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#1
Posted to rec.audio.tubes
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converting EL84 to triode mode
Dear all
Is there a rule of thumb to convert single-ended or push-pull EL84 from ultra-linear or pentode connection to triode connection? It seems that a 900 ohm is used to connect pin 7 (anode) and pin 9 (grid), how is such value calculated? Would the value be the same for 6AQ5? Thanks in advance |
#2
Posted to rec.audio.tubes
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converting EL84 to triode mode
On Wed, 1 Nov 2006 09:43:00 +0800, "william"
wrote: Is there a rule of thumb to convert single-ended or push-pull EL84 from ultra-linear or pentode connection to triode connection? It seems that a 900 ohm is used to connect pin 7 (anode) and pin 9 (grid), how is such value calculated? Would the value be the same for 6AQ5? The resistor usually seen is just a grid stopper; no special value need be calculated. Several hundred to a coupla thousand ohms is fine; actual voltage drop is always minimal anywho. All good fortune, Chris Hornbeck |
#3
Posted to rec.audio.tubes
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converting EL84 to triode mode
sorry, what's a grid stopper?
for pentode connection, how to calculate the B+ provided to the grid? thanks again "Chris Hornbeck" wrote in message ... On Wed, 1 Nov 2006 09:43:00 +0800, "william" wrote: Is there a rule of thumb to convert single-ended or push-pull EL84 from ultra-linear or pentode connection to triode connection? It seems that a 900 ohm is used to connect pin 7 (anode) and pin 9 (grid), how is such value calculated? Would the value be the same for 6AQ5? The resistor usually seen is just a grid stopper; no special value need be calculated. Several hundred to a coupla thousand ohms is fine; actual voltage drop is always minimal anywho. All good fortune, Chris Hornbeck |
#4
Posted to rec.audio.tubes
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converting EL84 to triode mode
On Wed, 1 Nov 2006 10:05:49 +0800, "william"
wrote: sorry, what's a grid stopper? Vacuum tubes/valves have a combination of very high possible bandwidth and normally fairly sloppy large dimensions and large external parasitic reactances. IOW, they'd really, really like to oscillate. "Grid stop" is just and old fashioned term for the series side of a low-pass filter. The tube's stray capacitances provide the shunt side. BTW, the second grid is conventionally called either "G2" or the "screen". Everybody calls the first grid the "grid". for pentode connection, how to calculate the B+ provided to the grid? You'll probable enjoy an old tube manual as a good jump-off point. If not available nearby, I'd bet that Ned has one of the RCA manuals that were reprinted a coupla years ago, for pretty cheap. These are where *all* the old geezers learned their way around things. As essential to a young man's bathroom reading as Playboy was. All good fortune, Chris Hornbeck |
#5
Posted to rec.audio.tubes
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converting EL84 to triode mode
thank you so much!!
"Chris Hornbeck" wrote in message ... On Wed, 1 Nov 2006 10:05:49 +0800, "william" wrote: sorry, what's a grid stopper? Vacuum tubes/valves have a combination of very high possible bandwidth and normally fairly sloppy large dimensions and large external parasitic reactances. IOW, they'd really, really like to oscillate. "Grid stop" is just and old fashioned term for the series side of a low-pass filter. The tube's stray capacitances provide the shunt side. BTW, the second grid is conventionally called either "G2" or the "screen". Everybody calls the first grid the "grid". for pentode connection, how to calculate the B+ provided to the grid? You'll probable enjoy an old tube manual as a good jump-off point. If not available nearby, I'd bet that Ned has one of the RCA manuals that were reprinted a coupla years ago, for pretty cheap. These are where *all* the old geezers learned their way around things. As essential to a young man's bathroom reading as Playboy was. All good fortune, Chris Hornbeck |
#6
Posted to rec.audio.tubes
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converting EL84 to triode mode
"william" wrote in message
... thank you so much!! "Chris Hornbeck" wrote in message ... On Wed, 1 Nov 2006 10:05:49 +0800, "william" wrote: sorry, what's a grid stopper? Vacuum tubes/valves have a combination of very high possible bandwidth and normally fairly sloppy large dimensions and large external parasitic reactances. IOW, they'd really, really like to oscillate. "Grid stop" is just and old fashioned term for the series side of a low-pass filter. The tube's stray capacitances provide the shunt side. BTW, the second grid is conventionally called either "G2" or the "screen". Everybody calls the first grid the "grid". for pentode connection, how to calculate the B+ provided to the grid? You'll probable enjoy an old tube manual as a good jump-off point. If not available nearby, I'd bet that Ned has one of the RCA manuals that were reprinted a coupla years ago, for pretty cheap. These are where *all* the old geezers learned their way around things. As essential to a young man's bathroom reading as Playboy was. All good fortune, Chris Hornbeck Hi William, Just a minor point. When posting to UseNet it is generally accepted as good ettiquette to post in plain text and to reply at the bottom of the post. Anyhow good luck with finding more info on tubes and how to use them. Cheers, Alan |
#7
Posted to rec.audio.tubes
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converting EL84 to triode mode
"Alan Rutlidge" wrote in message ... "william" wrote in message ... thank you so much!! "Chris Hornbeck" wrote in message ... On Wed, 1 Nov 2006 10:05:49 +0800, "william" wrote: sorry, what's a grid stopper? Vacuum tubes/valves have a combination of very high possible bandwidth and normally fairly sloppy large dimensions and large external parasitic reactances. IOW, they'd really, really like to oscillate. "Grid stop" is just and old fashioned term for the series side of a low-pass filter. The tube's stray capacitances provide the shunt side. BTW, the second grid is conventionally called either "G2" or the "screen". Everybody calls the first grid the "grid". for pentode connection, how to calculate the B+ provided to the grid? You'll probable enjoy an old tube manual as a good jump-off point. If not available nearby, I'd bet that Ned has one of the RCA manuals that were reprinted a coupla years ago, for pretty cheap. These are where *all* the old geezers learned their way around things. As essential to a young man's bathroom reading as Playboy was. All good fortune, Chris Hornbeck Hi William, Just a minor point. When posting to UseNet it is generally accepted as good ettiquette to post in plain text and to reply at the bottom of the post. Anyhow good luck with finding more info on tubes and how to use them. Cheers, Alan ************************** Thanks for the advice I read everything in plain text so nver realised when I went out of my mind and send html post... |
#8
Posted to rec.audio.tubes
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converting EL84 to triode mode
Hi RATs!
OK, posting protocols are pretty much local. Sorry, people get upset if their world is turned upside down, even if it was upside down to begin .... It is OK to call the resistor between the plate and the screen a screen stopper Does the same job as a grid stopper, in a different place. Mox nix. You can also put a diode in the sceen stopper circuit. It is some mumbo-jumbo idea that seems to work. Try it and see for yourself. Diodes are cheap. Not as cheap as rude opinions in all capital letters, but, cheap enough for anyone with access to this Internet _____ EL84 and 6BQ5 are very similar SV-83 is close, but does have some lower voltage ratings. Many rich guys are sure you can tell a great tube by its markings. Sigh. Us old guys know all we can do is listen to the tubes we actually have and pick the ones we like by the way they sound. Life is even more complicated than manufacuturing, but manufacturing still produces surprises. There are billions of tubes. In a truly random Universe, you might just get the very best ones in your first attempt. More likely, you will try more and change what you think sounds good as well as the tubes and circuits It is OK, only Eyesore thinks he knew everything when he started Either way, somebody here or on some othe NG will know for certain you are stupid and/or deaf. Don't worry, they are just bored and like to type Don't kill yourself with high voltages. Being dragged into the woods by an entire Girl Scout troup and gang raped to death by teenage girls and their adult leaders is the only way to go ... unless you are too old .... us old guys don't really have a good way to die mapped out ... it will happen however it happens. So, enjoy your experiments and tell us about them. There is more to RAT than personality problems, perhaps not by volume, but, we take what we can get at these prices Happy Ears! Al |
#9
Posted to rec.audio.tubes
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converting EL84 to triode mode
Hi, good day
I suppose you mean to say EL84 and 6AQ5 are similar? "tubegarden" wrote in message ups.com... Hi RATs! OK, posting protocols are pretty much local. Sorry, people get upset if their world is turned upside down, even if it was upside down to begin .... It is OK to call the resistor between the plate and the screen a screen stopper Does the same job as a grid stopper, in a different place. Mox nix. You can also put a diode in the sceen stopper circuit. It is some mumbo-jumbo idea that seems to work. Try it and see for yourself. Diodes are cheap. Not as cheap as rude opinions in all capital letters, but, cheap enough for anyone with access to this Internet _____ EL84 and 6BQ5 are very similar SV-83 is close, but does have some lower voltage ratings. Many rich guys are sure you can tell a great tube by its markings. Sigh. Us old guys know all we can do is listen to the tubes we actually have and pick the ones we like by the way they sound. Life is even more complicated than manufacuturing, but manufacturing still produces surprises. There are billions of tubes. In a truly random Universe, you might just get the very best ones in your first attempt. More likely, you will try more and change what you think sounds good as well as the tubes and circuits It is OK, only Eyesore thinks he knew everything when he started Either way, somebody here or on some othe NG will know for certain you are stupid and/or deaf. Don't worry, they are just bored and like to type Don't kill yourself with high voltages. Being dragged into the woods by an entire Girl Scout troup and gang raped to death by teenage girls and their adult leaders is the only way to go ... unless you are too old .... us old guys don't really have a good way to die mapped out ... it will happen however it happens. So, enjoy your experiments and tell us about them. There is more to RAT than personality problems, perhaps not by volume, but, we take what we can get at these prices Happy Ears! Al |
#10
Posted to rec.audio.tubes
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converting EL84 to triode mode
cough... cough... how to put the polarity of the diode between the plate and
the screen? should a high voltage diode like IN4007 be used? thanks "tubegarden" wrote in message ups.com... Hi RATs! OK, posting protocols are pretty much local. Sorry, people get upset if their world is turned upside down, even if it was upside down to begin .... It is OK to call the resistor between the plate and the screen a screen stopper Does the same job as a grid stopper, in a different place. Mox nix. You can also put a diode in the sceen stopper circuit. It is some mumbo-jumbo idea that seems to work. Try it and see for yourself. Diodes are cheap. Not as cheap as rude opinions in all capital letters, but, cheap enough for anyone with access to this Internet _____ EL84 and 6BQ5 are very similar SV-83 is close, but does have some lower voltage ratings. Many rich guys are sure you can tell a great tube by its markings. Sigh. Us old guys know all we can do is listen to the tubes we actually have and pick the ones we like by the way they sound. Life is even more complicated than manufacuturing, but manufacturing still produces surprises. There are billions of tubes. In a truly random Universe, you might just get the very best ones in your first attempt. More likely, you will try more and change what you think sounds good as well as the tubes and circuits It is OK, only Eyesore thinks he knew everything when he started Either way, somebody here or on some othe NG will know for certain you are stupid and/or deaf. Don't worry, they are just bored and like to type Don't kill yourself with high voltages. Being dragged into the woods by an entire Girl Scout troup and gang raped to death by teenage girls and their adult leaders is the only way to go ... unless you are too old .... us old guys don't really have a good way to die mapped out ... it will happen however it happens. So, enjoy your experiments and tell us about them. There is more to RAT than personality problems, perhaps not by volume, but, we take what we can get at these prices Happy Ears! Al |
#11
Posted to rec.audio.tubes
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converting EL84 to triode mode
william wrote: cough... cough... how to put the polarity of the diode between the plate and the screen? should a high voltage diode like IN4007 be used? thanks "tubegarden" wrote in message ups.com... Hi RATs! OK, posting protocols are pretty much local. Sorry, people get upset if their world is turned upside down, even if it was upside down to begin ... Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. It is OK to call the resistor between the plate and the screen a screen stopper Does the same job as a grid stopper, in a different place. Mox nix. You can also put a diode in the sceen stopper circuit. It is some mumbo-jumbo idea that seems to work. Try it and see for yourself. Diodes are cheap. Not as cheap as rude opinions in all capital letters, but, cheap enough for anyone with access to this Internet _____ EL84 and 6BQ5 are very similar SV-83 is close, but does have some lower voltage ratings. Many rich guys are sure you can tell a great tube by its markings. Sigh. Us old guys know all we can do is listen to the tubes we actually have and pick the ones we like by the way they sound. Life is even more complicated than manufacuturing, but manufacturing still produces surprises. There are billions of tubes. In a truly random Universe, you might just get the very best ones in your first attempt. More likely, you will try more and change what you think sounds good as well as the tubes and circuits It is OK, only Eyesore thinks he knew everything when he started Either way, somebody here or on some othe NG will know for certain you are stupid and/or deaf. Don't worry, they are just bored and like to type Don't kill yourself with high voltages. Being dragged into the woods by an entire Girl Scout troup and gang raped to death by teenage girls and their adult leaders is the only way to go ... unless you are too old ... us old guys don't really have a good way to die mapped out ... it will happen however it happens. So, enjoy your experiments and tell us about them. There is more to RAT than personality problems, perhaps not by volume, but, we take what we can get at these prices Happy Ears! Al |
#12
Posted to rec.audio.tubes
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converting EL84 to triode mode
Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style 12A6 rule! Happy Ears! Al |
#13
Posted to rec.audio.tubes
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converting EL84 to triode mode
Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style 12A6 rule! Happy Ears! Al *********************************** I thought 6BQ5 and EL84 are same stuff, not "similar"? |
#14
Posted to rec.audio.tubes
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converting EL84 to triode mode
william wrote: I thought 6BQ5 and EL84 are same stuff, not "similar"? Yes, now same tube is branded as both. I think there were two seperate tubes, once upon a time, but, I may have that wrong, too Sorry for confusion. Happy Ears! Al |
#15
Posted to rec.audio.tubes
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converting EL84 to triode mode
"tubegarden" wrote in message ups.com... william wrote: I thought 6BQ5 and EL84 are same stuff, not "similar"? Yes, now same tube is branded as both. I think there were two seperate tubes, once upon a time, but, I may have that wrong, too Sorry for confusion. Happy Ears! Al ****************** no problem mate, I consider 6BQ5 and 6AQ5 are similar in the sense that they can use similar OPT |
#16
Posted to rec.audio.tubes
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converting EL84 to triode mode
tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al |
#17
Posted to rec.audio.tubes
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converting EL84 to triode mode
"Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al ************** btw how to have outlook express insert "" to provious post? I saw that click box some years ago and couldn't find it any more? |
#18
Posted to rec.audio.tubes
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converting EL84 to triode mode
You can also put a diode in the sceen stopper circuit. It is some mumbo-jumbo idea that seems to work. Try it and see for yourself. Hmmm. 6/10 v drop across the screen supply, and what else? High resistance to oscillatoin from the screen back to the PS? I have seen diodes placed inline to prevent voltage dropping by reverse biasing. Is this using the same concept? Bob H. |
#19
Posted to rec.audio.tubes
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converting EL84 to triode mode
"william" wrote in message ... "Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al ************** btw how to have outlook express insert "" to provious post? I saw that click box some years ago and couldn't find it any more? Tools Options Send Plain Text Settings for News Check "Indent ... with (Select '') OK OK |
#20
Posted to rec.audio.tubes
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converting EL84 to triode mode
"Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? A diode dropping 0.7V at 5ma would have an equivalent resistance of 140 ohms. Might work as a stopper; how would one know without trying it, Patrick? Isn't that the form of learning you preach? Fred I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al |
#21
Posted to rec.audio.tubes
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converting EL84 to triode mode
william wrote: "Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al ************** btw how to have outlook express insert "" to provious post? I saw that click box some years ago and couldn't find it any more? I use Netscape 4.7 for the groups since about 1998 and it does it automatically. But yeah, I dunno how to place the in front of the post I am replying to either when I use OE for ordinary mail. Many ppl send me emails about electronics each week and about repair work and new amps etc and nearly all DO NOT use plain text because they send HTML posts, so I convert all that rubbish into plain text on the replies, but then its hard for them to see what is their own posting and what is my new text, so sometimes I just use ** in front of what I am saying so they get the drift OK. So indeed, what does one click to make appear infront of plain text in OE????? Patrick Turner. |
#22
Posted to rec.audio.tubes
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converting EL84 to triode mode
"Bob H." wrote: You can also put a diode in the sceen stopper circuit. It is some mumbo-jumbo idea that seems to work. Try it and see for yourself. Hmmm. 6/10 v drop across the screen supply, and what else? High resistance to oscillatoin from the screen back to the PS? I have seen diodes placed inline to prevent voltage dropping by reverse biasing. Is this using the same concept? Bob H. But just when does screen current ever try to flow backwards? Patrick Turner. |
#23
Posted to rec.audio.tubes
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converting EL84 to triode mode
Phread wrote: "william" wrote in message ... "Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al ************** btw how to have outlook express insert "" to provious post? I saw that click box some years ago and couldn't find it any more? Tools Options Send Plain Text Settings for News Check "Indent ... with (Select '') OK OK Please be more usefully specific. I went to my OE, opened an email, clicked reply. The reply window has Tools, and I see in the Tools sub-window menu that 'Options' is not listed. So your advice is BS. Patrick Turner. |
#24
Posted to rec.audio.tubes
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converting EL84 to triode mode
Patrick Turner wrote: "Bob H." wrote: You can also put a diode in the sceen stopper circuit. It is some mumbo-jumbo idea that seems to work. Try it and see for yourself. Hmmm. 6/10 v drop across the screen supply, and what else? High resistance to oscillatoin from the screen back to the PS? I have seen diodes placed inline to prevent voltage dropping by reverse biasing. Is this using the same concept? Bob H. But just when does screen current ever try to flow backwards? Patrick Turner. I was thinking more of tube oscillation affecting the power supply. The diode reversed biased would offer a huge resistance between the tube and the power source. Current could flow into the grid, but would not reverse, cutting oscillation in half on one half of the cycle, in addition to the grid stopper on the other cycle. Sort of like a half wave rectifier. Therefore, the oscillation which could spiral out of control could be damped enough to prevent that. Possible, maybe? bob H. |
#25
Posted to rec.audio.tubes
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converting EL84 to triode mode
"Patrick Turner" wrote in message ... Phread wrote: "william" wrote in message ... "Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al ************** btw how to have outlook express insert "" to provious post? I saw that click box some years ago and couldn't find it any more? Tools Options Send Plain Text Settings for News Check "Indent ... with (Select '') OK OK Please be more usefully specific. I went to my OE, opened an email, clicked reply. The reply window has Tools, and I see in the Tools sub-window menu that 'Options' is not listed. So your advice is BS. Patrick Turner. Patrick, Don't click reply... just go Tools/Options/General from the main menu in OE. That where it is on mine. Then you tick your choices on "send/receive". Cheers, Nelson |
#26
Posted to rec.audio.tubes
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converting EL84 to triode mode
Phread wrote: "Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? A diode dropping 0.7V at 5ma would have an equivalent resistance of 140 ohms. Might work as a stopper; how would one know without trying it, Patrick? Isn't that the form of learning you preach? Fred 99% of the oscillations in amps using multgrid tubes are due to incorrectly set up feedback loops around the amp which do not shelve the HF response with zobel networks which is the art and science of "critical damping". (Buckets of water are not required). I have rarely ever had screen stoppers ever do much against HF oscillations and the main function of the screen stopper resistors is to allow something to burn out or fuse where the screen current has become excessive. In my own amps where I have wound the OPT the leakage inductance is so low that there are very low values of L&C reactances that encourage the possibility of HF oscillations. Even 470 ohms which is commonly used in guitar amps will only have a mild effect and they typically use 2W resistors so they won't burn open which seems self defeating and so why bother using screen stoppers at all: its a conventional thing to do theough so everyone uses a screen stopper. But there are none in a Quad II amp for example. Did Walker know something we don't? Perhaps. I always use them just in case but use 1W max, sometimes 1/4W x 270 ohms and I have had them get hot and flame and fuse open rather than have the tube which has gone into runaway destroy an OPT or itself. Much more important is the control grid stopper which never should be less than 2k2, and in may amps its much more, even 47k in a radio 6V6 output stage. I may have once tried a series diode and have forgotten the results; hell I have tried lots of things. But maybe there was nothing positive to remember. I am due to book in to my Refreshment Triodologists Course at the local University Of Pharking Old Electronicals in a month's time. Maybe they'll cover the subject, but if you wanna know the answer sooner then FOY. Patrick Turner. I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al |
#27
Posted to rec.audio.tubes
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converting EL84 to triode mode
"Phread" wrote in message ... "william" wrote in message ... "Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al ************** btw how to have outlook express insert "" to provious post? I saw that click box some years ago and couldn't find it any more? Tools Options Send Plain Text Settings for News Check "Indent ... with (Select '') OK OK thanks! I did the Plain Text Settings for Mail only |
#28
Posted to rec.audio.tubes
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converting EL84 to triode mode
"Bob H." wrote: Patrick Turner wrote: "Bob H." wrote: You can also put a diode in the sceen stopper circuit. It is some mumbo-jumbo idea that seems to work. Try it and see for yourself. Hmmm. 6/10 v drop across the screen supply, and what else? High resistance to oscillatoin from the screen back to the PS? I have seen diodes placed inline to prevent voltage dropping by reverse biasing. Is this using the same concept? Bob H. But just when does screen current ever try to flow backwards? Patrick Turner. I was thinking more of tube oscillation affecting the power supply. The diode reversed biased would offer a huge resistance between the tube and the power source. Current could flow into the grid, but would not reverse, cutting oscillation in half on one half of the cycle, in addition to the grid stopper on the other cycle. Sort of like a half wave rectifier. Therefore, the oscillation which could spiral out of control could be damped enough to prevent that. Possible, maybe? Oscillation does not spiral out of control. When it starts, it builds up in amplitude until the output tubes saturate, ie, become grossly over driven, sometimes there consecutive stop start bursts of HF oscillations and the stop start sequence between oscillation and paralysis is heard as a lower frequency tone especially if the oscillations are at RF. Most oscillator tubes in radio sets are operating as would a grossly overloaded tube would, and run and maximum pk-pk output and with square wave currents; the tuned circuits make the wanted voltage output into a sinne wave with low level harmonics depending on the Q of the LC circuit. Halving the wave form in many oscillators is already evident when you examine wave forms in a typical grid circuit of an oscillator. But what effect a diode has in the circumstances mentioned is something I don't know. Patrick Turner. bob H. |
#29
Posted to rec.audio.tubes
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converting EL84 to triode mode
Nelson Gietz wrote: "Patrick Turner" wrote in message ... Phread wrote: "william" wrote in message ... "Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al ************** btw how to have outlook express insert "" to provious post? I saw that click box some years ago and couldn't find it any more? Tools Options Send Plain Text Settings for News Check "Indent ... with (Select '') OK OK Please be more usefully specific. I went to my OE, opened an email, clicked reply. The reply window has Tools, and I see in the Tools sub-window menu that 'Options' is not listed. So your advice is BS. Patrick Turner. Patrick, Don't click reply... just go Tools/Options/General from the main menu in OE. That where it is on mine. Then you tick your choices on "send/receive". Cheers, Nelson OK, I understand. The options were already turned on for plain text for emails and the news postings. When someone emails me and I hit reply, their message appears on my screen without any and when i type out a reply the receivers say sometimes they don't notice all of what i am saying because its seems mixed up with what they just posted. The ' ' business seems to work in netscape, but maybe not in OE. Patrick Turner. |
#30
Posted to rec.audio.tubes
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converting EL84 to triode mode
In article ,
Patrick Turner wrote: "Bob H." wrote: You can also put a diode in the sceen stopper circuit. It is some mumbo-jumbo idea that seems to work. Try it and see for yourself. Hmmm. 6/10 v drop across the screen supply, and what else? High resistance to oscillatoin from the screen back to the PS? I have seen diodes placed inline to prevent voltage dropping by reverse biasing. Is this using the same concept? Bob H. But just when does screen current ever try to flow backwards? I don't know, maybe in a transmitter when the tube is not correctly neutralized? Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
#31
Posted to rec.audio.tubes
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converting EL84 to triode mode
"Patrick Turner" wrote in message ... Nelson Gietz wrote: "Patrick Turner" wrote in message ... Phread wrote: "william" wrote in message ... "Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al ************** btw how to have outlook express insert "" to provious post? I saw that click box some years ago and couldn't find it any more? Tools Options Send Plain Text Settings for News Check "Indent ... with (Select '') OK OK Please be more usefully specific. I went to my OE, opened an email, clicked reply. The reply window has Tools, and I see in the Tools sub-window menu that 'Options' is not listed. So your advice is BS. Patrick Turner. Patrick, Don't click reply... just go Tools/Options/General from the main menu in OE. That where it is on mine. Then you tick your choices on "send/receive". Cheers, Nelson OK, I understand. The options were already turned on for plain text for emails and the news postings. When someone emails me and I hit reply, their message appears on my screen without any and when i type out a reply the receivers say sometimes they don't notice all of what i am saying because its seems mixed up with what they just posted. The ' ' business seems to work in netscape, but maybe not in OE. Patrick Turner. Patrick, In OE6, if you check, "Read all messages in plain text," in Tools Options Read, then you'll get indenting with the carat () in all your email replies. But you will lose the ability to see html in email and news messages, and attachments won't display in your preview window (although you will still be able to open attachments to view them). It's not that big a deal to turn the 'all messages in plain text' option on and off as the need arises. I don't think that option exists in OE5. Fred |
#32
Posted to rec.audio.tubes
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converting EL84 to triode mode
Oscillation does not spiral out of control. When it starts, it builds up in amplitude until the output tubes saturate, ie, become grossly over driven, Yes, the tube spirals out of control, and being a power tube, can then sustain damage to itself or the power supply. Bob H. |
#33
Posted to rec.audio.tubes
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converting EL84 to triode mode
John Byrns wrote: In article , Patrick Turner wrote: "Bob H." wrote: You can also put a diode in the sceen stopper circuit. It is some mumbo-jumbo idea that seems to work. Try it and see for yourself. Hmmm. 6/10 v drop across the screen supply, and what else? High resistance to oscillatoin from the screen back to the PS? I have seen diodes placed inline to prevent voltage dropping by reverse biasing. Is this using the same concept? Bob H. But just when does screen current ever try to flow backwards? I don't know, maybe in a transmitter when the tube is not correctly neutralized? Regards, John Byrns Electrons are attracted to g2 and thus flow to the PS in normal operation. if they were to flow in the other direction which is abnormal, it means that g2 is an emitter of electrons. Now control grid emission can occur when it becomes over heated, and especially if the the grid has some cathode material which has moved from the cathode to the grid. such an emitting situtation is a condition of fault, and presumably if the screen, g2, gets hot it could emit rather than receive electrons, but these grid & screen conditions are those not normal to ordinary audio or RF amplification. So, my question remains unanswered. Why use a diode in series with the screen? Patrick Turner. -- Surf my web pages at, http://fmamradios.com/ |
#34
Posted to rec.audio.tubes
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converting EL84 to triode mode
Phread wrote: "Patrick Turner" wrote in message ... Nelson Gietz wrote: "Patrick Turner" wrote in message ... Phread wrote: "william" wrote in message ... "Patrick Turner" wrote in message ... tubegarden wrote: Patrick Turner wrote: Top posting is seen by many to be poor netiquette. Think about it. if you top post without your valued comments placed BELOW the post to which you are replying then ALL those in the group get confused about what YOU are trying to say and reply to. You may know what you are saying, but the group finds it hard to follow. The diode in series with the screen of 6BQ5 6AQ5 etc should have its anode connected to the anode of the tube; ie, the arrow of the diode points toward the screen to allow a screen current flow or the tube just won't work. Don't ask me if a diode helps the fidelity or power; I have never tried this BS. And of course at least an IN4007 should be used since tube circuits give rise to highish peak inverse voltages across the diode. Patrick Turner. Hi RATs! I go with local custom. Some NG's top post, some bottom post. There is no clear correlation to quality of posts, but, bottom spewers seem to be bitchier. 6AQ5: 7 pin 6BQ5: 9 pin EL84: 9 pin "I have never tried this BS" is the mating call of the closed mind. Well what exactly isn't BS about connecting a diode in series with g2? I hope you don't mind my open minded question that isn't sexy, and is not a mating call. It's OK, none of the tweaks really make any difference whatsoever, it is just existential makework ... Who listens to Music, anyway The sound is so glorious ... Netiquette? Sigh. I find it amusing we choose to think we are writing these insults in a Politically Correct style Usually, there are reasons for what is done and said, and some that is done or said is more effective for the group. I'm for the group. I am only one small cog. I wish that when i turn around in this machine I do not cause unecessary noise or mayhem or confusion or belittlement. BS isn't the best lubricant for this cog either. Happy lystening. Patrick Turner. 12A6 rule! Happy Ears! Al ************** btw how to have outlook express insert "" to provious post? I saw that click box some years ago and couldn't find it any more? Tools Options Send Plain Text Settings for News Check "Indent ... with (Select '') OK OK Please be more usefully specific. I went to my OE, opened an email, clicked reply. The reply window has Tools, and I see in the Tools sub-window menu that 'Options' is not listed. So your advice is BS. Patrick Turner. Patrick, Don't click reply... just go Tools/Options/General from the main menu in OE. That where it is on mine. Then you tick your choices on "send/receive". Cheers, Nelson OK, I understand. The options were already turned on for plain text for emails and the news postings. When someone emails me and I hit reply, their message appears on my screen without any and when i type out a reply the receivers say sometimes they don't notice all of what i am saying because its seems mixed up with what they just posted. The ' ' business seems to work in netscape, but maybe not in OE. Patrick Turner. Patrick, In OE6, if you check, "Read all messages in plain text," in Tools Options Read, then you'll get indenting with the carat () in all your email replies. But you will lose the ability to see html in email and news messages, and attachments won't display in your preview window (although you will still be able to open attachments to view them). It's not that big a deal to turn the 'all messages in plain text' option on and off as the need arises. I don't think that option exists in OE5. I presently am using OE6, which always downloads any message with html and all attachments. When I hit reply to emails, and compose in html, it then allows me to place my text in with the sender's text and when he gets my reply there is no distinction marks between his text and mine; he should automatically see his original text shown with in front because I am quoting him and replying. I often compose my replies to emails in plain text to avoid sending images and attachments back since they are noty needed to be returned, and afaik, the same confusion occurs. My solution is to mark the beginnings of my paragraphs with *** so the sender can see my text better, ot compose above or below his undisturbed lot of text. I am presently using a pc MADE IN 1995 AND WITH 2gb hd AND 166MhZ processor and W98se. My sister has swapped to a laptop and didn't want her 2003 made PC with Windows XP, 80gB HD and faster processor so I now have this for my "new" set up with OE7 but for the news groups I will probably stay with Netscape 4.7 which works well and is simple. I am very fortunate to have such a sister indeed! Patrick Turner. Fred |
#35
Posted to rec.audio.tubes
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converting EL84 to triode mode
"Bob H." wrote: Oscillation does not spiral out of control. When it starts, it builds up in amplitude until the output tubes saturate, ie, become grossly over driven, Yes, the tube spirals out of control, and being a power tube, can then sustain damage to itself or the power supply. It depends on the dissipation of the anode, screen and grid. Guitar amps are regularly driven with a 40dB overload on their inputs but the grid current charges up the coupling cap and the tube is thus biased off heavily, and only able to pass a kind of square wave so the dissipation is not damaging because even with heavy metal the duty cycle isn't 100%. Still, outpt tubes do tend to expire more often in guitar amps than in hifi amps. But often its the loading that is lower in guitar amps, tending towards class B, with a tiny amount of class A wheras with hi-fi amps the loading tends towards class A, and the tubes are not biased too near the rated dissipation level as they are in guitar amps. Vox AC30 is a classic example with EL84 running at 15 watts each I find so often, and all biased from the one cathode resistance, a cheap nasty trick because the original makers couldn't afford the 4 bias R and C to make a network for each tube. Quad II also has one bias R for both output tubes, and this makes bias failure more likely. Saturated tubes, or one saturated output tube may not cause enough Ia to flow to make a fuse blow, and indeed can cause heat damage to OPT or PT. Hence its why I have active over-current protection in all my amps. Patrick Turner. Bob H. |
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