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Патент USA US2124805

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My 26, 1938.
E. A. LAPORT
2,124,805
MIXING AMPLIFIER
Filed June 19, 1956
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BY 8‘ I
i. ATTORNEY.
Patented July 26, 1938
2,124,805
UNITED STATES
PATENT OFFICE
2,124,805
7
MIXING AMPLIFIER
Edmund A. Laport, Glen Ridge, N. J., assignor to
Wired Radio, Inc., New York, N. Y., a corpora
tion of Delaware
Application June 19, 1936, Serial No. 86,129
2 Claims. (01. 179—171)
This invention pertains in general to radio transmitted as carrier eliminated modulation
circuits and specifically relates to a circuit for side band energy in discrete frequency ranges.
combining signalling energy of different fre
After passing through a ?lter and amplifying cir
quencies.
cuits, this energy is directed to the input circuit
The principal object of the invention consists of electron tube 4 having the control electrode
in providing an electron tube circuit for com
thereof adjustably connected with the poten
bining different signalling energy frequencies tiometer 3, as shown. The tube 4 is of the triode
supplied from different sources without inter
type, although other forms of tubes may be em
action between the sources for producing an'out
ployed, when desired. The anode circuit of the
put current which is the algebraic addition of tube 4 includes a connection through a radio fre
the plural input currents.
quency choke 5 and thence to the positive “B”
A further object comprises providing a sys
tem for combining. modulated high frequency
energy from which the carrier frequency has
' been eliminated, with a replacement carrier fre
quency to reproduce desired signals.
A further object consists in producing a mixing
ampli?er circuit for amplifying and combining
one frequency with another in an electron tube
to produce a combined ampli?ed output.
These and other objects will be apparent from
the following, reference being had to the accom
panying drawing which is a diagrammatic illus
tration of a preferred embodiment of the inven
25 tion.
‘
The invention contemplates the provision of a
system such as a wired radio receiving organiza
tion which receives modulated high frequency
energy comprising modulation side band energy
30 with the carrier frequency substantially elimi
nated. A separate and distinct carrier frequency
is supplied at the point of reception to be com
bined with the modulation side band energy for
replacement purposes to reproduce the original
35 signal. In accordance with the invention, the
modulation side band energy and the indepen
dent replacement carrier frequency are combined
in a mixing ampli?er circuit to produce an alge
braic addition of the two frequencies in a linear
40 ampli?cation process without inter-action be
tween the two sources of frequencies. A multi
electrode electron tube is provided with the elec
trodes thereof respectively connected in a circuit
arrangement for producing the desired mixing
45 and amplifying effect.
Referring to the drawing in detail, a source
of modulated high frequency energy is connected
to the primary winding of a transformer 2 having
a secondary winding connection to a poten
50 tiometer 3. The source I represents means for
supplying modulation side band energy com
prising one side band with the carrier frequency
and other side band substantially eliminated, and
may correspond to a power transmission network
55 over which several programs are simultaneously
supply at terminal 6.
’
The carrier frequency source 8 is ‘connected
with the primary of the transformer 9. The M
source 8 comprises the means for supplying the 15
independent replacement carrier frequency cor
responding to the frequency eliminated from the
energy available at the source I. In accordance
with the invention, means are provided for ad
justing the phase relationship between the volt
ages of the source I and source 8.
‘This carrier
frequency may be impressed upon the transmis
sion medium common to the source I or may be
generated locally. The energy from the source
8 is directed through transformer 9 to a poten 25
tiometer I0 having an adjustable connection to
the control electrode I I of a multi-electrode elec
tron tube I2. The tube I-2 also includes a cath
ode, a screen electrode I3, a suppressor electrode
I4, and an anode I5. The anode I5 is connected 30
through the primary winding of a transformer
I6 in an output circuit ‘connection including the
positive “B” supply terminal 6. The transformer
I6 includes a secondary output connection with a
load circuit I‘I representing the utilization means,
such as a program reproducing system.
In accordance with the invention, the suppres
sor electrode I4 is connected with the cathode
of the tube I2 and is maintained at the same po
tential as the cathode. The screen electrode I 3 is
connected in the anode circuit of the tube 4, as
shown. Other circuit components not described
are of an obvious nature and known to those
skilled in the art.
In the operation of the system, the tubes 4
and I2 are provided with biasing potentials for
optimum linear operating conditions as ampli
?ers. The potentiometers 3 and Ill are adjusted
to provide an adjustable ratio or voltages from
the sources I and 8. The modulation side band
energy from the source I is then amplified by
the tube 4 and directed to the screen electrode
of the tube I2. Concomitantly, the carrier fre
quency from the source 8 is directed to the con
trol electrode II of the tube I2. The two fre 55
2,124,805
2
quencies are then combined in a linear ampli
?cation to produce algebraic addition frequen
cies transmitted to the load circuit l'l. It is a
feature of the invention that the circuit includ
ing the screen electrode I3 is substantially the
correct impedance to serve as a load for the cas
cade stage of ampli?cation represented by the
tube 4.
However, when necessary and desired,
a transformer may be interposed in this circuit
to produce matched impedances,
In operating the system, it may be desired
to change the relation of the side band energy
with respect to the replacement carrier frequen
cy. To accomplish this, it is only necessary to
15 adjust the potentiometers 3 and I0 to bring about
a desired relation of energy levels. In ‘accord
ance with the invention, the two inputs are com
pletely isolated from each other and no reaction
between the inputs is possible through the mix
ing system. Although a preferred form of the
mixing ampli?er has been disclosed, it will be
recognized that various changes and modi?ca
tions as well as equivalent forms can be pro
2.?
duced without departing from the intended scope
of the invention. Accordingly, no limitation of
the invention is intended other than as imposed
by the scope of the appended claims.
What I claim as new and desire to secure by
Letters Patent ‘of the United States is:
1. A mixing ampli?er comprising, a source of
modulation side band energy with carrier fre
quency substantially eliminated, a source of car
rier frequency energy corresponding in frequen
cy to said eliminated carrier, a load circuit, a
35 common combining circuit interconnecting said
sources and said load circuit and including a
multi-grid electron tube, the parameters of which
are so chosen and adjusted with respect to the
control grids thereof that said tube functions as
a linear ampli?er only, said circuit being inter
posed between one of said sources and said load
and including a connection from one of the grids
thereof with said one source, and means ‘con
necting the other of said sources with another
of the grids of said tube for supplying energy
thereto under control of the source connected
with said second mentioned grid whereby the
foregoing arrangement as a whole operates for
producing currents in said load circuit corre
sponding respectively to said carrier frequency
and said modulation side band to provide said
modulation side band energy with a replaced car
rier frequency.
2. A-mixing ampli?er comprising, a source of
modulation side band energy with carrier fre
quency substantially eliminated, a source of car
rier frequency, energy corresponding in frequency
to said eliminated carrier, a load circuit, a com
mon combining circuit interconnecting said
“'
sources and said load,v circuit and including a
multi-grid electron tube, the parameters of which
are so chosen and adjusted with respect to the
control grids thereof that said tube functions as
a linear ampli?er only, said combining circuit ‘
including a connection from one of the grids
thereof with one of said sources, and another
electron tube connected with the other of said
sources, said second electron tube being coupled
with another of the grids of said ?rst mentioned '
tube for supplying ampli?ed energy thereto un
der control of the source connected with said sec
ond tube whereby the foregoing arrangement as
a Whole operates for producing ampli?ed cur
rents in said load circuit corresponding respec- -
tively to said carrier frequency and said modula
tion side band to provide said modulation side
band energy with a replaced carrier frequency.
EDMUND A. LAPORT.
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