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Author Topic: Basic L/R VHF Parasitic Oscillation Suppressor Design  (Read 71059 times)
N4NYY
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Posts: 5224




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« Reply #15 on: October 04, 2011, 06:32:27 AM »

Quote
••  Thanks Ken.  Preview helps.  .  .  This application was not intended to use with Apple's Unix-based OS 10.4.  I find this semi amazing since Apple Computer is now the most valuable company in America.  cheers

While that may be the case, their market share is like 15%, so most websites will not be optimized for Macs.
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AG6K
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« Reply #16 on: October 04, 2011, 07:05:43 AM »

Quote
••  Thanks Ken.  Preview helps.  .  .  This application was not intended to use with Apple's Unix-based OS 10.4.  I find this semi amazing since Apple Computer is now the most valuable company in America.  cheers

While that may be the case, their market share is like 15%, so most websites will not be optimized for Macs.

  15% is quite true - except at colleges, universities, and in the music business.  Every OS has a useful life expectancy.   For this reason Apple's Steve Jobs abandoned OS 9 and went to Unix-based OS 10.  Methinks that at some point, Microsoft needs to switch from a carburetor-era OS to the era of fuel-injection and go to a Unix based OS.  -- but then I am no expert.  cheers
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N4NYY
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« Reply #17 on: October 04, 2011, 07:40:46 AM »

Quote
  15% is quite true - except at colleges, universities, and in the music business.  Every OS has a useful life expectancy.   For this reason Apple's Steve Jobs abandoned OS 9 and went to Unix-based OS 10.  Methinks that at some point, Microsoft needs to switch from a carburetor-era OS to the era of fuel-injection and go to a Unix based OS.  -- but then I am no expert.  cheers

Microsoft is the next RIM. They missed the boat and are trying to catch up. Ballmer is an idiot.
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AG6K
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« Reply #18 on: October 04, 2011, 10:32:33 AM »

Quote
  15% is quite true - except at colleges, universities, and in the music business.  Every OS has a useful life expectancy.   For this reason Apple's Steve Jobs abandoned OS 9 and went to Unix-based OS 10.  Methinks that at some point, Microsoft needs to switch from a carburetor-era OS to the era of fuel-injection and go to a Unix based OS.  -- but then I am no expert.  cheers

Microsoft is the next RIM. They missed the boat and are trying to catch up. Ballmer is an idiot.

  HOWEVER, HE'S A RICH ONE.
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W3LK
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« Reply #19 on: October 04, 2011, 10:38:23 AM »


••  Thanks Ken.  Preview helps.  .  .  This application was not intended to use with Apple's Unix-based OS 10.4.  I find this semi amazing since Apple Computer is now the most valuable company in America.  cheers

Hogwash! This site and it's software run just fine on Macs - I've been doing it for years and never had a problem with any version of the Mac OS rendering the site correctly. Same deal with the quote function. YOU JUST HAVE TO PAY ATTENTION TO WHAT YOU ARE DOING.

To put it in simple words, what you want to quote goes INSIDE the quote commands and what YOU want to say goes outside. It ain't rocket science or even parasitic suppression. Don't blame eHam of the Mac OS for the problem; it's all you. My seven-year old grandson can't spell, but he knows how to use the quote function correctly. <gg>
« Last Edit: October 04, 2011, 10:40:51 AM by W3LK » Logged

A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
AG6K
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Posts: 1




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« Reply #20 on: October 04, 2011, 11:19:54 AM »


••  Thanks Ken.  Preview helps.  .  .  This application was not intended to use with Apple's Unix-based OS 10.4.  I find this semi amazing since Apple Computer is now the most valuable company in America.  cheers

Hogwash! This site and it's software run just fine on Macs -
Quote

  This is inside the quote commands. 

I've been doing it for years and never had a problem with any version of the Mac OS rendering the site correctly. Same deal with the quote function. YOU JUST HAVE TO PAY ATTENTION TO WHAT YOU ARE DOING.

To put it in simple words, what you want to quote goes INSIDE the quote commands and what YOU want to say goes outside. It ain't rocket science or even parasitic suppression. Don't blame eHam of the Mac OS for the problem; it's all you. My seven-year old grandson can't spell, but he knows how to use the quote function correctly. <gg>
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G3RZP
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Posts: 1271




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« Reply #21 on: October 04, 2011, 11:48:48 AM »

There seems to have been an enormous thread drift away from the errors in the first posting.
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AG6K
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Posts: 1




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« Reply #22 on: October 04, 2011, 12:32:54 PM »


••  Thanks Ken.  Preview helps.  .  .  This application was not intended to use with Apple's Unix-based OS 10.4.  I find this semi amazing since Apple Computer is now the most valuable company in America.  cheers

Quote
Hogwash! This site and it's software run just fine on Macs - I've been doing it for years and never had a problem with any version of the Mac OS rendering the site correctly. Same deal with the quote function. YOU JUST HAVE TO PAY ATTENTION TO WHAT YOU ARE DOING.

Quote
To put it in simple words, what you want to quote goes INSIDE the quote commands and what YOU want to say goes outside. It ain't rocket science or even parasitic suppression. Don't blame eHam of the Mac OS for the problem; it's all you. My seven-year old grandson can't spell, but he knows how to use the quote function correctly. <gg>

  This is putting a comment outside.   Tnx for explaining.  This is the first discussion group I have participated in that has manual quote-back,
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W8JI
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WWW

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« Reply #23 on: October 04, 2011, 12:36:09 PM »

There seems to have been an enormous thread drift away from the errors in the first posting.

Looks like any hope of keeping threads useful and somewhat on topic are dashed.
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G3RZP
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« Reply #24 on: October 04, 2011, 12:56:43 PM »

Tom,

A bit like the advantages (?) of using nichrome!
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AG6K
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Posts: 1




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« Reply #25 on: October 04, 2011, 01:48:45 PM »

Tom,

A bit like the advantages (?) of using nichrome!

 It's possible to build a  VHF-Q=2 parasitic suppressor's inductor out of the same   AWG-ga. Ag. or Cu. or Ni-Cr. wire by using more turns on the coil for Cu and Ag suppressors. Naturally this increases the V-drop the R and increases dissipation.  If  at 28 MHz - with Ag wire,  the R dissipation is 10W. with Cu wire it would be c. 9.5w and with Ni-Cr wire the suppressor R would dissipate c. 5.5w. With Ag or Cu wire there would be liitle warmth in the suppressor L - but with Ni-Cr wire the L would be hot.  - note - builders of low Q suppressors for the 3CX3000A7 have reported seeing glow in the dark Ni-Cr ribbon inductors at 28MHz A0.  Rich, ag6k
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W8JI
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« Reply #26 on: October 04, 2011, 01:50:54 PM »

Tom,

A bit like the advantages (?) of using nichrome!

The entire forum is now bizarre and almost useless. :-)
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N2EY
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Posts: 5079




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« Reply #27 on: October 04, 2011, 03:57:31 PM »

I don't like to get bogged down in math, and eham makes it difficult to post equations. So I'm going to go at this conceptually, which for me is easier to understand anyway.

To lower the Q of a L/R parallel circuit one needs to increase R.

No. That's just not right.

To lower the Q of an LR parallel circuit one needs to decrease R.

To lower the Q of an LR series circuit one needs to increase R.

The obvious way to do this is to increase the resistance of R.

No it isn't.

However as resistance increases, so does dissipation - and that problem is most severe at 28MHz since that is the band where the V-drop across L is max.  Since the R component of a suppressor needs to have low self-inductance to function properly, suitable resistors are few. A workaround is to use resistance-wire for L.

Let's see where this goes.....

Even though its resistance is in series, by doing a series to parallel equivalent conversion one can see that it has the same effect that a parallel resistance has.

No it doesn't. It has a completely different effect. Series to parallel equivalent conversion is not valid in this case because the frequency changes, and so does the reactance.

Here's proof:

Consider a conventional suppressor consisting of a coil of very high conductivity (very high Q coil) in parallel with a resistor of very low inductance.

At "high" (parasitic) frequencies the inductor has quite high XL and very low R. Not much RF current can pass through it because of the XL, so most of the RF current has to go through the resistor - which is so lossy a parasitic can't start.
 
At "low" (desired) frequencies the inductor has very low XL and very low R. RF currents can pass right through it with very low loss. Only a tiny bit of the RF current has to go through the resistor and be dissipated, because the XL and R of the coil are very low.

Now consider an unconventional suppressor consisting of a coil of resistance wire (low Q coil) in parallel with a resistor of low inductance.

At "high" (parasitic) frequencies the inductor has quite high XL and considerable R. Not much RF current can pass through it because of the XL, so most of the RF current has to go through the resistor - which is so lossy a parasitic can't start. So it "works" in the sense that the parasitic problem is solved.
 
At "low" (desired) frequencies the inductor has very low XL but considerable R. RF currents can pass through it, but there is considerable loss due to the R. Not only that, but more of the RF current has to go through the resistor and be dissipated, because while the XL of the coil is low the R isn't.

If we take the limiting case (DC), the unconventional suppressor dissipates more than the conventional, because the resistance wire has more loss right down to f equals zero.

IOW, what we want in a parasitic suppressor is a coil that has as high Q as possible and a resistor with as little reactance as possible. The ideal would be a coil of pure L and a resistor of pure R.

Intentionally making the coil resistive is the absolute wrong approach because the coil will then dissipate more, not less, desired-frequency RF.

Now of course we can't get ideal parts. But we can come close by using large copper wire or strap for the coil, and the lowest inductance resistors available.

Remember that if a parasitic suppressor works, the parasitic never starts. All the heat dissipated in a parasitic suppressor is either DC or desired RF. Therefore it makes sense for the suppressor to have as low loss at the desired frequency as possible.

73 de Jim, N2EY

 


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N4NYY
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« Reply #28 on: October 04, 2011, 06:25:46 PM »

Quote
The entire forum is now bizarre and almost useless. :-)

That is my fault. I was having trouble following with everything in quotes, and when I said something, the thread drifted.

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K8AXW
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« Reply #29 on: October 04, 2011, 09:25:27 PM »

All:  I've been trying to follow this thread as close as I can but must admit that I am now reading words, and while I can read and say the words, they finally have lost all meaning to me.

So, with that being said, let me ask this.  If a commercial amplifier is designed, tested and approved for sale it should be considered "stable."  After all, the wiring and component values and placement are pretty much identical on each unit.  The only variable from that point would be if the tubes are changed.  Is the parasitic suppressors designed for that particular amplifier or is some preconceived configuration used?

Now with the Heathkit amplifiers.  Since each amplifier is built with basically the same components but the wiring and lead dressing can take on an infinite number of variations, how is "stability" accomplished in them?  Again, are the parasitic suppressors some preconceived configuration and not specifically designed for that model of amplifier.

You know, you guys are getting into some pretty deep sh..t here and I sincerely doubt if much of it is of any practical use to the average eHam reader...... unless some basic conclusions are presented.  So far I haven't been able to see any.



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A Pessimist is Never Disappointed!
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