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Патент USA US2297389

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Sept. 29, 1942.
K. BRANDHOLT
2,297,339
DRIVE FOR ELECTRIC TUNING MEANS
-Filed July 29, 1939
fm/enfar:
Kurz‘ Brcmdholt
by
Patented Sept. 29, 1942
~
*
2,297,389‘
UNITED STATES PATENT OFFICE
2,297,389
DRIVE FOR ELECTRIC TUNING MEANS
Kurt Brandholt, Berlin, Germany; vested in the
Alien Property Custodian
Application July 29, 1939, Serial No. 287,193
In Germany August 3, 1938
5 Claims.
Certain difficulties are encountered in the tun
ing methods employed in very large radio sets,
especially in those using coil tuning. Such sets,
especially receivers, are equipped with a great
number of tuning means with the consequence
that in order to tune the apparatus many coils
must be adjusted. This large number includes
many coils which to be tuned must be turned.
This operation involves a succession of harmful
(Cl. 250-11)
translated by a Geneva movement 12 through a
cam Hi to goniometer control contacts [3. Driv
ing the coil-drum in conjunction with the range
control of the goniometer occurs only when the
elliptical shaped gear 5 is turned through 360
degrees. As the illustration shows the gear train
begins with a large gear ratio. In this position
it is able to exert a large torque which is a factor
important in turning the drum out of a ratchet
mechanical jolts. These jolts in particular affect 10 setting. The gears change their transmission
ratio from small to large, and the drum after un
the tubes in which mechanical vibrations are
ratcheting enters into the next sphere of opera
necessarily set up in the electrodes. Such vibra
tion. The momentum of the drum is also used at
tions have a destructive effect on tube life as
the same time for operating the goniometer con
well as altering its electrical properties, for in
response to such a change the tube fades out for 15 trol contact, and in a reverse operation this acts
as a brake upon the drum. As the drum nears
a while after adjustment so that the set will not
its new position the gear ratio between 5 and 4
operate normally again until a certain period of
time has elapsed.
This disadvantage is overcome by the use of
the present invention. It will be assumed that
the coil drum which serves for tuning adjust
ments is set in motion by a tuning operation.
This operation is to be effected by a gear train,
which has a variable transmission ratio, which
again becomes large tending to slow down the
coil drum so that a shock is not transmitted to
the radio set.
A further feature of the invention is that the
contacts ‘I are removed from the drum until a
setting is made. This is accomplished with the
ratchet arm 9, which lifts the contact supports 8
so that the contacts are removed by the strength
may, for example, be accomplished by elliptical
of their own springs. This arrangement thus
or other odd-shaped gears; and it is so designed
avoids contact wear due to sliding friction.
that by a change of the transmission ratio from
What is claimed is:
step-down to step-up to step-down position again
1. A radio apparatus employing coils for tun
the drum reaches a position of rest, the momen
tum acquired by the drum while the high gear ° ing, comprising carrier means carrying a plu
rality of coils, adjusting means for moving said
ratio is effective being gradually reduced as the
carrier means into different positions to render a
effective gear ratio becomes lower.
desired one of said coils effective, said adjusting
My invention will be more fully understood
means comprising a drive mechanism for rotat
when considered in conjunction with the follow
ing description and drawing, of which the ?gure 35 ing said carrier means, and eccentrically mounted
rotary control means operative to render said
shows a preferred embodiment of the invention.
rotary movement slow upon initiation of rota
In this illustration a coil-drum I carrying a plu
tion, more rapid during an intermediate portion
rality of coils 20A—20D is shown to be geared
of its rotation and slow again upon its approach
through a gear train 2, 3, 4, 5, and a toothed disc
to said adjusted position.
6 operates to apply contacts ‘I to the di?erent
2. In radio apparatus as in claim 1, wherein
coils for different positions of the drum, in the
said last named means comprises an elliptical
desired circuit such as the tuning condenser.
gear train to effect a gear ratio variation from
These contacts ‘I can be controlled by an insu
step-up to step-down and back again to step-up
lated spring contact support 8. Tension from
45 by one control operation.
the spring l0 forces a ratchet arm 9 to follow
3. In radio apparatus employing coils for
the recesses of the disc 6.
tuning and contacts for connecting such coils to
At the same time as this operation is being
external circuits, mechanical means for adjust
effected, a change is likewise being made from
ing said tuning coils with a variable transmission
one goniometer range to another by switch 13
ratio varying from low ratio, to higher ratio, to
controlling the circuit for goniometers G1 and
lower ratio for each adjustment, insulated spring
G2. By this switching arrangement the fre
contact supports controlled by said mechanical
quency range of the goniometers may be brought
adjusting means and means for raising said con
into suitable relation with the circuit tuned by
tacts during said adjustment.
the coils 2UA--20D. This other change is initi
4. In ratio apparatus according to claim 3,
ated in a gear 2 meshing another gear I I, is then 55
2
_
2,297,389
wherein said last named means comprises ratchet
means operatively associated With the said coils
to effect the said control.
5. In radio apparatus employing coils for tun
ing, and goniometer circuits, mechanical means
for adjusting said tuning coils with a variable
transmission ratio which varies from low, to
higher, to low during an adjustment, means such
as a Geneva movement operatively associated
with the said mechanical means for alternately
rendering said goniometer circuits e?ective and
ineffective, and means for utilizing the momen
tum of the said coils generated during adjust
ment to facilitate operation of said Geneva
movement.
KURT BRANDHOLT.
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