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Post 1 of Joined Oct 9, Messages Reaction score Joined Oct 9, Posts Likes Hi, I have a tube amplifier that uses 2x6J8P and 2x6P13P The sound is a bit harsh for my taste and the output tubes seem a little 'analytical'.
I want more of the warm tube sound, but I'm not sure where to look. So I took these out. A fellow head-fi member tested the tubes and found that they weren't defective. I'm a little worried that I won't be able to find replacement 6P13P tubes when these ones burn out. Does anyone know if there are any substitutes? I love this amplifier, and it seems to have rather obscene output power it drives two 91 db sensitivity tower speakers to a higher SPL than a watt onkyo makes no sense and sounds about 10x better.
Did I mention it's supposedly 12wpc output? Share This Post. Apr 13, at PM. Post 2 of Joined Apr 9, Messages 2, Reaction score Joined Apr 9, Posts 2, Likes I did a little bit of scouting, and came up with a data sheet.
Give me some time to scout, but let me say this: The tube seems to be a very cheap Chinese one, I very highyl doubt you are going to fine a replacement that will sound better than what you have, unless you can come up with a cross reference match.Posted: Feb Fri 18, am. Trying to fix an old GE radio, already restuffed the filter caps.
Still nothing. Are these interchangeable or at least close enough to work? Or if not, is there a chance that putting in the right tube will fix the radio? I dont have a 6SG7 in stock and wont be able to get my mitts on one for a few days. Were all in this together.
I have to admit it Frosts me as to WHY!!! They have different basing but haven't seen this to be a problem. These have higher gain and draw. The others draw. Use for parallel wired filaments only. These are great tubes, will give more gain but some radios go into oscillation. Thanks Norm, I often wondered why there were so many tubes that were considered interchangeable but now I can understand where they may cause adverse conditions in different circuit configurations.
I learn many things every day. Posted: Feb Fri 18, pm. It's amazing what you can do with red hot micro-sized chicken wire Other than the electrical differences, the pin-outs differ as well. In the 6SK7, the cathode connection pin 5 is separate from the suppressor grid pin 3.Turn off erg mode zwift
Substituting a 6SG7 in such a circuit will ground the cathode, removing the bias from the tube. You may get "bit" if you don't!Ben 10 video
Take it from someone that has been "bitten" once. Ed's point is well taken. If you compare the two plate current charts, the 6SG7 draws a lot less plate current for a given bias. For example, at -3 volts on the grid and volts on the plate, the 6SG7 draws just over 1 mA, while the 6SK7 draws almost 10 mA.He responds to my texts but never initiates
This can make a big difference in plate voltage depending on the dropping resistors in the set. It all boils down to the fact that even thou it seems that a lot of tubes are near duplicates of another, they are all different, some in minute ways, some in ways that will astound you. Im no expert but I would think that if you have a 6SK7 then make sure pins 3 and 5 are tied together. Be sure the difference in plate values doesnt effect the circuit. Posted: Feb Sat 19, am. Posted: Feb Sat 19, pm. Some GE tube manuals refer to the 6SG7 as a semiremote-cutoff pentode.
Sort of half-way between a sharp cutoff and a remote cutoff pentode I suppose.Heater voltage 6. Pentodes were introduced to eliminate the restriction on plate voltage swing of the tetrode, by getting rid of the dip.
A new third grid between the screen grid and the plate, the suppressor, was held at cathode potential and repelled secondary electrons back into the plate, as well as making the electron division independent of plate voltage.
This made pentodes useful for audio and power amplifiers in general as well as for RF amplifiers. The screen grid, at signal ground, reduced the grid-plate or Miller capacitance to very low values, less than 1 pF, as for tetrodes.
The consequent reduction in negative feedback at high frequencies made RF amplification possible without hard-to-adjust neutralizing circuits. Therefore, pentodes were always found as RF and IF amplifiers in radio receivers. These were voltage amplifiers, and of two kinds: sharp cutoff and remote cutoff. The remote cutoff pentode had a control grid of uneven spacing, so that when the bias was large, the transconductance of the tube became small, limiting the gain so that the amplifier would not be overdriven and produce distortion.
Usual plate currents were 10 mA or less. It was also found that pentodes, like tetrodes, made excellent voltage amplifiers, because of the increased plate resistance. A pentode acted like a current source instead of a voltage source.
This put a premium on high transconductance, which made large gain possible in a single stage. Gains of 40 or 50 are quite practical in a pentode voltage amplifier, in contrast with gains of around 15 for a medium-mu triode amplifier. On the other hand, the gain of a stage now depended sensitively on the load resistance; if this varied with frequency, as for a loudspeaker, so did the gain. This was only a disadvantage in final power amplifiers, of course. Sharp-cutoff pentodes were widely used as audio amplifiers.
The circuit for measuring pentode characteristics is shown at the left. The tube used as the example is the 6SJ7, but any sharp-cutoff pentode will do, such as the miniature 6AU6. It makes things very easy if you have four DMM's for the various measurements. The screen supply can be fixed-voltage. I used V from a VR tube at first, later the all-in-one supply described above, which proved very convenient.
The plate supply should be variable, as well as the grid bias. When screen and plate voltages are first applied, the grid bias should be set to some negative value to avoid surprise. The cutoff bias can be estimated at about 1. Vacuum tubes are much more rugged than transistors, and a momentary oversight will not usually result in disaster.
The suppressor grid of a pentode is always connected to the cathode, and is often not even brought outside the envelope, but is connected internally to the cathode. The first thing to do is probably to measure the screen or triode-connection characteristics. To do this, connect the screen and plate together and measure the total current with a single DMM.
Set the grid bias, and then measure the total current as a function of voltage over the range available to you. Repeat for several values of the grid bias, so you obtain a family of curves like the plate characteristics of a triode.Contenedores de pl stico con tapa
From these curves, estimate the amplification factor, plate resistance and transconductance, just as for a triode. Now connect the plate and screen to their separate supplies, and run plate characteristics for a fixed screen voltage. In this case, the cathode current will be about constant, and will divide between the screen and plate. Determine the ratio of division at various plate voltages.User Name Stay logged in?
Last edited by Kagliostro; 30th April at PM. Looking at the curves: yes. The max g2 voltage rating is different, but russian ratings are more of suggestions than actual ratings. Thanks I was thinking 6zh7 is a 6J7 not a 6J8 6J7 has a top cap. Originally Posted by Kagliostro. There are also a number of Russian tubes for which no exact equivalent exists.
I'm a big fan of a good number of Russian types. The vademecum found at Frank's here: electron Tube Data sheets - Search will frequently list equivalents and near equivalents if you check the box when you do a datasheet search.
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The 6SN7GT – the best general-purpose dual triode?
Find More Posts by MrCurwen. Send a private message to elektroj.QRZ Forums. I'd like to build an AM tuner I found in an old Poptronics magazine but would like to use a miniature tube. Can anyone suggest a mini tube that has same or very similar characteristics to a 6SK7? W8TMTJan 4, I'll check through my stash; I know I have a few somewhere. Let me know if you don't find a replacement.
KL7AJJan 4, I also suspect a 6SJ7 will work. The 6SK7 is remote cutoff, while the 'J7 is a sharp cutoff. If the tuner isn't using AGC, you can use a sharp cutoff tube. A 6BA6 should work, if you don't mind a mini 7-pin sub.
Last edited: Jan 4, W1BRJan 4, N2EYJan 4, K8ERVJan 4, KE5OFJ likes this. I like to use 6sk7 for a voltage amplifier, buffer after the vfo and I wanted to use a miniature tube. The 6bd6 is it, but I haven't tried it yet. Good luck. W7FOXJan 5, N2EY likes this. W8TMTJan 5, KG5RKP likes this. You must log in or sign up to reply here.
Show Ignored Content. Share This Page. Your name or email address: Password: Forgot your password? Register for a free QRZ account.Welcome, Guest. Please login or register. Home Help Search Login Register. Author Topic: alternate EF86 pentode? Read times.Www netflix com download
Is there any pentode that can replace an EF86 and do it's job without added gain? I'm waiting for an EF86 to complete a job but was wondering if there was an alternative. They look interesting.
I'm not sure if I remember well may be ef83?? The world is a nice place if there is health and there are friends.
E80F is a pin-for-pin substitute, and according to some reports on other forums is a damn fine audio tube. When I find one to try, I'll report back. Quote from: phsyconoodler on June 20,pm. To steal ideas from one person is plagiarism. To steal from many is research. I don't know of a direct replacement for the EF The 6SJ7 tends to perform similarly. Phsyco mentioned the 6EJ7 which looks like an EF86 at a glance. I've been meaning to experiment with these since I have a baggie full of them.
Is this the same as an EF86?Antique radios, Old Time Radios. Cunningham Inc. Quantity of Models at Radiomuseum. Museum "Wireless In Wales Museum". Collection of Markus Meier CH. Collection of Jacob Roschy D. Collection of Georges Van Campenhout B. Collection of Christian Schaufelberger CH. Collection of Patrice Zeissloff F. Collection of Karlheinz Fischer D. Collection of Peter Steffen CH.
Collection of Karl - Heinz Bossan D. Collection of Aldo Patriarca CH. Collection of Ottmar Rollmann D. Collection of Emilio Ciardiello I. Collection of Georges Werts B. Collection of Hermann Fleischanderl A. Collection of Tomasz Szczesniak PL. Collection of Eduard Abfalterer I. Collection of Bekir Yurdakul F.
Collection of Stig Comstedt S. Collection of Geri Meier CH. Collection of Oskar Elm D. Collection of Tor Steinnes N. You reach this tube or valve page from a search after clicking the "tubes" tab or by clicking a tube on a radio model page. You will find thousands of tubes or valves with interesting links. You even can look up radio models with a certain tube line up.
Other shape e. Octal Int.
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