GB1112304A - Improvements in or relating to radio frequency devices - Google Patents

Abstract

1,112,304. Valve amplifying and oscillating circuits. TRAK MICROWAVE CORPORATION. 29 June, 1965, No. 27599/65. Headings H3F, H3R and H3W. [Also in Divisions H1 and H2] A radio frequency device having distributed constants for operation with an electron tube having anode 28, control grid 26 and cathode 24 terminals successively spaced along the tube axis, is constructed to provide an outer conductive cylinder 54, an inner conductive cylinder 88 disposed coaxially within the outer cylinder and an intermediate conductive cylinder 40 disposed coaxially between the outer and inner cylinders. The intermediate cylinder forms with outer cylinder an outer coaxial section 32 and with the inner cylinder an inner coaxial section 34 of a folded coaxial transmission line. An annular conductive wall 38 extends radially between, and conductively connects the outer and intermediate cylinders at one end thereof the two sections of the folded coaxial line being coupled in series at the end remote from the wall 38. At the opposite side of the wall 38 to the transmission line 32, 34 and coaxial therewith is a hollow conductive structure 30 forming an anode cavity resonant in a radial mode, from which energy is removed by output means comprising a coupling loop 130. The device is adapted to house the tube coaxially with the cylinders and cavity, the inner cylinder, intermediate cylinder and cavity structure having contacts 88a, 98, 108a respectively, insulated from one another and disposed for engaging cathode, control grid and anode terminals 24, 26, 28 respectively of the tube. The coupling between the two sections of the folded line comprises conductive flanges 58, 62 respectively connected to the inner and outer cylinders 88, 54, extending radially in parallel overlapping and closely spaced relation, and insulated from one another by means of a disc of insulating material 63 which may have a radial length comprising a quarter wavelength. Contact with the anode 28 of the tube is made by means of a conductive ring 108 which is bolted to, but separated by an insulating ring 113 from, the conductive plate 106 which completes the anode cavity 30. The cathode connection of the tube comprises a hollow cylinder 24 within which is a second hollow conductive cylinder 80 separated from it by a tube of insulating material 82: the filament is connected between the cylinders 24, 80, connection with the cylinder 80 being made by means of a member 90. The arrangement may be used as an oscillator, the transmission line and anode cavity being coupled together at their low potential ends by means of coupling loops 132, 134: the oscillator may be frequency modulated by means of a varactor diode (216, Fig. 4, not shown) attached to a probe which is inserted in the side wall of the outer cylinder. Alternatively the arrangement may be used as a radio frequency amplifier, in which case the coupling loops 132, 134 are omitted and an input probe is inserted in place of the varactor diode.