US1579930A - Radiotransmitter - Google Patents

Description

April 6 1926. 1,579,930

A. HADDOCK RADIOTRANSMITTER Filed Sept. 28, 1923 Ilel 'f ya circuit.

Patented Apr. 6, 1926.

PATENT ,g

mTiU/nmmoox, 59N EAST QRANGE, NEW y,J-Ensntr, AssIeNoR To' wnsrnnNnLEc- .Tmc icoMPArNY, .JzNoonneRA'nnn ler NEW ,-YoR'K, N. Y., A yoom?omyrroN orNnW YORK.

To all 'fwfzomdt mcg-y concern.: u l

.l3e it known that Z-XR'THUR HADDOCK, l'a citizenv ot 'the UnitedStates of America., 'rejsiding at East "Orange, in the .Count-y 'of Essex .and State of New Tersey, have in;- Vented certain. new and useful improvements` in Radiotransmitters, of which the following is'a full, clear, concise, and lexact description. l

The present invention relates to 'high voltage transmission and particularly to high voltage radio 'transmission In radio ztransmitters for long .distance transmission it is not .uncommon t'or the high frequencyy energy developed in the). antema to vamount lto several kilowatts A'The capacity and "inductance 4off an antenna'are generally .of such "an order of magnitude that the voltages developed at this `energgy are very high and may frequently amount -`to 50,000 volts or more. j

In any practicalfsystem fit bis Vd'esiiable to cha-nge the connections of `the` circuits lassociated With theiosoillation Acircuit iorshi'i-ting the Wavelength, varying fthe coupling, or otherwise adjusting the 'setof different conditions. Il 'these .changes vare made.dur'-` ing operation o'ftheset, as is frequently desirable or` necejssa.ry`switching. arrangements must 'be vprovided ivliich will inet only y-eiect the required A'circuit ich'ange's Ahut which -will operate at the'ligh voltgesipresentrin the fit ijs. an abject Lofthe Yein-vennon to ferrea circuit :changes in "fa high' voltage t-os eill ation circuit with ease 'and with "safety, andin an efficient manner. p The variou'sauxiliary object'sandithe dilierent i'eatures oit `the invention vvillhe clear from the ZVfollowing 'detailed description V'in connection AWitlrthe accompany-ing draw-ing, in which Fig. l-lshows a plan vview,partlyfin section, 'of the switching structure -otitlfie invention `-and` Fig, ',2 is a schematic -representation in "simplified form fof 'a typeoi circuit to lwhich -the @switching mean-'si is lap- 'plicable "Briefly and "specifically, the-invention `provides ay 'plurality of switches' mechanically `connected sol as tofbe actuated rom la comm'on Wheel I'or lever. In the case oi each farm. Preferably, :the farm itseli1 fis noncon'ductingqbut Jcaiirifes at itseeid Ea. sh-'ort bridging Vmember,` of 'conducting' mateiiial which Wipes l-over contacts vbetween which connections are to he made. The mechanical driving Vconnection "between the separate switches isgrounded a plurality 'of Vpoints tofprevent the Vdevelopment of vhigh voltages in it with consequent heating. yContact madeonly to the centers of the v'terminal leon tacts which are of relatively large 4surface and are of kthe lproper curvature to frelieve the strain on lthe insulators. The entire structure Iis enclosed Within fa vground-ed shield. s

*ItNvill aid-'in the'descriptiono'f the various features illust-rated in Fig. l to `refer first 5to Vthejcirrcuit diagram 'of 2. In this --latter figure the antenna circuit coinpriscsthe-aerial l, the linductance 22, an'dfone or :more of the capacities z3, vv'hich may he connected finto the 4eircuitas desired. As "is Well :known the aerial has capacity to ground `so that lth'e circuit l, i2, ground, comprises `an oscillation circuit. Enfergyis supplied to lthis oscillation circuit from the vacuunrtube l iWhie-h has its cathode connected to ground and `its anode and grid connected to different points on the indue tance 12. This manner of connectionis-coin- -m'only lknovfii as thefGolpittis type of connection. Y y

Vliitlii's type -fo'f connection-'it is-n'ecessary or 'desirable `in a --pra.ctical 'lins'tsrfllation 'to ya y 4the j oint-,of connection'of-the aerial l to "the inductance 2 and ia'lsorto vary 'the points iet connection #of i the anode and v,gg-rid o'thfe-tube 4 to theinductance 2 a'nd to Vcon-e neet r` 'different ones lof the capacities f3 into the ici-rcut. "These changes controlboth `the naturaljperiod of the antenna circuit. andthe coupling between 'the vtube 4 andA the antenna circuit. This general arrangement of circuit Aandmea'ns vvfor eiiectinp,` the lcircuit changes are disclosed. in *U.\S. :patent'pto Clement -1,f395,390,jdated 4Noveinlier '1, :1921, to which .reference may/be made fora -ullerdisclosurefo'ff'the .pun-pose and .eiectfoi the circuit changes, fthe'present invention having to do ivith 4the arrangement fior .producing these circuit changes in an installation utilizing high power 'and in which very high voltages -existvbetween points in the circuit.

The switching, arrangementswith which ytheinvention 1s particularly concerned are ithose diagramm atically indicated, in Fig., 2,

at iand :at f6, respectively.

Referring now to Fig. 1 the inductance 2 is slrown in the form of a tubing preferably of copper wound on the insulating posts 7 which may be of porcelain or any other suitable material. The switch 5 is shown in this ligure below the inductance 2 and the switch 6 is shown to the right of the inductance 2.

F or convenience in the description the switch 5 will be designated the inductancechange switch and the switch 6 the capacitychange switch, although this is not to be taken as accurately characterizing the functions which these switches are to perform.

The inductance 2, and the switches 5 and 6 together with the major portion of their driving mechanisms, are enclosed within the metallic casing 8 which is preferably of sheet copper. The condensers, the tube 4 and other portions of the circuit may be contained in the same enclosure or in a separate enclosure. The enclosure or shield 8 is preferably faced by a sheet 9 of micarta or other suitable insulating material.

The control wheel 10, mounted outside of the shield, serves to actuate both switches 5 and 6 through suitable driving mechanism which will be explained hereinafter. The shaft of this wheel extends through the casing and has fixed to it the driving pinion 11 and the high voltage insulator 12. This shaft passes through a bearing member 13 which is provided with a double ball race 14, 15 which permits of easy rotation of the shaft and which acts both as a thrust bearing and as al rotary bearing for the shaft. The bearing member 13 may be enclosed in a suitably fashioned index pointer 16 which is secured to the shaft and is adapted to move over a scale on the front of the panel 9.

vSecured to the ends of the insulator 12 opposite the controlwheel isa switch arm 17 preferably of micarta and provided with a'stiffening rib as shown. Thisswitch arm supports at each end the respective brushes 18 and 19 which uponmovement of the wheel 10 are adapted to wipe over the contact ring 2O and a row of contacts 21 arranged m the arc of the circle as shown 1n Fig. 2.

Each of the contact terminals 21 comprises a metal cap mounted on the end of a high voltage insulator 22. This cap is cup-shaped and Vsuitably curved to relieve -undue strain on the insulator 22 due to high voltages existing across it. Connection is made from the individual terminals 21 to desired points in the inductance coil 2, one such connection being indicated at 23. This connection may consist of a copper rod inserted into a hole drilled in the terminal 21, the rod being clamped by a screw or otherwise held fast. The contact ring 20 (which in reality is divided into segments as shown in Fig. 2) is channel shaped and its section resembles that of the terminal caps 21, the curvature being for the purpose of relieving the high Uvolta-ge strains, as explained above.

VAs is seen from Fig. 2 the capacity change switch is located nearer the earth terminal than is the inductance change switchv 5 so that the Yvoltages across the terminals of this switch are not as high as those at which switch 5 operates and the insulation can, therefore, be somewhat less. 1n the case of the switch 6 the switch arm 25 is shown as metallic and is supported by insulators 26 from the sprocket 27. The sprocket is mounted for free rotation on the stub shaft 28 which is secured to the shieldingl 8. The switch arm 25 carries at one end a brush member 29 which is adapted to sweep over the contact terminals 30 and at its other end carries a single brush 31 adapted to wipe the individual contacts 32. Since lower voltages are dealt with in this switch and lower insulation is required, the leads from contacts 30 and 31 may extend through'the insulators as shown. The grid connection is made to a ring 33 mounted on the micarta support 34. Brush 35 secured to the arm 25 makes contact with the ring 33 which is preferably split to prevent aifording a closed circuit in which comparatively heavy current may be induced.

The sprocket 27 is driven by means of a chain 36 which passes around a sprocket 37 secured to the shaft 3S, this shaft being driven by pinion 39 from pinion 11.

It will be noted that the shaft 38 has a bearing near each end secured to the shield sie 8. The shaft 28 carrying the sprocket 27 is also secured to the shield 8. Since this shieldis of highly conducting material and all of the driving mechanism from the pinion 11 to the sprocket 27 is shunted by the shielding, no high voltages are set up in the driving mechanism. If this were not the case, excessive heating might be produced in the driving mechanism which is usually composed of iron or steel.

In operation, the connections from the inductance 2 and the condensers 3 will be brought out to terminals, as explained in Clements patent, cited, in such manner that corresponding wave length and coupling changes are simultaneously made and that for each new wave length the proper coupling is produced for the best operation of the circuit. The ratios between the pinions 11 and 39 and the sprockets 37 and 27 and also the spacing between the various terminals will be made such that as brushes 18 and 19 are moved from one terminal 21 to the next, corresponding circuit changes will be effected between the brushes 29 and 31 and their respective terminals 30 and 32. The wheel 10, the casing 8 and the driving mechanism are all at ground potential so that adjustments of the set may be made with safety although it is in the energized condition. Furthermore, the physical connection between the control wheel and the terminals 2O and 21 carrying the highest voltage consists of the insulating bar 17 and the insulator 12 in series.

By providing the relatively short contact members 18 and 19 not only is the insulation between the terminals 2O and 21 and the control wheel 10 increased, but the contact ring 2() can by this manner of construction be divided into segments which are convenient for wiring. The contact members oi brushes 18 and 19 preferably bear at only the center portion of the contact members 2O and 21.

I claim:

1. In a wave change switch, a plurality of terminals arranged in an arc of Va circle, a contact ring concentric therewith, each terminal comprising a metal cap supported on a separate high-voltage insulator, connections from the caps kdirectly to respective points in an oscillation circuit, said ring being supported on high voltage insulators, a connection from said ring to another circuit, a control post rotatably mounted concentric with said ring and terminals, a bar supported from said control post on a high voltage insulator, and a bridging contact member supported on said bar and adapted to wipe over said contact ring and -said terminals.

2. In a wave change switch, an oscillation circuit containing an inductance coil adapted to carry high voltage, a pair of Vcircuits arranged for connection to different points of said coil, a switch for each circuit arranged to change the oint of connection between the respective circuit and said coil, a common driving means for both of said switches comprising a metallic mechanical connection between them, and a metallic shield of high conductivity, coiiductively connected to said driving connection at two points situated near the respective ends of the driving connection to reduce the heating vof the driving connection due to its coupling with said oscillation circuit.

3. In a high voltage switch, a plurality of i curved exterior surface, said contact ring comprising a channel-shaped member with its' shortest cross-section 'concave on the sidev next to the insulator, and curved on its eX- terior side, and a bridging contact member having its endsarranged to wipe along the centers of the terminal caps and along the median line of said ring respectively.

4. In a wave change switch, an oscillation circuit having a portion of its elements enclosed in a metallic shield, a pair of circuits adapted for connection to different points in said oscillatory circuit, a pair of switches, each for connecting adilferent one of said pair of circuits to the oscillatory circuit, said switches comprising each a movable brush arranged to wipe over terminals permanently connected to points in the oscillation circuit, a mechanical driving connectionV between said brushes and insulated from the brushes, said driving connection being conductively connected to said shield at points near the respective ends of the driving connection.

-5. In a wave change switch, an oscillation circuit comprising an inductance, sets of terminals permanently connected to points in said inductance, energizing means for said circuit whereby voltage differences are set up between said sets of terminals of the order l ARTHUR HADDocK.

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