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Патент USA US2129037

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Sept. 6, 1938.
K. S'CHLESINGER
2,129,037
DETECTOR
Original Filed Nov. 7, 1934
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Patented Sept. 6, 1938
2,129,037
UNITED STATES PATENT QFFECE
2,129,037
DETECTOR .
>Kurt Schlesinger, Berlin, Germany, assignor to
Radioaktiengesellschaft D. S. Loewe, Berlin
Steglitz, Germany
Original application November 7, 1934, Serial No.
751,927. Divided and this application June 5,
1936, Serial No. 83,704. In Germany Novem
ber 10, 1933
3 Claims. (Cl. 250—27)
In the recti?cation of carrier waves preferably
modulated with a frequency band of large width,
good insulating coating, on the surface of which,
however, there is provided a conductive layer 24,
e. g., as occurring in television, there are» em~
which is common to both grids and may be con
nected with a terminal 22. Valves of this char
acter have for television purposes, in accordance
ployed with advantage grid detector arrange
5 ments, preferably of the push-pull type, as in
these recti?ers the carrier wave is removed from
the output circuit by compensation, a disturbing
grain in the image thus being avoided. In this
connection it is necessary, generally speaking,
10 assuming it is desired to avoid an expensive re
versing tube, to employ transformers, as already
shown by the applicant in his earlier application
No. 747,011 and Patent 2,068,769. With trans
formers of this nature, however, there is en
15 countered the characteristic difliculty that, gen
erally speaking, the secondary potential is in no
way symmetrically positive and negative against
earth, but always reveals a one-sidedly directed
additional potential.
20
The stated methods are of signi?cance only in
connection with- freely oscillating coils, the
centres of which cannot be earthed in direct
fashion.
This connection alrises consequently
upon use of the push-pull detector without grid
25 condensers as in the patent application No.
747,011.
The present invention is an improvement of
grid-current detector arrangements preferably
of those operated in push-pull connection and is
30 a division of Patent 2,072,315. By the arrange
ment according to the present invention it is
possible by special construction of therecti?er
valve to have in fact a sufficient blocking of the
modulation potential against short-circuiting by
35 the high frequency input coil of the detector valve
and at the same time good e?icie‘ncy.
The
present invention is relative to a particlular em
bodiment of a grid current detector arrangement,
more particularly for television purposes, where
40 in a detector valve is employed having control
electrodes comprising at least one grid, which is
insulated completely or incompletely from the
inner electronic discharge space and is furnished
with a conductive layer arranged on the insulat
45 ing coating thereof.
In a preferred form of the
present invention a double grid detector‘ valve is
employed in push-pull fashion in connection with
transformer input coupling.
In a preferred form of the present invention
50 set forth in the accompanying drawing there is
‘employed as detector a valve l9 having an insu
lated grid, or preferably two insulated grids 20,
2|, which are similar and have the same ampli?
cation factor and arranged to co-operate with the
65 common cathode 23, and are furnished with a
with the invention, the following advantages.
A potential produced in the push-pull. trans
former coil 4 may be applied directly and un
weakened to the grids 20, 2| without grid con
densers, which on account of their requisite small 10
size would mean a considerable loss in sensitive
ness. Since these grids are insulated against the
interior of the Valve, the middle of the trans
former 4 may be connected directly with‘ earth.
An incoming particular positive half-wave causes 16
the outer coating 24 common to both grids to be
charged negatively. This charge is leaked away
by a resistance 25, which may either be provided
outside of the valve, or alternatively the leak may
be provided inside the valve by making the insu 20
lating layer slightly conductive. As will be ap
parent, it is possible, particularly in. the latter
case, to reduce considerably the capacity of the
arrangement, and in consequence to employ a
comparatively larger grid leak resistance 25 than 25
in the circuits shown in Patent 2,068,768, so that
the sensitiveness of the arrangement may be fur
ther increased as compared with the previous ar
rangement with the same lack of inertia. Owing
to the possibility of earthing the transformer coil 30
4 in direct fashion, the danger of lack of sym
metry is practically obviated, so that proper com
pensation of the carrier wave is possible.
I claim:
1. A push-pull grid-current detector arrange
ment, more particularly for television purposes
comprising a detector valve having two separate
grids connected in push-pull, anda secondary of
an input transformer, said two grids being ar-‘
ranged with the same ampli?cation factor op
posite a common cathode which is directly earthed
and being insulated from the inner electronic dis
charge space by an insulating coating and fur
nished with a conductive coating arranged on the
insulating coating, and common to both grids, 45
the ends of said secondary being earthed in its
midpoint and connected directly to the grids, said
conductive coating being connected to the oath
ode of said valve.
2. A push-pull grid-current detector arrange 50
ment, more particularly for television purposes
comprising a detector valve having two separate
grids connected in push-pull, and a secondary of
an input transformer, said two grids being ar
ranged with the same ampli?cation factor oppo 55
2
2,129,037
site a common cathode which is directly earthed
and being insulated from the inner electronic dis
charge space by an insulating coating and fur
nished with a conductive coating arranged on the
insulating coating thereof, and common to both
grids, the endsofsaidsecondaryearthedinits mid
point connected directly to the grids, said conduc
tive coating being connected to the cathode via a
special leakage resistance, said insulating coating
10 consisting of a complete insulating material.
3. A push-pull grid-current detector arrange
ment, more particularly for television purposes
comprising a detector valve having two separate
grids connected in push-pull, and a secondary of
an input transformer, said two grids being ar
ranged With the same ampli?cation factor op
posite a common cathode which is directly
earthed and being insulated from the inner elec
tronic discharge space by an insulating coating
and furnished with a conductive coating arranged
on the insulating coating thereof, and common to
both grids, the ends of said secondary earthed in
its midpoint connected directly to the grids, said
conductive coating being directly connected to
the cathode of said valve, said insulating coating
consisting of a semi-conductive material.
KURT SCHLESINGER.
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