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Author Topic: Background Radiation - Could It Be a Vexation ?  (Read 41394 times)
AF6LJ
Member

Posts: 582




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« Reply #135 on: November 04, 2011, 03:46:46 PM »

I have been around long enough to know that every field has their cults and their cult followers. The only good that can come from exchanges like this is to wake up and educate people. Vacuum tube tech is over a hundred years old. Everything there is to know about them is in print, all factual and all scientifically based and all solidly referenced. There are no magic bullets, or God Particles that can slam an amplifier out of cutoff, or just idling and into oscillation dampened or otherwise. One would even be challenged to make this happen in a poorly designed amplifier if it didn't oscillate when the B+ was applied.

There was one other man so invested in his theories that he ended up being laughed at by his peers but Immanuel Velikovsky, at least wrote three books that were good fiction if nothing else. The ideas presented here are not even good fiction, they have to work within the laws of the physical universe to be considered good fiction.

Misinformation is a bad thing, worse yet are those who perpetuate it without consideration for the facts.

What originally brought me here was the October QST article after considerable discussion over on QRZ.com I had to see what had transpired over here since I know a few who post here often. It seems I have found the headwaters from which the river I have followed originate.

Reality never ceases to amaze me, as long as I live and no matter how much pain I have to endure (and I know from what I speak) I will always go to sleep in anticipation of what the next day brings like a little girl on Christmas eve.
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Take Care
Sue,
AF6LJ

Don't Kalifornicate My Life
AG6K
Member

Posts: 1




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« Reply #136 on: November 04, 2011, 03:58:34 PM »

Quote
AF6LJ, Susan
My alternate theory is the design of the amplifier is at fault.

  Alternate?  I've repeatedly been preaching that the design fault is that VHF amplification has not been reduced enough to avoid regeneration. 

Quote
There are more crap designs than good designs. I would also add that bad tubes get built sometimes with virtual leaks. (contaminated materials that outgas into the vacuum over time).

  The  majority of the tubes I tested after a big-bang had good vacuums.

Quote
You have not provided any documentation on what happens during this "big bang"

  One of the QST Staffers and I brainstormed on the elapsed time for a push-push parasitic big bang and we concluded that it's over in c. 100uSec for a 3-400Z or 3-500Z.  Who can take notes that fast?

Quote
and what I mean by documentation are meter readings or any way to repeat the failure mode. You make a religious leap of faith based on not being able to find another cause.

  There can not be more than one.


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Google "Effects of high energy particles on vacuum tube operation" and see what you come up with, nothing, zipp, nadda....

  I Googled parasitic oscillation and I got 607,000 hits. 

Quote
Show me just one peer reviewed paper that supports your failure mode

  stop by sometime and you can help me autopsy a 3-400Z that fil/grid shorted during a big-bang and you can see for yourself Susan.

Quote
If what you say actually dose happen it would have been reported in the semiconductor industry decades ago when they first began ion implantation, a big bang like that could cause tens of thousands even  hundreds of thousands of dollars in damage to implantation equipment.
The same level of damage would be happening to ion discharge milling equipment.

If you have had the physics then you know one high energy particle or even a few hundred won't do what you are claiming happened. A million amps of aurora is distributed over several tens to hundreds of cubic miles in the upper atmosphere.

I respectfully submit the science and the logic just isn't there.
Show me the peer reviewed papers and I'll gladly change my mind. If I have sufficient proof I will believe anything no matter how strange it may appear.

  No alternate theory.

Rich, ag6k
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AG6K
Member

Posts: 1




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« Reply #137 on: November 07, 2011, 01:49:23 AM »

Quote
Ignore
   
   
RE: Background Radiation - Could It Be a Vexation ?
« Reply #125 on: November 04, 2011, 07:49:25 AM »
   
Reply with quoteQuote
Quote from: AF6LJ on November 04, 2011, 07:32:25 AM
Your logic Rich is based on circumstantial deviance and isn't supported by real world experience.

Logical thought and facing the truth will not sell suppressor kits. Tom Rauch W8JI

   Tom R.:  Since the time that you told me you had repaired hundreds of SB-220s with VHF parasitic osc. damage, we have sold c. 10,000 lower VHF-Q parasitic suppressor retrofit kits.  I made no profit on these  because I pay my helpers a fair wage.   This has the benefit of reducing turnover.  My current helper is 24 and she has been doing mail orders since she was 11. 
  The reason we are still selling retrofit kits is because they decrease VHF amplification, which decreases the chance of VHF oscillation.  The trade-off is that they decrease P-output at 28MHz by about 1/11 of an S-unit. 
Rich, ag6k
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AG6K
Member

Posts: 1




Ignore
« Reply #138 on: November 07, 2011, 03:13:35 AM »

I have been around long enough to know that every field has their cults and their cult followers. The only good that can come from exchanges like this is to wake up and educate people.

  bull's-eye, 10-points for Susan.

Quote
Vacuum tube tech is over a hundred years old. Everything there is to know about them is in print, all factual and all scientifically based and all solidly referenced. There are no magic bullets, or God Particles that can slam an amplifier out of cutoff, or just idling and into oscillation dampened or otherwise.

  Correct.  Any mechanism or rapid sequence of events that causes gold to evaporate from the grid of an $800 8877 has for damn sure got to be from the mo-fo Devil Himself.

Quote
One would even be challenged to make this happen in a poorly designed amplifier if it didn't oscillate when the B+ was applied.

   Applying +HV to the anode will not in itself case a parasitic osc. because it takes an anode current pulse to ring the VHF parasitic resonance and create the VHF signal that can lead to VHF oscillation -- provided the stage has enough VHF-amplification to support regeneration.
   Feedback-C is a given.  There is no real-special esoteric layout or voodoo incantation that will cancel C-fb Susan.  Of course, feedback-C is smallish, being only 0.6pF in an 811A or 572B and 0.1pF in an 8877, however at VHF feedback's XC is not inconsiderable.  Example:  the SB-220's parasitic-resonance is 110MHz.  Two 3-500Zs have 0.3pF of C-fb, which is –j4300-ohms at 110MHz.  As I see it 4300-ohms of feedback at the parasitic-resonance should probably not be ignored.

Quote
There was one other man so invested in his theories that he ended up being laughed at by his peers but Immanuel Velikovsky, at least wrote three books that were good fiction if nothing else. The ideas presented here are not even good fiction, they have to work within the laws of the physical universe to be considered good fiction.

Misinformation is a bad thing, worse yet are those who perpetuate it without consideration for the facts.

What originally brought me here was the October QST article after considerable discussion over on QRZ.com I had to see what had transpired over here since I know a few who post here often. It seems I have found the headwaters from which the river I have followed originate.

  A  laugher about the original Oct. 1988 article:  A celeb owner of a TenTec amplifier who had no success in keeping his TenTec amplifier from arcing and sparking from what appeared to be intermittent parasitic oscillations - even after he had sent it to TenTec twice to have the problem fixed, tried reducing the Q of the VHF suppressors.  Eureka, the arcing and sparking stopped,  so he wrote a letter to TenTec giving them the good news.  TenTec wrote back saying they read the Oct. 1988 QST article, tried using lower VHF-Q suppressors, but abandoned the idea when they discovered that the new VHF (30-300 MHz) suppressors got very hot at 29MHz.  . 

Quote
Reality never ceases to amaze me, as long as I live and no matter how much pain I have to endure (and I know from what I speak) I will always go to sleep in anticipation of what the next day brings like a little girl on Christmas eve. [/i]

  When I was writing the manuscript for the 1988 QST article, I had no idea that I was tipping over a hornet's nest of "recognized experts". 
cheers Susan
Rich, ag6k
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