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	Vacuum tube (Site not responding. Last check: 2007-11-03)
		De Forest discovered that the current flow from filament to plate depended on the voltage applied to the grid, and that the current drawn by the grid was very low, being composed of the electrons which are intercepted by the grid.
		C Batteries were used to provide grid bias, although many circuits used grid leak resistors or voltage dividers to provide proper bias.
		The positive voltage on the second grid accelerated the electrons, causing them to strike the anode hard enough to knock out secondary electrons which tended to be captured by the second grid, reducing the plate current and the amplification of the circuit.
	bopedia.com /en/wikipedia/v/va/vacuum_tube.html (1860 words)

	Grid leak - Wikipedia, the free encyclopedia
		Grid leak is an inherent operating characteristic of triodes and other vacuum tubes.
		It is the small flow of current through the grid of a tube into the circuit which feeds the grid.
		This current is caused by the small negative EMF which is present in all vacuum valves as a result of a space charge within the envelope of the tube.
	en.wikipedia.org /wiki/Grid_leak (106 words)

	Antique Radio Classified--Homebrewing
		Thus a grid leak of 250,000 ohms resistance would be referred to as a 1/4-megohm leak and, similarly one having a resistance of two million ohms would be referred to as a two megohm grid leak.
		GRID CONDENSER -- A small fixed condenser, generally from.00025 to.0005 microfarad capacity, inserted in the circuit of a detector tube between the tuning coil and the grid member of the tube.
		This condenser insulates the grid from the filament by breaking the path F to G and permits the tube to act as a rectifier or detector.
	www.antiqueradio.com /Oct02_Corkutt_gridleak.html (2234 words)

	THE SET blocking oscillator theory (Site not responding. Last check: 2007-11-03)
		As the grid is driven positive during this process, the flow of plate current rapidly increases, quickly driving the tube into full conduction.
		The grid is now more positive than the cathode, so grid current is drawn (the grid effectivly acts as a plate), developing "grid-leak" bias as the grid current effectivly flows through the grid-leak capacitor, charging it.
		The negative side of the now-charged grid-leak capacitor is connected to the grid, thereby holding the grid in its cut-off state.
	home.att.net /~pldexnis/CTC2_how_it_works/blocking_oscillator.html (376 words)

	[No title] (Site not responding. Last check: 2007-11-03)
		The 2.7 Meg Ohm resistor is the grid leak in this circuit.
		The Grid Leak Detector uses the grid of the tube as the anode of a rectifying diode for this purpose.
		The voltage of the carrier wave is applied to the grid of the 6AU6 tube through the capacitor and grid leak resistor.
	www.angelfire.com /electronic/funwithtubes/Grid_Leak-1.html (1173 words)

	Vacuum tube - Wikipedia, the free encyclopedia
		DeForest discovered that the current flow from filament to plate depended on the voltage applied to the grid, and that the current drawn by the grid was very low, being composed of the electrons which are intercepted by the grid.
		The control grid and screen grid are also wound with the same pitch, or number of wires per inch.
		Once the tube envelope is evacuated and sealed, the getter is heated to a high temperature (usually by means of RF induction heating) causing the material to evaporate, adsorbing/reacting with any residual gases and usually leaving a silver-colored metallic deposit on the inside of the envelope of the tube.
	en.wikipedia.org /wiki/Vacuum_tube (3265 words)

	Patent Specification No. 458,585 (Site not responding. Last check: 2007-11-03)
		The inner control grid is suitably biased through a leak 33, and the bias value may be so adjusted that the inner grid comes to cathode potential during each pulse 32 but falls during the remainder of the cycle t such a negative value that the valve 29 is then entirely inoperative.
		The grid of the valve 52 is connected to the cathode through the leak 54 and this leak, together with a diode 55, re-establishes the direct current component f the wave on the grid of valve 52 with reference to the peak values P of the signals.
		The grid of the valve 52 is connected to the cathode through the leak 54, and this leak, together with a diode 55, serves to re-establish the direct current component of the applied signals on the grid of valve 52 with reference to the peak values P of the signals.
	www.doramusic.com /patents/458585.htm (14046 words)

	BAGA II
		The "low" side of these caps is tied to both a 1M grid leak resistor and the grids of the 12AT7.
		In terms of the low drive impedances, being direct coupled, the grids of the KT90’s experience an impedance which is both the value of the Rk (10K) as well as the cathode impedance of the EL84 itself.
		Grid blocking occurs, and the normal operation of the output stage is thrown out the window.
	ken-gilbert.com /techstuff/bigamp2.html (2237 words)

	[No title]
		Hence, if the grid signal is supplied from a source of low impedance, so that the loading effect on the source due to the flow of grid current may be ignored, the tube will continue to operate linearly even if the grid signal makes an excursion into the positive-grid region.
		By analogy with the definition of the dynamic plate resistance, the dynamic grid resistance r is given by dV/dIg, where V, and IG are the instantaneous values of grid voltage and current, respectively.
		Under such circumstances, where the grid is held at the cathode voltage because of the flow of grid current, we shall refer to the grid as being clamped to the cathode.
	www.geofex.com /Article_Folders/mandt.htm (2087 words)

	CT-100 simplified theory
		The transformer used for positive feedback from plate to grid does not have the conventional isolated windings.
		At the junction of the plate and grid windings, a third inductor is added and an external 0.01 uF cap is strapped across it (C130 Sams, 2C234 RCA, C at left).
		This horizontal-rate 'Sine wave' voltage combines with the 'Oscillator grid voltage' waveform to sharpen the waveform slope as it rises toward the conduction point.
	home.att.net /~pldexnis/CTC2_how_it_works/CTC2_horiz_osc.html (634 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.
		, and is proportional to the square of the input voltage on the grid.
		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)

	[No title] (Site not responding. Last check: 2007-11-03)
		However, ordinarily a grid leak circuit 42 and grid capacitor 40 are used to supply a grid-bias voltage.
		When the potential on the grid is positive with respect to the cathode potential, some of the current from the triode cathode will charge capacitor 40 and flow through leak circuit 42.
		Thus, during periods of a RF cycle when the grid bias is positive with respect to the cathode potential, capacitor 40 will be charged to a negative potential relative to ground and current will then slowly leak from capacitor 40 through leak circuit 42 during other portions of the RF cycle.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=01/05020.010118&ELEMENT_SET=DECL (8925 words)

	G'Zot! - How It Works (Site not responding. Last check: 2007-11-03)
		Most of the grid bias is obtained using "grid-leak bias." The grid is driven from an external oscillator (using a 6C4 triode) via a coupling capacitor (C12) and grid-leak resistor (R12) to negative supply.
		During the first few cycles of operation, the grid of the final will be driven positive, causing it to draw a considerable amount of current.
		The oscillator is a standard "Hartley" configuration, in which a tuned circuit (a parallel connection of a coil, or "inductor" and a capacitor) is connected via the grid and ground, and a tap on the the coil is connected to the cathode.
	www.dogstar.dantimax.dk /tubestuf/gzot2.htm (886 words)

	RCA
		The grid of the tube is connected to the mid-tap of the tuned grid circuit to minimize change in oscillator frequency with tubes.
		The oscillator tuned circuit is coupled to the secondary of the radio-frequency transformer which is in the grid circuit of the first detector.
		All grid returns are grounded and most of the tubes are self-biased by their plate current flowing through resistors in their cathode circuits, further reducing any chance of coupling through common resistance.
	www.antiqueradios.org /gazette/rca.htm (1885 words)

	OTB - Rotten Signals: How To Cure Them
		The excitation is increased in the Hartley circuit by moving the filament tap nearer the plate end; in the t.p.t.g.
		Use the highest value of grid leak resistance that will permit the tube to oscillate stably with normal input--between 10,000 and 20,000 ohms for a single tube, usually.
		And remember that the higher the leak resistance the greater is the excitation voltage required, so every time the leak resistance is changed there must be a corresponding change in the excitation tap or condenser setting.
	www.antiquewireless.org /otb/rotten.htm (3085 words)

	The Nuvistor
		Owing to electrochemical activity between the cathode and grid, a small potential develops across the grid resistor, and it is this which is used to bias the valve.
		The grid of the valve is returned direct to chassis through L2, and neutralisation is effected by L5.
		The first is arranged in the earthed-cathode mode with leaky-grid biasing, as in Figure 2, while the second is wired in an earthed-grid circuit with the amplified signal tapped off L2 at a suitable point to match the cathode circuit of the second valve.
	www.thevalvepage.com /valvetek/Nuvistor/nuvistor.htm (1783 words)

	kd0ar MOPA transmitter built 12-2-01 (Site not responding. Last check: 2007-11-03)
		The oscillator is tuned by 2 fixed mica's in series and grounded in the middle between plate and grid.
		Grid leak consists of a 50k resistor (1-100k's in parallel) and a 200pf condenser..
		The grid leak consists of the 50pf cap and an 18k resistor in series with a 2.5 mH choke from grid to ground.
	www.qsl.net /kd0ar/1929/early/mopa (635 words)

	Vacuum Tube Theory - Tube Biasing (Site not responding. Last check: 2007-11-03)
		The GRID BIAS is a constant DC that is placed in the external circuit between the grid and cathode and is always in series with the input signal.
		Grid voltage is kept at ground potential with a high value Rg resistor.
		Therefore, the average grid potential is negative, provided the grid becomes positive for at least a small part of each cycle.
	www.lh-electric.4t.com /vtprimer2.html (314 words)

	A Glossary of Common Amplifier Terms
		The grid is referred to ground through a resistor, and the current flow through the cathode resistor produces a positive cathode voltage with respect to the grid, which is effectively the same as making the grid negative with respect to the cathode.
		Voltage variations on the control grid, with respect to the cathode, cause variations in plate current, which is the basis of amplification within the tube.
		Since the grid element controls of the current flow in the tube, it allows the tube to be used as an amplifier to take a relatively small input signal on the grid and generate a relatively large signal swing at the plate.
	www.aikenamps.com /AmpTerms.html (10350 words)

	The AA8V/W8EXI 6CL6 One-Tube Transmitter - Schematic Diagrams and Circuit Descriptions (Site not responding. Last check: 2007-11-03)
		In this circuit the cathode is grounded and the screen grid of the tube is being used as the plate.
		The control grid is the common element in the two circuits, and they are only coupled by the common electron stream within the tube.
		Rectified grid current flowing through the grid leak resistor produces a negative bias on the control grid of the tube.
	faculty.frostburg.edu /phys/latta/ee/6cl6xmtr/6cl6schematic.html (1883 words)

	[No title] (Site not responding. Last check: 2007-11-03)
		5-7, the grid corresponds to the diode plate and the rectifying action is exactly the same as in a diode.
		voltage from rectified-current flow through the grid leak, R1, biases the grid negatively, and the audio-frequency variations in voltage across R1 are amplified through the tube as in a normal a.f.
		The wrong value of grid leak plus too-high plate and screen voltage are also frequent causes of lack of smoothness in going into oscillation.
	www.qsl.net /n6ev/Regen.html (1667 words)

	Alba R16 (Site not responding. Last check: 2007-11-03)
		The coupling capacitor between the preceeding audio stage connects its anode which sits at say 100 volts to the grid of the output valve which is shunted to ground, typically via a 2 Mohm resistor.
		All things being equal the output valve sees a grid voltage due to potentiometer action of the capacitor and its grid leak of 66 volts.
		However you would not be able to measure this voltage because long before it could have been established the grid, once commencing to go positive, will be drawing current and this will reduce the voltage by virtue of the drop across the leaky capacitor.
	www.thorneyhill.freeserve.co.uk /r16.html (574 words)

	DX-100 Mods
		The grid resistor should be anything from 5 to 10 MegOhms, with a 100pf (max.) disk or mica cap bypassing grid to ground, (to keep RF out).
		For example, in the DX100 second stage the grid leak resistor is a 500 kOhm potentiometer.
		However, there is no form of bypassing from the center tap of driver transformer, and as a result, the rectified grid current gets kicked up and down on the bias divider string (feeding driver, modulators and final).
	www.amwindow.org /tech/htm/dx100.htm (1118 words)

	Shunt grid leak biasing (Site not responding. Last check: 2007-11-03)
		When the grid goes positive in response to the positive-going input signal, electrostatic attraction between the grid and cathode increases.
		Current drawn from the electron stream by the grid never reaches the plate; therefore the negative-going output is not a faithful reproduction of the input, while the positive-going output (during the negative input cycle) will be a faithful reproduction of the input.
		This is similar to the situation shown in the flattopped portion of the output signal in figure 1-20.
	www.tpub.com /neets/book6/20i.htm (1079 words)

	sparks from small tube TC (MOT driven) (Site not responding. Last check: 2007-11-03)
		The circuit for the tube coil is the common and traditional one which is so well known, and most commonly used: Tank cap and primary are wired in parallel, one side goes to the level shifted power supply HV, the other side goes to the plate of the tube.
		One side of the grid coil connects to the grid of the tube, the other side goes to one side of the grid leak network (grid leak cap and resistor in parallel).
		Tube filament leads connect to the filament tranny, the filament bypass cap is placed across the filament, and one side of tube filament is grounded.
	www.vfr.net /~rpike/vacuumtube/833Tube_coil.htm (531 words)

	[No title] (Site not responding. Last check: 2007-11-03)
		Second, and equally or slightly less important, is the use of a high value grid leak and a low value grid capacitor.
		I use a 10-20 meg ohm grid leak and a 10-20pf capacitor, rather than the older values.
		The audio stage uses a grid leak of around 10K-470K (check for optimum value --- i.e., loudest signal with least distortion although distortion on CW is not bad and actually helps to make the signal easier to hear and copy).
	www.qsl.net /n6ev/Regen1.txt (1220 words)

	Thomas 6V6GT Push-Pull Beam Tetrode Power Amplifier
		It is directly coupled from the input stage and capacitively coupled to the output stage via a pair of 0.047uF foil capacitors of unknown composition.
		The bias was not adjustable and was coupled to each grid via a 220k grid leak resistor.
		Shielded audio cable was used between the RCA jacks and the input tube grids with signal ground termination occurring on the bus bar near the grounding point for the grid leak resistors.
	snow.prohosting.com /rknize/russ/electronics/tubeaudio/thomas/description.html (1991 words)

	Output Tube Biasing Problems (Site not responding. Last check: 2007-11-03)
		All of them involve the grid not being held at a negative enough voltage with respect to the cathode.
		Rarely, an output tube itself that is shorted grid to cathode Note that the chances are that only one of the multiple output tubes will have this problem.
		If one grid has a lot higher resistance to ground or to the bias supply, there is a problem with the grid leak resistor on that tube.
	www.geofex.com /ampdbug/biasing.htm (684 words)

	[No title]
		Method of keying a circuit by applying negative grid bias several times cutoff value to the grid of a tube during key-up conditions; when the key is down, the blocking bias is removed and normal current flows through the keyed circuit.
		Blocking of capacitance-coupled stages in an amplifier caused by the accumulation of charge on the coupling capacitors due to grid current passed during the reception of excessive signals.
		] A detector in which the desired audio-frequency voltage is developed across a grid leak and grid capacitor by the flow of modulated radio-frequency current; the circuit provides square-law detection on weak signals and linear detection on strong signals, along with amplification of the audio-frequency signal.
	www.accessscience.com /Dictionary/G/G18/DictG18.html (2857 words)

	Tube Terminology for Dummies
		The Grid is where the signal enters the tube.
		What this means to you is that the grid leak resistor can be used to control the level into the stage.
		The cathode resistor, plate resistor and grid resistor, determine the biasing of the tube stage.
	www.diystompboxes.com /pedals/tubedummy.html (1038 words)

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