US2210497A - Amplifying system - Google Patents

Amplifying system Download PDF

Info

Publication number
US2210497A
US2210497A US171678A US17167837A US2210497A US 2210497 A US2210497 A US 2210497A US 171678 A US171678 A US 171678A US 17167837 A US17167837 A US 17167837A US 2210497 A US2210497 A US 2210497A
Authority
US
United States
Prior art keywords
valve
pass
resistance
anode
rectifier
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US171678A
Other languages
English (en)
Inventor
Percival William Spencer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EMI Ltd
Electrical and Musical Industries Ltd
Original Assignee
EMI Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by EMI Ltd filed Critical EMI Ltd
Application granted granted Critical
Publication of US2210497A publication Critical patent/US2210497A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/60—Receiver circuitry for the reception of television signals according to analogue transmission standards for the sound signals

Definitions

  • This invention relates to radio receivers and is mainly concerned'with a receiver for the reception for both vision and sound signals in television reception.
  • receiver for this purpose is one employing several stages of radio frequency circuits, tuned either to the carrier frequency, for example, 45 megacycles, or to an intermediate frequency of, for example, 10 megacycles, but
  • a superheterodyne receiver for television reception in which both the sound and the vision signals are heterodyned by local oscillationsand the resulting intermediate frequency outputs are amplified by a low pass amplifier.
  • the amplifier is of the type comprising a plurality of thermionic valves, the intervalve coupling or couplings including a low pass network or low pass networks designed in such a manner and terminated by appropriate resistances as to have the required characteristics.
  • the use of an intervalve coupling designed as a low pass network and not as a band-pass net work is advantageous since it affords adequate stage gain and band-pass with a smaller number of components compared with the band-pass case with much less critical adjustment of these components.
  • the sound signals are rejected or suppressed at a suitable point in the low pass amplifier by the provision of an additional rejector circuit or circuits and a band-pass output circuit is provided for feeding the vision signals to a suitable rectifier.
  • a superheterodyne receiver for television reception in which the intermediate frequencysignals, after amplification, are fed to a band-pass output circuit for feeding the signals to a suitable rectifier, the terminating resistance (01. its-5.8)
  • a band-pass network which consists of a parallel tuned circuit provided by an inductance in the anode circuit of the thermionic valve and the anode-to-earth capacity of the said valve, coupled by a series resonant circuit, to a further parallel tuned circuit connected to an additional valve or rectifier the capacity of which forms the capacity of the further tunedcircuit, the series resonant circuit being tapped into one or both of said parallel tuned circuits to take account of the difference in the capacities of said valves.
  • the receiver includes an oscillator valve VI, first rectifier V2, four intermediate frequency amplifier valves, V3, V4, V5 and V6, and a second rectifier V1, from which the vision signals are obtained.
  • the valve VI is associated with circuit elements as shown and is arranged to generate oscillations of about 40 megacycles. The operation of the oscillator circuitwill not be described in detail as it forms no part of the present invention.
  • the valve V2 is arrangedto function as an anode bend rectifier and is biased I bya suitable resistance '8 between cathode and to pass the sound carrier frequency and the television sidebands.
  • the anode of valve V2 is connected' to the positive terminal of the anode high tension sourcethrough a pair of coupled coils H and I2, a load resistance I3 and a decoupling resistance [4 associated with 'a decoupling condenser l5.
  • the intermediate frequency outputs of the valve V2 are applied through a coupling condenser it to the control grid of valve V3, a leak resistance I! being provided as shown.
  • valve V3 is coupled to the valve V4 and the latter valve is coupled to the valve V5 and valve V5 to valve V6 through similar inter-valve couplings consisting of coupled coils H and I2, resistances l3 and the anode-to-earth and grid-to-earth capacities of the associated valves. Decoupling resistances I4 and condensers are provided as shown.
  • the valves V3, V4, and V5 and V6 are,
  • the low pass intervalve couplings are designed in conjunction with the anode-to-cathode capacity of the first valve and the grid-to-earth capacity of the second valve of each stage in such a manner as suggested in the specification of British application No. 5335/36 as to provide the optimum product of the pass-band and stage gain.
  • the bandof frequencies passed by the first stage of the amplifier comprises the sound carrier frequency of about 1.5 megacycles, and the television carrier of about 5 megacycles with sidebands of about 2.5 megacycles.
  • the lowpass amplifier described is arranged to have a cut-off at 7 megacy'cles and in the specific ex ample shown, the intervalve couplings of the low-pass amplifier may have the following values: Coil ll, 44 microhenries; coil i2, 25 microhenries; resistance [3, 2000 ohms; resistance I4, 500 ohms and the condenser B5, 0.04 microfarad.
  • the coupling condenser 16 may be of 0.0005 microfarad, the anode-to-cathode capacity of the valves may be 11 microfarads and the grid-toearth capacity of the valves may be 16 microfarads, while the leak resistance ll may be of 100,000 ohms.
  • the low-pass amplifier has a cut-off at the lower end of the intermediate frequency spectrum for instance at about 1 megacycle.
  • a cutoff is effected through the medium of the coupling condenser l6 and leak resistance [1.
  • the condensers I9 it may be arranged that the biasing resistance is not shunted by this capacity at the lower frequencies and degeneration at these frequencies results.
  • the condensers is each may have a capacity of 0.01 microfarad. If the cut-off is arranged to extend to frequencies above 1 megacycle, some attenuation of the lower side band frequencies of the vision signals may result.
  • these lower side-band frequencies may be boosted by employing an additional resistance and condenser, not shown, in the anode circuit of one of the stages between the resistance l3 and the condenser I5 which in effect sharpens the cut-off.
  • the sound carriers frequency occupies only a relatively narrow band at the lower end of the intermediate frequency spectrum, the sound signals can be substantially rejected or suppressed at a suitable point in the low-pass amplifier.
  • such suppression is effected at the valve V4; by degeneratiomfor which purpose between the cathode of valve V4 and earth there is inserted a rejector circuit comprising an inductance 22 shunted by a condenser 23, the inductance being tuned to the sound carrier frequency of 1.5 megacycles.
  • the intermediate frequency voltage across this rejector circuit is supplied to a separate sound amplifier (not shown) which may be connected to the pair of terminals S.
  • a similar rejector circuit may be included in the cathode of valve V5 in order to reject further the sound carrier.
  • Volume control may be elfected by the provision of a variable resistance 24 associated with a by-pass condenser 25.
  • the output from the valve V6 is fed via a bandpass output circuit to a diode rectifier Vl from which vision signals are fed to a cathode ray tube in the manner hereinafter described.
  • the anode of the valve V6 is connected to the positive terminal of the high tension source through an inductance 25 and a decoupling resistance 2'! associated with a decoupling condenser 28.
  • the anode of valve V6 is coupled through a series resonant circuit comprising a; condenser 29 in series with an inductance 30, to a shunt circuit comprising an inductance 3
  • the diode load comprises a relatively low resistance 32 shunted by a series tuned circuit comprising a condenser 35 and an inductance 35. Since the rectifier circuit is a low impedance at the intermediate frequencies the coupling between valves V6 and V1 is a terminated bandpass network of low characteristic impedance, the input impedance of the rectifier being incorporated as part of the terminating resistance of the network the termination being such that the network is substantially non-reflective at the terminated end.
  • the band-pass network which aids in completing the rejection.
  • the coil 26 which may have an inductance of 85 microhenries, in parallel with the anode-to-earth capacity of the valve V6, and the series resonant circuit, consisting of condenser 29 and coil 30 is tapped into the coil 26 at a point to take account of the differences in the capacities of valves V6 and V1.
  • the condenser 29 may have a capacity of 11.6 micromicrofarads, coil Swan inductance of '78 microhenries. have an inductance of microhenries and is tuned as aforesaid by the input capacity of the diode rectifier V! between the anode of such valve and earth.
  • the condenser 35 in the example shown may have a capacity of 21.5 micromicrofarads and the coil 35 may have an inductance of 40 microhenries.
  • the Series resonant circuit may be tapped into the inductance 3
  • the connection of the series resonant circuit to either inductances 26 or the inductance 3! in the manner aforesaid can be employed to take account of the value of the effective termination resistance which is fixed, not by consideration of the design of the band-pass network alone, but by the requirements for a low impedance out-
  • the coil 3! may J put from the diode rectifier. The leaking inductance resulting from tapping down of the inductance is effectively included in the inductance of theseries resonant circuit.
  • the coil 3! which is the coil at the loaded end of the network, has very close coupling between its sections such as results from using a suitable iron core.
  • the damping provided by the iron core may be employed in some cases to replace the resistance 34.
  • the band-pass network is terminated as aforesaid by the input impedance of the diode rectifier in parallel with the resistance 34, the resistance 32 in the example shown being 5,600 ohms and the resistance 34 being 4,300 ohms.
  • valve Vl During rapid decreases of the amplitude of signals applied to valve Vl, this valve, as is usually the case, does not conductat the peaks of the applied high frequency oscillations. at Consequently, the damping provided by the rectifier is removed during these periods resulting in a distortion of rapid decreases of picture illumination.
  • the non-reflective terminated band-pass network has, in addition to the selective property mentioned earlier, the advantage that for the given shuntcapacities of valves V8 and Vi, the load in the anode of valve V6 is a maximum, so that the gain of valve V6 for a given pass-band is a maximum and also the power output from valve V6 is the highest possible.
  • the output from the diode valve V7 is fed through a network comprising a coil 3? damped by a resistance 38, and a condenser 39, such network being designed in conjunction with the input capacity of the cathode ray tube to pass all frequencies up to 2 megacycles without appreciable attenuation.
  • the signals to be fed to the cathode ray tube are established across the terminal 40 and earth while signals for application to the synchronizing circuits are taken from a tapping point in the resistance 4 l.
  • anode bend rectifier inplace of the diode Vl. Since such a rectifier has a high input impedance, a low pass network similar to those coupling the amplifying valves can be used to couple the valve Vt thereto. In this case, for selectivity purposes, a band-pass network should be employed at a suitable stage in the amplifier, for example, in the anode circuit of valve V2.
  • a local source of oscillations means for heterodyning the local oscillator with the sound and picture carrier frequencies to produce separate sound and picture intermediate frequencies
  • common means for amplifying both the intermediate frequencies comprising a plurality of 'iermionic discharge tubes, means including a low-pass network for coupling the tubes whereby WILLIAM SPENCER PERCIVAL.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Networks Using Active Elements (AREA)
  • Superheterodyne Receivers (AREA)
  • Toys (AREA)
  • Amplifiers (AREA)
US171678A 1936-11-02 1937-10-29 Amplifying system Expired - Lifetime US2210497A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB29756/36A GB484404A (en) 1936-11-02 1936-11-02 Improvements in or relating to radio receivers

Publications (1)

Publication Number Publication Date
US2210497A true US2210497A (en) 1940-08-06

Family

ID=10296667

Family Applications (1)

Application Number Title Priority Date Filing Date
US171678A Expired - Lifetime US2210497A (en) 1936-11-02 1937-10-29 Amplifying system

Country Status (3)

Country Link
US (1) US2210497A (fr)
FR (1) FR828418A (fr)
GB (1) GB484404A (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2549761A (en) * 1947-04-30 1951-04-24 Int Standard Electric Corp Low noise intermediate-frequency amplifier
US2629822A (en) * 1947-01-31 1953-02-24 Motorola Inc High-frequency coupling circuits
US2652447A (en) * 1949-01-19 1953-09-15 Bendix Aviat Corp Sound separation means for carrier frequency difference television receivers
US2706218A (en) * 1949-11-15 1955-04-12 William A Wootten System for television-program film recording and record reproduction
US2774825A (en) * 1953-02-17 1956-12-18 Gen Precision Lab Inc Logarithmic amplifier
DE976524C (de) * 1953-01-30 1963-10-24 Telefunken Patent Videoverstaerkerstufe fuer einen Fernsehempfaenger mit Tonempfang nach dem Differenztraegerverfahren

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2629822A (en) * 1947-01-31 1953-02-24 Motorola Inc High-frequency coupling circuits
US2549761A (en) * 1947-04-30 1951-04-24 Int Standard Electric Corp Low noise intermediate-frequency amplifier
US2652447A (en) * 1949-01-19 1953-09-15 Bendix Aviat Corp Sound separation means for carrier frequency difference television receivers
US2706218A (en) * 1949-11-15 1955-04-12 William A Wootten System for television-program film recording and record reproduction
DE976524C (de) * 1953-01-30 1963-10-24 Telefunken Patent Videoverstaerkerstufe fuer einen Fernsehempfaenger mit Tonempfang nach dem Differenztraegerverfahren
US2774825A (en) * 1953-02-17 1956-12-18 Gen Precision Lab Inc Logarithmic amplifier

Also Published As

Publication number Publication date
FR828418A (fr) 1938-05-18
GB484404A (en) 1938-05-02

Similar Documents

Publication Publication Date Title
US2579345A (en) Amplifier band width control
US3562417A (en) Signal-translating filter network for a television receiver
US2210497A (en) Amplifying system
GB464286A (en) Improvements in or relating to modulated carrier wave receivers
US2884485A (en) Television receiver
US2907960A (en) Signal transfer apparatus
US2273619A (en) Receiver circuits
US2619536A (en) Electrical signal network
US2486076A (en) Circuit arrangement for changing the frequency of electrical oscillations
US1905946A (en) Automatic gain control
US2789213A (en) Cascode amplifier-mixer with trap to prevent local oscillator in driven stage from affecting driving stage
US3372337A (en) Image frequency attenuation circuit
US2794866A (en) Device for the transmission of a video signal containing a direct-current component through a transmission cable
US2812433A (en) Plural band frequency converter with intermediate frequency trapping means
US2356308A (en) Wide band amplifier
US2261803A (en) Wide band amplifier
US2219396A (en) Electric translating system
US2376126A (en) Frequency modulated wave discriminator
US2273134A (en) Dual intermediate frequency amplifier circuit
US2256067A (en) Receiver selectivity control
US3562411A (en) Intermediate frequency coupling network with bridged-t sound trap for a color television receiver
US2707730A (en) Amplifier circuits for television picture signal channels
US2984791A (en) Frequency modulation reception circuits
US1762945A (en) Radio receiving system
US3103554A (en) Interstage network using cancellation trap