Well, If there is a voltage, there is a current (albeit, at times very
small)--the opposite is also true, ohms law is standing proof...



Why can't I measure the standing wave ratio as a ratio of power, as opposed
to voltage or even current reflected... the three are tied together, isn't
it impossible to separate any one from the other two (and, I mean in
reality, NOT in theory)--even though at times one can appear as
insignificant to an observer?



I see the design I sketched as an SWR device, perhaps not VSWR, or
ISWR--but, PSWR...



What would favor choosing the voltage device over the current or power SWR
devices?



Or, am I imagining something?



Warmest regards,

John


"Cecil Moore" wrote in message
...
| John Smith wrote:
| It seems to work, all I have is another SWR with analog meter I
constructed
| myself to compare it with, soon as I locate someone with a commercial
| meter--I will compare both of mine to it... Only real apparent problem
is
| the REF led changes brightness slowly (and here it is hard to "judge"
SWR by
| brilliance), until right at, or near, match, when it will plunge to
darkness
| rather quickly...
|
| You are not reading SWR. All you are reading is net current.
| Both LEDs have the same rectified net current through them.
|
| Well, show me what is wrong and suggest an alternative circuit or mods
to
| set it proper (or explain in text, I will see how good I am at word
problems
| here)--I am all EARS Cecil... smile
|
| Here's the last one I looked at:
|
| http://www.mfjenterprises.com/man/pdf/MFJ-974H.pdf
|
| You'll recognize the SWR circuitry at the input connector. Note
| the capacitive dividers. That's what your circuit is missing.
| Nowhere does your circuit sample the RF voltage.
|
| This type of SWR meter samples the RF voltage (using a capacitive
| divider) as one parameter. It samples the RF current (using the
| toroid) as the other parameter. The two parameters are added before
| rectification to obtain the forward power. The two parameters are
| subtracted before rectification to obtain the reflected power. The
| phasor addition and subtraction must be done before rectification.
| --
| 73, Cecil http://www.qsl.net/w5dxp
|
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On Wed, 4 May 2005 09:14:37 -0700, "John Smith"
wrote:
I see the design I sketched as an SWR device, perhaps not VSWR, or
ISWR--but, PSWR...
Not even that.

73's
Richard Clark, KB7QHC

John Smith wrote:
Well, If there is a voltage, there is a current (albeit, at times very
small)--the opposite is also true, ohms law is standing proof...

Yes, but the amplitude and phase relationship of current to
voltage can have any possible value and there are an infinite
number of possibilities. In the equation, Z = V/I, you cannot
determine Z unless you know BOTH V and I.

Why can't I measure the standing wave ratio as a ratio of power, ...

You need both voltage and current to determine power. Your design
senses only current.
--
73, Cecil http://www.qsl.net/w5dxp

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OK. Perhaps here the problem lies....

I am looking at it like this:
I don't care what value is V, nor what value is I...
I care only how much power the antenna is radiating, and how much is
"reflected" back and sits on the plates, collectors, or drains and is wasted
as heat--develops itself on the feedline--radiates from other antenna
components--etc....

I am thinking the "directional coupler" is doing that action, and forcing
the amount of "forward" power to one LED (amount of power actually leaving
the antenna (allowing for losses)) and giving indication--and the
"reflected" to the other LED (the amount of power "wasted") and giving
indication...
I take for granted that when 'Z' of "output of xmtr" = coax = antenna input,
I see the "REF LED" at dark condition....

There WELL may be an error in my thinking and, the "thing" (frankenstein?) I
have constructed only "seems" to work... (kinda like time yanno grin)

Thanks for your patience Cecil....

Warmest regards,
John

"Cecil Moore" wrote in message
...
| John Smith wrote:
| Well, If there is a voltage, there is a current (albeit, at times very
| small)--the opposite is also true, ohms law is standing proof...
|
| Yes, but the amplitude and phase relationship of current to
| voltage can have any possible value and there are an infinite
| number of possibilities. In the equation, Z = V/I, you cannot
| determine Z unless you know BOTH V and I.
|
| Why can't I measure the standing wave ratio as a ratio of power, ...
|
| You need both voltage and current to determine power. Your design
| senses only current.
| --
| 73, Cecil http://www.qsl.net/w5dxp
|
| ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet
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John Smith wrote:
There WELL may be an error in my thinking ...

No, there *IS* an error in your thinking. Blood from
a turnip comes to mind. The current in your feedline
is one amp. What is the power? See the problem?
--
73, Cecil http://www.qsl.net/w5dxp

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"Cecil Moore" wrote in message
...
John Smith wrote:
Well, If there is a voltage, there is a current (albeit, at times very
small)--the opposite is also true, ohms law is standing proof...

Yes, but the amplitude and phase relationship of current to
voltage can have any possible value and there are an infinite
number of possibilities. In the equation, Z = V/I, you cannot
determine Z unless you know BOTH V and I.

Why can't I measure the standing wave ratio as a ratio of power, ...

You need both voltage and current to determine power. Your design
senses only current.
--
73, Cecil http://www.qsl.net/w5dxp


Cecil is right. Also, the 100K implies 200V to get 2ma of LED current. The
1N914 won't hack that.

Tam/WB2TT

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Yes. I frequently find I overtax a components max. ratings (the smell of
burnt electronics is an acquired taste, like tobacco smoke and beer
grin)... I tend to pick up large quantities at auctions and surplus
outlets... replacing "sane design methods" with brute force and the
wholesale slaughter of un-counted components...



And, one should use caution with my labeling of components--I have boxes of
silicone diodes which are "similar" to 1n914's--and pounds of mis-valued
resistors/caps (the manufacturers just don't realize the value of a resistor
marked as one-ohm--when the actual value is one meg-ohm!!!)



"Whatever works!" sometimes becomes, "A list of what doesn't work!"



Quite often, the answer lies in "what I haven't tried..."



I don't expect all to be able to appreciate my "methods"... but, it breaks
the monotony of having to be so precise--which my field places upon me...



Warmest regards,

John



"Tam/WB2TT" wrote in message
...
|
| "Cecil Moore" wrote in message
| ...
| John Smith wrote:
| Well, If there is a voltage, there is a current (albeit, at times very
| small)--the opposite is also true, ohms law is standing proof...
|
| Yes, but the amplitude and phase relationship of current to
| voltage can have any possible value and there are an infinite
| number of possibilities. In the equation, Z = V/I, you cannot
| determine Z unless you know BOTH V and I.
|
| Why can't I measure the standing wave ratio as a ratio of power, ...
|
| You need both voltage and current to determine power. Your design
| senses only current.
| --
| 73, Cecil http://www.qsl.net/w5dxp
|
|
| Cecil is right. Also, the 100K implies 200V to get 2ma of LED current. The
| 1N914 won't hack that.
|
| Tam/WB2TT
|
| ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet
| News==----
| http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+
| Newsgroups
| ----= East and West-Coast Server Farms - Total Privacy via Encryption
| =----
|
|

Errr, make that that "silicon diodes", I keep gettin' 'em confused with the
girls! grin

Warmest regards,
John

"John Smith" wrote in message
news | Yes. I frequently find I overtax a components max. ratings (the smell of
| burnt electronics is an acquired taste, like tobacco smoke and beer
| grin)... I tend to pick up large quantities at auctions and surplus
| outlets... replacing "sane design methods" with brute force and the
| wholesale slaughter of un-counted components...
|
|
|
| And, one should use caution with my labeling of components--I have boxes
of
| silicone diodes which are "similar" to 1n914's--and pounds of mis-valued
| resistors/caps (the manufacturers just don't realize the value of a
resistor
| marked as one-ohm--when the actual value is one meg-ohm!!!)
|
|
|
| "Whatever works!" sometimes becomes, "A list of what doesn't work!"
|
|
|
| Quite often, the answer lies in "what I haven't tried..."
|
|
|
| I don't expect all to be able to appreciate my "methods"... but, it
breaks
| the monotony of having to be so precise--which my field places upon me...
|
|
|
| Warmest regards,
|
| John
|
|
|
| "Tam/WB2TT" wrote in message
| ...
||
|| "Cecil Moore" wrote in message
|| ...
|| John Smith wrote:
|| Well, If there is a voltage, there is a current (albeit, at times very
|| small)--the opposite is also true, ohms law is standing proof...
||
|| Yes, but the amplitude and phase relationship of current to
|| voltage can have any possible value and there are an infinite
|| number of possibilities. In the equation, Z = V/I, you cannot
|| determine Z unless you know BOTH V and I.
||
|| Why can't I measure the standing wave ratio as a ratio of power, ...
||
|| You need both voltage and current to determine power. Your design
|| senses only current.
|| --
|| 73, Cecil http://www.qsl.net/w5dxp
||
||
|| Cecil is right. Also, the 100K implies 200V to get 2ma of LED current.
The
|| 1N914 won't hack that.
||
|| Tam/WB2TT
||
|| ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet
|| News==----
|| http://www.newsfeeds.com The #1 Newsgroup Service in the World!
120,000+
|| Newsgroups
|| ----= East and West-Coast Server Farms - Total Privacy via Encryption
|| =----
||
||
|
|

While there's nothing wrong with this kind of approach when you're
making one of something for your own use, the resulting design isn't
likely to be useful to others because of the slim chance of someone else
being able to make a copy work.

Roy Lewallen, W7EL

John Smith wrote:
Yes. I frequently find I overtax a components max. ratings (the smell of
burnt electronics is an acquired taste, like tobacco smoke and beer
grin)... I tend to pick up large quantities at auctions and surplus
outlets... replacing "sane design methods" with brute force and the
wholesale slaughter of un-counted components...



And, one should use caution with my labeling of components--I have boxes of
silicone diodes which are "similar" to 1n914's--and pounds of mis-valued
resistors/caps (the manufacturers just don't realize the value of a resistor
marked as one-ohm--when the actual value is one meg-ohm!!!)



"Whatever works!" sometimes becomes, "A list of what doesn't work!"



Quite often, the answer lies in "what I haven't tried..."



I don't expect all to be able to appreciate my "methods"... but, it breaks
the monotony of having to be so precise--which my field places upon me...



Warmest regards,

John

Roy:

Yes. that is true... and an excellent point, now the others can't say they
haven't been warned...

Thanks Roy...

Warmest regards,
John

"Roy Lewallen" wrote in message
...
| While there's nothing wrong with this kind of approach when you're
| making one of something for your own use, the resulting design isn't
| likely to be useful to others because of the slim chance of someone else
| being able to make a copy work.
|
| Roy Lewallen, W7EL
|
| John Smith wrote:
| Yes. I frequently find I overtax a components max. ratings (the smell
of
| burnt electronics is an acquired taste, like tobacco smoke and beer
| grin)... I tend to pick up large quantities at auctions and surplus
| outlets... replacing "sane design methods" with brute force and the
| wholesale slaughter of un-counted components...
|
|
|
| And, one should use caution with my labeling of components--I have boxes
of
| silicone diodes which are "similar" to 1n914's--and pounds of mis-valued
| resistors/caps (the manufacturers just don't realize the value of a
resistor
| marked as one-ohm--when the actual value is one meg-ohm!!!)
|
|
|
| "Whatever works!" sometimes becomes, "A list of what doesn't work!"
|
|
|
| Quite often, the answer lies in "what I haven't tried..."
|
|
|
| I don't expect all to be able to appreciate my "methods"... but, it
breaks
| the monotony of having to be so precise--which my field places upon
me...
|
|
|
| Warmest regards,
|
| John