Gridded electron power tube

A linear beam electron tube having a longitudinal axis for use with an inductive-circuit output means, including a resonant cavity, and means providing a magnetic electron-beam focusing field, said tube comprising;

• an axially centered electron gun assembly at one end of said tube having a thermionic cathode and an anode spaced therefrom, said anode and cathod operable at a minimum several kilovolts DC electrical potential therebetween to form and accelerate along said axis an electron beam;
• axial collector means at the other end of said tube for accepting and dissipating therein the electron of said beam remaining after transit across said tube;
• axial drift tube means enclosing said beam and extending between said gun assembly and collector, said drift tube means interrupted by a gap generally intermediate said gun and collector, said gap opening into said cavity;
• an axially centered grid between said cathode and anode, closely spaced a predetermined distance from said cathode, and accepting a high-frequency control signal to density-modulate said beam, said distance being one-twentieth the diameter of said grid or less, said grid having a thickness half said distance or less, said grid defining a central active area and a peripheral support region;
• an inner grid support member apertured for passage of said beam, positioned adjacent and outwardly of said cathode, and transmitting said control signal;
• an outer grid support member positioned axially between said inner grid support member and said anode, said grid being held peripherally between said members;
• and
• a thin annular resilient conductive contact means of diameter similar to said grid peripheral support region, captured between said grid and at least one of said members, said means permitting differential expansion under heat of said members and grid without distortion of said grid while maintaining said grid accurately in said position.

A linear beam electron tube having a longitudinal axis for use with an inductive-circuit output means including a resonant cavity, and means providing an electron-beam focusing field, said tube comprising:

• an axially centered electron gun assembly at one end of said tube having a thermionic cathode and an anode spaced therefrom, said anode and cathode operable at a minimum several kilovolts DC electrical potential therebetween to form and accelerate along said axis an electron beam;
• axial collector means at the other end of said tube for accepting and dissipating therein the electrons of said beam remaining after transit across said tube;
• axial drift tube means enclosing said beam and extending between said gun assembly and collector, said drift tube means interrupted by a gap generally intermediate said gun and collector, said gap opening into said cavity;
• an axially centered grid between said cathode and anode, closely spaced a predetermined distance from said cathode, and accepting a high-frequency control signal to density-modulate said beam, said distance being one-twentieth the diameter of said grid or less, said grid having a thickness half said distance or less, said grid defining a central active area and a peripheral support region;
• an inner grid support member apertured for passage of said beam, positioned adjacent and outwardly of said cathode, and transmitting said control signal;
• an outer grid support member positioned axially between said inner grid support member and said anode, said grid being held peripherally between said members;
• said inner and outer support members defining respective first and second flat annular surfaces transverse to said axis and within which said grid is enclosed, an annular groove being defined on the of said annular surfaces;
• a thin annular conductive contact means for insertion between said grid and at least one of said members, said annular contact means being positioned within said groove so as to protrude from said one annular surface, said means permitting differential expansion under heat of said members and grid without distortion of said grid while maintaining said grid accurately in said position.

A linear beam electron tube having a longitudinal axis for use with an inductive-circuit output means including a resonant cavity, and means providing an electron-beam focusing field, said tube comprising:

• an axially centered electron gun assembly at one end of said tube having a thermionic cathode and an anode spaced therefrom, said anode and cathode operable at a minimum several kilovolts DC electrical potential therebetween to form and accelerate along said axis an electron beam;
• axial collector means at the other end of said tube for accepting and dissipating therein the electrons of said beam remaining after transit across said tube;
• axial drift tube means enclosing said beam and extending between said gun assembly and collector, said drift tube means interrupted by a gap generally intermediate said gun and collector, said gap opening into said cavity;
• an axially centered grid between said cathode and anode, closely spaced a predetermined distance from said cathode, and accepting a high-frequency control signal to density-modulate said beam, said distance being one-twentieth the diameter of said grid or less, said grid defining a central active area and a peripheral support region;
• an inner grid support member apertured for passage of said beam, positioned adjacent and outwardly of said cathode, and transmitting said control signal;
• an outer grid support member positioned axially between said inner grid support member and said anode, said grid being held peripherally between said members;
• and
• a thin annular conductive contact means comprising a metallic braid for insertion between said grid and at least one of said members, said means permitting differential expansion under heat of said members and grid without distortion of said grid while maintaining said grid accurately in said position.

A linear beam electron tube having a longitudinal axis for use with an inductive-circuit output means including a resonant cavity, and means providing an electron-beam focusing field, said tube comprising;

• an axially centered electron gun assembly at one end of said tube having a thermionic cathode and an anode spaced therefrom, said cathode defines a concave emitting surface, said anode and cathode operable at a minimum several kilovolts DC electrical potential therebetween to form and accelerate along said axis an electorn beam;
• axial drift tube means enclosing said beam and extending between said gun assembly and collector, said drift tube means interrupted by a gap generally intermediate said gun and collector, said gap opening into said cavity;
• an axially centered grid between said cathode and anode, closely spaced a predetermined distance form said cathode, and accepting a high-frequency control signal to density-modulate said beam, said grid being of a concave shape complementing said concave emitting surface, said distance being one-twentieth the diameter of said grid or less, said grid having a thickness half said distance or less, said grid defining a central active area and a peripheral support region;
• an inner grid support member apertured for passage of said beam, positioned adjacent and outwardly of said cathode, and transmitting said control signal;
• an outer grid support member positioned axially between said inner grid support member and said anode, said grid being held peripherally between said members;
• and
• a thin annular conductive contact means for insertion between said grid and at least one of said members, said means permitting differential expansion under heat of said members and grid without distortion of said grid while maintaining said grid accurately in said positon.

A grid and signal assembly for electron gun for an electron tube having a cathode and an anode, said assembly comprising:

• a control grid between said cathode and anode;
• an outer annular insulator extending at one end to said anode and having a first diameter larger than said cathode and grid;
• a generally annular grid lead having a leading end of a second diameter less than said first diameter, said grid lead being mounted at its trailing end to the other end of said insulator so as to position said leading end toward said anode, said leading end defining a first annular surface facing said anode;
• a cathode lead within and spaced from said grid lead;
• an inner annular insulator within and in spaced relationship to said grid lead intermediate said cathode lead and leading end of said grid lead;
• and mounting said cathode lead to said leading end;
• a cathode lead extension projecting axially through said inner insulator to a position adjacent said leading end, and mounting said cathode at said position;
• an annular metallic flange defining a second annular surface generally matching said first annular surface;
• and
• an annular deformable contact element of diameter less than the largest diameter of said annular surfaces, for insertion between said grid and one of said annular surfaces, and capturing said grid over its periphery between said element and the other of said annular surfaces upon said flange being mounted to said leading end of said grid lead.

In a vacuum tube modulated by a high-frequency control signal in which said tube includes an electron beam source with an accelerating electrode associated with said tube, an electron emitting cathode spaced from said accelerating electrode, and adaptable to establishment of a high DC potential therebetween in operation, and a grid between and spaced from said electrode and cathode for modulating said beam in accordance with said control signal, a wide-band signal input assembly comprising:

• annular outer insulator means having leading and trailing end portions, said leading end portion being sealed to said electrode;
• annular electrically conductive grid lead means having a trailing end portion sealingly mounted to said insulator means trailing end portion, and a leading end portion extending toward said electrode within and spaced from said annular insulator means, and spaced from said electrode, said grid being mounted to said leading end portion of said grid lead means;
• electrically conductive cathode lead means positioned within and in spaced relationship to said grid lead means;
• inner insulator means mounting said cathode lead means to said grid lead means, and said cathode lead means mounting said cathode adjacent said grid;
• said cathode lead means having a trailing end recessed substantially closer to said electrode than is said trailing end of said grid lead means;
• and grid support means associated with the leading end of said grid lead means for resiliently and accurately holding said grid in close predetermined spacing to said cathode, said grid being mounted to said leading end of said grid lead means in good electrical contact thereto between said end and said electrode;
• said grid support means including an annular metallic member of substantially smaller axial depth than said grid lead means, said member and the leading end of said grid lead means defining opposable annular surfaces, said support means further including an annular resilient member, said resilient member being of a diameter less than the largest diameter of said opposable annular surface, said grid being captured adjacent the periphery thereof between one of said annular surfaces and said resilient member, said resilient member further bearing on the other of said annular surfaces.

In a vacuum tube modulated by a high-frequency control signal in which said tube includes an electron beam source with an accelerating electrode associated with said tube, an electron emitting cathode spaced form said accelerating electrode, and adaptable to establishment of a high DC potential therebetween in operation, and a grid between and spaced form said electrode and cathode for modulating said beam in accordance with said control signal, a wide-band signal input assembly comprising:

• annular outer insulator means having leading and trailing end portions, said leading end portion being sealed to said electrode;
• annular electrically conductive grid lead means having a trailing end portion sealingly mounted to said insulator means trailing end portion, and a leading end portion extending toward said electrode within and spaced from said annular insulator means, and spaced from said electrode, said grid being mounted to said leading end portion of said grid lead means;
• electrically conductive cathode lead means positioned within and in spaced relationship to said grid lead means;
• inner insulator means mounting said cathode lead means to said grid lead means, and said cathode lead means mounting said cathode adjacent said grid;
• said cathode lead means having a trailing end recessed substantially closer to said electrode than is said trailing end of said grid lead means;
• and grid support means associated with the leading end of said grid lead means for resiliently and accurately holding said grid in close predetermined spacing to said cathode, said grid being mounted to said leading end of said grid lead means in good electrical contact thereto between said end and said electrode;
• said grid support mean including an annular metallic member of substantially smaller axial depth than said grid lead means, said member and the leading end of said grid lead means defining opposable annular surfaces, said support means further including an annular resilient member, said grid being captured adjacent the periphery thereof between one of said annular surfaces and said resilient member, said resilient member further bearing on the other of said annular surfaces;
• said one of said annular surfaces having defined therein a groove, said groove receiving said resilient member.

A linear-beam electron tube for use with a resonant cavity means for extracting output power, said tube comprising:

• a relatively flat cathode;
• a grid to enable density-modulation of said beam by a control signal, said grid being of a heat resistant carbon material closely spaced a predetermined distance form said cathode;
• a hollow anode;
• a drift tube for containing said linear beam of electrons, said tube having defined therein a gap;
• said resonant cavity being positioned about said drift tube and being connected tosaid tube on both sides of said gap;
• said drift tube being of relatively uniform internal diameter from said anode at least past said gap, and being elongated relative to said internal diameter;
• means for sustaining an axial magnetic field for focusing a uniform beam of electrons from said cathode at least through said gap;
• and
• a collector downstream of said cavity, and enlarged in diameter relative to said drift tube.

A gun for generating a density-modulated linear beam of electrons comprising:

• a thermionic cathode with a flat emissive surface;
• a radiant heater facing said cathode on the side opposite said emissive surface;
• a flat grid of heat-resistant carbon material;
• and
• means for maintaining said grid parallel to and at a closely spaced predetermined distance from said emissive surface, including
• a pair of annular grid supports, each with an aperture at least as large as said emissive surface, a first of said supports having a flat face in contact with a first side of the peripheral region of said grid;
• a second, conductive support having a side facing the second side of said peripheral region and spaced therefrom;
• a deformable conductive means compressed between said second, conductive, annular support and said peripheral region of said grid whereby said peripheral region can slide over said first support;
• and
• means for mounting said cathode and said grid supports in fixed insulated relation.