OK, one... more.... time!!! there is no time yanno!
Please someone, see if you can view the page he
http://blake.prohosting.com/mailguy2/JS-swr.jpg

Warmest regards,
John

"John Smith" wrote in message
...
| This is a SWR bridge I built using leds and a homemade "directional
| coupler."
|
| ALL critiques on it, and ideas for improvements are welcomed!!!
|
| Please excuse my rough drawing, I am NOT a draftsperson!
|
| Hopefully, the attachment of the .jpg was successful....
|
| Warmest regards,
| John
|
|

John Smith wrote:
OK, one... more.... time!!! there is no time yanno!
Please someone, see if you can view the page he
http://blake.prohosting.com/mailguy2/JS-swr.jpg

You have a number of problems. Where did you get that design?
In order to separate the forward power from the reflected
power, you need to use phasor addition/subtraction of voltage
and current. You only have current sampled. Where is your
voltage sample? Where is your phasor addition/subtraction?
--
73, Cecil http://www.qsl.net/w5dxp


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Well, can't remember where I seen that "directional coupler", but will be
willing to give the designer credit if he makes himself know...

The led indicating circuit is my design...

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...

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

Regards,
John

"Cecil Moore" wrote in message
...
| John Smith wrote:
| OK, one... more.... time!!! there is no time yanno!
| Please someone, see if you can view the page he
| http://blake.prohosting.com/mailguy2/JS-swr.jpg
|
| You have a number of problems. Where did you get that design?
| In order to separate the forward power from the reflected
| power, you need to use phasor addition/subtraction of voltage
| and current. You only have current sampled. Where is your
| voltage sample? Where is your phasor addition/subtraction?
| --
| 73, Cecil http://www.qsl.net/w5dxp
|
|
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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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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
|
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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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"John Smith" wrote in message
...
Well, can't remember where I seen that "directional coupler", but will be
willing to give the designer credit if he makes himself know...

The led indicating circuit is my design...

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...

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

Regards,
John

"Cecil Moore" wrote in message
...
| John Smith wrote:
| OK, one... more.... time!!! there is no time yanno!
| Please someone, see if you can view the page he
| http://blake.prohosting.com/mailguy2/JS-swr.jpg
|
| You have a number of problems. Where did you get that design?
| In order to separate the forward power from the reflected
| power, you need to use phasor addition/subtraction of voltage
| and current. You only have current sampled. Where is your
| voltage sample? Where is your phasor addition/subtraction?
| --
| 73, Cecil http://www.qsl.net/w5dxp
|
|
| ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet
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| http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000
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I found this while tidying my bookshelf last night:
CQ Amateur Radio magazine October 1997 "N7VE's One LED SWR Indicator".

73 Roger ZR3RC