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Topic: Screen grid

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	Screen grid - Wikipedia, the free encyclopedia
		The screen grid is a grid introduced into a thermionic valve or tube to greatly reduce the capacitance between two other parts of the electrode structure.
		The screen grid is usually connected to the high voltage anode supply via a resistor and is bypassed by a suitable capacitor to earth (ground).
		This A.C. grounding of the screen grid causes it to act as an electrostatic shield between the control grid and the anode, reducing the capacitance between those two electrodes to near zero.
	en.wikipedia.org /wiki/Screen_grid (312 words)

	Control grid - Wikipedia, the free encyclopedia
		The control grid is an electrode used in thermionic valves (vacuum tubes) used to modulate the flow of electrons in the cathode to anode or plate circuit.
		This is often exploited in R.F. amplifiers where an alteration of the grid bias changes the mu and hence the gain of the device.
		One of the principal limitations of the triode valve is that there is a significant capacitance between the grid and the anode (known as the Miller effect).
	en.wikipedia.org /wiki/Control_grid (503 words)

	Screen Driven, DC Coupled, Single-ended EL509 Amp (Site not responding. Last check: 2007-10-09)
		In this arrangement the audio signal is applied to the screen grid (g2 or "screen", for short) instead of the Control Grid (g1 or "grid" for short).
		Screen drive is generally much more linear than standard tetrode or pentode operation; such that lower levels of feedback are required.
		Screen bias curves (plate curves for a fixed grid bias and various screen voltages) are generally not published.
	www.geocities.com /bobdanielak/technoteNo33.html (1787 words)

	[No title] (Site not responding. Last check: 2007-10-09)
		Adjustment of the rf grid voltage to obtain the specified plate current at the specified bias, screen and plate voltages is assumed.
		The grid and screen currents which result when the desired plate current is obtained are incidental and vary from tube to tube.
		The product of the peak screen voltage It is good engineering practice to provide indiv- and the indicated dc screen current approximates idual metering and individual adjustment of bias the screen input power except when the screen or screen voltage to equalize the inputs.
	www.triodeel.com /4cx250.txt (2437 words)

	BeeSource.com \| Plans \| TRAPPING POLLEN FROM HONEY BEE COLONIES
		Pollen trapping is dependent on the use of a screen or perforated metal grid of about 5-mesh per inch through which the pollen-collecting field bees are forced to enter the colony.
		When passing through this grid, most of the pollen pellets are dislodged from the hind-legs of the returning bees and fall into a tray covered by screen (7- or 8- mesh) that allows the pollen pellets to pass but not the bees.
		When the trap is installed on the colony, the screen grid should be removed for at least 2 days to permit the bees to become accustomed to entering the hive through the trap.
	www.beesource.com /plans/pollentrap.htm (2966 words)

	Class A, AB & C Operation of Tetrode Single-Ended RF Amplifiers (Site not responding. Last check: 2007-10-09)
		The part of the cycle during which anode current flows is known as the 'operating angle.' This depends on the screen-grid-to-control-grid amplification factor, on grid DC bias, on the DC screen voltage and on the amplitude of RF grid drive volts.
		Screen Mu is approximately the +ve DC screen voltage divided by the -ve DC grid voltage needed just to cut off cathode current.
		Grid current through this resistor automatically provides the required -ve grid bias when the tube is used in CW non-linear conditions, or as an oscillator, or as an anode modulated amplifier.
	www.smeter.net /amplifiers/tetrode1.php (1121 words)

	Picture tube screen grid potential control - Patent 4692669
		A transistor with its collector connected to a point near the screen grid in the resistor network which feeds voltage from the high voltage rectifier of a picture tube to the screen grid electrode and its emitter connected to ground has two control circuits connected to its base electrode.
		In the screen grid voltage adjustment of the kind mentioned in the introduction to this specification, performed with a potentiometer, the variation of the screen grid voltage is carried out directly at the top of the potentiometer, therefore at a very high electric potential.
		The adjustable screen grid voltage U.sub.G2 is produced by rectification of horizontal pulses 18 by means of a diode 44 which operates in connection with a capacitance 46 and a series resistance 48.
	www.freepatentsonline.com /4692669.html (2967 words)

	Screen grid - Wikipedia, the free encyclopedia
		If the screen heats up enough, it can melt and damage the tube.
		Indeed, as the secondary emission increases, the actual anode current can decrease, giving the tetrode valve a distinctive negative resistance characteristic, sometimes called "tetrode kink".
		More than one screen grid can be present.
	www.wikipedia.org /wiki/Screen_grid (312 words)

	Electronics 27
		Grid bias was required, to hold the grids negative, demanding low voltages at small currents, and the corresponding battery was the C battery.
		The screen grid is usually bypassed to ground by a capacitor, whose reactance at the lower corner frequency should be smaller than the resistance connecting the screen grid to B+.
		The suppressor grid, when connected to the cathode, does indeed send secondary electrons back to the plate, but it is evident that it also affects the distribution of the cathode current between plate and screen, and the effect of secondary electrons is not as great as it may seem.
	www.du.edu /~etuttle/electron/elect27.htm (23318 words)

	Manipulating Widgets (Using the Editors)
		A grid unit is based on the average character size of the screen font.
		Grid units and characters are the most portable units of measure, since they are sensitive to the font in use.
		Grid Align, widgets align at their anchor specification along the nearest grid coordinate (refer to "How to Position a Widget on a Grid Coordinate" for more information).
	www.prolifics.com /docs/panther/html/eds_html/mwidgets.htm (3768 words)

	Cooling structure for a screen grid electron tube such as a transmitter tetrode - Patent 4779022
		The terminal of the screen grid 5 is composed of two annular screen grid terminal elements in the form of contact rings 1 and 2 which are spaced from each other in the axial direction.
		The annular screen grid terminal elements 1 and 2 are formed of a metal or alloy having high thermal conductivity and is preferably copper.
		The screen grid 5 is connected to the second bushing or washer-shaped element 4 by means of a screw 9.
	www.freepatentsonline.com /4779022.html (1388 words)

	Improved vacuum tube models for SPICE, Part 1
		Screen current is not as critical to the tube performance as plate current.
		Grid current flows in class AB push-pull amplifiers, but doesn't need to be modeled precisely because it does not contribute to the output signal.
		Plate curves (plate current as a function of plate voltage for a set of grid voltages) may be obtained by running one of four files in the tube models file, which can be downloaded by shift-clicking on Tubemods.zip.
	www.normankoren.com /Audio/Tubemodspice_article.html (4299 words)

	Screen grid -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-09)
		This acceleration is sufficient to cause (The emission of electrons from a surface that is bombarded by higher energy primary electrons) secondary emission from the anode's surface.
		Indeed, as the secondary emission increases, the actual anode current can decrease, giving the tetrode valve a distinctive (additional info and facts about negative resistance) negative resistance characteristic, sometimes called "tetrode kink".
		The secondary emission can be overcome by adding a (additional info and facts about suppressor grid) suppressor grid or even (additional info and facts about beam plates) beam plates to make repectively, a (A thermionic tube having five electrodes) pentode or a (additional info and facts about beam tetrode) beam tetrode.
	www.absoluteastronomy.com /encyclopedia/s/sc/screen_grid.htm (351 words)

	The AA8V/W8EXI 6CL6 One-Tube Transmitter - Schematic Diagrams and Circuit Descriptions (Site not responding. Last check: 2007-10-09)
		In this circuit the cathode is grounded and the screen grid of the tube is being used as the plate.
		In summary: The screen grid, control grid, and cathode are used as a grounded screen (plate) crystal oscillator, while the cathode, control grid, and real plate are used as an amplifier.
		In this circuit, the.005uf screen bypass capacitor is essentially a short circuit for RF, and thus the 220pf capacitor is essentially connected between the screen (oscillator plate) and cathode of the tube.
	faculty.frostburg.edu /phys/latta/ee/6cl6xmtr/6cl6schematic.html (1883 words)

	Eimac Care and Feeding of Power Grid Tubes (Site not responding. Last check: 2007-10-09)
		The third grid, the suppressor grid, is mounted in the region between the screen grid and the anode.
		Since the suppressor grid reduces the effects of secondary emission, screen grid power supply requirement to provide a reverse electron flow path may be reduced.
		The screen current requirement for a pentode may be somewhat higher than that for a tetrode of the same general characteristics; control grid power supply requirements will be the same as outlined for tetrodes.
	www.cpii.com /eimac/sec2-3.htm (295 words)

	SM 5 BSZ - A grid circuit for QBL5/3500 (Site not responding. Last check: 2007-10-09)
		The tube is pressed against the anode connector by the screen grid connector which is the circular copper sheet surrounding the tube.
		the screen grid capacitor is a copper plate with grounded aluminium plates on each side isolated by 0.5mm polypropylene.
		The distance from the screen grid to the end of the capacitor plate should be about a quarter of a wavelength to form efficient grounding of the screen grid by a series resonance.
	www.nitehawk.com /sm5bsz/qblg1.htm (727 words)

	KD5FZX GS-15B PAs
		If the grid cage and the screen cage windows are perfectly lined up the resulting screen current will be very low and stability improved.
		A tube that shows high grid and screen current doesn't have the grid & screen cage windows perfectly lined up and some accelerated electrons hit the screen instead of passing through the window.
		A tube that responds well to drive and has normal grid and screen current but low efficiency probably has a small variation in the distance between the elements around the circle.
	www.nd2x.net /KD5FZX.html (1123 words)

	Non-Colliding Concept (Site not responding. Last check: 2007-10-09)
		This grid is used to control the placement of projected artworks.
		Should the user then enter the Floor Grid and step on an illuminated grid space, the piece in the corresponding On-screen Grid space will "grow" or "enlarge" to its Presentation Size in the manner described by the Behavior Rules.
		This action would send the piece swooshing across the On-screen Grid in the direction of the touch screens (Ritsu's use of flashing is, in my opinion, a much more appealing effect and could be implemented here).
	a.parsons.edu /~mr/classwork/netspace/noncolliding.html (610 words)

	[No title] (Site not responding. Last check: 2007-10-09)
		By construction, a tube's control grid exerts more control over its electron stream than its screen; the control grid closer to the cathode than the screen and often made of finer wire.
		Because of this, severe grid* overdrive will likely result* if the control grid and screen are merely tied together for RF and dc.
		In this situation, the screen operates at the same dc potential as the grid and therefore doesn't draw electrons past and away from the grid as it does when it's significantly more positive than the grid.
	www.arrl.org /files/infoserv/tech/tubefaq.txt (686 words)

	Grid Based Game Design
		Grid Based Design or GBD is simply a system for making sure that the Player Character, Non-Player Characters, and all other elements of game play are controlled, laid out, and moved around based on a predefined screen or 3D grid.
		Based on this grid system, the Player Character, Non-Player Characters and all other items in the game are positioned and moved around based on this grid.
		Grid Paper recommended for maps is 8x8 squares per inch grid paper.
	www.gignews.com /gridbased.htm (1874 words)

	Translation for "Memory Buffer" "on screen grid" - WordReference Forums
		About "on-screen grid", "grid" could be "grilla" o "cuadrícula".
		These are used for example in graphical softwares for the reference grid, snap to the grid, etc...
		"On-screen" pordría ser "de la pantalla" (of the screen), "en la pantalla" (in the screen), "que se ve en pantalla" (seen on the screen) o "que aparece en pantalla" (that gets displayed on the screen).
	forum.wordreference.com /showthread.php?t=296 (610 words)

	[No title] (Site not responding. Last check: 2007-10-09)
		The proposed financial statements and resulting GRID Screens were based upon 1994 Microsoft Word form utilized by the NAIC in collecting data on receiverships.
		The GRID Technical Group also discussed and acknowledged the extremely important reasons for supplying financial information on receiverships to a centralized database such as GRID.
		For the GRID financial information reporting requirements to be most effective, a conceptual framework and specific methods and procedures need to be developed for the financial statements prepared by receivers for companies in liquidation.
	www.naic.org /receivership/documents/GRID_Timeline_Outline.doc (359 words)

	Banner Engineering Press Release: EZ-SCREEN Grid System (Site not responding. Last check: 2007-10-09)
		In these large-area applications, personnel pass through the light grid, at which point the hazardous motion stops; then they may safely continue into the guarded area.
		EZ-SCREEN Grid is an optically synchronized, dual-microprocessor controlled, opposed-mode optoelectronic "light grid" with solid-state safety outputs.
		The EZ-SCREEN Grid’s status indicators are clearly visible on each sensor’s front panel, keeping operators informed of system conditions.
	www.bannerengineering.com /whats_new/release.php?id=9 (466 words)

	Grid Screen for Digital Camera (Site not responding. Last check: 2007-10-09)
		The Split-Image or Microprism focus aid in the middle of the screen is ground into the glass.
		Most people don't - they're quite happy with the "standard" screen supplied with the camera, however some need specialised screens for specialised photographic tasks such as astro-photography, certain types of scientific photography and so on, and one type of screen is the Grid Screen.
		As the name implies, a grid screen is pretty much a regular screen with grid lines etched into the glass, much like the lines on graph paper.
	www.digitalcamera.com.au /tutorials/gridscreen/index.shtml (217 words)

	Screen grid software by Tim Nolet and others (Site not responding. Last check: 2007-10-09)
		Eyeball hides at the edge of your screen and comes out to run around the screen, slide down the sides of the screen, fall from the top of the screen, and to dance to music.
		Screen Printer is a powerful yet simple to use screen print and capture utility.
		Dcat Screen Saver is a screen saver which allows you to use your own images and audio.
	www3.freedownloadscenter.com /Best/screen-grid_R5.html (401 words)

	screen. The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
		To separate or sift out (fine particles of sand, for example) by means of a sieve or screen.
		To test or examine for the presence of disease or infection: screen blood; screen a patient.
		To obscure an opponent's view of (a shot) by positioning oneself between the opponent and the shooter.
	www.bartleby.com /61/75/S0167500.html (438 words)

	[No title] (Site not responding. Last check: 2007-10-09)
		Subject: Re: Synthesized Triode from Tetrode or Pentode By Dave Newkirk/ July 28, 1993 Connecting together the screen and control grid of a tetrode (or the suppressor, screen and control grid of a true pentode) turns the tube into a high-mu triode.
		So a high-mu triode synthesized by connecting together the multiple grids of a screen-grid tube may or may not be operated as a zero-bias tube, depending on its resulting control characteristics and how you power the tube.
		By construction, a tube's control grid exerts more control over its electron stream than its screen; it's closer to the cathode than the screen and made of finer wire.
	www.arrl.org /files/infoserv/tech/tetrode.txt (669 words)

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