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Патент USA US2406565

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-Aug.27,’1946.
‘R; G, ROWE‘
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42,406,565
IELEC'I‘RON‘IC AMPLIFIER AND MODIFIER
Filed Oct. 15, ‘1943'
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2,406,565
Patented Aug. 27,‘ 1946
UNITED STATE 5 PATENT OFFICE
2,406,565
ELECTRONIC AMPLIFIER AND MODIFIER
Robert G. Rowe, Niagara Falls, N. Y.
Application October 15, 1943, Serial No. 506,381
8 Claims. (Cl. 250—27)
1
2
My invention relates, generally, to an electronic
ampli?er and modi?er for controlling and modi
.
Still another object of my invention is to fur
ther control or modify these variations, the ratio,
fying the effective grid voltage-anode current
rate and slope of maximum to minimum, to effect
characteristics in electron tube circuits and, more
speci?cally, to an improved circuit for sensitive
new‘ and'useful circuit characteristics.
control devices.
by inserting serially in the master circuit a con
trollable resistance device with at least an anOde',
'
l
The designof amplifying, modulating‘, signal
ling, counting, cycling and like‘ apparatus which
'
‘
The aforementioned objects and other objects
ancillary thereto I prefer to accomplish, in short,
control grid and cathode together with a means
depends for its function on variations in elec
tronic tube anode-cathode voltage and current 10 for biasing the control grid of the resistive ele
ment which is responsive to current or voltage
is well known in the electronic art.
variation in the master ‘circuit.
>
In vacuum tube ampli?cation; variations in
anode current through a serially connected re
' Other and further objects of my invention
age, the maximum to minimum ratio, which in
a large part determines the effectiveness of the
control. In conventional ampli?ers the variation
in voltage or the voltage swing on the grid of the
tube is a determining factor in the output volt;
age of the stage. In conventional modulators
the variation in anode-cathode radio frequency
2 and inductance 3 comprising the resonant tank'
circuit. Plate blocking condenser 4 offers a low
impedance to radio frequency current, but effec
reside in the method and apparatus employed
sistor develop a varying potential for application
to the grid of the ensuing tube. In modulation, 15 therein as set forth more fully in the specification
hereinafter following by reference ‘to theaccom
variations in the radio frequency ampli?er plate
panying drawing, in which '
voltage produce similar variations in the ‘carrier
The single ?gure schematically illustrates a
power output. In photoelectric, inductive, ca
capacity sensitive circuit arrangement embodying
pacitive and like apparatus, variations in associ
ated vacuum tube anode currents operate serially 20 one of the principles of my invention.
With reference to the drawing, in which oath-‘7
coupled resistors, relays andeother current re
ode heaters are eliminated for convenience in
sponsi've devices.
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drawing, master tube l is employed in a modi?ed
In all of these and many other systems it is
Hartley oscillator circuit, with variable condenser‘.
the variation in current or the variation in volt
ampli?er voltage largely determines the percent
age modulation. In photoelectric, inductive and
capacitive apparatus the amount of variation in
anode current largely determines the reliability,
ruggedness and efficiency ofthe entire device.
I have found, however, that for many ‘applica
tions the variation in voltage or current, the
maximum to minimum ratio, is insufficient to
properly actuate the coupled device. Particu
larly in photoelectric, inductive and capacitive
equipment fragile, expensive, sensitive‘ relays
mustlbe used to respond to the small current
changes produced. 'Further, these 'sensitive're
tively isolates the direct current component on,
plate 5 of vacuum tube I from the grounded tank
coil assembly. Radio frequency choke 6 offers a
low resistance to the flow of direct current but
a high impedance to the alternating ‘current com
ponent appearing on plate 5 of vacuum tube l.
By-pass condenser ‘l effectively shunts to ground
stray radio frequency currents which ‘are not'im-'_
peded by choke ?. Grid condenser 8 offers a low,
impedance to‘ regenerative radio frequency cur
rent inductively obtained from tank coil 3 to pro- '
vide excitation for grid 9 of tube I, but effectively
isolates grid 9 from ground. I have found that
shunting grid condenser 8 by a resistor as usually ' '
employed in the Hartley circuit partially impairs ,
' sensitivity of this particular-arrangement and
that, especially when condenser 8 exhibits appre
lays usually are not designed to handle high sec 45 ciable leakage conductance, additional resistance
ondary voltages and currents. Often, they are
mayv bev omitted. The resistance from grid 9 to .
used in the control circuits of larger relays with
the cathode of tube I is somewhat critical in
high secondary power handling capabilities add
securing optimum circuit sensitivity and the
ing to the expense and complexity of the appa
proper value is best determined by experiment. . v
ratus'.. Still vfurther, sensitive relays are more 50
Such an oscillator circuit, which is connected _
susceptible‘ to damage and faulty ‘operation due
as shown in the drawing to leads A and B, is in
effect a variable resistance device across leads A ,
to low contact pressure and other effects.
It is, accordingly, an- object of myinventionto;
amplify these variations in current; and voltage
and B, the resistance of which varies in accord
to increase the maximum to minimum ratio. -
ance‘ with the condition of resonance or anti- ‘
’
2,406,565
3
4
resonance in the link-coupled external tank cir
bias, the resistance of tube I8 becomes higher,
cuit described below.
and a lower than maximum voltage appears on
the oscillator as measured from cathode 21 of
vacuum tube 24 to cathode 2| of vacuum tube
,
Pickup coils II) and I! provide link coupling to
the capacity-sensitive external tank circuit come
prising coil I2, condenser I3, antenna I4 and
ground.
I8. As the voltage becomes progressively lower
’
on the oscillator, vacuum tube I, the current
Normally closed relay I5 controls the signal-.
through resistor 25 and, ipso facto, the negative
ling, counting, cycling or like circuit to be oper
bias on grid 25 of tube 24 becomes progressively
ated by capacity variations in the external tank
smaller. Anode 23 of vacuum tube 24 draws pro
circuit. When the generator circuit comprising 10 gressively more current through resistor 22, and
tube I and its associated components is oscillat
more negative bias appears on grid 2i] of tube I8.
ing, by proper selection of components the ex
ternal tank circuit comprising coil I2, condenser'
_ The resistance of tube I8 progressively increases
'and current ?owing in the master circuit through
I3, antenna I4 and ground can be tuned to reso- , '
nance with the oscillator.
Components can be
so adjusted that when the external tank circuit '
istuned to resonance with. the'oscillator, tube I
will draw maximum anode current, and when ‘
this condition of resonance is disturbed by added
capacity between antenna I4 and ground tube I
will draw less than maximum anode current.
Thus,'in a condition‘ of resonance, current re
sponsive relay I5 will hold open contacts I6 and
I1 which control the external signalling,,count
ring, cycling or like circuit. Whenresonance is
disturbed by. a capacitance variation in the link‘.
coupled external tank circuit, the armature of
current responsive relay I5fwill drop out and
close contacts I6 and I1. 'This circuit is well‘
known in the electronic art.
.,
,
/'However, I have found that the anode’ current
1 ‘ change through current responsive relay I5 from
g a condition of resonance to o?-I'esormnce as oc-.
the ?eld coil of relay I5 progressively decreases
, to an equalization point.
I have found that the use of this controllable
resistive element increases the maximum to min
imum current ratio through the serially inserted
controlrelay. I am able to employ less expen- .
sive, more reliable current responsive relays, .se- '
cure greater sensitivity of the capacitive element
and insure sh'arperand more reliable relay ac
tion. Obviously,’ relay I5 may be inserted serially
between the cathode oi?v tube I and resistor 25,
above or below-the junction of cathode Z'I; or
between radio frequency choke t and cathode
2I of tube I8, to further increase sensitivity by
eliminating the reactive plate current component
of tube 24.
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.
Otherwise, my invention has ‘broad application
in the radio and electronic art.
In the case of
conventional electronic tube ampli?ers, the IR
voltage drop developed across a resistor inserted
casioned by the capacity changes :which I'en-.
serially in» the anode-cathode circuit is impressed
counter is insu?icient to properly operate, the 35 on the grid of the ensuing tube. When these
relay which I desire to employ. ,
_
tubes are operated‘ on the straight-line portion
One phase of my invention resides in the here
'of the grid voltage-anode current curve, the aminafter' described improvements; wherein a re
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pli?cation factor or mu of the tube remains sub- .
, sistive device, vacuum tube I 8, comprising at
stantially constant and the'maximum to mini
least ‘an anode I9, control grid‘ 20 and‘cathode 40 mum voltage or current ratio throughout the sys
ZI is inserted serially in the mastercircuit, that
tem ‘remains substantially uniform- Although
is to say, in series, with battery C, relay I5, resis
the peak values of current or voltage are ele
tor 25 and. oscillator supply leads A and B; and
vated, the minimum values are similarly ele-‘
wherein. bias potential on control grid 20 is sup-1
vated, in a manner such that the ratio between
plied by theIR drop through resistor 22 as de- up‘ the two remains constant. By inserting my'con
. termined-by the anode, current of anode 23 of ‘
I vacuum tube 24; and wherein the anode current
‘ of vacuum tube. 24 is responsive to current changes
trolled resistive element serially in one or more
of the ampli?er stages, I have found that I can
either increase or decrease the ratio between the
3 in ,the master circuit through resistor 25, grid
maximum and minimum values of current or
j 26 and cathode 21.
voltage by slight ‘circuit modi?cations. Thus, it
'
'
V In a condition‘ of resonance between the oscil-, j
; lator and the link coupled external circuit the I
I anode current of tube I is maximum. Thus, the .
‘ bias voltage on grid 26 of tube 24 is maximum"
becomes feasible to augment the ampli?cation V ‘
1 as determined by the IR drop acrossresistor 25,.‘
istics of a given vacuum tube, but only the effec
‘ Because of high negative bias on grid 26 of tube
tive characteristics of the circuit entity.
factor of an amplifying stage, or modify it in a
desirable manner. It is to‘ be understood that I
do not pretend to modify the inherent character
‘
24, anode 23' draws little current through resistor
To reduce cross-modulation and modulation~
22 and minimum bias appears on the grid 20 of
distortion in radio receivers and to obtainother
" tube I8. ,;With low grid bias, the resistance of ‘7 known effects, manufacturers are supplying so-'
tube I8 is’low, a maximum voltage appears on
called super-control or remote cut-off ampli?er.
;the oscillator as measured from cathode 21 of
tubesvof a modi?ed grid structure designed to
1» Vacuum tube 24 to cathode 2| of vacuum tube I8,
1 and a maximum current ?ows through the ?eld ,
I coil of current responsive relay I5.
In a condition of oiT-resonance between the
Eoscillator and the link. coupled external circuit
‘ as occasioned by‘the capacitive changes which I
encounter, the anode current of tube _| drops to
3a lower than maximum value. Thus, the bias
‘ voltage on grid26 of tube 24 decreases as deter
? mined by the IR drop across resistor 25. Because
Zof the lower negative bias on grid 26 of tube 24,
‘anode. 23 begins to draw‘ more current through
resistor 22 andv more negative bias appears on’
‘grid 20 of tube I8. With increasing negative grid
handle both large and small grid input signals
with a minimum of distortion over a wide range.
As noted on page 15 of the R. C. A. Receiving
. Tube Manual, Technical series, PUG-14, the grid
of the super-control ampli?er is wound with‘
coarse spacing in the center and close spacing
, at each end.
When weak signals and lowgrid '
bias are applied to the tube, the effect 'of the non
uniform turn spacing of the grid on ,tube char
acteristics in essentially the same as for uniform
spacing. As the. grid bias is made more negative I
r to handle larger input signals, the electron‘ ?ow 1
from the sections of ‘the cathode enclosed bythe
"ends of the grid is out on‘. The tube character
2,406,565:
v5
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istics ' are‘ then"? dependent {on the: electron ?ow
consisting-eta second electron tubeiwith at least
through the coarsetsection' of the grid. ‘As noted
furthenwh'ile the, curves manifest by'the super;
control grid and the uniformly 'spac‘edgrid are
similar at smallv grid bias and high plate current
ratings, the ‘plate current of; the super-control
ampli?er drops more-slowly with large valueslof
an anode, r‘cath'ode~ and ‘controlgrid electrode,
bias voltage.
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I have found. that-'I am able to secure this
and‘means' for'connecting the anode of the sec‘-' 7
, on'd ‘named tube 'toethe. grid of’ the first named
tube ‘and the grid ‘andlcathode of the second
named tube‘ across a resistance placedin the’
series circuit; whereby the maximum to minimum
current‘ ratio in‘ the series circuit is increased.’
3. A circuit arrangement for amplifying the
aforementioned super-control, remote cut-off and 10 currentchange in ‘a seriescircuit, comprising in
series'a sourceof at least substantially constant
variable mu function using a tube with a uni
formly spaced grid structure if I employ the
voltage, a variable resistance control device, a
principles of my invention and insert a variable
resistance element serially in the master circuit
and control its resistance from current ?ow in
relay device constituting a load, and the anode
and cathode of an electron tube, further pro
vided with at least one control grid electrode;
resistance element herein disclosed I am able to
accomplish the same effect when I control the
resistance means connecting the grid and cath
ode of the last named electron tube, means to
supply a potential difference between the last
named electrodes, said means consisting of a, second electron tube with at least an anode, cathode
and control grid electrode, and means for con
necting the anode of the second named tube to
the grid of the ?rst named tube and the grid and
cathode of the second named tube across a re
resistance of the resistive device at modulation
sistance placed in the series circuit, whereby the
the master circuit.
.y
'
To amplitude modulate a radio frequency am.
pli?er, the ampli?er voltage is increased and re
duced by the conventional modulators at modu
lation frequencies. I have found that by insert- "
ing serially, in place of the secondary of a mod
ulation transformer for example, the variable
frequencies.
Further, by the incorporation of
a current responsive control means such as I have
maximum to minimum current ratio in the series
circuit is increased.
.
illustrated in Figure 1, as tube 24 and its associ
4. A circuit arrangement for amplifying the
ated components, and by designing this means to
current change in a series circuit, comprising in
keep the proper average plate voltage on the 30 series a source of at least substantially constant
radio frequency ampli?er, I can increase the
voltage, an electron tube oscillator constituting
sensitivity of this modulation means to the point
with its output circuit a variable resistance con
Where it is practical.
trol device, a current responsive device constitut
While I have described my invention in only
ing a load, and the anode and cathode of an elec
several of its preferred embodiments I am aware 35 tron tube, further provided with at least one con
that various alterations and modi?cations of
trol grid electrode; resistance means connecting
the present invention may become apparent and
the grid and cathode. of the last named electron immediately suggest themselves to those versed
tube, means to supply a potential difference be
in the art to which. this invention is directed.
tween the last named electrodes. said means con-,
Thus, any and all such alterations and modi?ca 40 sisting of a second electron tube with at least
tions are to be considered within the purview
an anode, cathode and control grid electrode and
of the present invention except as limited by the
means for connecting the anode of the second
hereinafter appended claims.
\'
named tube to the grid of the ?rst named tube
What I claim is:
and the grid and cathode of the second named _
l. A circuit arrangement for amplifying the 45
tube across said load.
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current change in a series circuit, comprising in
5. A circuit arrangement for amplifying the
series a source of at least substantially constant
current changein a series circuit, comprising in
voltage, a variable resistance control device, a
series a source of at least substantially constant
current responsive device constituting a load, and
voltage, an electron tube oscillator constituting
the anode and cathode of an electron tube, fur 50 with its output circuit a variable resistance con
ther provided with at least one control grid elec
trol device, a relay device constituting a load,
trode; resistance means connecting the grid and
and the anode and cathode of .an electron tube,
cathode of the last named electron tube, means
further provided with'at least one control grid ,
to supply a potential difference between the last
.eelectrode; resistance means connecting the grid
named electrodes, said means consisting of a 55 and cathode of the last named electron tube,
second electron tube with at least an anode,
means to supply a potential differencebetween
cathode and control grid electrode, and means
the last named electrodes, said means consisting
for connecting the anode of the second named
of a second electron tube with at least an anode,
tube to the grid of the ?rst named tube and the
cathode and control grid electrode and means
grid and cathode of the second named tube across
for connecting the anode .of the second named
a resistance placed in the series circuit, whereby
tube to the grid of the ?rst named tube and the,
the maximum to minimum current ratio in the
grid and cathode of the second named tube
series circuit .is increased.
across
said relay device.
,
2. A circuit arrangement for amplifying the
6. A circuit arrangement for amplifying the
current change in a series circuit, comprising in
current change in a series circuit, comprising in
series a source of at least substantially constant
series a source'of at least substantially constant
voltage, an electron tube oscillator constituting
voltage, a current responsive load device, a nega
with its output circuit a variable resistance con
tive impedance, and a variable impedance con
trol device, a current responsive device vconsti
tuting a load, and the anode and cathode of an 70 trol device; said last named impedance including
the anode-cathode circuit of an electron tube os
electron tube, further provided with at least one
cillator provided with a load-circuit adaptable to
control grid electrode; resistance means connect
resonance or anti-resonance with said oscillator.
ing the grid and cathode of the last named elec
'7. A circuit arrangement for amplifying the
tron tube, means to supply a potential difference
between the last named electrodes, said means 75 current change in a series circuit, comprising in
2,406,565
7
8
series a sourceiof at least substantially, constant
series a source of at least substantially constant
voltage, a current responsive load device, a nega
tive impedance, and. a variable impedance con
voltage, a relay device, 'a negative impedance,
and. a variable impedance control device; said
trol device; said last namedimpedanceincluding
the anode-‘cathode circuit of an'electron' tube os
cillator, a remote load-circuit adaptable to reso
ode circuit of an electron tube oscillator provided
with a load-scircuit adaptable to resonancev or
name or anti-resonance with said oscillator. and
means to linkacouple said load-circuit to said os
cillator.‘
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last named impedance including the anodeicath
‘anti-‘resonance with said oscillator, whereby the
anode circuit impedance of said oscillator is con";
trolled by the tuning of said load-circuit.
' 8. A circuit arrangement for amplifying the 10
current change in a series circuit, comprising in
ROBERT G. ROWE.
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