuning unit, from the second resonant
lines 34, 35 and their associated tuning unit,
V
respectively.
I
' A mixer or converter stage includes a double
‘2,408,895
"triode 44 ‘having the two‘ anodes thereof-peon
nected together and to the primary of an inter
mediate frequencytransformer, not shown. The
justedby-a suitable motor drive to provide-a
f‘jamming” transmitter.
-
; p Thustheinvention described comprises several
modi?cations of a novel and efficient tuner for
cathode is connected to ground through a con
a, relatively wide band of ultra high frequencies
ventional self-biasing circuit including a cathode oi including
means for adapting the tuner to opera
resistor 45 and a parallel connected capacitor 46.
tion
in
an
ultra high frequency superheterodyne
The control electrodes of the two triodes are each
ampli?er-oscillator-converter circuit.
‘
connected to one end of separate resonant lines
I claim as my invention:
.
41, 48 which are mutually coupled to the second
resonant lines 34, 35 througha suitable aperture 10
1. An ultra high frequency tuning circuit in
cluding a pair of inductive elements, at least one
in the shield 36. The third resonant lines 41, 48
adjustable
capacitiveelement, a third inductive
are tuned by a third tuning unit 6", ‘l", 8", 9f’,
element
having
an inductance at least of the
I07’, of the type described heretofore. A ground
order of the inductance ,of one of said pairv‘of
ed center-tapped resistor network 49, 58 is con
nected between the ?xed capacitive elements 6", 15 elements and movable with said capacitive ele
ment, a utilization device, means connecting one
I’? toprovide a D.—C. grid return circuit for the
terminal of each of said pair of inductive ele
balanced converter.
ments to saidutilization device, means connect
I An ultra high frequency oscillator includes a
ing» the remaining terminals of said pair of ele
double triode 54 having its cathode connected
to ground through a cathode resistor 55 and 20 ments in series relation with said capacitive ele
‘ment and said third inductive element, and
cathode capacitor 55. The grid circuit of the
meanswfor adjusting said capacitive element-to
oscillator is comprised of a, loop of copper, foil
vary‘ simultaneously the effective series inductive
terminating in the two control electrodes and
and capacitive reactance of said circuit.
having its center-point grounded through a grid
2. An ultra high frequency tuning circuit in
resistor 51. The anode circuit of the push-pull
cluding a pair of inductive elements, a pair of
oscillator includes a fourth pair of resonant lines
adjustable capacitive elements each having at
58, 59 and a fourth tuning unit 6"’, 1”’, 8”’, 9"’
least a ?xed electrode and a movable electrode,
and lil'”. Anode potential is applied to the two
a third inductive element having an inductance
anodes through anode resistor 52, 53.
at least of the order of the inductance of one of
The four tuning units described heretofore may
said. pair of elements, means connecting and
be ganged as indicated by the dash lines 60. The
supporting said third inductive element between
balanced oscillator circuit may be coupled to the
said movable electrodes of said capacitive ele
converter input circuit by means of mutual cou
ments so that said third inductive element is
pling between the lines 48 and 58 through a suit
movable with said movable electrodes, means
able aperture in a third shield 38 which separates
connecting 'one extremity of each of said ele
the oscillator from the converter. t should be
ments ‘of said pair to a different one of ‘said ?xed
understood that the constants of the circuitwill
electrodes of said-capacitive elements, a utiliza
be so selected that the desired intermediate fre
tion device, means connecting the remaining ends
quency may be derived from the converter anode
of said pair of elements to said utilization de
circuit.
,
vice, and means for adjusting simultaneously
For example, the several tuning capacitors may
the‘ capacity of said capacitive elements to vary
be of a conventional type providing a capacity
simultaneously the effective series inductive and
range of the order of from one to ten micro
capacitive‘ reactance of said circuit.
micro-farads. As explained heretofore, the
» 3; A‘ plurality of circuits of the type described
length of the various resonant lines is selected
in claim'2 including means for adjusting simul
to be of the order of one-quarter to one-half
taneouslyall of said capacitive elements, and
wave length at the operating frequency. Cir
meanslfor coupling together at least two of‘ said
cuits of the type described have been constructed
circuits.
to provide suitable tuning over ranges extending
4. A plurality of circuits of the type described
from 250 to 400 megacycles and 400 to 600 mega 50
in claim 2 including means for adjusting simul
cycles. This range could be extended readily by
taneously all of said capacitive elements, and
proper selection of circuit constants.
inductive means for coupling together at least
Referring to Figure 5, the constructional de
two of said circuits.
tails of the circuit schematically described in
5. Apparatus of the type described in claim 2
Figure 4 indicate one satisfactory arrangement 55
including a tuning capacitor, and means con
of this apparatus. A single tuning knob Bl at
necting said tuning capacitor between said pair
tached to a single insulated tuning shaft 63 con
of elements adjacent said utilization device.
trols the rotation of all of the movable capacitive
6. A plurality of circuits described in claim 2
elements 8, 8’, 8", 8”’ and 9, 9', 9", 9"’. The '
entire assembly is enclosed in a suitable outer 60 including means for adjusting simultaneously all
of said capacitive elements, means for coupling
shield 65. Only the connections and apparatus
together at least two of said circuits, a plurality
corresponding to the ultra high frequency tuner
of tuning capacitors, and means connecting each
are shown in order to simplify the comparison
of said tuning capacitors between said pair of
of the structural and schematic layouts of Fig
ures 4 and 5. All elements are identi?ed with 65 elements adjacent each of said utilization de
the same reference numerals as corresponding
vices.
7. An ultra high frequency tuning circuit in
cluding a resonant section of concentric trans
mission line having an inner conductor coaxially
8 may be opened and closed synchronously by any
disposed with respect to an outer cylindrical con
70
suitable motor drive, and that the several tuning
portions of Figure 4.
It should be understood that all of the switches
units may be similarly adjusted synchronously,
to provide a scanning type tuner. Also the oscil
lator described may be utilized as a transmitter,
and the switch s, the tuning capacitor 0 or the
tuning unit thereof, or any of them may be ad
ductor, said conductor being discontinuous form
ing a capacitive gap between the portions there
of, conductive means connected to the extremity
of one of said portions of said inner conductor
75 remote from saidv gap in close capacitive rela
q.
2,408,893
tion with said outer conductor; a» utilization de
vice, means connecting the extremity‘ of said
outer conductor and the extremity of saidinner
conductor portion both‘ remote from Saar con
ductive means and said‘ capacitive‘ gap to said
utilization device, and’ means for adjusting‘ the
length of said capacitive gap between the por
tions of said inner conductor to- vary simultane
ously the effective series‘ inductive and capaci
tive reactance of said circuit.
8. An ultra high frequency tuning circuit in
cluding' a resonant section of concentric trans
mission line having an inner conductor coaxially
disposed with respect to an outer cylindrical con
‘simultaneously the" e?ectiv'e- series inductive and
capacitive reactan‘ce of said circuit.
‘ 10. A plurality of circuits of the type described
in claim 9' including means for adjusting simul
taneously all of said capacitive elements, and
means for coupling together at least two of said
circuits.
11. An ultra high frequency tuning circuit in
cluding a pair of inductive ‘elements, a pair of
10 adjustable capacitive‘ elements each- having at
least a ?xed electrode and a movable electrode,
a third inductive element having an effective in
ductance of the order of the inductance of one
of’ said pair of elements, means connecting
ductor, said conductor being discontinuous form
and‘ supporting said'third inductive element be
ing a capacitive gap between the portions there
tween said movable electrodes of said capacitive
of, conductive means connected to the extremity
elements so that said third inductive element is
or one of said portions of said inner conductor
movable with said movable electrodes, means
remote from said gap in close capacitive relation
connecting one extremity of each of said ele
with said outer conductor, a utilization device; 520 ments of said pair to a different one of said‘ ?xed
means connecting the extremity of said outer
electrodes of said capacitive elements, a utiliza
conductor and the extremity of said inner con
tion device,- means connecting the remaining
ductor portion both remote from said conductive
ends of said pair of elements to said utilization
means and said capacitive gap to said utilization
device, and means for adjusting simultaneously
device, and means operable e?ectively coaxially
the capacity of said‘ capacitive elements to vary
with said line for adjusting the length of said
simultaneously the effective series inductive and
capacitive gap between the portions of said‘ inner
capacitive reactance ‘of said circuit.
conductor to vary simultaneously the effective
12. An ultra high frequency tuning circuit in
series inductive and capacitive reactance of said
cluding a resonant section of concentric trans
circuit.
30 mission line having an inner conductor coaxially
9. An ultra high frequency tuning circuit in
disposed with respect to an outer cylindrical
cluding a pair of inductive elements, a pair of
conductor,
said conductor being discontinuous
adjustable capacitive‘ elements each having at
forming a capacitive gap between portions there
least a. ?xed electrode and a movable electrode,
of, conductive means connected to the extremity
a third inductive element, means connecting and 35 of one of said portions of said inner conductor
supporting said third inductive element between
remote from said- gap in close capacitive rela
‘said: movable electrodes of said capacitive ele
tion with said outerv conductor, a utilization de
ments so that said third inductive element is
vice, means connecting the extremity of said
movable with said movable electrodes, means
outer conductor and the extremity of said inner
connecting one extremity of each of said ele
conductor portion remote from said conductive
ments of said pair of inductive elements to a
means and said capacitive gap to said utilization
different one of said ?xed electrodes of said
device‘, and means for adjusting the length of
capacitive elements, a utilization device’ includ
said‘v capacitive gap between the portions of said
ing an input circuit and an output circuit, means
inner conductor to vary simultaneously‘ the ef
connecting the remaining ends of said pair of 45 fective series inductive and capacitive reactance
elements to one of said circuits of said utilization
of ‘said circuit.
device, and means for adjusting simultaneously
ALFRED H. TURNER.
the capacity of said- capacitive elements‘ to» vary
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