US2254377A - Repeater station - Google Patents

Description

Sept. 2., 1941. I 3 MAGGIO 2,254,377

REPEATER STATION Filed 0Gt. 1.2, 1959 INVENTOR J 8. MAGGIO ATTORNE Patented Sept. 2, 1941 UNTES'TES 10 Claims.

This invention relatesto a repeater station or installation for a telephone system, and, more particuiarly, to a power. supply arrangement for a multiplicity of amplifiers at such astation.

An object of this invention is to simplify and reduce the expense of amplifier circuits for telephone systems.

A feature of the invention compn'ses operating a plurality ofstages of an amplifier with their plate circuits in series, and utilizing the series-connected stages as a potentiometer or voltage divider to provide a desired potential for a specific electrode of oneystage of the amplifie-r.

Another feature comprises providing a multiplicity of such amplifiers at a repeater station and connecting them in multiple 'at the point in each potentiometer from whichis obtairied the potential for the specific electrode of one stage of each amplifier. Y

Other andfurther features will. be apparent fromthe general-and detailed description which follows.

In accordance with the invention, anamplifier may comprse aplurality of amplifying stages utlizing electron discharge devices, at least two stages having their plate circuitsconnected in series, and including a power stage having an electron discharge device withagrid auxiliary to its input control grid. A, eonneetiori is made from a point intermediate the series-connected wire telephonepars. Each amplifier is similar in detailto amplifier V The amplifier A is connected ih=the cominunication circuit through input and.output transformers il), |2, and 'comprisesthreestages' ci amplification provided; by amplifyng electron discharge devices I4, Iii; [8. These devices are sh0Wn as pentodes, but the initial two stages could be triodes, screen grid" tubes, or other multigrid devices. The finaistage is' a-power stage, and, preferably comprisesia s'creen grid or other multgrid tube. ;neithe'r eVent, the

cathodes may be of the directly or indirectly heated type. The screen voltage of the power tube is lower than that of the plate; for comparatively high power outputs With 1ow plate currents this is, in genera], necessary.

The initial stages of the amplifier A have their space current circuits connected in series, the anode of device I! being directly connected to the input centrol grid of device !6, the interstage network N1 being proportioned so that its resistance component is sufficient to provide the desired biasing potential for the-control grid of device l. Although the conventional blocking condenser between the devices M, 16 has been eliminated, the circuit does not constitute a direct-current amplifier, since the infinite impedanceat zero frequency of by-pass condenser C reduces the gain to zero. The gain is not reduced, however, until the reactance of the condenser is comparable to the internal resstance of device H3. Basing potential for the control grids of devices l4 and l8 may be provided in conventional mannr, i. e, either by cathode resistors, or by biasing batteries. interstage network N2 and blocking condenser 20 couple the output circuit of device Iii and the input circuit of the power stage. Space current for the amplifiers A, B, C N is provided from a common source 30, which, as shown, may be a storage battery, or the filtered output of a reatifier, or a motor generator set. This source 30 may be at the repeater station, or it may be at a remote point, e, g., another repeater station, or at a terminal of the system. Space current for the first two stages of amplifier A is supplied conductors 52, '44. If the battery 30 has its midpoint grounded, the point in each amplifier may be connected to a common ground. The screen grid of tube M s connected to the point 439 through filtering resistance 46, and that of tube 16 to the high potential end of the network N2. k

The arrangement desci*ibed is particularly advantageous in a carrier telephone system in which one or more auxiliary and unattendedrepeater statons are provided between main or A sutable terminal and attended stations and the p1ate power supply balanced to ground at the auxiliary station is furnished from a main station, the power supply ground, however, not being carried over the cable connecting the stations. The output or power stage of the repeater station amplifiers may be operated at the full supply voltage, that is, for example, the plate or anode would be 125 vo1ts above ground and the cathode 125 vo1ts below ground with a plate supply of 250 volts at the repeater station. The conventional procedure with reference to the voltage ampli-- fication stages would then be to reduce the plate supply to a value suitable to the voltage amplifier tubes by means of a series resistance common to the station, thus introducing a power loss.

With the arrangement of this invention, however, the space current circuits of the first and second stages of the amplifier are connected in series so that approximately one-half of the plate supply voltage is applied to each tube. Since the tubes are in series, their space currents must.

be the same. The value of the space current Will be determined by the resistane of the interstage network N1, and the amount of bias on the input control grid of the first tube.

Although the voltage distribution and space current w1'11 vary from tube to tube used in the voltage amplification stages, this effect is substantially eliminated by the multiplying of point 40 throughout the repeater station. With screen current of the output tube not tuo great, this point is a conVenient source of screen supply for the output tube.

Although this invention has been disclosed with reference to a specific embodiment, it is to be understood that its scope is limited by the appended claims only.

W'hat is c1aimed 15:

1. An electric wave amplifier comprising a plurality of amplifying electron discharge devices with their space current circuits connected in series and so that the space current in eachis the same, and an additional amplifying electron discharge device having a screen grid and whose space current circuit is independent of that of said pluralty of devices, said plurality of devices constituting a potentiometer providing potential for said screen grid.

2. A11 electric wave amplifier comprising a piurality of electron discharge devices with their space current circuits connected in seriesand so, that the space current in each is the same, another electron discharge device having its space current circuit independent of that of said piurality of, devices and 'having an input control grid and an auxiliary grid, and a connection from a point in said series connected devices to said auxiliary gridto provide operating potential for said auxiliary grid.

3. A transmission system comprising a multiplicity of electric wave amplifiers, each amplifier comprising apair of electron dscharge devices with their space current circuitsconnected in series such that the space currents in the devices are the same and such that approximately onehalf of the anode supply voltage is applied to each device, a common power supply for said amplifiers such that substantially the same voltage is supplied across the series-connected pair of devices in each amplifier, the replacement of a:device by another tending to alter the Voltage distribution between the pair of devices and the space current in the seriespath of a pair of devices, and means connecting said amplifiers in multiple at a point in the circuit of each intermediate its devices substantially to eliminate such tendency.

4. A transmission system comprising a multiplicity of electric wave amplifiers, each amplifier comprising a pair of electron discharge devices with their space current circuits connected in series such that the space current in each device is the same, each amplifier a1so comprising an output electron discharge device having a grid auxiliary to its input control grid, a common power supply for said amplifiers, connections for applying the full potential of said supp1y between the cathode of the first and the anode of the second of the series-connected devices of each amplifier, and between the cathode and the anode of said output device, said amplifiers being connected in multiple at a point in the circiiit of each intermediate said series-connected devices, and a connection from said intermediate point in eaohamplifier to the auxiliary grid of its respective output device. y

5. An ele ctric wave amplifrer comprising a pair of electron discharge devices each having a cathode, an anode and an input control grid, a source of space current connected between the cathode of one device and the anode of the second device, a direct connection between the anode of said one device and the grid of the second device, a connection through ari interstgenet- Work from the anode of said one device to the cathode of said second device, thespace current circuits of said devices being connected in series and said network having a resistive component the potential drop across which provides biasing potential for the grid of said second device, av

third electron dischar-ge device comprising a. cathode, an anode, an input control grid, and an auxiliary grid, and a connection fro'm'the cathode end of said interstage network to said auxiliary grid.

4 '6. A11 e1ectric wave amplifier comprising a pair of electron discharge devices each having a cathode, an anode and an input control grid, a source of space current connected between the cathode of one device and the anode of the second device, a direct connection between the anode of said one device and the grid of the second device, a connection through an interstage network from the anode of said one device to the cathode of said second device, saidnetwork having a resistive component the potential drop across whichprovides biasing potential for the grid of said second device, a condens er connected between said cathodes, a third electron discharge device comprising a cathode, an anode, an input control grid,and a screen grid, and a connection from the cathode end of said interstage network to said screen grid.

7. An electric wave amplifiercomprising a pair of electron discharge devices each having a cathode, an anode and an input control grid, a source of space current connected between the cathode of one device and the anode of the second device, a direct connection between the anode of said on'e device and the grid of the second device, a connection through an interstage network from the anode of said one device to the cathode of said second device; said network hav- :ing a resistive component the potential drop across which provides biasing potential for the grid of said second device, a third e1ectrdn discharge device comprising acathode, an anode, an input controigrid, a grid auxiliaryto said contro1 grid, and a connection from the cathode end of said interstage network to said auxiliary grid.

8. A transmssion system comprsing an unattended repeater station, a. plurality of electric wave amplifiers at sad station, each 'amplifier comprising a pair of electron discharge devices With their space current crcuts connected in series such that the space current in each is the same, each amplfier also comprising an output multigrd electron discharge device, a pair of power supply conductors connecting the unattended. station Wth another repeater station in sad system whereby power supply for the amplifiers at the unattended station is provided over said conductors from said other station, a connecton from one supply conductor to the cathode of the first of sad series-connected devices and a connection from the other supply conductor to the anode of the second of said series-connected devices, the cathode and the anode of the output devce being connected across the supply conductors, said amplifiers beng connected in multiple at a point in the circut of each intermedate said seres-connected devices to equalize for dflerences in the characterstics of the devices successively employed in the series space current circuts portion of said amplifiers, and a connection from sad intermediate point in each amplifier to a grd of its respectve output device to provide operating potential for said grid.

9. A transmisson system comprising a multiplicty of eleotric wave amplifiers, each amplifier comprisng a pair of electron dischar-ge devices having a cathode, anode and input grid and with their space current crcuits cnnected in series such that the space current in each s the same, each amplifier a1so comprisng an output de'vce, a common power supply for sad. amplifiers, connections for applying the full potential of said supply between the cathode of the first and the anode of the second of the series-connected devices of each amplifier, and between the cathode and the anode of said output devce, said output device comprising also an input control grid and an auxiliary grid, said amplifiers being connected in multiple at a point in the circuit of each intermediate said seres-connected. devices to equalize for differences in characteristics of the devices successively employed in the seres space current circuts por-tion of said amplifiers, and a connection from said intermediate point in each amplifier to the auxiliary grd of its respective output device to provide operating potential for said auxiliary grid.

10. A11 electric wave circuit comprising a. plurality of electron discharge devices each comprising a cathode, an anode, and an input control grid, said devices having their space current'circuits connected in series such that the space current in each device is the same, another discharge device whose space current circuit is independent of that of said plurality of devices and having a grid auxliary to its input control grid, and a connection from a point in sad series-connected devices to said auxiliary grid to provide,

operating potential for said auxiliary grid.

JOHN B. MAGGIO.

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