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Патент USA US2134590

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@et 25, 1938A
Original Filed Dec. 6, 1935
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Patented Oct. 25, 1938
VBertram Trevor and Ralph Waldo George, River
head, N. Y.,.a`ssignors to Radio Corporation of
America, acorporation of Delaware’
Original application December 6, 1935, vSerial No.
53,136. Divided andthis application Septem
ber 16, 1936, Serial' No. 100,974
L:Í claims. (ci. 25o-_20)
This application is a division of our copend
ing application Serial No. 53,136, ñledDecember
Ultra short wave lengthV receivers, such as de
scribed in our parent application," employ suc
cessive stages of heterodyning» >Asthe local os
cillators vary in frequency with changes in tem
Which‘is grounded as shown.‘ The far end of
the second rod 24 is tuned by means of the vari
able tuning condenserv 28V. The rod. 2i and con
denser 28 form a second non-radiating highly V
selective circuit and adjusted to have a resonant
curvevvvhich overlaps the resonant curve of Vthe
rod lli-condenser 2l! combination. In this Way,
perature, the differencev or slum* frequency cur
the-frequency'pass band-width of the two pre
rents change in frequency,` normally requiring i selector circuits i4, 2li, I2 and 24, 26, 28 is fur
retuning or the use of beat frequency amplifiers ther widened.
having wide pass bands. . Returning, obviously,
r The received filtered energy is then fed to the
is objectionable fromthe operating pointof `ViewV grid of -a` first detector tube 34. This first detec
and use of wide pass band amplifiers' is undesira
tor is also vsupplied with heterodyning energy
ble since they increase the overall noise level- or from a ñrst local oscillator comprising a discharge
backgroundl in theffinal receiver output.
t '
To overcome these disadvantages is theïmain
object of our invention.A
This object is effected by,V utilizing the follow
ing relations of frequency-"of operation and tem
20 perature coeñicient of frequency:
1. , When the ñrst beating oscillator is operated
on the high frequency side of the signal, both the
ñrst and second beating oscillators are made to
have the same sign of temperature coefficient, re
25 gardless of Which side of the first intermediate
i frequency the second beating oscillator is on.
2. When the first beating oscillator is onV the
low frequency side of the signal, the temperature
coefficient of the first and second beating oscil
lators are made opposite in sign in order to have
frequency compensation which will take place
regardless of Which side of the first intermediate
frequency the second beating oscillator is on.
Our present invention is more fully described
in connection with the accompanying drawing
which is a Wiring diagram of the first and sec
ond heterodyníng stages of our ccpending appli
cation hereinabove referred to.
Turning to thedrawing, energy collected upon
40 the receiving antenna 2 is fed through a cou
pling transformer having a primary Il and a sec
_ „
4--As described in more detail in our copending
parent-application Ser; No. 53,136, the oscillatory
- energy is injected into a thermo-responsive fre
quency > compensating Vvmeans 90 and thence
through the cathode leads of the detector tube 34
for producing therein a beating of the oscillator
frequency with the incoming frequency collected
by the antenna 2. The oscillator, itself, is tuned
by means of a coil 58 and tuning condenser 60 in
the plate circuit. A by-pass condenser B2 sepa
rates the plate potential lead @It from the ground
ed device âû. The beat frequency energy is
resonated in the plate circuit of the first detector
3a by means of a tuning coil 42 and tuning con
denser 44, both of which are adjusted to the beat 30
frequency. The beat frequency energy is fed
through a by-passing condenser ¿56 to a first
beat frequency amplifier and then fed to a second
detector |34. The latter is supplied with oscil
lations from a second local oscillation generatorV 35
having a discharge tube Mil and the beat fre
quency output from the second detector is fed
into a second intermediate frequency amplifier
Whose output is utilized as desired. The‘first
local oscillator and the second local oscillator
are made to -have temperature coefficients of
Concentrically mounted rWithin the _ frequency such that despite variations in am
cylinder i2 there is a rod or metal pipe i4 bient temperature, the final beat frequency ener
grounded at its left-hand end I6 -and connected gy fed to the third detector and second inter
45 to ground at its right-hand end through a damp
mediate frequency amplifier remains substantial 45
ing resistor I8 and variable tuning condenser 20. ly constant.
The metal rod I4 within the metal cylinder I2
The structural details of the thermo-respon
forms a sharply selective input circuit, standing sive frequency compensating means 90 may be
t `_ondary 6.
current waves being set up thereon by virtue of
50 the input from the secondary 6 and by virtue
of the tuning of condenser 20.
The received energy resonated in the rod M
and condenser 20 is fed through a 10W impedance
connection 22 to a second rod, tube or metallic
55 pipe 24 mounted Within a second cylinder 26
in accordance with the disclosure of our afore
said parent application, or they may be in ac
cordance with other devices Well known in the
art having as their function to stabilize the fre
quency of an oscillatory circuit and to render
said frequency relatively independent of temper
ature changes.
Preferably, the second local oscillator |40 is
tuned below the frequency of the intermediate
frequency oscillations produced by the first de
tector 34, and the first local oscillator 48 is ad
justed to produce oscillations at a frequency
above the incoming wave frequency. Then, if
the two local oscillators have the same or ap
proximately the same, frequency variation with
ambient temperature changes, the resultant
10 beat-frequency in the circuit |44 will remain ef
fectively constant despite changes in the sur
rounding temperature.
The same result may be obtained by having
the desired changes in frequency with tempera
ture are produced.
Having thus described our invention, what we
claim is:
l. In a heterodyne receiver of high frequency
waves a ñrst local oscillator, means for hetero
a second local
oscillator, means for
oscillator 48 adjusted to produce oscillations of
a frequency lower than the incoming wave
and thermo-responsive means for so controlling
frequency while at the same time producing the
desired beat frequencies.
To summarize, if the first beating or local oscil
lator is operated on the high frequency side of
the signal, both beating oscillators for frequency
compensation should be made to have the same
sign of temperature coefficient regardless of which
25 side of the first intermediate frequency the sec
ond beating local or heterodyning oscillator is on.
On the other hand, if the first beating oscillator
is on the low frequency side of the signal, fre
quency compensation will occur provided the tern
30 perature coefficient of the second beating oscil
lator is made opposite in sign to that of the first.
This latter effect will take place regardless of
which side of the first intermediate frequency the
second beating oscillator is on.
The desired frequency temperature coeflicient
for the ñrst and second local oscillators may be
obtained by proper choice of the materials used in
their construction, particularly the materials
used in the frequency controlling circuits. If
dyning said waves with output energy from said
oscillator thereby to produce a first beat fre
heterodyning Waves of said first beat frequency
with» output energy from said second local oscil
lator, thereby to produce a second beat frequency,
the second local oscillator` |40 tuned above the
first intermediate-frequency and the first local
desired, the frequency controlling circuits of each
oscillator may be provided with a movable tuning
condenser plate which is moved in such a way by
a temperature responsive bi-metallic strip that
the» frequency relationship between the two os
cillators that said second beat frequency remains
substantially constant, despite variations in the
ambient temperature.
2. Apparatus in. accordance with claim 1 and
having the first local oscillator adjusted to a
higher frequency than that of the waves with
which its output energy is heterodyned, said
thermo-responsive means being operable to Vary
the frequency adjustments of the two said oscil
' lators in the same direction upon the occurrence
of a given change in the ambient temperature.
3. Apparatus in accordance with claim 1 and
having the first local oscillator adjusted to a
lower frequency than that of the waves with
which its output energy is heterodyned, said
thermo-responsive means being operable to si
multaneously vary the frequency adjustments of 35
_the two said oscillators opposingly.
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