Pentode load lines. Across many types you could come up with 2 to 50.
Pentode load lines. I'd have to draw me a load line for this.
Pentode load lines The reason the loadline balances around the B+ voltage is because of the inductive load, rather than any pentode thing. Triatic Now since I could not sim the 6AS6, The EF86, which by the way is a very good audio This makes the signal appear at the cathode of the pentode and has the effect of making the triode's load resistor R5 appear to be much larger that it actually is, giving a very high AC load to the triode and an almost horizontal load line. Thanks! Log in to Reply. This is an operating conditions table from the actual data sheet. Status Not open 1. You said this is for a 7 pin project. There is indeed a distinct and sharp null at pentode. For pentodes you can chose your preferrer operating modality among triode, pentode, or ultralinear mode. RE: Small signal Pentode load line Posted by dave slagle (M) on August 24, 2009 at 17:00:45 . The Champ's power tube, V2 is a tetrode with four electrodes. Draw a load line for 2x the class-B load, which is your class-A load line, and slide it up in the usual manner until you reach your desired bias point (~70% max dissipation). Attachments I substituted the 6BQ5 for a try out. The plate characteristics of the pentode section pretty much flatten out at V PK = 75V at the V GK = 0 line. In this case the tube Load line calculators. Triode (wrong supply voltage - 250V), not with the triode simulator. Rant from Pease. And even then, you can oly derive the Vg1 = 0 curve. Attachments. You can easily write off 10-20% of the hypothetical peak-to-peak swing once you factor in where p-pmax is on the load line. Otherwise the pentode load resistor may need re-sizing too (for the pentode operating current achievable with a screen voltage optimized for the triode Reference: List of material referenced in this marine order: Load lines convention (search, register or borrow); Survey guidelines under the harmonised system of survey and certification (HSSC), 2011, IMO resolution A. If you want more information, seek out material such as "Understanding HiFi Circuits" written by Crowhurst, where he goes into this matter in much greater detail. The results below present circuit simulations for a push-pull pentode 2-tube power amplifier. Radio tubes are valves. It considers both reactive loads and Even without a load line you can estimate the output power for a typical pentode, assuming the load impedance isn't unusually small for the type of valve being used: P = 2 * (HT-50)^2 / Rload Where Rload is the anode-to-anode This calculator allows you to compute and tune loadline and operating point of tube amplifiers’ power stages. Not a pentode as such, but since we're using it in triode who cares! Andy . The chart shows changes in power and distortion with load for a pentode stage with 540V B+ and a 400V screen. I do know the basic difference but the point of this thread is for me to learn more about pentode operation so any detailed implications that you can explain would be welcome. OK, the frequency is a very little higher than that, Design concept: (tube) pentode hybrid line signal conditioner, transformer input and output 2 tube modes: triode and pentode 2 channels Output mode: Transformer or solid state balanced driver Minimum output load: 600Ohm Being constant current devices themselves, trying to CCS load a pentode is, at best, highly problematic. Joined 2019. The load line intercepts the curve for a 0V grid at a plate voltage of 48V and a plate current of 127mA. Origin of rotation is the quiescent point. png. Pentode Curves (10) – Here are the What I mean is say you have a pentode that likes a load of 8K and you want to find one that is comfortable with relatively smaller (or greater) load impedance. 43 in RDH4). 12. Gary . Examine the circuits that are built around them. In fact, below 190V the reactive load seen by the Hello everyone. fonar. A triode can be used as an active load for another triode, in the so called totem pole push-pull circuit. . SE, to be more precise. 14 . Wavebourn. The horizontal line represents the load line when using a CCS plate load. 14K subscribers in the diytubes community. For your enjoyment or lack of girlfriend, i present my latest find, Triode / Pentode Loadline Simulator. When we come to calculate the gain, we find that the anode characteristic begins to curve as we reach its intersection with the load line. The grid lines go from zero to 3 or four volts negative with respect to the cathode. I'd have to draw me a load line for this. The dotted line curve is the corresponding one for an ordinary triode output valve and is included to show, at a glance, the great difference in the nature of the characteristics for the two . Would be nice if one can define a load line around an operating point drag the load line pivoted at the operating point. In reality, you need to be careful about When out of this range, as explained in Section 4. As the load for the pentode will be one of the triodes in the Pentodes I believe (example circuit is a 6U8 and the chart is from the 6AU6 data sheet). in other words, we passed on the chore voltage gain to the line-stage amplifier. ) 801A load line. Maximum power output and more-or-less minimum distortion for the pentode occurs where the load line goes through the "knee" of the curve. Joined Nov 18, 2015 Messages 6,348. The lower down the knee that the load line cuts (i. This calculator allows you to trace the anode characteristics graph, and to compute and tune loadline and operating point of various vacuum tubes. Like in the shunt cascode, the triode operates in a vertical load line correct. pdf), Text File (. Triode/Pentode Loadline Calculator. The more horizontal the curve, the higher the impedance. There is a whole bunch of theory involving load lines to determine the drive voltage, load point, and power output. If it passes above the knee we will get a more rounded, triode tone (albeit The plate characteristics of the pentode section pretty much flatten out at V PK = 75V at the V GK = 0 line. You could use that, but selecting V pk = 100V would be better. Load Lines – Load lines are horizontal lines are extending forward and aft from a vertical line placed at a distance of 540mm from the centre of the disc. The anode output impedance is equal to the anode load If the load line passes above the knee then the gain and signal swing are reduced and operation becomes more like that of a triode, with less odd-harmonic content. Anyway a Pentode has TWO plate resistances. 4 KB · Views: 116 Screen Shot 2021-08-09 at 4. Little more with a GZ34, little less with a 5R4. Article 15 . Then you don't have to be limited by Va, eg. So, I couldn’t wait longer and with the limited time available I put together a rat’s nest testing jig with the following implementation of the D3a pentode as driver: D3a pentode driver with If I decide to aim for 6AU6 with 150V on screen grid and operating conditions of 30K load resistor with the load line running from 300V, 0mA screens to 0V, 10mA and bias grids at -2. Link to our FB page ----- https://www. 4% THD with an 11K Zaa load. Just added to my pending list. The transfer curvature of the top triode opposes the curvature of the bottom triode, giving a low distortion circuit that handles high signal levels. My B+ feeding the 6SN7 2nd tube of the Aikido is going to be 300vdc with 10mA going thru The hybrid mu-follower is formed with the pentode and the active load (aka gyrator) which provides the maximum output swing at very low distortion. Join Date: Oct 2007; It could also be used to take a given load line and find the most linear load line position. in order to estimate where the Vg0 knee is and put the load line a bit below that. The ideal load would be a constant voltage (vertical load line). Look at the manufacturer anode while the DC loadline is an almost vertical line corresponding to the DC resistance of the The optimum load for a power pentode is normally a line that passes through, or a little below, the knee of the 0V grid curve. Many data sheets show pentode load lines becoming very slightly more vertical as G2 approaches anode voltage. The math is such that if you get the component values too non-identical, the thing may not oscillate at all. Long time lurker, first time poster. 2M || 330k) steepens the AC load line (in green above) for less gain compared to the Marshall below. Is that planned for some future moment? The load-line is an important detail, but you still have to take the other tubes that participate in creating the end result into consideration: - Even harmonics cancellation with the preceding stages; - Eventual feedback loops and their effects. youtube. As an example, I've attached a load line for a 5K primary 8ohm secondary. Working off the too small graph we can determine roughly that with a 12 volt P-P input signal the resistive load would give an output voltage of 188 volts P-P where the CCS load would give an output voltage of 269 The following curve family has a 4kOhm load line that crosses pentode curves of a substantially higher impedance. 5 with I am considering to use Siemens F2a tube in pentode mode as SE output. The optimum pentode load line cannot be determined directly from the characteristic curves. More close to 90 in total. Or, we can just read the 6146 data sheet. Thread starter the better the CCs, the more perfectly horizontal the load line. In Reply to: Small signal Pentode load line posted by slownlo on August 23, 2009 at 17:43:21: Hey, My guess is your best option would be to look at a Another idea is to do a vanilla pentode topology, but with a regulated screen supply. I know No similar direct relation exists in the pentode case, where the load is usually less than the valve impedance. . load line zones - Free download as PDF File (. Using a pentode or transistor for the driver allows the feedback to correct the grid signal as needed with the residual cathode-grid nonlinearity adding to the near-linear plate-grid swing and resulting in a percent or so f2 distortion at full signal. I'm playing around with the EL84 load lines, trying to educate myself at poweramp design. The lower down Triode/Pentode Loadline Calculator . With a CCS the load line is horizontal. Calculate its resistance load value = maximum theoretical +/- Ea swing / +/- max theoretical Ia swing = 253V / 100mA = 2,530r. The AC load line is always rotated clockwise from the DC load line. My English teacher would have given me an F grade. Thread starter Tubetec; Start date Sep 3, 2022; Help Support GroupDIY Audio Forum: This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others. Koonw. UL mode can be used in both SE and PP amps. com) NickKUK. That makes the pentode dissipate much less power for a certain AC output signal power. (The load-line moves "below the corner". And the prototype on my protoboard. The load that the pentode sees (for one tube) is then the difference in plate voltage between the red vertical Soldano Cold Clipper Load Lines. Maintenance of Conditions after Survey . It is my first such experiment, and I am abandoning triode linestages based on the results. "Head butting" occurs. In reality, you need to be careful about Another idea is to do a vanilla pentode topology, but with a regulated screen supply. asc. Wayne . the more horizontal the line is), the higher the screen dissipation will be (though this can be managed with a screen stopper resistor). The reason they look like a cross between pentode and triode curves is because they are! In this example I'm operating the tube (a 6V6GT beam tetrode) in ultra-linear mode. line output or horizontal deflection pentodes, such as the PL36, 27GB5/PL500, As with the pentode, the load line should pass through or slightly below the 'knee' for the most 'pentode-like' tone. Old-dog summary. If we plot a 2K Ohm load line on the G2 current curve rather than the plate current curve we find a very linear region with bias of -12V and B+ of 80V and G2 at 250V if we limit the G1 voltage swing. Screen Shot 2021-08-10 at 8. (The load-line moves "above the corner" of the pentode curves. IMO, the way to improve on resistive loading of pentode CFs is the installation of a suitable inductor ($$). G. I find that with many tubes, such as the 2A3, the shallower the slope of the loadline (the higher Ra In the pentode mode, tube operation is described by the load line in Fig. Vintage or new, boutique or not, let's Understanding load lines . Normally you’re just going to look at the 0 volt line and to the right of it. comWarning!The circuits discussed in thisvideo I understand why a CCS plate load would be a good thing for a triode (flat load line, linearity of the stage becomes equal to linearity of mu), With a resistor as the plate load of a pentode, the value of that plate resistor becomes the output impedance of that stage. I meant Increasing the impedance that the plate has to drive. The Microcap simulator was used to produce the graphs for a signal The plate Above is the load line plot. Triode/Pentode Loadline Calculator . The difference between a resistor load line and a transformer (or choke) load line is not the slope, but the position. Thank you for this link ! 🙂 This calculator allows you to compute and tune loadline and operating point for a vacuum tube concertina phase splitter stage. A place for tone seekers to discuss tube amps and analog goodies. I'm going to try and set up the input pentode on my 5C1 clone to cathode bias to make it more pedal friendly. pl. Tubetec Well-known member. In AB push-pull, even though each tube is drawing some current at the quiescent point, the net effect is zero current through the transformer. When using resistive loads, it is possible to draw both the DC and the AC loadlines. For a given power output near clipping, increasing the load impedance will cause an increase in third-order distortion, while lowering the load impedance will result in The optimum pentode load line cannot be determined directly from the characteristic curves. 5kHz. txt) or read online for free. If my load lines are accurate, I think the 70V dropout will work with my 400V B+. 2011-09-23 2:17 pm #1 2011-09-23 2:17 pm #1 The question I Triode/Pentode Loadline Calculator . Joined 2011. As with the pentode, the load line should pass through or slightly below the 'knee' for the most 'pentode-like' tone. They can be found here: Triode Strapped Curves for the 6BM8 Pentode – Greg's Stuff Hope someone finds them useful Because we will force the current through the valve to be constant, we can simply draw a vertical line at a half HT and choose a bias point somewhere on it. For a given power output near clipping, increasing the load impedance will cause an increase in third-order distortion, while lowering the load impedance will result in increased A tube with five electrodes is called a pentode. In fact, pentode output tubes typically display a plate resistance characteristic in the tens of thousands of ohms, yet require a load impedance of only a few thousand ohms for optimum performance. In fact, UL mode is a form of local NFB. e. Lifetime Member. The best way to design a tube (or any other low distortion amp) is to design (voltage and/or power) gain and as much linearity as possible, including local negative feedback, and then add enough overall negative feedback to achieve your other objectives -- gain, distortion, bandwidth, output impedance etc. So far we have only considered the peaks of the wave-form, but it is obvious from the figures that the harmonics will represent changes in Sad News from Jensen Capacitors - September 1, 2019 Duelund Standard Resistor with Tinned Copper Lead - August 19, 2018; RIP Glenn Frey, Guitarist and Singer of The Eagles - January 19, 2016; Manley Would really like to play with ecc99 and 7581a in the reactive load line calculator. Thread starter EddieRich; Start date 2011-09-23 2:17 pm; Status Not open for further replies. The max voltage on the A 480 volt transformer will mkae a B+ of 550 to 600 volts. Is that even close to right. The red lines are the actual operating points seen by the tube. It is impossible to have high supply voltage 250V, load resistance 2K5 and anode current 60mA. It is at about 5. Mr. I am trying to design an amplifier with a 6Au6 pentode operating as a constant current source plate load for a medium mu triode. With small signal pentodes, the screen current is usually about 20% of the plate current. Hey, My guess is your best option would be to look at a 4-5K loadline and use the 126C. 4k. theory. Regulated g2 at 75V, used a 100R cathode resistor and a 750R plate load. More Soldano Cold Clipper Load Lines. Joined 2004. Log in to is it possible to add 7857 nuvustor tube in pentode mode since it is a tetrode (Similar curves to pendode but with only 4 active elctrodes)? Log in The red load line therefore connects 300V, 0mA and 0V, 150mA. This transformer is not designed to handle the higher I PQ = 60 mA of pentode-mode operation, so Triode / Pentode Loadline Simulator 03-06-2017, 01:45 AM. Questions welcome, but please For a small signal pentode with fully bypassed screen and cathode, gain can be approximated as The reactive component can affect AC gain too, such as Miller capacitance. However all schematics and load lines that I could find online use F2a triode strapped (which is Calculating Load Lines for Power Tubes and Pentodes. Therefore, the distances between yellow lines and white line are not the same and depend on the operating point (nonlinearity). This calculator allows you to compute and tune loadline and operating point for a vacuum tube concertina phase splitter stage. com. Sep 3, 2022 So, it occurs to me last night that with the load lines off the published chart, something needs to be done with the chart. 0 (20161216 www. Yes, both will work, if no further NFB is used, the 8k will The optimum load for a power pentode is normally a line that passes through, or a little below, the knee of the 0V grid curve. Also don't be afraid of non-linear regions But "10" is just coincidence. At the low current end there is quick bunching up of the grid lines as the tube cuts off. cheers, Douglas D3a Pentode Driver. Prev. I would prefer to see a pentode load-line simulator, though. 001Mho conductor. Here are a few pictures of the tubes. 6. Fortunately, triode curves for the EL84 are easily available. The load seen by the The simulator can operate with reactive load (for power vacuum ubes) and resistive load. pentode is not as sensitive to plate load as the triode or ul is and a lower load is not neccasarlly a bad thing, it may be Seems it's time to learn how to draw pentode load lines. I need to end up with 150volts on the plate of the 6SJ7. Pentode Loadlines PP. 10. This is "necessary" to establish the load line for a push pull amplifier, regardless of whether it is going to be Class A or Class AB. G. The Pentode does not impose a Heavy Drain on the HT Battery. So at least on the positive swing, the grid will go past zero. -~-~~-~~~-~~-~-Please watch: "Marshall Dual Video 8" https://www. 42/13. com/watch?v=O4sSc471kg0-~-~~-~~~ Another question about plate curves and pentode load lines. Output power is 1 - Plot the LOAD LINE This line intercepts at the Y axis at Ip = Vb / (Rl + Rk) = 370 / (2. You need to operate the valve at high current levels (where transconductance is the highest), however, as I proved This results in about 1% second harmonic distortion for my load line at full signal. Pullen's emphasis on Conductance is just math. I intend to use traditional fixed bias in order to maximize my plate and screen voltages (and, really, haven't drawn up my load lines yet, but I'm estimating I'll have around 375V for the plates once resistive losses in the filtering are accounted for. I'll try to do one and post back the results if you are interested. R. Disabled Account. 7. This gives you the floor of the plate voltage swing. Joined 2007. Parallel pentodes it is! I'm glad that this finally motivated me to do some pentode load lines. A 1K resistor is a 0. Member. Pentode / beam power modes: The screen is at AC / Signal ground. There is an interesting H3 contribution to this output beam tetrode triode strapped. 1104(29). The anode output For pentodes, the advice seems to be to draw the load line from the 'knee' in the pentode curve to the quiescent voltage point at zero current (figures 13. Tubes setup in UL mode exhibit behavior in between triode and full pentode mode. Your plate-to-plate load is then 2x your class-A load. Old Tele man. Move a slider and the graph is instantly redrawn. Current 2015 guidelines are available in IMO resolution A. The diagonal load line represents a 15K resistive plate load. Anyway, I'm going to Green Country Hamfest when it opens this Saturday at 8am (thanks for the tip, Win!) and am drawing up quite a shopping list. If it passes above the knee we will get a more rounded, triode tone (albeit If you look at the pentode load line chart, there isn't that much grid voltage to work with. Because I built the Vox Student V5 pentode preamp into my design, I had the quiescent voltages recorded. You could also load the 45 with a pentode to move that heat above the chassis plate, which would help with the lifetime of all the components inside the amp. trioda. 936. You can: choose among most common vacuum tubes (I am slowly adding more), set the operation The "loss of power" when connected UL or triode vs. Run the EL34 as a pentode. 6 KB · Views: 246 K. For a resistor it goes from the supply rail voltage and the quiescent point is the somewhere in the middle so lower voltage; for a transformer the quiescent point has the same anode voltage (roughly) as the supply rail - it looks almost like you have Picture of a PCF802, which includes a triode and a pentode designed for television line oscillator applications, a model introduced no later than 1962, and in common use in In the ideal textbook world a pentode is a voltage controlled current device. You can: choose among most common vacuum tubes (I am slowly adding more), set the operation The pentode equation differs from the triode equation in that the screen grid replaces the plate as a controlling element, and an arctangent term Fortunately, this is not a As an example for a 5k load line with 380V and 80mA as the idle point (left part of picutre). If you make R large, gain can be exceedingly There are a number of Pentode UL Triode curve in this article you can use as reference if you try to plot and compare using our model. We don't need to be a aggressive in Source & Line Analogue Source Analog Line Level Digital Source Digital Line Level PC Based. Notice I have "exceeded" the tubes rating If we shoot for the knee it seems like a rather low value load of 3Kohms at 250V B+ (orange line) is what we need. On 6HB6, above Vp=40V it is about 50k. For example the pentode section in the 7199 in the Dynaco circuit is 270k, but it is only driving the grid of a small triode used for phase splitting. Triode / Pentode Loadline Simulator v. Pentode Loadlines PP . It's a tricky bit of math, even after the script realizes that the values are non-identical. It has transconductance. This will offer the most clean output power. You already specify a 6600 ohm load. Jump to Latest EddieRich. Both the mains and 5K:8ohm transformers are custom from Sowter for this design. The higher the impedance the plate "sees", the lower 'the loading' is on the plate (easier load, not worse load). The document outlines the winter seasonal zones and areas for ships in various bodies of water. 975A. This will work best for tubes with g2 voltage/plate current curves similar to the 7199 pentode. Every resistor is also a conductor. I take it you haven't got Merlin's 1st or 2nd pre-amp book? When setting the Vg2 With 75V on the screen, the 47k DC load line went right through the knee of the curve. Thread starter tvrgeek; Start date 2010-01-17 7:37 pm; Status Not open for but something still needs improvement sonically when my "afternoon project" EL84 SE (in pentode mode) amp sounds as good or better. The screen resistor might be in the region of 470k to 680k, to provide a screen voltage that is in the region of the plate voltage but somewhat lower. 807 circuit for inspiration. That dominant pole, the series 270k pentode load, 100pF cap, and 20k to ground is also interesting. Further work to see which load line gives optimum results. my limit is the +B, about 275VDC. This is about two thirds of them, there is another container of loose ones somewhere and a dozen or so in boxes. Note that this graph includes positive grid values as well. A 480 volt transformer will mkae a B+ of 550 to 600 volts. 2 KB · Views: 234 A pentode is an electronic device having five electrodes. pentode is all about how much voltage swing you can get between cutoff and saturation. For a resistor it goes from the supply rail voltage and the quiescent point is the somewhere in the middle so lower voltage; for a transformer the quiescent point has the same anode voltage (roughly) as the supply rail - it looks almost like you have Although the load is in the cathode circuit rather than the anode, a load line can still be drawn in the usual way (see the basic triode gain stage). Thanks Gregg. Also, the screen to plate voltage is in the middle of that plate peak-to-peak voltage, so you halve it again. There are a number of Pentode UL Triode curve in this article you can use as reference if you try to plot and compare using our model. Rudolf Moers - UL Investigation. T. facebook. 1. Actually the pentode load-line is not exactly symmetrical, so that there may be a certain amount of second harmonic in addition. -Varying the degree of negative feedback - altering the feedback fraction, pentode load-FET CCS load on the cathode follower - this will necessitate a time delay circuit to keep the 801A grid happy during startup In the ideal textbook world a pentode is a voltage controlled current device. Low impedance (high load) downstream of 287k (2. Blitz. I just built a linestage with a 6AV5GA running full pentode. In the North Atlantic, winter seasonal zones are in Tube 6П15П or Röhre 6П15П ID20532, Vacuum Pentode, Noval, 9 pin miniature (USA pico-9) B9A and shown. Loudspeakers Multi-Way Full Range Subwoofers Planars & Exotics. com/BUGAMPSLink to our website ----- https://www. another cool one to add would be the triode-strapped 813another high voltage one, LOL, with a Vmax of 2500 ROTFL but I'm serious, these are two tubes I am using at high voltages, and when I finish the project I'm working on and post it here, I'm sure there will be members who would like to Since gain from a pentode is about Load*gm there is a large region available for drawing a load line. If we take a 6EJ7 (EF184) It's difficult to make a pentode into a triode load line except when you have curves at Vg1=0 and varying Vg2. of sufficient electron emission to give the required current through the tube to produce the desired power in the load impedance. This transformer will not handle the higher I PQ = 60 mA of pentode-mode operation, so The optimum load impedance (primary Z) is derived by plotting out the load lines for the tube based on these variables. Pullen was just a pup then. 2021-02-08 1:51 pm #469 2021-02-08 1:51 pm #469 aleksh said: Since gain from a pentode is about Load*gm there is a large region available for drawing a load line. It's easy to visualize if you draw a load line on the plate curves for each of the configurations. The pentode I would prefer to see a pentode load-line simulator, though. Generally we would like the load resistor In theory there might be for an amp with plates sitting at 500V, but in practice amps aren’t that efficient. 16 pm. Is there a characteristic like gm, rp or such that would roughly correlate to this or an easily recognized attribute of the curves that would allow you to identify likely suspects before The pentode is not fully free of it, but with sufficient anode voltage Ua the Ia curves are much more horizontal than for the triode. The primary constraint is to choose a load line that maximizes the undistorted signal output. 1053(27). But "10" is just coincidence. Gain will be close to the triode's mu and distortion will be very low. That is why we like triodes. the International Load Line Certificate (1966) or on the International Load Line Exemption Certificate issued to a ship exempted under paragraph (2) of Article 6 of the present Convention. With preamp stages, you're dealing with resistive loads instead. B+ is ~190. Source & Line Analogue Source Analog Line Level Digital Source Digital Line Level PC Based. ABQCD is the completed load class A SE load line. As the load for the pentode will be one of the triodes in the same tube as a SRPP Ok, being honest here and never having used a set of pentode load lines I have some questions if I may. 09 am. Joined 2002. Giuseppe Amato says: 6 March 2021 at 9:01. The A couple years ago I started drawing load lines (with the help of a generous member on a different forum) for a 6CA5 push pull amp. you will need to adjust the operating voltage/idle current but that only means drawing new load lines and adjusting the specified b+ and one or two Scaled bigA, little b, asymmetric pentode load line Here is a 6L6GC scaled down to 100V G2 to illustrate the idea of a push-pull output stage operating point, using this basic idea. You can use the Triode Pentode load line calculator to optimize As with the pentode, the load line should pass through or slightly below the 'knee' for the most 'pentode-like' tone. You can also set push-pull or single-ended configurations. 2020-11-27 9:32 am #3 2020-11-27 9:32 am Type '37 data from 1937 shows Plate Resistance. such as the PL84 and the pentode sections of the 18GV8/PCL85. If it passes above the knee we will get a more rounded, triode tone (albeit It’s not always the case. Any form of verse with five lines, like a limerick, or a haiku written by an innumerate poet. The calculator: So there are two load lines to draw in an AB amp: the load line when both tubes are conducting, and the load line when only one tube is conducting. Output from the mu, and take a resistor from plate to ground. 2010-04-17 3:32 pm #18 2010-04-17 3:32 pm #18 Hey guys, Thanks Gregg. I don't think I have as many as I thought though. Set i_regulated for the V_plate/R + plate current. Triode, ultra linear, or pentode Follow Ups: RE: Small signal Pentode load line - dave slagle 17:00:45 08/24/09 (0) In Reply to: RE: Small signal Pentode load line posted by slownlo on August 23, 2009 at 17:43:21 . bugamps. Reducing the load on the plate . wrote: ↑ Tue Jun 20, 2023 5:17 pm I'm not sure an online calculator can handle odd values in the typical phase shift oscillator. revintage. At 125v on the plates with a 6k primary OT, I figured about 3. Joined 2013 No voltage gain is realized and the goal of unity-gain is not completely reached. ) Going the other way, either raising the anode load, or raising the screen voltage, tends to make the signal flat-top on both positive and negative half-cycles, and the timbre is definitely different. Thread starter mashaffer; Start date 2018-07-13 4:21 pm; Status Not open for further replies. I noticed the 1k sine wave had the characteristic 2nd order distortion with flattened bottom curve and peaked upper curve when I biased Take a pentode, apply a plate load CCS with a mu follower output. happy new year! B. Could do a simulation with an EL84 to get you in the ballpark. 5V for an anode current of 4mA per valve. 952. In order to get any power out of the stage a load line is drawn to optimize the circuit to its intended load. A 100k plate load is small. Come learn about, share, and drool over awesome tube amplification projects. It is perfectly valid to treat the anode curve as a straight line, and to project this line onto our The red lines are the plate curves as found in datasheets. This is illustrated above for a load of 2. The EL84 pentode idles at 25mA, while the MOSFET idles at 1. Sorry I used the pentode curves while you clearly are thinking triode. Again this happens in real time. A typical plate load for a pentode might be 100k. The slope of the load line We will discuss how to create a composite load line for a pentode. Don't have the exact numbers in front of me at the moment. Thread starter any chance adding load lines for kt120 ultra linear ? thank you. I made some rough triode curves for the pentode section. Look at the Mullard data sheet, And there is no such thing as a load line. In fact, my limit is the +B, about 275VDC. The load line will be R, output Z of the mu follower and no way for much PS noise to get into the circuit through the CCS. Note that the design of the original triode-mode amplifier used the 125BSE for T 1 . 24K subscribers in the ToobAmps community. Then the output transformer impedance is selected so that it is right in the middle of the range. 31. Joined I would expect that this amp puts out about 2W when properly set up; less if the driver can't give sufficient voltage swing to drive the output tube to clipping. gsmok. com) Tags: None. Understanding load lines. 6, one of the two vacuum tubes quits conducting and the other one sees just one fourth of the whole transformer impedance. The equation I'm attempting to apply is in the back of An AC load line is the next step and represents the total combined load presented to an AC signal, so for a driver stage you might have a plate resistor and it will be in parallel with the grid resistor of the following stage since they are usually capacitor coupled and so both load the tube for AC signals. If the line-stage amplifier is tube-based, +/-16Vpk of output swing should not prove difficult. Click to expand I think the pentode curves should be very accurate in the upper left where is the 0V knee and the lower right because this is where the tube is really operating in a power amplifier circuit, where pass the AC load line. Note the distortion curves. They measure 230mm Looking at the load-lines you can easily get 20W at 1. Has anyone done this already? I was thinking of creating an Octave Triode / Pentode Loadline Simulator v. 2014-09-04 2:46 pm #65 Even an improved pentode model called "Derk" described on "uTracer" site, for the parameters indicated there There have been many comments online advising against operating a pentode with Vp much less than Vg2, yet on the data sheet curves posted below for example, one of the most linear operating points is with Vg2=250V and Vp=162. I have not tried to build it yet. 5 watts output. Government. I guess you could say a light bulb is a uniode with just one electrode ;) Usually you'd have the pentode screen grid at a lower voltage than the plate but the sim indicates that the design (with a 1K screen resistor) is higher than the plate. You could use that, but selecting V pk = 100V would be the tube can give, at realistic anode voltages and currents. 1; 2; First Prev 2 of 2 Go to page. Triode Strapped Curves generated for 6BM8 Pentode Hi All, The 6BM8 contains a high mu line-level triode and medium power pentode (Pa ~7W) in one convenient glass envelope. why are there load-lines on with Ug2 > -20V where the tube would go over max dissipation most of the time??? There’s skilled folks here building Pentode Spice Models and nobody can shed some light on some basic Pentode testing values? load-curves please see above, I want to test against these curves (prove, re-build, model, see on my The difference between a resistor load line and a transformer (or choke) load line is not the slope, but the position. Go. 500 + 360) = 0,130 = 130 mA Ip = Plate Current (100% tapping from the 375V end would give you a triode connected pentode and 0% gives you a straight pentode. In the pentode mode, tube operation is described by the load line in Fig. a ccs load When using resistive loads, it is possible to draw both the DC and the AC loadlines. I'm holding -2 volts as an operating point. To deal with this side-effect, the pentode was invented, which adds yet another grid called the suppressor in between anode and screen, held at a low voltage (often tied to cathode) and this keeps those bounced To do so, you'll need to increase Vmax to 1250. 40-43% is common with UL and gives least distortion As far as using triode pentode to improve performance over a single pentode - of course. Across many types you could come up with 2 to 50. Most lowish power pentodes such as EL84 seem to call for higher values like 5K which on this tube would seem to put the crossing point to the left of the knee at any reasonable bias point. pdf pp load line-UL-2. I printed out the load lines and need to make sense of them so any help would be appreciated. You can: set the Power Supply V+ voltage, the screen voltage, the screen tap, the quiescent bias current. With the variable pitch control grid of the remote cut-off this bunching up is spread out, and the change in gm with increasing plate current is more If the load line passes above the knee then the gain and signal swing are reduced and operation becomes more like that of a triode, with less odd-harmonic content. tipbjhoixwqmklnlolycgdcyguhbtnvsyxbsvvqfihutgmshglg