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06L 29, 1946-
w. M. KELLOGG
, 2,410,080
v
HIGH FREQUENCY APPARATUS
Filed nee. 11,‘ 1941
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Oct. 29, 1946.
‘2,410,080
w, M, KELLQGG
HIGH FREQUENCY APPARATUS
2 Sheéts-Sheét 2
Filed Dec. 11, 1941
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ATTORAE'V
Patented cs. 29.1946‘ ‘
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2,410,080
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UNITED FSrATES
2,410,080 ‘a
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mGn-FnnQUnNcr maaa'rus
William M. Kellogg, Morrlstown, N. Lgassignor to
Bell Telephone Laboratories, Incorporated,
New York, N. ‘2., a corporation of New York
Application December 11, 1941, Serial No. 422,510
4 Claims- (Cl. 179—1'i1)
2
1
.
just described and ‘at the same time is readily
capable of adjustment for operation at different
frequencies. Such systems are not only‘suitable
for coupling to the input of an ampli?er but also
This invention relates to ampli?ers for use at
ultra-high frequencies and particularly to tuning,
impedance matching and neutralizing circuits
therefor.
An object of the invention is to provide an am 5 for output and interstage coupling.
pli?er for ultra-high frequency radio waves which '
‘
In accordance with another feature of the in
vention the grid to plate capacity of an ultra-high
is simple in construction and readily adjustable
frequency ampli?er is neutralized by means of a
,
short-circuited two-wire line connected . to the
A further object of the invention is to provide
grid and plate. This line is surrounded by a cy
a neutralizing system for ultra-high frequency 10 lindrical
shield which forms on each side of the
for operation at different frequencies.
ampli?ers.
.
_
two-wire line a substantially concentric line.‘
This invention can be more readily understood
-
- In the operation of. ampli?ers and similar cir
‘ cults. in the ultra-high frequency range, it has
by reference to the following detailed description
been found that circuits having distributed con-_
of one embodiment of- the invention in an ultra
15
stants are superior to lumped constant circuits for:
use for tuning, impedance matching, neutralizing, . high radio frequency ampli?er as shown inthe,
and the like. For example, one method ‘of. tuning]
the input of an ampli?er and matching its-im
1 ' drawings in which:
‘
,
Fig. 1_ is a schematic circuit diagram thereof;
Fig. 2 is a plan view;
pedance to the incoming line is to connect to the
ampli?er input a short-circuited section of trans 20
'
Fig. 3 is a front elevation, partly in section;
Fig. 4 is an end view partly in section;
'
Figs. 5 and 5A are detailed views of the stub '
' mission line the length of'which is so adjusted
that in combination with the input impedance of
line ll, Fig. 5 being an end elevation and Fig. 5A
the ampli?er it acts as a quarter wave-length line
elevation;
v
_
.
at the frequency, of the waves to be ampli?ed. 25 aside
Fig. 6 is a detailed plan view (in'enlarged scale)
‘ with such an arrangement the incoming line may
taken along the line 6-6 of Fig. 3;
be tapped onto the short-circuited line at a point
Fig. ‘7 is a detailed front elevation of the por-é '
where'the two impedances are equal. Electrically,
tion shown in Fig. 6;
.
‘such 'a system operates very satisfactorily. Also
8 is a detailed end elevation taken along
where the ampli?er is to be used only at a single 30 vtheFig.
line 8—.-8 of Fig. 6 and showing the construc-v
frequency the apparatus can be quite readily
tion of the ?lament by-pass condensers;
constructed and adjusted for such satisfactory op- v
. Fig. 9 is a detailed inverted plan view of the
eration. However, where the‘system is to be ad
?lament by-pass condensers; and
' ' :lustable to permit operation at any of a number
' culties. Among these is the problem of providing 35 ing condenser 34.
for the variable‘ connection between the incoming '
line and the quarter wave line ‘particularly since
.
Fig. 10 is a detailed exploded view of the block
of frequencies,.there are certain structural dim;
v
'
Fig. 1 shows in a somewhat conventional sche
matic circuit form theultra-high frequencyam
pli?er of the present invention, the construction
?exible lines are not entirely satisfactory for
ofwhich is illustrated in the other ?gures. This
waves in the ultra-high frequency range.
In accordance with a feature of the present in 40 ampli?er vcomprises a triode vacuum tube ll en
'closed in a shield comprising a portion l2 sur
vention there is provided a system in which the
rounding the tube itself and a section portion I3
_
is
connected
directly
to
the
am;
. incoming. line
the top of the tube shield and also en- pli?er input and there is further provided a stub . closing
closing the neutralizing line, tobe described later.
line of adjustable length which may be connected
radio frequer Y input'to the tube is brought
to the incoming line at various points along the 45 The
in through a concentric line‘comprising an outer
length of the latter. - The characteristic imped
conductor or sheath H andea tubular inner con
ance of this section of input line is the same as
ductor II. The outer conductor is grounded to
that of the line from which the ampli?er signal
1 is derived. In this system the ampli?er is tuned J the shield l2 and connected to the cathode of the
by the line formed by the portion of the incoming 50 tube H through the direct current blocking con- .
densers l6 and 26. A short-circuited stub line H
line between the ampli?er and the tapping point
is, provided to tune the input circuit and provide
of the stub line in series with the stub line and
proper impedance matching for the input.
at the same time impedance matching is. achieved
' The stub llne'comprises an outer conductor or
by the adjustment of- the tapping point. Such a
‘system is the electrical equivalent of the system to shield l1, an inner conductor‘ i8 anda short-cir
2,410,030
3
cuiting member It.
4
(This latter member I! is
shown adjustable in Fig. l for purposes of ex
' planation though in the actual construction of
if desired.
the other ?gures it is ?xed, thus ?xing the length
of the stub line.) The shield I'I contacts the outer
.conductor ll of the input line and the inner con
ductor ' l3 contacts the inner conductor l5 of the
input line.
The stub line H is movable along the input .
line so that the length of the short-circuited sec
tion from the grid of tube H to the shorting
member l9 may be adjusted. This provides a
tuning section between the grid connection and
the short-circuited terminal which when adjust~
ed to thaequivalent quarter wave-length of the
input oscillations in e?ect tunes the ampli?er
input circuit, At the same time the input portion
of the line "-45 is in effect tapped into this
' resonant line section at the Junction of the line
reactance of the stub line H, i. e., its length is
determined by the position of the shorting mem
ber l9, it is also possible to obtain a proper im
pedance match for the e?lcient termination or
sheath are at substantially the same radio fre
quency potential the grid and plate circuits are
additionally tuned by this system. Therefore,
these concentric lines should be self-resonant or
have su?lcient inductive reactance to partially or
the inner diameter of‘the sheath or shield I3. It
of the characteristic impedance of the rods as a
balanced line or as individual unbalanced (con
ampli?er is intended for operation over a narrow
centric) lines. Accordingly,'at any setting of the
frequency range, to determine by'preliminary cal
30 member 33 less than a quarter wave-length a tri
culation and trial the necessary length of the
stub line I‘! and fix the position of the member
Hi. This is done in the embodiment shown in
angle of approximately equal inductive react
ances is presented to the tube I i. This provides
the reactances desired for a tube such as the
the other ?gures, though, of course, applicant's
invention is not limited to such an arrangement.
The equivalent electrical circuit, that is a quar
ter wave-length line for tuning with an interme
diate tap for impedance matching, is familiar to
those skilled in the art. However, applicant's
The plate or output circuit of the ampli?er is
tuned and e?lciently coupled to the outgoing co
axial line 24—25 by a similar arrangement. This
comprises the coaxial line having an inner tubu
lar conductor 24 connected at the inner end to
the plate of the tube ll through a blocking con
denser 34 and an outer conductor 25 connected
to the grounded shield l2.‘ The blocking con
densers l6 and 26 serve to connect the cathode of
these concentric lines. The length is determined
by the shorting member 33 which is extended to
contact the sheath l3. Since the cathode and
is preferable that there be approximate equality
adjustment, it is possible, particularly where the
order to make the impedance matching adjust
ment to use a flexible section of incoming line.
Such an arrangement is undesirable, particularly
when operating in the higher frequency ranges.
from the grid to the sheath l3 that isdetermined
by the characteristic impedance and length of
ameters of the neutralizing rods 3l_ and 32 and
Since the latter adjustment for impedance
match is somewhat less critical than the tuning
structure avoids a serious handicap of the previ
'
position that permits the balanced line 3 l-—3Z to
tune the grid-plate capacitance to‘ resonance.
These [requirements place a restriction on the di
-’
ous arrangements in which it was necessary in
'
The line 3l-32 is enclosed in the shield l-3.
Each side of the line 3l-32 acts as the center
conductor of an approximately concentric line
of which the cylindrical shield I3 is the sheath.
This presents an impedance from the plate and
wholly resonate the grid-sheath and plate-sheath
capacitances With the shorting member 33 in the
l4-l5 and the stub line II. By adjusting the
coupling of the input line.
.
The adjustment may also be made to cause the
ampli?er to operate as a regenerative. ampli?er.
Western Electric 703A vacuum tube, the inter
‘electrode capacitances of which are approxi
mately equal. For a tube of different character
istics, different line parameters would be pre-‘
ferred.
}
'
'
In neutralizing the ampli?er, the plate volt
40 age is removed and with a high signal input the
input and output stub lines I‘! and 21 are set for
maximum output while the member 33 is ad
justed for the maximum ratio of input to output.
When so neutralized, the input and output cir
cuits can be retuned independentlylby a read
justment of the stub lines ll and 27.
For the actual structure of a practical embodi
ment of my invention reference is made to Figs.
2 to 10 of. the drawings in which the same ref
erence numerals are used throughout for like
elements.
Referring ?rst to Figs. 2 and 3, the
amplifier is built on a panel or base 48.
Above
this base and secured thereto by screws is a
shielding housing l3. This shield 33 is made
tube ll. The adjustable stub line 21, which is 55 square in cross section for mechanical reasons
similar to the line I l, is also provided and com
prises a shield 21 contacting the outer conductor
26, an inner conductor 28 contacting the inner
conductor 25 and a shorting‘member 29. ' The
direct current plate supply is brought in through
the insulated wire 30 carried within the tubular
inner conductor 25. The line 24-25 may- be used
for interstage coupling in which case it leads to
a ‘second ampli?er and is terminated in a similar
manner to the input line I l-l 5.
a
but is the substantial electrical equivalent of a
circular shield as regards its cooperation with
the neutralizing rods 3| and 32 in tuning the
grid and plate circuits.
‘
The ampli?er is supported mainly by the hous
ing l3 as is more clearly shown in Figs. 6 to 9.
The input concentric line comprising the sheath
I4 and the inner conductor I5 is supported in
the right wall of .the housing l3. For this pur
65 pose the inner end 4| is turned down forming
The tube II is neutralized to prevent the gen
a reduced portion and a shoulder which is mount
eration of spurious oscillations by means of the
ed in a hole in the wall 42 by a press ?t. A disc
balanced line 3l—32. One side 3| of this line is ' ‘ insulator 43 is mounted in a recess in the inner
connected to the grid of tube II. The other side
end of the sheath It by means of a spring re
is connected to the plate of tube ll through the 70 tainingring 44. The inner hollow tubular con
blocking condenser 34. The line 3l—-32 is ad
ductor I5 is mounted in a centrally located hole ‘
justably short-circuited by the member 33 so that
in the disc 43 and secured there by the nut 45.
its inductance can be adJusted to give a react
r Clamped on the end of the‘ conductor I5 is a
ance equal tothat of thegrid to plate capacity,
clamping block 36.
thus neutralizing the en'ect of the latter.
75 The. clamping block 43 carries an L-shaped
2,410,0s0
: bracket 41 and the plate terminal socket 40. The '
,‘neutralizing rod 3| is carried by the bracket 41.
' e?ective length ot'the balanced -neutralizing line
The ‘plate circuit concentric line‘ 24-45 is sim
and the unbalanced plateandlg-rid lines may be
adjusted.
A pointer 02 andi‘sc'al '
dication of the adiustmena'r'f-i '
ilarly mounted in a second hole in the wall 42.
An insulated wire 30 forming-the direct current
connection to the plate is run through the hollow
inner conductor 25. > The wire 30 is brought out
" ivelanin
‘
Figs; 5 and 5A show the construction "of the
stub line I1, the stub line 21 being‘identicalithere
"to. This comprises an outer‘ housingsor-rshield
I00 formed largely of sheet metal but ‘having two
of the conductor 25 at a point of low radio ire-I ‘1 solid end blocks IOI soldered to theisheet'lmetai
quency impedance as shown in Fig. 3 thus sim
portion. The lower end of eachof these end
plifying the ?ltering of the direct current circuit. 10 -blocks IN is machinedto form a tongue I02,
A clamping block 56 is mounted on the inner end
which rides in the slot “J in the top of the outer
of the conductor 25. Like the block‘ 46, this block
conductor I4. ‘ Riding on the inside of the con
56 carries a neutralizing rod 32 and the socket
50 for the plate terminal or the tube II. How
ductor I4 is a shoe I03 vthat is fastened to the
end blocks IN by means of the machine screws
ever,_the socket 48 is directly mounted in block 15 I04 and springs I05. A wiper I08 contacts the
46, while terminal 58 is mounted in the block 56
through the medium of an insulating bushing
to form the blocking condenser 34. Fig. 10 shows
this construction.
inner conductor I5. This wiper is carried; by a
stem I8 forming the inner conductor of the stub
line I1. The stem I8 is carried by two guide
blocks I01 to which it is riveted. The assembly
,
Referring to Fig. 10, which is an exploded view 20 of blocks I01 and stem I8 are secured to the
or the condenser 34, the socket 50 is screwed
casing I00 by means of machine screws I08 and
onto the threaded end of rod 00. The other end
I09. The screw I09 in addition carries a strip
GI is of reduced size forming a soldering terminal
IIO the-lower end of which is bent outwardly
for the direct current lead 30. A bushing 62 ?ts
and pointed to iorin an indicator III.v This in
25
over the intermediate portion of the rod 60. This
dicator cooperateswith the scale H2 to indicate ’
bushing 82 is of a lava type insulating material
the adjustment of the stub lines I1 and 21'.
which is ?rst coated with silver and then copper
What is claimed is:
I
plated, both inside and out. An externally
_1. In a high frequency ampli?er, a vacuum
threaded metallic bushing 63 ?ts over the in
having a cathode, an ‘anode and a control
sulating bushing 62. The rod 50 and bushings 30 tube
grid, 2. two-wire line, a shield surrounding said
62 and63 are sweated together. Then the bush
line and so spaced with respect‘ thereto and to
ing 03 is screwed into the tapped hole 59 inthe
the spacing between the two wires of said line
block 55. In this way the plate of the tube II
that each of said wires forms a substantially con
is capacity coupled to the neutralizing rod 32 and
‘centric line with said shield, means for connect
35
the inner conductor 25. The rod 80 and bushings
ing one set of terminals of said two-wire line to
62 and 63 form the blocking condenser 34.
.
said anode and control grid, means for connecting
It will be observed that the‘ conductor 25 is ' the corresponding end of said shield to 'said
clamped in a split portion 0! the block 55 by
cathode, and an adjustable device forming ‘a
means of the screw 64. A similar construction
short circuit at the other set of terminals of _
is used for clamping the block 40 to the con 40 said two wires and a point on said shield spaced
ductor _ I 5.
An assembly of cathode circuit condensers I6
and‘26 is also mounted in the shield". These
comprise a mounting plate 10 screwed to angles
69 suitably mounted on the inner walls of the
_- shield I3. Two irregularly shaped plates H and
12 are screwed to the plate 10 and separated
from said corresponding end thereof, the spacing
of the wires of said two-wire line with respect
to each other and to said shield being such that
said adjustable device simultaneously controls
the length of said substantially concentric lines
to tune the grid and anode circuits to the operat
ing frequency and the length of said two-wire
therefrom by the sheet of mica 13. Insulating
line to prevent the generation of spurious oscil-_v
washers 14 prevent the screw heads from making
iations.
50
high frequency ampli?er, a vacuum
electrical contact with the plates 1| and 12. Sol
2.Ina
dering terminals 1 I .I and 12.I are provided on the
“tube ampli?er having a cathode, an anode, and
plates H and 12 respectively, for connecting the
a control grid, a two-wire line having a set of
leads which furnish heating current to the cath- ' terminals connected to said anode and control
grid, an adjustable short-circuiting element for ‘
ode of the tube II. Cathode terminal sockets 15
and 10 for the tube II are mounted on the plates 55 said line whereby the regenerative action or said
1I' and 12 respectively.
‘
_
_
The tube- II is mounted below the panel 40,
being supported from the sockets 48, 58, 15‘ and
16 by its electrode terminals. The shield l2 sur
rounds the tube II and is provided with a remov
able cover I2.I for access to the tube.
v
'
. The short-circuit member 33 is mounted in
the shield I3. This is provided with a wine: 82
tube may be controlled to prevent the generation
a. shield surrounding said
of spurious oscillations,
line and so spaced therefromrelative to the spac
ing of the wires of said line that each of said
80 wires'forms a substantially concentric line with
an adjustable device for short- »
said shield, and
circuiting said wires ‘to said shield to tune the
grid and anode circuits to the operating fre
which contacts the rod 32.. v A similar wiper, not
quency of the ampli?er.
‘
visible in the drawings, contacts the rod it. The 35 3. In an ultra-high frequency ampli?er ac
plate member 33 is also provided with brushes
cording to ‘claim 2, means for simultaneously ad-,
83 which make contact with the inner surface'oi
iusting said adjustable short-circuit element and
the shield I3. A block as is attached to the plate ' said adjustable device.
43.- A shaft 88 isJcurnaied-in this block ‘at and
4. In ‘a high frequency ampli?er. a vacuum
carries two pinions .81 {and 88 within the shield 10 tube having a cathode, ananode and a control
I3 and a knurled knob 89 outside. The pinions ' grid, 2. two-wire line, a shield surrounding said
line and so spaced relative to said line and to
' 81 and 80 mesh with the teeth of the respective .
racks 90 and 0| secured to ‘the inside oirthe
the spacing between the two wires thereof as
shield I3. Thus by turning the knob 09 the
to form a substantially concentric line with each
position of the plate 33 and consequently-the 75
2,410,0s0
a
7
of said-two wires, electrical connections between
corresponding ends of said two wires and said
anode and said control grid, respectively, elec
trical connections between the corresponding end
of said shield and said cathode, a plunger ele
ment making electrical contact with said shield
'8
trol means for adjusting the position of said
plunger in said shield to simultaneously adjust
the length of said two-wire line to prevent the
generation of spurious oscillations and the sub
‘ stantially concentric lines formed between each
of said two wires and said shield to tune the
and each ‘of said two wires and having such
grid
and anode circuits to the operating fre
electrical characteristics as to form a substantial
quency.
_
short circuit between said two wires and between
each of said two wires and said shield, and con- 10
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