6v6 screen grid voltage. For this study I used an Edcor GXSE 10-5K transformer.

6v6 screen grid voltage Pick any plate voltage for the 0v gridline on the top graph on page 4, and compare it to the same plate voltage on the 0v gridline for the top graph of page 7. Aug 17, 2014 · Hey guys. This nonlinear behaviour will lead to nonlinear voltage drop across a mere resistor in front of the screen grid, introducing distortion. While I would prefer lower voltage, the silverface Champs ran higher voltage. That means the latter may be more susceptible to oscillating, and so bigger grid stopper should be seen as "normal". 5 ratio between Vsg (screen operating voltage) and Vss (screen supply voltage), screen dissipation is well-limited. The inductive reactance of a 4H choke at 120Hz is about 3k ohms. Apr 13, 2008 · Max screen dissipation 2 watts Plate voltage 285 Screen 285 Bias - 19 38 p-p drive volts Zero signal plate current 70mA (pair) Max signal plate urrent 92mA (pair) Zero signal screen current 4mA (pair) Max signal screen current 13. The best candidates for screen drive have sensitive screens, hence low voltage ratings. By connecting the screen right to the center tap as early tweeds did, the screen sits at pretty much the same voltage throughout the cycle and the tube can develop its maximum High transconductance (Gm) tubes, like the EL34 and EL84, will have bigger changes of plate current with a given grid voltage input than lower-Gm tubes. Pin 2 is the cathode. Just finishing up a Princeton Reverb build. Regards Tom Mar 24, 2014 · Then, as you get into the early 50s, this approach was generally abandoned in favor of dropping the screen voltage below plate voltage. Naturally OT impedance and loadline and Screen voltage effect here and voltage alone when amp idle when bias is checked is just on "idle point". 5mA (pair) Plate resistance 70,000 ohms Transconductance 3600 umhos Load 8k Max signal power 14 watts Oct 27, 2024 · At each plate voltage I varied the bias voltage and collected data on power out (in the 8Ω load), harmonic distortion, plate and screen dissipation, and current levels. So I regard 5k6 grid stoppers as a minimum, 10k would be better. . Apr 6, 2017 · Some of the older ones will go grid-current if too much plate voltage is used (they're only rated at 285v- some RCA, Raytheon and other older 6V6GT tubes can only take that voltage without going bad over time), but any of them that are labeled "6V6GTA"- you can hammer the hell out of them. This results in a load line that hits just below the knee of Vg0 grid curve and ensures screen current isn’t Jul 9, 2022 · "Optimum" screen grid resistor for maximum power output is 0Ω. Oct 13, 2024 · 1R or 10R current sensing resistors can equally be used elsewhere, eg in series with the screen grid in this case. 6V6 Octal socket basing diagram. With screen supply voltages much over 2x desired voltage, and with a regulator at the screen grid, excessive fault dissipation in R1 and wasted supply power become disadvantages. 6V6 and 6L6 are "low-ish Gm" when compared to EL34 and EL84. 6V6 SE and Screen Grid Voltage. Apr 4, 2014 · The screen grids of the 6V6 can be run as high as the anode, which means that the screens are not very sensitive. It's cathode biased, and I pretty much followed the AA1164 schematic, but added a VVR circuit. 3 volt tubes of this class. Typically these are 'TV tubes'. Sep 12, 2013 · My thinking is that the VDC across the screen grid resistor (at max squarewave output into a resistive load), divided by the resistor value, will be the average screen grid current under this worst case condition. Pin 1 is not used by the 6v6, its just a convenient tie point like Feb 12, 2017 · In fact, most such tubes have a maximum screen grid voltage rating of little over 200 vdc, and in reality, typically operate with only 125 to 175 volts on the screen. Your setting the difference between the plate and G2 at what ever bias Apr 11, 2006 · from the RCA manual (RC-28, pp. Fender's measured voltage across the 470Ω cathode resistor is 19 volts, so by Ohm's Law the current through it is 40mA. I discovered that, as long as the output stage is not pushed into clipping, screen grid dissipation is within the 2. I see this pattern in the first 6V6/6L6 designs by both Hammond and Leslie. The screen grid voltage basically determines the maximum current that can flow to the plate, while 2. So higher screen voltage leads to higher idle plate current with the same G1 bias voltage, and higher possible peak plate current Dec 16, 2023 · To flesh this out a bit, our wise friend @tubeswell said in the el34 thread: "In one of these amps, running the sorts of B+ it runs, this keeps the 6V6 screen voltage about 50v below the plate voltage, while running the tube at Pmax. The screen voltage dictates the peak plate current the tube can manage, which is the point of the graph below, found on the top of Page 6 of the 6L6GC data sheet. The In tetrodes and pentodes, the screen insulates grid 1 and the cathode from that changing plate voltage so that plate current is no longer affected much by plate voltage. The higher screen voltage always results in a higher plate current for a given grid voltage. Even worse, the effect only occurs on one side of the anode voltage swing (towards low Ea and high Ia) but not when the anode swings in the opposite direction (high Ea, low Ia). The screen current is approximately 3mA. They were all revised around '51-'52 to drop the screen voltage. Once the output stages begins to clip, the current through the screen grid resistor increases rapidly. In most AB1 push pull amps, the Screen voltage is is very close to the same value as the plate voltage, most tube failure is due to exceeding screen voltage and current ratings. G1 voltage change causes plate current change, but only as big as the screen voltage allows it to be. 99): "When the screen-grid voltage is supplied through a series voltage-dropping resistor, the maximum screen-grid voltage rating may be exceeded, provided the maximum screen-grid dissipation rating is not exceeded at any signal condition, and the maximum screen-grid voltage rating is not exceeded at the maximum-signal condition. Hence a 10k resistor here might be expected to provide better smoothing. Are these resistors just for tube Jan 4, 2023 · 6V6 data sheets never seemed to get an update of their true voltage-handling capability (and plate current with screen volts over 250v) the way it was done with the 6L6-family of tubes. May 17, 2019 · I read that if you connect the screen grid to the plate, it reduces the power of your output pentode, and changes the harmonic character to act and sound more like a triode (amp uses a single 6L6 power tube). Pin normally absent 8 - Cathode & Beam-Forming Plates. 2W maximum. jpg (154. Feb 12, 2017 · 1. Make sure pin 1 is not connected to 2 . A screen grid to cathode VDC measurement in that scenario will be the average screen grid voltage. These two graphs show characteristics for a screen voltage of 250v and 400v, respectively. Mar 2, 2012 · In a pentode, anode current is most defined by screen voltage, the anode voltage is less important defining the plate current. Here are the screen transfer characteristics from a 6V6 data sheet. Screen resistors drop a tiny voltage that is unimportant overall in the operation of the tube, particulalrly with respect to protecting the tube while clipping. Such important is the screen voltage, that this value divided voltage at grid #1 (Signal) defines the cut off current by a coefficient called g2/g1 mu value. Aug 25, 2009 · before the screen grid resistors, try adding an extra bleeder and cap after one extra resistor from the PS rail, this extra resistor will allow you to precisely set the screen voltage without using excessive series screen grid resistors . This power dissipation data is especially important for the 6V6 family because of the two types of tubes available. When screen volts fall, the Oct 4, 2008 · NOS 6V6 tubes usually can't handle more than 300 volts on the plates. Oct 22, 2022 · These are plate and screen power dissipations verses power output and plate and screen currents verses power output. The control grid controls how much plate current actually flows within the maximum amount set by the screen grid voltage. This makes such tubes incompatible with traditional UL operation, and they also pull a very high heater current for the 6. JJ 6v6s will take that no problem! Feb 8, 2016 · I then calculated the DC current through the resistor, and multiplied by the screen voltage. Jun 15, 2013 · Screen voltage in an of itself is not important except that it is what grid control voltage relates to - not plate voltage. I regard the 1k shared screen grid (g2) resistor as being essential. As a matter of fact, at just 1. 6V6 pDiss and Voltage ratings. So you will need a very high drive voltage to change the anode current. Thread starter zxx123; Start date 2005-02-02 3:52 am; Status Not open for further replies. 2 kB, 813x718 - viewed 5096 times. 350 and even 400v plate was regularly used on these Sep 28, 2017 · If using the screen grid resistor then install the screen connection to pin 6 and the screen resistor ( 470 ohm 1w) from pin 6 to pin 4. It's why many 1950s amps like this, and this, and this, and this had no screen resistors. This is the current through the cathode, which is the sum of the plate and screen currents. That protection comes from the value of this resistor. 1 - * Unconnected in all versions except for the shell connection of the metal 6V6 2 & 7 - Filament / Heater 3 - Anode / Plate 4 - Grid 2 / Screen Grid 5 - Grid 1 / Control Grid 6 - No connection. For this study I used an Edcor GXSE 10-5K transformer. It provides a degree of local NFB, linearises the high power waveform, and reduces g2 dissipation. The 6V6 is a beam-power tetrode vacuum tube. ) technically speaking for the screen grid voltage measurement & reading - what does the Jan 15, 2019 · With cathode bias the tube is only seing the difference between the plate voltage and the cathode voltage, so if for example you have the tube idling with 460 on the plate and 22 volts on the cathode the tube is then running at 438 volts. Screen (G2) voltage is like a governor for the plate current, with control grid (G1) voltage being the throttle. Feb 2, 2005 · 6V6 SE and Screen Grid Voltage . But due to the ruggedness and quality, most people got away with it. Jun 8, 2020 · It looks like when voltage is 300V or less biasing TS 6V6 to 12W or but higher does not lead to redplating but bring good sound back. All data was taken at 1kHz. Plus lowering the screen grid voltage and anode current will tend to reduce stage gain. you can install the grid resistor from pin 1 to pin 5 , PI connected to pin 1. Down to the last solder joints, and notice that some PR schematics and layouts show the 470/1500 screen and grid resistors and some solder straight to the pins. ebuzls jnr gjvldqw myrve vzwdqo ljqc ufnqp mmfa gfiw ktjekr icefj art cletk tctrgz mpdicgw