US1988270A - Telegraphic transmitter - Google Patents

Description

Jan- 15, 935- H. R. FISCHER ET AL TELEGRAPHIC TRANSMITTER Filed Aug. 3, 1952 fzzVmfazzst' Hans Fuaaf/Zscfier and Faber/flerzay 5y W Patented Jan. 15, 1935 ED f STATE V L G HE T'KA W'E'TFR ns d Fis h r Be l n-.Temndm and Robertll ei Berli Ge manmess' norsw Lorcnz A en ihaf fBarlin-Tempel hof, 'Ger1 nany, 'a company nn i atm Au ustfi; 932,--Sezia1 Nq. 627,35

In; G man ugus e 19, 1

' i 1' Claims wl-ygoem invention relates: .to telegraphic valve transmitters and'moreparticularly toixthe keying-devices therefor, andit has for its object to keep the frequency constant;

' i i This frequency in the case ofv transmitters for shorter ultrashort waves largely depends upon thesignaling speed. This is due to the anode plates of the valves being subjected to. different degreesof temperature during the marking and. spacing periods. The varying temperature causes physical distortion of the plateswith the result that the inter-electrode capacity of the valves is'chan'ged. The shorter the wave length the :greater is the influence. of the inter-electro'de: capacity of the valves on the tuning of the..oscillatory circuits of the transmitters, and thegreater are thus the-variations in frequency.

According to the invention, the thermal effect. onv the anode plate is equalized. .To such end; the continuousanodecurrent that flows at the pauses of keying may be-caus'ed to be equal, or nearly so, to the alternating anode current which. flows during a sign being given.

Other features will appear fromthe following description and be-particularly pointed outin the:appendedclaims-deference being had to thewacc'ompanyingdrawing in Fig'. 1 0i which one embodim'ent of the invention is-shown dia-' grammatically by way of example, andin Fig. 280iwhich is shown an arrangement .for short circuiting the oscillatory circuitwhich may be employed instead of -the grounding arrangement of Fi .1. I

vReferring-to Fig. 1, -B denotes the antenna, S. "the oscillatory circuit comprising inductance 5. and variable condenser 6, R the valve, W1 arresistance, W2 a second resistance, P a poten-' tiometer, R1 a relay,-R2 .a second relayjv the source of.;biasing potential, Afithe source of anode potential, and T the signalling key 0011-. nected witha source of current so as to control ihwp za q of la s ;R.- an R12- T e pa ts a $=Q1 1 Qt in h an e th w pea from the. drawing, so that relays R1 and R 2 are. alternately energizedby manipulation of signalling ,key I to cause the alternate generae ti 0n and non-generation of'oscillations by the tube R during marking and spacing periods, r sp vel Theapparatus of Fig. 1 is shown inthe positiOnofproducingand sending a marking signal. ,this position the left lcontact ,of :key T is lqsedk 3- izin l 2. the b on e n esi tanc WH t ti met ef el witlrresistance W2 "to decrease the negative polarizing potential on the: grid; of-valve or tube R. duringithe-n'iarking period. The connection of resistance W1 to the potentiometer P "has the same efiect as moving the" point-of Iconnectiorryof: resistance 'W2 on' the potentiometer P to the left would'have} namely, t'o deoreasethe negative polarizing potential on the grid. While key T is thus infmarking 'posi tioi1;its right contact" is open and relay RI is-' d'e energized so that;the :high frequency: grounding connectionfor 'the. oscillatory' circuit Sth'rough resistance W3i-and condenser F 'is'open atthe contact of relay-R 1. The valve or tube-B, withits circuits, is novv so connected- 'as' to produce oscillations which are impressed. through 'the transformer onto the antenna B. When a spacing signalis to be sent, signalling key I is manipulated so as. to openiits leften'd close its: right contact. Thereu'p'on, relay- B2 releases and relay Rl energize'si" The releaseof relay R2 aisco'nneets resistance Wl' from the potentiometer 'P," tlierby increasing the'negefi tiv'e polari'zirig"potential on the grid of? tubeR during 'thf'spacin'g period; Energization'of r lay R11- TclOs's lts'floofitact' completing the high frequency groundeonnection 'for the oscillatorycircuit S. Tliere the g eneI-a/tion f '0sci1-'- lations ceases? Howeveffi'the source of anode potential A remains cor-inee't'ed' tothe anode or tube R. Therefore; unress proper provision-is made,"me increased new be spacedur'rem during spacing p'eribds would causethe temperature of the tube 33. to 'be-greater diiring sipacing 'than veh'lth'at 'atthe'flb inning of thespacii1gperiod the negative pelanziiig pbteht iaL the grid. (if tube Rf"-ha'sbeen ificreasedi Th1 sufilcient to prevent lfl he rise ili' space'curi ent in other words; the T res i s't'ances' -W1 arfd -W2 I are "so proportioned withrespected thepotenti ome'te'r' Fahd SOtlI-C V 'th t the tiital-ifiow of current- 111 the an" cmt mg' markingand spacing period's 's b'stantiaillyi constant;

tube remains whereby th'e temprature (if-it otfs'.ltlias beenseen; how I Y increase is substituted, in Fig. 1, for the apparatus located within the dotted enclosure. With such substitution the operation of the sending arrange- 5 ment is the same as above described in connection with Fig. 1, with the, same results realized.

The grid currents that arise on the oscillations starting cause the grid to get hot so' as to give rise to the same phenomena as described advantageous also to operate by 'meansof grid currents which are as small as possible. This is accomplished by making the resistanceof W1 and W2 of the order of 10,000 ohms. The loss pensated by increasing the anode potential.

ed as here described, during a keying pause that lasted 5 minutes and with a 13 meters wave a.

frequency variation of only 500 cycles occurred, that is a value not obtained hitherto insimple transmitters without. the aid.of artificiallconnections. .1

Changes may be made within the scope indicated by the appended claims, without departing from the idea of the invention.

What is claimed is:.

1. In a telegraphic transmitter, the combination of a thermionic valve, cathode, grid and anode, a source of space current connected to the anode, an oscillatory circuit, a. signalling key for producing marking and spacing signals, means controlled by the key when in marking position ,to so relate the oscillatory circuit with 'the, valve as to cause the generation of oscillations, and means under control of said key for maintaining a constant thermal effect on the anode duringspacing andmarking periods.

2, In a telegraphic transmitter, the combinationof a thermionic valve, cathode, grid and anode, .a source of space current connected to the anode, an oscillatory circuit, a signalling key for producing marking and spacing signals, means controlled by the key when in marking position to so relate the oscillatory circuit with the valve as to cause the generation of oscillations, and means undencpntrol of said key for making the continuous anode current during spacing periods equal to the alternating anode current during marking periods. v

. 3.;In a telegraphic transmitter, the combination of a, thermionic three-electrode valve, cathode, grid and anode, a source of space current connected to theanode, an oscillatory circuit, asignalling key for producing marking and. spacing signals, means controlled by the key when in marking position to so relate, the oscillatory circuit with thevalve as to cause the generation of oscillations, and means under control of said key for so altering the grid potential thereof as to make the continuous anode current during spacing periods equal to the alternating anode current during marking'periods.

4. In a telegraphic transmitter, the combination of a thermionic three-electrode valve having cathode, grid and anode,-a source of space current connected to said anode, an oscillatory circuit coupled to said valve, a signalling key for producing marking and spacing signals, means for short-circuiting such, oscillatory circuit during spacing periods, and means for increasing the negative grid polarizing potential applied to the grid during spacing periods, both these means being operable conjointly under control of sai k with respect to the anode plate. It is, therefore,

in output brought about thereby can be com-- 1,988,270 I arrangement is shown in Fig. 2 which may be 5. In a telegraphic transmitter, the combination of a thermionic three-electrode valvehaving cathode, grid and anode, a source of space current connected to said anode, a source of polarizing potential connected to said grid,v an oscillatory circuit coupled to said valve, means for earthing such oscillatory circuit during spacing periods, and means forincreasing the negative polarizing potential applied to said grid during spacing periods, both these means being operable conjointly under control of said key.

6. In a telegraph transmitter, the combination of a thermionic tube having cathode, grid and anode, a source; of space current connected to U the anode, anj oscillatory circuit, a signalling key for providing marking and spacing signals,

means for applying a polarizing potential to said grid, means controlled by said key for causing an efiective connection of said oscillatory circuit to said tube during marking periods whereby during said periods oscillations are generated, and means controlled by said key during spacing intervals for causing said tube .to cease generation of oscillations and for so altering the polar-. izing potential applied to said grid that the anode current during spacing periods is maintained atsubstantially the same value as during marking periods.

7. In a telegraphic transmitter, the combination of a thermionic tube having cathode, grid and anode electrodes, a source of space current connected to the anode, anoscillatory circuit, means for connecting, said circuit to the electrodesof said tube whereby oscillations are generated, a signalling key for providing spacing and marking signals, means controlled bysaid key for causing the tube to generate oscillations during marking periods, and means responsive to manipulation of the key .from marking to spacing position to establish a path from said cathode to said grid external to said tube thereby causing said tube to cease generation of oscillations whilst, maintainingv said-v space current source connected to said anode. a

8. In a telegraphic transmitter, the combination of a thermionic tube. having a grounded cathode, agrid and an anode, a source of space current connected to the anode,,an oscillatory circuit, means for connecting said circuit to the cathode, grid and anode of said tube whereby oscillations are generated, a signalling key for providing spacing and marking signals, means controlled by said key for causing the, tube. to generate oscillations during marking periods, and means responsive to .manipulation of the key from marking to spacing position to establish a path from. said oscillatory circuit to ground whereby generation, of oscillations ceases whilst maintaining said space current sourc connected to said anode. l r

9. In a telegraphic transmitter, the combination of a thermionic tube having cathode, grid and anode, a sourceof space current connected to the anode, an oscillatory circuit, means for connecting said circuit to the cathode, grid and anodeof said tube whereby oscillations are generated, a signalling key for providing spacing and marking signals, means controlled by said key for causing the tubetogenerate oscillations during marking periods, and means responsive to the manipulation of the key from marking to spacing position to shortcircuit said oscillatory circuit, thereby to cause a cessation of the generation of oscillations during spacing periods whilst maintaining said space current source connected to said anode.

10. In a telegraphic transmitter, the combination of a thermionic tube having cathode, grid and anode, a source of space current connected to the anode, means for negatively polarizing said grid, an oscillatory circuit, means for connecting said circuit to the cathode, grid and anode of said tube whereby oscillations are generated, a signalling key for providing spacing and marking signals, means controlled by said key for causing the'tube to generate oscillations during marking periods, and means responsive to manipulation of the key from marking to spacing position to cause the tube to cease generation of oscillations and for so increasing negatively the polarization potential applied to said grid that the anode current during spacing periods is maintained at substantially the same

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