ELECTRIC COMMUNICATIONS

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81-01043R002700130003-1
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 132
• Document Creation Date: December 27, 2016
• Document Release Date: November 13, 2013
• Sequence Number: 3
• Publication Date: October 9, 1958
• Content Type: REPORT

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STAT
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.
1,E:on
ELECTRIC COMNIUN I CAT! ONS
(ELEKTROSVYAZ) ?
BY VARIOUS AUTHORS
NO. 5, MAY 1957
PAGES 3-80
STAT
STAT
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1 4-I
6 1
-1 i
TABLE OF CONTENTS
qt 87 Page
10:10n Radio Day i 1
!
-1 1
12-4he Most Efficient Use of Coding Systems, by V.I.Siforov a
1
,--1 1
1,----Theoretically Optimum Communication System, by A.A.Kharkevich 20
--I ;
15--UHF Oscillator Modulator, by Te.Morchagina 27
I
18--:Designing an Oscillator Operating at Overvoltage and Detuned ?
20:i
I
Load, by Te.Mhmeltnitskiy 40 ,
99---:Fse of Ferrites in Waveguide Engineering, by A.K.Stolyarov 52/
----) i
--Determination of Steady-State Error in Pulsed Systems with
24-1 70 /
Linear Synchronism, by L.N.Shchelovanov
_It I
26--Network Analysis of DC Telegraph Apparatus, by Kh.I.Cherne 79//
23--bscillograph Technique for Measuring the "Hunt" of the 'Scanning and
30: 1 Transmitting Part of Facsimile Apparatus, by
M.A.Kudryashov, and P.N.Ivanov ! 93
1
, ?1
s2 -Systems Designed for Reduction of the Telephone Signal
34_1 Bandwidth, by G.I.Tsemell 100'
I
--Resolutions of the Eighth Plenary Session of the CCIR on
36_4
Problems of Television, by MJ.Krivosheyev
111
I
?
3
40
42__
44
46-1
48_
50_-
52-
54
?
STAT
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ON RADIO Da
Next Radio Day, our country may mark a number of substantial achievements in the
_
field of progress in domestic radio engineering and its most diverse applications.
The further broadening of the radio-frequency ranges which can be made accessi-
ble and useful and the simultaneous striving for a more efficient utilization of the.
ranges already accessible remain the main trends of modern radio development. This
. ? is due to tbe fact that the demand for radio channels of various purposes is inereas=
I. ing at a sharply rising rate. A very short time ago, it seemed that the capacity ofi
radio waves in the centimeter range was inexhaustible. However, in practice, it was!
,..__ found that various services 'must already compete for their place in the air and in
_ the centimeter range of wavelengths. 1
2:_ Presently, radar, radio-relay communication links, sound. and television broad-
__
.i casting on ultrashort waves are predominant among the domains of radio engineering.
_ !
-, A short survey cannot throw sufficient light upon all the achievements and all the
:most important trends of these domains; therefore let us consider the main ones only:.
w :Ii_., Television is developing quite intensively in our country. To date, the number
1
:,.__of television broadcasting centers has groun to 24; moreover, a considerable number]
--1 1 ;
ii:-. of them are in the building stage. At present, throughout the RSFSa alone, 28 tele
40_ vision broadcasting centers and eight relay television stations are being built. i
1
Little more than one year has elapsed since the Twentieth Congress of the Communist!
i
/.._ Party of the Soviet Union (CPSU) decided to bring the number of television broad- I
-Th
4(. casting centers in the Soviet Union to not less than 75 by the end of the sixth-
.IFive-Year Plan. But it is already obvious now that, as a result of the population's
exceptional interest in television and of the local agencies' energetic efforts, the
? 1 Twentieth Congress 'assignment will be overfilled. The number of television sets is
!growing at a correspondingly rapid rate. At the end of 1956, a total of 1,350,000
? :television sets mere registered, whereas there were only 60,000 television sets in
SI-AT
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1951. Tho industry is turning out many new types of teliAsion-setswith-rectaiii:-?
lar picture tubes of large size.
The new neu types of television sets are continuously being improved with respect
to their parameters. Thus, by the Use of new tubes and better circuitsl-the video- -'
? channel sensitivity of the television receiver has been increased to 200 uv as cam- '
pared to the previous 500 and 100011v. A substantial improvement in the new tele-
I. .
vision sets was the introduction of automatic amplification control and of automatic
focusing; this simplifies the operation of the receiver and decreases the number of
tuning elements. New, even better types of television sets are being developed and
_put into use.
I ?
In 1956, a notable step forward was made as far as the development of a color
_ television system is concerned. After a long technical discussion, the field seven-
tial version was rejected; the dot sequenae system compatible with black-White tele-
_
vision was approved for final development. Laboratory installations of such a sys-
`r__
. tem were publicly demonstrated in Moscow and Leningrad. The task of the scientific
__collectives which are working in this interesting field is to make color television
available to the working masses at large, as soon as possible.
While noting the undoubted achievsements in the field of television, the fact
_- must be stressed at the same time that a large number of technical problems associ-
3E-2
- ated with the further development of television broadcasting are still being solved
- at quite a slow pace by the workers of the radio-engineering industry.
42_2t :- ?
First of All, this concerns making accessible and useful the range of 174 - 230-
_ mc in which seven additional television broadcasting channels are planned.
-
The designing of radio transmitters and television sets operating in this range
'must be completed and their production inadequate numbers organized as soon as p05-
!)0-1
-fsible, since new television broadcasting centers cannot be built to operate on the -
,;e:
? ;five existing channels.
r/
The situation is much worse as to carrying out the Instruction of the Twentieth
_ - ^?^?"^-rc
?-???1
STAT
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Congress of the Party concerning the development of -ultraihort-wave. broaddasting-id-1
the European part of the USSR. The plan for the building of ultrashort-wave broad-
casting stations was disrupted in 1956 due to the fault of the radio-engineering
in-
dus1ry. The development of new types of equipment with tetrades has been delayed
--
considerably. The situation as far as the creation of a receiving uitrashort.,wave
FM network is concerned is particularly bad. So far, a negligible number of radio
receivers which can operate in the ultrashort-wave range have been produced. The
ultrashort-wave broadcasting range is also absent inmost of the television sets pro-
duced. The solution of this design problem cannot be considered successful even in
_ television sets which are equipped with the above-indicated range.
Apparently, a number of workers of the industry still lack an understanding of
_ the role and of the prospects of ultrashort-wave broadcasting. Actually, however,
an analysis of the trends in development of modern broadcasting engineering quite
_ definitely dhows that, simultaneously with the broadest possible development of te1-!
evision in the
must gradually
32_1
_.ning for radio
course of the next 10 - 15 years, ultrasbort-wave FM broadcasting
become the basic means of sound broadcasting. Accordingly, all plan-
broadcasting development must be based on the prospects of erecting a'
_ network of radio stations combini ng television broadcasting centers and ultrashort-i
_ wave FM transmitters, at first for two, and later for 4 - 5, sound channels. There-I
_ fore, the recent practice of designing and constructing television broadcasting cen.
ters without simultaneous installation of ultrashort-wave FR transmitters for sound.1
4'7_1
_ broadcasting should be considered incorrect:
-. From the above considerations, it naturally follows that all new types of tele-
_ vision sets must definitely-be provided with the ultrashort-wave FR range. The
- fastest possible development of the most rational designs of band switches and of
.,:taining controls is the most urgent task of the designers.
Certain achievements in the field of radio-relay communications development in:
---!the past year may noted. Several radio-relay links are already
I
built and add!-
STAT
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. tional ones are being built at the present time On the be:Sid-of the systea introduced
? by the Scientific Research Institute (SRI) of the Ministry of Communications. Ryazan
. and Stall nogorsk are now receiving Moscow television programs by means of radio-relay
links. The Institute completed the development of the new, completely modern radio-
F..
relay communication system R-60, and one of the large-scale plants has begun organiz-
ing the production of this system which U play an important role in carrying out i
the instruction of the Twentieth Party Congress. The task of the designers and of I
1
the engineers is to ensure a proper development of the work undertaken to build a
number of radio-relay links based on the new system.
1 _
The collectives of the SRI of the Ministry of Communications have also done con='.
20_
siderable work in developing a more powerful radio-relay communication system de-
__
_ signed so that every band be multiplexed with 240 telephone channels or one televi- 1
, .
- sion channel. Laboratory models of such a system were tested successfully in exper-i
. iments and, once its production will have been organized, this system must become the
,,, ! ;
basic type of equipment for main radio-relay communication systems. The honor-bound
F41...i i
duty of the collectives of the plant and of the SRI is to complete the work under-.
taken in organizing the production of such an important system as soon as possible.
The vacuum-tube industry has an important role in the large-scale introduction
. .of radio-relay communications. A radio-relay system includes a number of new types
- of radio tubes. The qualitative indexes of some of then are technically not satis-
i. _ !
factory. The insufficient life of these tubes is particularly a subject of alarm;
the guarantee is 500 hours, whereas corresponding radio tubes of foreign firms oper-
a- te from 5000 - 10,000 hours. The rapid failure of the radio tubes maybe the basie
!
_ cause of communication failures and may increase the operating costs considerably.
The creation of a modern radio-relay links requires the creative efforts of
- 'many collectives. The multiplexing unit is a rather important part of the total sys7
. 'tem. The fact that the BMW methods of multiplexing of channels are used in radio-
_
_ relay links and in cable communication lines is characteristic of modern communica- ?
S TAT
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-tions technique. TE!, standard specifications for the -Ce_miinication-channels?iii?thel
2
1
_ same in both cases. Thus, the development of_radio_communications_is inseparable :
from the general development of electrical communications. The past year has brought
- a number of substantial achievements with respect te-the-inprovement-Of multipiexing
1
systems; this will help in a larger measure the creation of modern multichannel radio-
relay systems. Let us mention here the development of the new 12-channel system
32
_ V12-2 and the completion of the development of the 60-channel system K,60 for multi-i
_ plexing of cable lines as well as of radio-relay links. The creation of a simplified
60- -channel multiplexing system of small size, K111-30/60, suitable for short cable [
1E__1
_ lines as well as radio-relay linki of the type 13,60 is a great success. Finally,
- the equipment of the experimental section .of the coaxial cable with a 900-channel
??
multiplexing system is very important. On the basis of the experiments carried. out
- with this system, the final models of the multiplexing system for coaxial cables and
? for powerful radio-relay links will be built.
The entire above-described complicated pattern is a result of the creative co-
? 33_i
_-operation of the workers of the radio-engineering industry and of the Ministry of
32_J
Communications and is an important step toward elimination of the lag in the field
?
_ of modern electrical communications engineering. However, in order to capitalize on
?.these achievements, the production of the necessary number of the indicated models
3
- of modern communication engineering must be ensured. We insistently request the
--Minister of the radio engineering industry, V.D.KalnYkar, that he ensure the produc-,
- tion of allabove-mentioned types of systems and give special consideration to the
4
?
- question of the qualitative indexes and of the lives of radio tubes. We Also invite
- the workers of the vacuum-tube industry to come forward on the pages of our magazine
and to report on the reason for our lagging behind the world standards in this in-
- portant field. ,
. ,
We have already noted the close correlation of modern radio communications with
.the general electric communications system. Such a coordination becones more and
-
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_ .
.more necessary as far as broadcasting ii concerned. In order that the tranexilision
"
_ of programs to the many broadcasting stations and. to the radio rebroadcasting and re-..
_ _ _
4
? ceiving stations be of high quality, the network of intercity broadcasting channels I
must be broadened in every way, by means-of cablei.and radio-relay 1 ink For-thin
. purpose, a special unit is being built which combines three standard telephone chan-I
?
nels into a wide broadcasting channel. Such channels, in particular, must by all
1.17
means be made available when ultrashort-wave 111 broadcasting stations are built.
The resolutions of the Twentieth Con,,oreos of the CP specify also the building
of a network of main lines for exchanging television programs between the largest I -
_television centers. Radio-relay links are the basic technical means of solving this!
_ problem. In the course of the sixth Five-Year Plan, such long-distance links as Len1,-
ingrad - Tallin - Riga - Vilnyus - Minsk; Moscow - Kharkov - Dnepropetrovsk _siiarerf
opol; Moscow - Kazan - Sverdlovsk; and a number of others will be built. Many shorti
__distance radio-relay 1 inks will be built to increase the effective range of a numberI;
_ of television centers.
. 10_1
i . ..
Twenty years ago, Prof. P.V.ShrielPov had already proposed to extend the effec-
1
_tive range of television centers by means of aircraft relaying. Unfortunately, no 1
i
3 4 ____i 1
j 1 -
practical steps toward realizing this proposition have been taken to date. This
36_1
_ current year, the collectives of the Leningrad and of the Odessa electric communica4,
90 i 1
_ tions engineering institutes have vigorously undertaken the real i gation of this in- I '
40_J 1
_ teresting proposition. Lot us hope that their work will be completely successful. 1
A new trend in the develoent of radio communications has been to utilize the!
;
__tropospheric. scattering of rltrashort-waves in order to build radio-relay i i nkI in t;
4 c:._...1
1
___ 'which the distance between intermediate stations would be more than 200 km. Such
--: radio-relay links may be very efficient for comunications over sparsely populated i
50__I I
1
.- and difficultly accessible regions. Presently, experimental links which 'utilize
- :tropospheric scattering are being erected. This type of work mast be boosted.by all.
',;:- I
. --means.'
ct= !
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One is forced to adiit that the development of reiiiich in of
i?iio-
spheric scattering of ultrashort-waves is mediocre, and_it _is hoped that by next
. yoarls Radio Day our scientific organizations will have achieved more substantial re-
E.
sults.
liany data on long-distance television reception have shown how insufficiently
?1
_ the laws of propagation of radio waves have been investigated so far. In connection i
, 1
i
. with this, the organization of the International Geophysical Year beginning in July !
i
_
1957 may be welcomed. The thorough investigation of the magnetic and other proper- :
ties of the earth and of the atmosphere surrounding it and their interaction with the
sun and the adjoining cosmos will no doubt provide many valuable data .for the ,further
--
20_. I
investigation of radio facilities. i
_ i
_ Soviet specialists of all branches of radio may boast of new and remarkable
_ achievements in the field of technical progress on Radio Day 1957. At the same time;
,
_ it must be stated that the rate and scale of the development of certain important I
- i
_branches of radio engineering and of electric communications lag behind the general !
__rate of development of the basic branches of the national economy of the Soviet
32_
Union. The further considerable expansion of the radio-engineering industry and of i
_
34_2 i
its scientific and engineering basis is a prime requisite. i
1
1
3C?i ;
!
;
52?
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2 :2
3C--
of the telegram will be distorted. It is proved that, for given probabilities.
of the distortion of letters and for .a given rate of transmitting messages,
20__
there exists a most efficient set of statistical properties of the letters.
THE HOST EFFICIENT USE OF CODING SYSTERS
V.I.Siforov
The properties of coding systems, which operate under conditions of inter-
ference and various statistical properties of the transmitted letters, are con-
sidered. A general expression is derived, for the probability that One letter.
.62
Quantitative relationships which characterize the various performances of the
21?
coding system are derived and they are subjected to a comparative evaluation.
26-;
` _Introduction
1
Lately, new trends in the theory of coding have emerged. They are reflected in
part in the papers presented at the Second Symposium on Information Theory at Camp-
bridge (U.S.A.) in September 1956, in which Soviet scientists took part.
The papers read by member of the academy A.N.Kolmogorov on the theory of the -
.,:-.---transmission of continuous messages, of the American scientist C.Shannon on the
-Th
traffic capacity of a communication channel with noise at zero error; by D.Huffaan
!: _- .(U.S.A.) on the linear circuit theory of error - correcting code systems; by V.I.Si-
44_'forov on the theory of coding systems with small errors, and by ether authors were
1J-- 'devoted to these new trends.
In our work, an attempt was made to determine the total combination of paraae-
which reflect the basic properties of coding systems related to the class of
-.,-- 'binary coding systems.
, ? 1
- The present article gives an account of the results of the investigations car-
(
0-- ried out by the author, which were devoted to the most efficient utilization of
ri
SIWF_
? ??? rz.". ?-?-=
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_
. coding systems, i.e., to a utilization which would ensiie-obteiiiing.the-beat-POible
characteristics of the signal transmitting system under conditions of interference,
. _ _
4_
When the selected code is used.
6
Probability of the Distortion of the Transmitted Message
ir_ Let us assume that the letters al, a22 a,... ,a are transmitted through a ays-.
--
tem uhich transmits discrete messages. When the binary coding system is used, each 1
_
1 of these letters is a code combination which consists of several elements; each cam;
1
,bination being able to assume only two posible meanings. !
When the transmission system is subject to interference, the letters being tran-
smitted will be distorted. For instance, while the letter al is fed to the input of
1
the system, the letter a3 may appear at the output of the system.
24_ Let us denote the probability of distortion of the letters alp Ile ay...,
?-
by yi, y21 yy..., respectively. This probability, under given conditions of
interference in the channel transmitting the messages, apparently is dependent upon
_ the coding system selected.
Let pi, p2, pmr be the probabilities of the appearance, at the input of
the transmission system, of the letters al, a2, a32..,a, respectively.
In accordance with this notation, the probability that the letter a will ap-
t
3:-.pear at the input of the systems will be equal to pi, and the conditional probabil-.
4:__ ity that this letter, having appeared at the input, will undergo distortion will be:.
4: _ yi. It follows, from the. multiplication theorem of probability, that the probabil-i
4! _ ity of the letter ai appearing at the input and that this letter will undergo die- I
1
/. tortion is equal to piyi. I
4t.._ Since any of the letters i a 2., a , i a..,..., aN may appear at the input of the sys4 i ;.
- ten, then, in accordance with the addition theorem of probability, the probibil- -
--. l'
1
. .,- ity y of the distortion of any of the letters being transmitted, through the system z,
1
may be represented as a sum of the products.piyi at all possible values of I from,l;
I ?
116-..t0 NI
1.
9
STAT'
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4
n I
'
ply,.
(1)
Let the message transmitted or "telegram" consist ofletters.- The probability
. of an undistorted transmission of each of these letters is equal to ly, and the
!t; -
_ probability of an undistorted transmission of the entire telegram, in accordance with
??1
the multiplication theorem of probability, will be equal to
The probability yr that the telegram being transmitted will be subject to
kind of distortion will be
-n
30__J
then
If
Yr -= ? (1 ?3)41
YT--= MY M "
1,2 (M ? I )-(M ? 2)
Y3? ? - ?
2 6
My < 1,
(2)
any
Yr MY ? (3)
Equation (3) shows that when the probability of distortion of each letter is
sufficiently snail, the probability of distortion of the telegram in its entirety ii
_ approximately proportional to the number of letters it contains.
4C_
_
5
. all by the total combination of the probabilities pl, of appearance of
the letters al, a2,..., aN.. It is known from the inforaation theory (Bib1.2) that -
Fran eq. (3) it also follows that the quantity y? determined by the relationship
(1), is the probability of distortion of the telegram with respect to one letter.
The Most Efficient Statistical Properties of the Message Source
The statistical properties of the message sources are characterized first of ,
- - - -
_ the number of messages referred to one letter which enter the system (entropyl
-
f
_
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1..
4---
6
will be
, E pi lo. g2 pi.
/-1
When the probabilities of distortian 'Of the transmitted lateri
are small, the number of messages transmitted through the system with respect to one
I G
letter will be approximately expressed by eq.(14).
The probability y that the transmitted telegram will be distorted, with respect
? to one letter depends on the probabilities yis y2,.." TN, p2,..., pm, in accor-
dance with eq.(3., and consequently also upon the entropy H.
For given values of the probabilities yis yip corresponding to the se- ?
1
lected coding system, and for a given value of the entropy Hs the probability y will
?
evidently depend on the magnitudes of pi, p2,..., pu, i.e., on the statistical prop-:
Ir.
_
3.----
message source, for which the probability with respect to one letter that the tele- i
_gram will be distorted is minimized.
1 i
t
?:In order to discover this most efficient set of statistical properties of the ;
1
;
_
message sourea and the minimum specific probability that the telegram will be die-
3 .
,
. ;
_
mized. In other words, for every coding system and. for a given rate of message i
transmission, there exists a most efficient set of statistical properties of the i
1
erties of the message source. For a definite total caabination of pi, .p2s..., pm,
the specific probability y that the telegram transmitted will be distorted is mini-
4
torted with respect to this set of properties, let us turn to the system of equations
________ _ _
Eln?H1n2.1
y =tE pal
st-1
11
(5)
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(-
Here, the first expression coincides with eq.(1), the second follows-from ?1
- ?
eq.(4), and the third expresses the fact that any one of the N possible letters Al-
_
_ ways appears at the input of the considered coding system.
1
In the system of equations (5) yi = const; H constp vari and
In accordance with the method of determining relative maxima and minima, known
IC
from mathematics (Bib1.3), let us consider the function
[( pa ln pi) -1-H ln 21 +12 [(p1)? 11, ?
where arid X and X2 are certain unknown quantities.
1
If the partial derivatives of the function with respect to all the variables
pi, are equated to zero, while the quantities pi are considered independent and Xi
-
and X2 constant, we will obtain
yi-1-21(1npi-1-1)+2.2=---0 (1=1, 2,... A). (6)
This relationship together with the second and third expressions in the sys-
3O__!
tea (5), will form a system of N + 2 equations in N + 2 unknowns ply p2,..., PH' Ai
32_2!
and X2' The quantities pi, pN obtained as a result of solving this system
3 r , the probability of_a correct reception q1 would increase if d9
A
_ were replaced by dQa. Thus dQb should be associated with 92, and dQa with Ql. If
such i discussion is applied to any pair of symmetrical -volume elements, We-come tO7-
0 i
- the conclusion that if the distribution density of the distortion decreases with de-
- creasing distance (in accordance with what law is immaterial), the ideal receiver '
1'1_,
I -
will be one which associates the signal received with the nearest possible signal.
1:
This is the ideal receiver according to Kotelnikov.
JS- The optimum code remains to be found. However, in the given simple case, it is
hardly necessary to prove that the minimum distortion decreases with increasing d
2 C./. )
and that, consequently, assuming that condition (1) is valid, the points of the sig-
nals must be placed at the ends of the diameter of the sphere of the signals. The
r I
distance will then be d 2ii;
25_1
Example 2. Let, as before, the distribution density of distortion decrease
M_J
with increasing distance, but let us now take N = 8sn =,3. The points of the signals
_are placed on a three-dimensional sphere. If a binary code is selected, the code
3 2J
points will place themselves at the vortices of a cube. The regions of correct re-
3_I
ception will be octants, i.e., the interiors of trihedral angles, formed by the
__ , ?
SE__1 i
- planes normal to the edges of the cubes and bisecting these edges. However, the
3 3-1 . .
__binary code is actually the most advantageous code; its geometric presentation is
4 o.J
obtained if one of the faces of the cube is rotated through 45? in its plane. The
42_1
_figure so obtained is an irregular decahedron (8 triangles, 2 squares) with 16 equal
edges which are longer than the edge of the cube inscribed in the same sphere. The
!Ci_J
_ 'region of correct reception is located inside the tetrahedral angle, as shown in
6
- Fig.3. Let us note that the polyhedron considered, though irregular, is symmetrical
_:in the sense that if any vertex is placed at a given point, the figure may coincide
52,4
?
with itself by rotating it about the center. Therefore, All the regions Q are
'equal and, consequently, the probabilities qi are Also equal.
`? 06 I
1
24
1
STAT
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xamp3. Let us again r assuae N = -2 and let, foi-.the-Sake-Of -simPlicitY;76-;-2
(Which allows representation of the entire picture_ in one plane), but now let the
1
o
Fig.3
2
.10__;
32 Fig.5
Z
a
qt
fp-1
Q4
43
42
0.1
2 Jr
? Fig
probability density of distortion decrease at a ra-
pid rate. Let, for instance,
- - - --
cp (r)= Cr
(Fig.4). Let us discuss -the location of the boundary
of the correct reception region Along the same lines'
as in example 1, let us formulate the conclusion
_ slightly differently, namely, each element of volume dQ should be associated with
__the region of correct reception of that signal, which upon reception has the highest
38-J
_ probability of fal1ing into dQ. In other words, the boundary of the region of cor-
,..0._j
__rect reception rust be the locus of the points where the probability density for two
:signals becomes equal. In the case considered, this gives
G_J
[(xi ? -2- )2.-1- x: The x p [ (xi ? x: =
? I
-or
2-J,
. where_
r2 ?412 =0,
th 2xid 4
_
T2 =
? ? ?
?5 -
STAT
1
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?
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CIA-RDP81-01043R002700130003-1
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.; The boundary of the region of correct reception ii-ifieii.iciail-Fig.5:--Tfie-Contour;
. .
of the boundary obviouily depends upon d.
1
Article received by the Editors 4 February 1957.
26
---
S TAT i
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..??? ?.
2
- -
t e _
--
1.0
This circuit allows larger frequency deviations than the reactance-tube circuit:
and gives a better stability of the carrier frequency, at fluctuations in the I
24 -1
supplied voltages.
26
Introduction
A .
Two-tube networks used for frequency 'control are discussed below. Single-tube!
networks, in which control is effected by means of varying the grid currents, are 1
-Tnot considered.
?
1
Frequency control in two-tube networks may be achieved by means of two types ofi
,L
UHF OSCILLATOR MODULATOR
by
E.P.Korehagina
A two-tube network of an UHF oscillator, permitting frequency control, is
?
described. In this network, both tubes deliver power to the load and both par-
ticipate in frequency control. The frequency doviations produced by the tubes
will be cumulative if the feedback factors of both tubes are complex conjugate
1
numbers. The modulating voltages are supplied to the tubes 180? out of phase. I
1
f !
duty. The type of duty, in which one of the tubes operates as a generator, while 1
_j i . !
40_1 the second tube (the reactance tube) is used for fre4
, .
/..2 ! /2 qtency control, is widely known. The second type of!
. -
duty, in which both tubes are used for frequency con-
trol and in which both deliver power to the circuit, 1
is described in Mansfeldis paper (Bib1.1). We will ,
refer to this type of duty as the oscillator-modtla-
Piga
tor duty. Let us discuss the problem of using both
1
types of duty UHF_oscillators.
STAT
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f.;
Basic Rolationshi a
2
Let us consider the conditions of the steady-state operation of the two-tube
- - - -
4_
oscillator shown in Fig.l. The notations and the positive directions of the current
6 .
and voltages are shown in Fig.l.
If the inertia of the electrons and the plate reaction are neglected, the fel,-
10
_ lowing expressions for the amplitudes of the first harmonics of the tube plate cur-
1.2 -
_ rents may be written:
_
i
r2 = s2r/c2 ----- s2K2(7., _
---:
,
. ii-ea _ rIc2
where 71 . TT p a K2 = are the feedback factors of the first and of the second
Ua ;
u I
tithe respectively;
1
/..-._ Si = syl (01) and S2 = 5)1 (02) are average transconductances;
S is the steepness of the statistical characteristic of the
; .
,
plate current;
I
1 i
- Y (0) 2n ? (20 - sin 20) is the scanning factor for the plate current first harmon-
ic; i
i
36 1 0 is the cutoff angle of the plate current.
1 1
.12-7 If we let 7 denote the total impedance in the plate circuits of the tubes, then
-,
i I
.0_...the plate voltage will be i
_j I
42_4 ! 1-Ja = (I; ? -f)Z-
;
4.4-1
-Th
__existence
I
_j
-...
- - -
If the values of the currents are substituted, the following condition for the
of steady-state operation is obtained:
(1)
If we suitably substitute the real and imaginary terms in the right-hand and
, left-hand sides of eq.(1), taking into consideration that__
_ --------- - - KI=Ket'x'; K2=Kei?x2- Z?
R
---3
STAT.
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. where
2._
_
Mob
a tg p,
(A)o is the resonant frequency of the plate circuit formed by the impedances i
zi" Z20 Z31 Z4' Z5;
15 is the plate circuit damping;
(pa is the phase shift between the total current of the two tubes and the
voltage in the circuit;
Roe is the resonant resistance of the plate circuit;
andp are the phase angles of the-feedback factors.
k2
Then we will obtain the amplitude balance and phase balance equations in the
following form:
,0
R 0, (K1S1 cos 41 .1-i- K2S2 cos
tg cp. ? R (KiS I sin pit 1+ K2S2 sin
- -
(2)
(3)
These equations, strictly speaking, are valid only-in the case when the imped- ?
32._ances in the plate circuits of the tubes form a single-circuit modulating system.
In the UHF range, two-circuit oscillators with a common grid are used. In this case,
oe
the expression = + is approximate and is valid only when the cathode-grid
1
3 . 'circuits are considerably detuned.
Usually, these conditions are satisfied so that eqs.(2) and (3) maybe consid-
//ered adequate for evaluating the operation of UHF oscillators. The frequency wo in
such a case is understood to be one of the corLsanication frequencies which undergoes
self-oscillation.
Let us now consider the behavior of the network operating as an oscillator with
!10- a reactance tube.
Single-circuit oscillators are used in the ranges of long and short waves. In,
_J
r; this case, the feedback factor phase angle of the oscillator tube is (pt_0,_and____'
the phase Angle of the feedback factor of the reactance tube can be given a.value_of-
t
SI7J,
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6 o-- -
9 Rs 90 . Under these conditions, the equations I'Oi-t,fiase and amplitUde-haiiido
- k2
will have the form
6 '
_
I.
SiKike=-- 1,
Ig = RoX2S2 sin 9.2-
Fram the expressions obtained, it follows that the change in the transconduc-
-
(4)
(5)
tance of the reactance tube
? tion amplitude.
The performance of an
controls the frequency and does not affect the oscine,-
oscillator with a reactance tube is less efficient in the
reasons. First, due to the effect of the in-_
the phase angle of the feedback factor of the reactance
causes a decrease in the frequency deviations due to the
of the reactance tube. Secondly, UHF oscillators are us-
UHF range than on long waves, for two
terelectrode capacitances,
- tube differs from 90?. This
change in transconductance
tally designed as two-circuit networks so that the phase angle of the feedback
_tor of the oscillator tube is not equal to zero. In this case, as follows from the
30_1 I
__amplitude-balance equation (2), a change in transconductance of the reactance tube
will be accompanied by a change in the equivalent transconductance of the oscillat-
3t_j
ing tube, due to a change in the oscillation amplitude. A change in the transcon-
3 6
d- uctance of the oscillating tube, in turn, will cause a change in the frequency of
the self-oscillations, as follows from the phase-balance equation (3). The magni
tude of the resulting decrease in frequency will be essentially dependent on the "
sign of the feedback factor phase angles of the oscillating tube and of the react-
- ance tube. If the respective phase angles of the self-excited oscillator tube and ;
46_1.
of
the reactance tube are of the same sign, the change in frequency caused by the
I
iioscillator tube will decrease the resultant frequency decrement. If K.1 = IC2 and
50_1
9 then the resulting frequency will be equal to zero. In the networks that
- kl= k2/
- :are generally used for UHF, the frequency change caused by the oscillator tube de-
.-.creases the resultant frequency decrement.
30
STAT
?
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Declassified in Part- Sanitized Copy Approved for Release ? 50-Yr 2013/11/13: CIA-RDP81-01043R002700130003-1
_
actance tube is no less useful in the UHF range than in that of long waves only be-1
-,- _ _
1
It follows from the above statementa that the-du-V.-Of-an
4_
cause of poor phase angle ratios of the reactance tube; but also because the feedback
factor phase angle of the oscillating tube impairs the-operation of the-netork;----1
6 .
Physically, this can be explained by the fact that when the feedback factor of the 1
oscillating tube is a complex numbers this tube in addition to having a negative im-
1
pedance which perpetuates self-oscillations, also introduces into the circuit a re-
actance whose magnitude varies with changes in,the oscillation amplitude.
^ ?
(.;
?1
I
results in the UHF range.
By virtue of the above reasons, the use of reactance tubes does not give good
20_
Let us now switch to consideration of the behavior of the network as an oscil-
lator-modulator. For a summation of the frequency deviations produced by both tubes,
24_
the feedback factors must be complex conjugate numbers:
9' I
11(11=1/(21=-IKI;
1
30_1
The steady-state performance eqs.(2) and (3) in such a case take the fora
32
34_J RoeK(Si + S2) cos-cp., (6)
tg cp.= ? RoeK(Si ? S2) sin 1).. (7)
38-11
Equations (6) (6) and (7) show that, in the process of frequency control, an in,
t I
,r; - crease in the transconductance of one tube must be accompanied by a decrease in the
;/7.transconductance of the other tube. Therefore, the modulating voltage must be sup-
,...:,__- plied to the tubes 180o out of phase. i
i 1
The mean transconductance may be changed by the plate voltage or the
1 i
control grid voltage. Grid modulation is of great practical interest since it re-
1
.-:quires lower voltages for frequency control. .
---1, ,
, 1
,...2 __The relationship between the mean transconductance and the shift_is.determined,.
1 t
__'as is generally known, by the function Yi(cos 0) which has a nonlinear section at
? _31_
?
STAT
7_ 7:7. , """" ""' ? ?
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?7
?
2
conductance and
mately the same
the -application
_ tance
10
12
16
ihave
18D
'snal 1 cutoff angle.- If it Is assuMed that -the- relations?Kip-- -13Otiiien the mean trans- I
_t
;
44-4
24 1
' Equation (9) shows that, if the above assumptions
25_J
viation will be proportional to the transconductance increment S. Then, the oscil-
22
_ lation amplitude which is determined by eq.(8) is independent of the modulating vol-
30_4
__itage and is determined by the steepness at the initial performance level. Naturally,
32_I
sustain the oscillations, the feedback phase angles of both tubes must be less than
34_i
90". The smaller the phase angle ok, the ?larger will be the radio?frequency power
36
and the lower will be the frequency variation which is obtained in the oscillator-
38-1
modulator network. ,
421
with the flip-flop frequency modulator. When the oscillator-modulator network is
.:synnetricall a change in the voltages supplied has no effect on the frequency since!
_ such a change will be cophasal for both tubes.
48__A
If the nonlinearity of the function yi(cos 0) is taken into account, the oscil-
lation amplitude changes somewhat in the process of frequency control.
the shift is approximately linear and_that_:both_tubes_heff_e_Appr_94.-
- I
mean transconductance SI in the absence of a modulating -voltage, thezi
of a modulating voltage will cause the same change izi-fran?sCOndlia----1
for both
If the values
tubes.
Under these circumstances,
-
S 2 = S AS.
of Si and of S2 are substituted into eqs.(6) and (7), we will
1 2R.,KS cos pe
tg KR., 2AS sin
(8)
(9)
are valid, the frequency de-
It must be emphasized that the oscillator-modulator duty has much in common
?
1,0_1
The relationship between the frequency and the modulating voltage becomes
r-
linear and the maximum frequency deviation decreases as well.
32
_
non-
STAT
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p
A comparative evaluation of the r-f pater and of the frequency deviations whichi_
L--
are obtainable by means of an oscillator with a reactance tube and of those obtain
a- ble by means of an oscillator-modulator with a single-circuit oscillator network. 1
The oscillator-modulatorwas designed with the nonlineariti-ok the -fUnctiO( )
taken into consideration. The irregularity of the power in the frequency coatrol
. ? -
process depends on the choice of the cutoff angle at the initial operating conditioni.
_ - A cutoff angle of 0 = 800 was selected at which the irregularity of the power does
1,
_
_ not exceed ? 10%. The phase angle of the reactance tube feedback factor was assumed
_
to be equal to 90o; therefore the power of an oscillator with a reactance tese re-
- mains unchanged in the process of frequency control. It was assumed that one tube
20___
was used as much as the other.
The calculations showed that, in order to obtain the same amount of peuer from
_ the oscillator-modulator as from the oscillator with a reactance tube, it will be
_practical to give the oscillator-modulator a feedback factor phase angle of the or-
- der of 40o. The maximum frequency deviation produced by the oscillator-modulator is
30 ;
__then 35% larger than the frequency deviation produced by the reactance tube.
32_j
It follows from the above comparison that the oscillator-modulator duty has cer-
34_1
__tain advantages in the long-wave and short-wave ranges for which single-circuit self-
- excited generators are used.
9 0
As shown above, no satisfactory results can be obtained in the UHF range by us-
4
- ing a reactance tube; therefore, an investigation of oscillator-modulator duty as
42_1
__applied to UHF generators is of practical interest. It should be mentioned that the.
4/,
. obtained expressions which characterize the behavior of an oscillator-modulator with
4.6
_ a multicircuit self-excited generator network are valid as first approximmtinns only.
j The phase angle of the feedback factor in a multicircuit generator is deuer-
50____;
- Mined by a detuning of the circuits at the frequency of self-oscillations; therefore,
- in the frequency control process, the phase angle will not remain constant as it did
- in a single-circuit generator network. A special investigation is necessary in 1
SI-AT 1
33
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Declassified in Part- Sanitized Cop Approved for Release ? 50-Yr 2013/11/13: CIA-RDP81-01043R002700130003-1
_ .order to evaluate the operation of an osciilator-nodular in the UHF range. How- i
,
ever, the above relationships illustrate the operating_principle of the network and i
,
make it possible to fo ate the basic requirements to be met by the UHF oscillator-
;
!
,
1
1
*modulator.
c_
Equations (6) and (7) for an oscillator-modulator were obtained for parallel
12_1
valid for a flip-flop plate circuit connection. Since parallel connection of. the
tubes is undesirable for the UHF range, the UHF oscillator-modulator must be de-
16
__signed on the basis of the flip-flop circuit. The feedback factor phase angle of
LC__J
__UHF generators is determined by the sign of the detuning of the cathode-grid circuit;
therefore, in order to obtain complex conjugate feedback factors, one of the tubes
_ must be operating in accordance with the equivalent circuit of a capacitive Hartley
24_i
__oscillator and the other in accordance with an equivalent circuit of an inductive
26_J
_ Hartley oscillator. If the design of the existing tubes is taken into account, the
_ oscillator-modulator must be built in accordance with the common-grid circuit. The
30_1
__modulating voltages must be supplied to the tubes 1800 out of phase; therefore, the
tube grid circuits must be DC isolated.
34_1
3(... Description of a UHF Oscillator-Modulator
The layout of an oscillator-modulator with ceramic tubes is shown in Fig.2.
40The oscillator is designed onthe basis of a common-grid circuit. The plate-grid
42__circuit is common to both tubes and consists of a coaxial line whose terminals are -
,
44_ 'connected to the plate-grid capacitance of the tube. The oscillating voltages
4C.iacross the plates and the grids of both tubes are 180? out of phase. The load is .
?.connected by means of a coupling loop (4). The blocking capacitors (5) protect the
!JO_ plate cylinder from the DC plate voltage. 1
The tubes have distinct cathode-grid circuits which are tuned by means of may-
able pistons providing high frequency short-circuiting. The mechanism which con-..?
_ connection of the plate circuits of both tubes; evidently, the equations remain
the piston is located inside the cathode cylinder and is not
STAT
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2013/11/13: CIA-RDP81-01043R002700130003-1
-Shown in Fig.2.
__'______The tube grid cylinders are DC isolated by: the blocking capacitor_.(l). The 1
,
. modulating voltage is supplied to the grid cylinders through the opening in the plate
? ? 6 _ .
cylinder located at the voltage node.
Feedback is achieved by means of the two loop couplings (2), which are attached
- to the cathode-grid cylinders. The loop couplings must not short-circuit the cathode
1.2
- and the grid cylinders in direct current; therefore, they must be connected to the
capaciLrs (3).
_ grid cylinders across the blocking
The oscillator-modulator duty
.r t
__back factors are of opposite sign.
2 0j
- edances must be of different sign
_exist under these circumstances if
requires that the phase angles of the tube feed-
For this purpose, the cathode-grid circuit ion,-
at the generating frequency. Oscillations can
the loop couplings are oriented in such a way that
?
-- the voltages applied to the cathode-grid circuits are 1800 out of phase. The manner
__in which the loop couplings should be oriented in order to sustain oscillations is
28_1
_ shown in Fig.2.
3O
321
__middle of the plate cylinder.
34_j
361
39
442.0
The air for cooling the tubes
44 '
4G
48_1
50?j
?7
'circuit is shown in Fig.3.
to the network of a two-circuit
. To illustrate
is introduced through the opening located in the
1
the operation of the UHF oscillator-modulator, its equivalent
Fig .2
Fig.3
This circuit Shows that each of the tubes is connected
self-excited generator. A characteristic feature of
a common plate-grid circuit....The connec-
STAT
e networks is-the fact that they have
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2
.tion with the cathode-grid circuits i3 of ihe inductiveikie; -the
cathode-grid circuits is 1800 out of phase. In such a three-circuit network there I
_ exist three coupling frequencies. One of these frequencies is higher than the plate--;
grid frequency while the other is lowei.- The third frequency coincides With the----1
, plate-grid circuit frequency, when the circuit is symmetrical. Only at this frequen4
_ cy can correct phase relationships be obtained for both parts of the network. In
order that the feedback factors be complex conjugate numbers, the cathode-grid cir-
cuits must be tuned to both sides of the resonant frequency. Then, the reactances 1
1
1,1-.
which they introduce into the plate-grid circuit will have different signs, and if 1
,
. i
- the network is symmetrical, the generated frequency will coincide with the plate-grid
LO__!
circuit frequency.
;7. I
_Experimental Testing of the UHF Oscillator-Modulator
The experimental testing was carried out for an oscillator design on the basis
._ of Fig.2. The relationships between the modulating voltage supplied 180? out of
, _ phase to the tubes, and the frequency, and between.the-modulating voltage and the
were measured. The frequency was measured by means of the resonance wavemeter
3_VST-2D. The power was measured by means of a photometric power meter, connected to
oscillator by means of a cable of known attenuation.
nr-1
Figure 4 gives graphs to illustrate the operation of the network. The general
character of the relationships corresponds to the calculations made on the basis of
the approximate equations. A certain asymmetry of the graphs is visible. The net-
4!___ 'work permits complete blocking of the tube which operates as an inductive Hartley
/:".. oscillator. When the tube operating as a capacitive Hartley oscillator is blocked,
_
l; 'the oscillations are disrupted. The asymmetry of the graphs indicates an asymmetry!
I i
---.
50___of the network. The experiment was carried out with GI-78 tubes, whose plate-
!i2-icathode capacitance is not equal to zero. Therefore, the tube operating as an in-
- ! 1
!..ductive Hartley oscillator requires a more powerful external feedback than the cap-.
T.&.- lacitive Hartley oscillator. The graphs shown in Fig.4 correspond to the case when
36
_
STAT
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2013/11/13: CIA-RDP81-01043R002700130003-1
one tube has two feedback: loop couplings and the other thied:- The network-oPer-atii-1
. with cathode bias, and the frequency of the generated oscillations is equal to 489 EX4
1
The experimental testing showed that the oscillator-modulator circuit can be
. used for frequency control in UHF oscillator.' The total frequency deviation is'of-T
the order of one percent for a power irregularity of the order of ? 10%.
3.0
It is essential to point out that the tuning of cathode-grid circuits,
_
. for normal operation of the oscillator-modulator, corresponds to tuning for maximum
load power. This is due to the fact that a retuning of the cathode-grid circuits
1
necessary
causes a change in the modules and the phase angles of the feedback factors. With
the usual UHF oscillator parameters, the maximum power given up to the load corre-
sponds to the maximum control impedance under which the phase angle of the feedback
factor is close to 45o. Such a feedback phase angle is completely sufficient to
21 _
_make the oscillator-modulator operation practicable. Thus, each of the UHF oscill- !
.c._-' ? I
ator-modUlator tubes must be tuned for maximum load power, and frequency control may
, ? __
be achieved without decreasing the power supplied by the tubes. The low value of
_
30_1 1 ,
the r-f power given in the data of Fig.4 is due to the fact that we had tubes in
39_1
which the thermoelectric grid currents, forbidding normal use of the tubes on cur-
__
rent were significant.
I
ri? I
_J The above-described oscillator-modulator design can be used on wavelengths
'',f,-I i
,,,.--t i
- greater than 60 am. As the wave becomes shorter, difficulties arise in tuning the
40_1 i
cathode-grid circuit of the oscillator operating as an inductive Hartley osciilator.i
__The point is that such a circuit must have a length shorter than the resonant length
44_1 I
- so that its impedance can be of the inductive type at the self-oscillation frequency:
46__! 1
'On waves shorter than 60 cm, the necessary length of the GI-7B tube cathode circuit.
_:is so small that it cannot be constructed in practice. Shorter waves require change-
50.i i
__ 'over to the use of cathode line overtones, which cannot be done in the described de-
52-J .
Isign. In such a case, the use of a design in which cathode-grid circuits are ar-
5/..2
. ranged on different sides of the plate-grid circuit, is preferable.
56 I 1 .
1 SI-AT
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01.
?-? ?
It should be mentioned that, in-die-Cussing the oidillatbr--codulatai-oi66ritici5T-
i
we idealized the problem and neglected the inertia of the electrons. Due to the in,.
- ----------
?
32__
ertia of the electrons, the slope of the plate current becomes complex, which causes.
;j4/1. LW
MC %AmA
4-600t1
4 -.4?89mc.
/j'
13,
Z
N.,
olf
i
0
il(
N
..?
10 WO
N
2
1
A/
,?, ?
FE, 30 20
-E2
10a
10
20
30
-Et
+Et
1
2
Fig.4
the steady-state phase balance to change;
The electron inertia affects the oscilla-
tor operation in various ways, depending
on the oscillator circuit. In the capaci-
tive Hartley oscillator, the phase angle .
of the slope compensates the feedback
phase angle; as a result, at small angles',
the condition of self-excitation becomes
easier to satisfy. In the inductive Hart-
ley oscillator, the phase angle of the
slope and phase angle of the feedback
have the same sign; this makes self-
excitation more difficult. Apparently,
the asymmetry in the oscillator-modulator
0)
operation, which was pointed out above, is not merely due to the asymmetry of the
3E_
circuit. The asymmetry of the circuit, which is due to the plate-cathode capaci-
i
3a__1
tance of the tube, may be eliminated by a suitable choice of the size and number of
40.1
feedback loops. This problem was given considerable attention but complete elimina-!
42_j
tion of the asymmetry of operation was impossible. Apparently, the obtained asymme-
try of operation is indicative of the effect of the electron inertia. As the wave
46-1,
is shortened, the transconductance will increase and the operation asymmetry will
4-E-4
. !increase.
50-1 1
It follows from the above that, from the viewpoint of design as well as from
re, I
'that of the electronic performance, the proposed hookup can be recommended for oscil;-
!ifri _
. Ilators which operate in the upper portion of the decimeter-W-iie-rting?e.----------1
56_-II
38_
I
STAT
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0
V.Ivanov and I.Seversky, Fngineers, took part in the realization or the given 1
t
__ project.
it.
6 I BIBLIOGRAPHY
1. Mansfeld,W. ? Funk und Ton, Vol.5, No.7 (1951)
I
,
_ 'Article received by the Editors 6 June 1956.
1 4
r;
n9_1
34 11
32?,1
8_1
v V-
54
56
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STAT- .
1 ?
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DESIGNING AN OSCILLATOR OPERATING AT_OyMRVOLTAgE AND DEWED LOAD
Gt by
E.P.Khmelnitsky
10
-1 An account is given of a method for the engineering design of an oscillator
1 operating at overvoltage and with detuned load, in order to improve efficiency.;
The general performance characteristic of an oscillator which operates with a
p_- detuned load at a considerably overvoltage has been discussed in two papers
_J
? 1
(Bib1.1,2).
The present article gives an account of the engineering computations for such
performance which is advantageous fraa the energetics viewpoint.
The current-voltage relations in the plate and grid circuits of an oscillator
_j ? 1
7which operates in the above-mentioned state, form the basis for the method of com-
putation described here. The character of these relations is plotted in Fig.1,
3tareful consideration of the diagram will show that a given displacement of the gap
34_:- to the right of its center in the plate current pulse is accompanied by such a phas-
_j
of currents and voltages in the oscillator plate circuit that, at the instant
corresponding to the amplitude of the positive grid voltage, i.e., at wt - 0, the ?
'(negative plate voltage E0 - U1cos Till is compensated by the voltage of the second
!2._ and third harmonics.
By virtue of this, the residual plate voltage at wt - 0
0
Eo? II cos cp., --t- u 2 COS pia -t- U3 COS To
r ' "
- -
- - - - -
4 (1
a positive sign, despite the fact that the plate voltage efficiency is Z>1.
50_
Under certain conditions, the residual voltage may be higher than the positive 1-
04-1
--Arid voltage at that instant
SI tS.
- I
E +U
z g
_ ? _
S TAT
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As a resul-- t, the platenegative voltage region axd, CO-n-s-eq-u-entl,y,-tfiE.-zofie of i
_ deep trough in the plate current pulse, are_displaced to the_left of the origin of 1
4_1
6
_ coordinates. The displacment of the center of the trough is indicated in Fig.1 by
6.--!
22
32
42
-
;
Fig.1
48-.11
- the angle Iv, while the width of the trough, limited by the instants - tat]. and -
?as denoted by the angle Or 1
s
The displacement of the pulse trough yields a number of qualitative results._
- 'First of all, a relatively rapid increase of the coefficient of the first harmonic
;
STAT
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. 1,1
1 ra(11g.2) takes place. Here and further on, 1.1 denotes the current amplitude
.. .
,
_
of the fundamental frequency,- a currentsiihiCE-ii-i-C6P&ient-Of the pulse,X i
_ 1
_ denotes the ma=imun value of the current pulse as indicated in Fig.l. Then, the co-
'-- -- ---------------
i
- efficient of the direct component increases considerably more slowly. As a result, 1
. the coefficient of the form y 'c -a-, when the trough is displaced by an angle of only
. -
! o i 1
:-----
?
___.11 .1.1 30p (Fig.3), attains the value of this coefficient if the pulse is cosinusoidal.i
i i 1
A second Characteristic feature of a pulse with, an asymmetrical trough, is a i
i..: _certain phase shift equal to the angle Tui of the voltage amplitude of the first 1
I_I harmonic. This facilitates the task of compensation by meansof plate voltage her.-
ISOnies of negative potential, at the instnt wt 0.
Finday, the advantageous change in the amplitude and phase relationship for
1
-
,
0-75?
-
0 ID 20 ill
. 40 )5
4-_,the voltage of the second and third harmonics, from the viewpoint of compensation of
the negative Plate voltage mentioned above, is an important feet
leftward displacement of the trough. If this were not so, the width of the trough
associated with the
.,; -would have been determined by the instants -t3 and wt4' The capacitive branch of
__J, !
1
, _the circuit serves as the oscillator plate circuit load for these harmonics.______
In networks in which the feeding is in parallel, the load for the highest _bar-
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0
. monies consists of the blocking capacitor- Ca ind- Of -file -CiiiitaifinCit- f..O
, P
Ck, connected in series
n_
The total voltage of the 'second and third harmonics may be determined as fol-
C Cx - -1
C? P .
C 1-c
p
:IC
_ lows" at (at - 0:
12
U2-1-U3=-- alirm
2.c cos po T3.?)c- cospo ?
a3/ni /, a2 a.
wc 2 COS 7,42 ?1-1. COS po) .
IC
An investigation of the plate current pulses, at various values of the trough
width and. shift at various lower cutoff angles of the plate current showed that the
20_1
expression
CI.)
24
I I__
7-2-(12 cos pu2---1- 14--1- COS ?id
7f always has a maximum when the trough shifts to the left of the pulse center by an
angle of v fw 30 ? as shown, for instance, in Fig.4 for a cutoff angle of 0 = 750.
;o
It follows from the above that v x 39 is the optimum trough shift angle and
that all computations for an oscillator of the described duty, should be based on
- the proposition that v x 300.
1
0c The computational graphs of the breakdown factors al and a?, as well as the
1
3form factor y, as a function of the cutoff angle A, are given in Figs.5 and 6 for
4 O_ - trough of width
42_1 91= 20?, 30?.?nti 400.
Figure 7 gives the relationship of the quantity
4611
50.731
for the same values of 8 and O. 1
Al]. these graphs are based on v 300 and may serve as a basis for the engineer-
1
?
_ 'ing computations of the operating conditions since, if the shape of the pulse, i.e.;
1;6
a22 COS ci7.2 cos pu3
43 STAT
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Declassified in Part - Sanitized Copy Approved for Release ? 50-Yr 2013/11/13: CIA-RDP81-01043R002700130003-1
e
, g3ie -0 aid 0i, are given,' the breakdown-factor-6f the-iiar6O- Oan b?eternined-.--
.
Computations of the breakdown factors and of the phase angles were carried out
_
by means of the woil-known graphical method with a 5? shift of the ordinates. Be- ,
6
sides, the form of the trough was assumed to be" based upon ei but to have' sides Uwal
-are not vertical but rather inclined by 5? fraa the top on both sides (see Fig.1).
The selected plate current pulse shape is obtained, in our case, without deter-1
!
mination of the usual factors, such as the magnitudes of the DC plate-grid voltages
1=
and of the AC voltage of the first harmonic, by satisfying two additional conditions:
a
- 1
--- I 44
'JP= rti+ Tice...1'16
gg `
of-41
30
2 . -. 0,10
20
i
i 1
i II 10 20 30 40 509) , 41
......,
; I .? . 1 ?
,0 ? ..i
ASEI Fig.4
I
3a1
i We must consider that, the first condition is
40__ 1 i
???????
of total voltage of the highest harmonics:
.......
4 2_.....i ;
....._ The required magnitude of this voltage may be deternined from the consideration
_that, at the instant wt = 0, the total plate voltage of the AC components must have.,
__'a magnitude below
LJ
,
__. A sufficient condition for undervoltage at that instant is the inequality
sc_J ;
I
S 2.1 U 1 COS ?al c ( CiL COS Pu2 + IP C OS CPu3) < 0,8EO?
4.1 -.
54 ....L - I
5 (... The required magnitude of the plate circuit capacitance which will satisfy the ,
_
8-75*
2
SO _....-??"
GO
ci
?
I
7:11p
6 ,..e.
,
- GO
a
6,7
ra aa ode
to obtain
Fig.5
the required magnitude
?
STAT
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?. above-indicated first ?Conditi-on- of pulse-en-cira. tion-iuti-daceimined.
In this formula, the phase angle of the fundamental frequency q) voltage, has
_ _ ___.____
i
always a value close to 150, as shown by investigations at an optimum angle of trough
o -
... shift w- 2` 30 . It nay safely be assUmed that -Tui - 150; without interferillg?with- the
6- i
_ accuracy of the computations. 1
.10--i !
A second condition which will secure the given pulse shape is the choice of the
12
required magnitude of the utilization factor of the plate voltage.
It mv be seen from Fig.1 that the left-hand limit of the pulse trough is the
16
instant
12-1
20d
22 Sines
24-1
251-7)
it may be considered that
20-1
30 _J
32 _J
Hence,
34_1
36_
- - -
38:1
a formula
_
Ul
;
E0
obtained,
c o s (