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Author Topic: • Favorite Old Wives' Tales •  (Read 29889 times)
W8JI
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« Reply #120 on: November 17, 2011, 07:20:07 PM »

  Fortunately, unlike Tom R.,  I do not attract many groupies Jeff.  One reason is  my lack of charisma. 

I think the real problem Rich is not with you personally at all. In my experience, intelligent open-minded people generally want to like other people, regardless of charisma levels.

The real problem is the total lack of references and good science behind the stream of very bizarre theories you offer as fact. It's more about the bad science than anything else. If the science you offered was good at all, you would have many people agreeing with you.
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AG6K
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« Reply #121 on: November 17, 2011, 08:28:48 PM »

  Fortunately, unlike Tom R.,  I do not attract many groupies Jeff.  One reason is  my lack of charisma. 

I think the real problem Rich is not with you personally at all. In my experience, intelligent open-minded people generally want to like other people, regardless of charisma levels.

The real problem is the total lack of references and good science behind the stream of very bizarre theories you offer as fact. It's more about the bad science than anything else. If the science you offered was good at all, you would have many people agreeing with you.

  I know that the battle of references is not winable on the electromagnetic radiation issue because there are still many hubristic "recognized experts" out there who are mired in the current-only myth.
Rich, ag6k
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AG6K
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« Reply #122 on: November 17, 2011, 08:38:15 PM »

Rich,

The Foote letter has nothing to do with filament voltage, or anything else.

  Nothing else? .  .  Does the Foote letter have anything to with the reason for gold boiling off of an 8877 grid?
•••  Rich, ag6k
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W7SMJ
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« Reply #123 on: November 17, 2011, 10:21:58 PM »

  Like quoting what Michelle Bachmann said about Paul Revere warning the Brits? 
•••  Rich, ag6k

It's not an "Old Wives' Tale", but it is a tall tale, so why not...  Roll Eyes

73,
Scott

P.S. Could you please provide the reference for the (V2/V1)^23.4 formula?
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N2EY
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« Reply #124 on: November 18, 2011, 03:56:20 AM »

The real problem is the total lack of references and good science behind the stream of very bizarre theories you offer as fact. It's more about the bad science than anything else. If the science you offered was good at all, you would have many people agreeing with you.

That's the whole thing, right there.

It's not about who says it.

It's about what they're actually saying, and how much sense it makes in the real world.

Much of what AG6K writes here simply does not make sense in the real world.

73 de Jim, N2EY
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AG6K
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« Reply #125 on: November 18, 2011, 04:26:43 AM »

  Like quoting what Michelle Bachmann said about Paul Revere warning the Brits? 
•••  Rich, ag6k

It's not an "Old Wives' Tale", but it is a tall tale, so why not...  Roll Eyes

  According to Michelle B., Paul Revere rode to the Brits to warn them that they would get their butts kicked if the tried to attack the Colonists - plus she says Revere used bells in the church steeple to let the Colonists know how the Brits were coming. . . . At this point it seems that R. voters have figured out that Michelle B. has a lot in common with Sarah P., so her poll numbers are headed to the basement. 
Quote
73,
Scott

P.S. Could you please provide the reference for the (V2/V1)^23.4 formula?

  Eimac states that each 3% increase in filament potential above that which produces full PEP decreases the emissive life of the tungsten dicarbide layer by 50%.  If one puts this relationship into a math formula, one arrives at (V2/V1)23.4. . . Checking the formula:  ((1.0/1.03)23.4= 0.500 . Real world example:  A stock TL-922 being operated from 240VAC mains:  The filament V at the sockets is 5.31v.  The max/min filament V rating is 5.25v/4.75v.  If the filament V is reduced from 5.31v to 4.8v, the emissive life is (5.31v/4.8v)23.4 = 10.6 x what it would have been at 5.31v.
  This formula was included in the  article "The Nearly Perfect Amplifier" which was published in the January, 1994 issue of QST Magazine.
cheers Scott
Rich, ag6k
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AG6K
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« Reply #126 on: November 18, 2011, 04:36:19 AM »

Absolutely Tom has behind the scenes offered me much wonderful advice and he never asked nothing in return. Not only would i call him a expert in his feild but a damned great Elmer too. 

Jeff

But none of this matters.

Education does not matter, years licensed do not matter, experience does not matter, how nice or mean someone is does not matter.

If someone is correct, they should be able to coherently explain why they are correct. Almost everyone should be able to follow the logic and not see any flaws in the logic. They should also be able to use some reference other than "because I say so", "xxxxx told me" or "xxxxxxx said".

That is what got QST in trouble a few times in the past with his stuff, and they did it again with filament voltage. They took his word for what Eimac said, instead of actually looking at what Eimac really said.

  Puck was right.
Rich, ag6k
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AG6K
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« Reply #127 on: November 18, 2011, 04:43:23 AM »

The real problem is the total lack of references and good science behind the stream of very bizarre theories you offer as fact. It's more about the bad science than anything else. If the science you offered was good at all, you would have many people agreeing with you.

That's the whole thing, right there.

It's not about who says it.

It's about what they're actually saying, and how much sense it makes in the real world.

Much of what AG6K writes here simply does not make sense in the real world.

73 de Jim, N2EY


  How about giving us a nonsensical example Jim ?  tnx
Rich, ag6k
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W8JI
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« Reply #128 on: November 18, 2011, 05:31:19 AM »

Never trust an author who cannot provide a reference except himself and what he says others say.

  Eimac states that each 3% increase in filament potential above that which produces full PEP decreases the emissive life of the tungsten dicarbide layer by 50%.  If one puts this relationship into a math formula, one arrives at (V2/V1)23.4. . . Checking the formula:  ((1.0/1.03)23.4= 0.500 . Real world example:  A stock TL-922 being operated from 240VAC mains:  The filament V at the sockets is 5.31v.  The max/min filament V rating is 5.25v/4.75v.  If the filament V is reduced from 5.31v to 4.8v, the emissive life is (5.31v/4.8v)23.4 = 10.6 x what it would have been at 5.31v.
  This formula was included in the  article "The Nearly Perfect Amplifier" which was published in the January, 1994 issue of QST Magazine.
cheers Scott
Rich, ag6k

So as we all see....

when pressed for Eimac's data, Rich quotes himself as the Eimac example.

It is so easy to do things right and reference sources, but Rich cannot reference anyone but himself for most of what he claims.

Eimac, unfortunately for Rich, disagrees with what Rich claims.

If you want to read filament voltage data, here is a web page with links to the actual Eimac publications:

http://www.w8ji.com/filament_voltage_life.htm

Eimac links    http://www.w8ji.com/Vacuum%20Tubes/CPI%20AB-18%20New%20v2.pdf    and direct quotes from Eimac state:

"NOTE: If the filament voltage cannot be regulated to within ± 3%, the filament should always be operated at the rated nominal voltage specified on the data sheet.

It should be noted that there is a danger to operating the emitter too much on the “cold” temperature side. It may become “poisoned.” A cold filament acts as a getter; that is, it attracts contaminants. When a contaminant becomes attached to the surface of the emitter, the affected area of the emitter is rendered inactive, causing loss of emission. "

and Eimac says:

"When a noticeable change occurs in the output power or if the distortion level changes, the de-rating procedure must stop. Obviously, operation at and beyond this point is unwise since there is no margin allowed for a drop in line voltage. The voltage should be raised 0.2V above the critical voltage at which changes are observed to occur. Finally, recheck power output or distortion to see if they are acceptable at the chosen filament voltage level. Recheck again after 24 hours to determine if emission is stable and that the desired performance is maintained. If performance is not repeatable, the derating procedure must be repeated. Continuing the Program The filament voltage should be held at the properly de-rated level as long as minimum power or maximum distortion requirements are met. Filament voltage can be raised to reestablish minimum requirements as necessary. This procedure will yield results similar to those shown in the illustration (Figure eight), to achieve as much as 10% to 15% additional life extension. When it becomes necessary to start increasing the filament voltage in order to maintain the same power output, it is time to order a new tube. Filament voltage can be increased as long as the increase results in maintaining minimum level requirements. However, when a voltage increase fails to result in meeting output level requirements, filament emission must be considered inadequate and the tube should be replaced. Don’t discard it or sell it for scrap! Put it on the shelf and save it. It will serve as a good emergency spare and may come in handy some day. Also, in AM transmitters, a low-emission RF amplifier tube can be shifted to modulator use where the peak filament emission requirement is not as severe. "

end of Eimac's quoted text.

Eimac ACTUALLY says:

1.)    DO NOT derate the filament if you cannot regulate the filament

2.)  If you derate, you must measure either output power reduction or distortion and set the filament 0.2 volts above the critical point, and monitor that point for changes in operation

3.) Eimac says if you do this complex filament management right and wring things out to the end, you can get 10-15% more life.

None of it says anything remotely similar to what Rich claims, and everyone can read it for themselves.

Since Eimac says NOTHING like Rich claims they say, and he knows this, he is intentionally misleading people. Worse than that, if Rich's instructions are followed, people can damage tubes faster than leaving them at higher voltage, and can trash the bands with splatter. This not only ruins people's tubes, it ruins our bands with splatter.

By the way, I changed a two-year old pair of 3-500Z's out in an amplifier that was loaded with Rich's mods, because the tubes were weak. His changes don't do a thing to increase life or reliablility, and increase the splatter and reduce the output.  

73 Tom

« Last Edit: November 18, 2011, 07:18:02 AM by W8JI » Logged
AF6LJ
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« Reply #129 on: November 18, 2011, 06:41:27 AM »

I am still waiting for the textbook title and chapter that backs up your claim this statement is wrong.

Quote
A half-wave dipole radiates mostly from where the RF current is max. 

Not providing any supporting material from an athoritave source source does little to win the minds of those who actually know better.


Because we can read and anybody who just says something and doesn't back it up is trying to sell snake oil.
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Take Care
Sue,
AF6LJ
When it's time it's time, and it may be sooner than you think.
KB8E
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« Reply #130 on: November 18, 2011, 06:44:24 AM »

Eimac's Application Bulletin AB-18 covers filament voltage and its affect on tube life. My understanding is that there are significant tradeoffs involved and too low a filament voltage can be a real problem. Tom R. and few others have written extensively about this subject and how it pertains to SSB and ICAS applications. It's good reading and puts the filament voltage subject into context.

However, on page 163 of Eimac's Care and Feeding of Power Grid Tubes, it says: "Theoretically a 3% increase in filament voltage will result in a 20 Kelvin increase in temperature, a 20% increase in peak emission, and a 50% decrease in life due to carbon loss. This, of course, works the other way, too." I understand that this statement is taken out of context and comes with many caveats, but it is where Rich say it is for people to use or misuse as they see fit.

Sam
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W8JI
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« Reply #131 on: November 18, 2011, 06:50:29 AM »

I am still waiting for the textbook title and chapter that backs up your claim this statement is wrong.

Quote
A half-wave dipole radiates mostly from where the RF current is max. 

Not providing any supporting material from an athoritave source source does little to win the minds of those who actually know better.


Because we can read and anybody who just says something and doesn't back it up is trying to sell snake oil.

He obviously is wrong about filament voltage, and can't provide a reference for his his filement voltage formula except himself. Eimac clearly warns to not do what he tells people to do.

The photon stimulated emission stuff is nonsense.

The balun on the tuner input stuff was wrong.

The Rp and parasitic suppressor stuff is wrong.

The Palin / Bachmann stuff was backwards.

I expect the antenna stuff will be more of the same the same, although eventually one would expect something would be accurate.     :-)
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G3TXQ
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« Reply #132 on: November 18, 2011, 07:19:01 AM »

I'm a simple soul, and all this talk of photons etc makes my head spin Smiley

So, I looked at a simple modelling experiment. I modelled a 20m, centre-fed, Inverted-V, half-wave dipole with its apex at 35ft and the two ends at 25ft. I noted:
Maximum radiation at 31 degrees elevation; Radiation at 10 degrees elevation +0.87dBi

Then I flipped the dipole - apex now at 25ft and the ends at 35ft. I then noted:
Maximum radiation at 34 degrees elevation; Radiation at 10 degrees elevation -0.08dBi

So, flipping the dipole raised the angle of maximum radiation, and reduced the radiation at 10 degrees elevation - an effect equivalent to a drop in mean height.

What could explain that other than that the centre of the dipole, where the current is highest, makes more contribution to the Far-Field radiation than do the ends?

Steve G3TXQ
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W8JI
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« Reply #133 on: November 18, 2011, 07:23:17 AM »

I'm a simple soul, and all this talk of photons etc makes my head spin Smiley

So, I looked at a simple modelling experiment. I modelled a 20m, centre-fed, Inverted-V, half-wave dipole with its apex at 35ft and the two ends at 25ft. I noted:
Maximum radiation at 31 degrees elevation; Radiation at 10 degrees elevation +0.87dBi

Then I flipped the dipole - apex now at 25ft and the ends at 35ft. I then noted:
Maximum radiation at 34 degrees elevation; Radiation at 10 degrees elevation -0.08dBi

So, flipping the dipole raised the angle of maximum radiation, and reduced the radiation at 10 degrees elevation - an effect equivalent to a drop in mean height.

What could explain that other than that the centre of the dipole, where the current is highest, makes more contribution to the Far-Field radiation than do the ends?

Steve G3TXQ

Please don't bother Rich with examples of how things really work.       :-)
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AF6LJ
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« Reply #134 on: November 18, 2011, 07:41:58 AM »

I'm a simple soul, and all this talk of photons etc makes my head spin Smiley

So, I looked at a simple modelling experiment. I modelled a 20m, centre-fed, Inverted-V, half-wave dipole with its apex at 35ft and the two ends at 25ft. I noted:
Maximum radiation at 31 degrees elevation; Radiation at 10 degrees elevation +0.87dBi

Then I flipped the dipole - apex now at 25ft and the ends at 35ft. I then noted:
Maximum radiation at 34 degrees elevation; Radiation at 10 degrees elevation -0.08dBi

So, flipping the dipole raised the angle of maximum radiation, and reduced the radiation at 10 degrees elevation - an effect equivalent to a drop in mean height.

What could explain that other than that the centre of the dipole, where the current is highest, makes more contribution to the Far-Field radiation than do the ends?

Steve G3TXQ

Please don't bother Rich with examples of how things really work.       :-)

Ouch

Well busy day today; it's been educational to say the least.
Time to do my shopping for the day, which includes a trip by the hardware store for some rope and small hardware in order to get my twenty meter inverted V off the ground and in the air before the Turkey Day Net.

Have a good day everyone, and remember; the truth is always worth defending, if for no other reason than to keep the ignorant among us from going down the wrong path.
 
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Take Care
Sue,
AF6LJ
When it's time it's time, and it may be sooner than you think.
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