K3 Watt-meter question!

[JIM DAVIS-11]

Gentlemen,

How accurate is the built-in watt meter indicator in the K3???

I'm asking because when I've used a supposed;y accurate "Bird 43" while measuring the K3's various
outputs on the various HF bands there seems to be a slight discrepitancy between what the K3 is
showing and what's actually there according to the "BIRD!!!"  I'm particularly interested in the
output readings as concerns "6 metres!" Which is MORE ACCURATE???

Regards,

Jim/nn6ee
S/N 2406
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[Jack Smith-6]

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[Jack Smith-6]

Jim:

You might be interested in my K3 output power comparison using lab grade
power measurement equipment.
http://www.cliftonlaboratories.com/k3_power_setting_accuracy.htm

Jack K8ZOA


JIM DAVIS wrote:

> Gentlemen,
>
> How accurate is the built-in watt meter indicator in the K3???
>
> I'm asking because when I've used a supposed;y accurate "Bird 43" while measuring the K3's various
> outputs on the various HF bands there seems to be a slight discrepitancy between what the K3 is
> showing and what's actually there according to the "BIRD!!!"  I'm particularly interested in the
> output readings as concerns "6 metres!" Which is MORE ACCURATE???
>
> Regards,
>
> Jim/nn6ee
> S/N 2406
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>  

... [show rest of quote]

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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Phil LaMarche-2]

Ron,

And to add, it's not important to most hams because a few watts isn't even
noticed on the S meter.  I run mine at 95 watts.

Phil


Philip LaMarche
LaMarche Enterprises, Inc.
www.instantgourmetspices.com

www.w9dvm.com
800-395-7795 pin 02
727-944-3226
FAX [phone]
NASFT 30210

K3  #1605

CCA 98  00827
W9DVM



-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Ron D'Eau Claire
Sent: Friday, May 29, 2009 12:11 PM
To: [hidden email]
Subject: Re: [Elecraft] K3 Watt-meter question!

Jim, you said "supposedly accurate". A Bird wattmeter is accurate only if
it's been properly calibrated and handled carefully - especially the
"slugs". Bumps and bangs can easily ruin the calibration (That's why all
Birds used in critical applications carry calibration stickers showing when
it was last checked - normally no less often than annually - and is
carefully handled and stored in approved containers).

Let's assume the Bird is recently calibrated and treated kindly:

1) Its calibration is then dependent upon using the right slug. You probably
know better, but a surprising number of Bird owners think the frequency
range on the slug isn't very important. I believe the proper Bird 43 element
for 6 meters is the type A slug spec'd for 25-60 MHz.

2) Are you allowing for the normal error in even a perfectly-calibrated
Bird? That's +/- 5% of *full scale*. IIRC the Bird 6 meter slugs have full
scale ranges of 25 or 250 watts. If you're measuring 100 watts with the 250
watt slug, the possible error in a properly-calibrated Bird is +/- 5% of 250
watts *anywhere* in the scale. So at 100 watts indicated, the actual power
may be anywhere between 87 and 112 watts.  

That's plenty good enough accuracy for nearly all field use, including for
showing that transmitter power levels comply with FCC regs (although when I
demonstrate a marine transmitter to FCC engineers, it's *their* Bird that is
the final word ;-)

Now, the K3 has simply another wattmeter built in, so it's normal for the
two wattmeters to disagree by the sum of their possible errors.

You asked, "Which one is more accurate?" One of the Elecraft engineers would
have to answer that, but let's assume the K3's built in wattmeter is as good
as the Bird. In that case a perfectly calibrated Bird on a perfectly
calibrated K3 may disagree by as much as 15 watts at 100 watts giving you an
indication of anywhere between 85 and 115 watts on the Bird when the K3
meter says 100 watts.

And don't forget that assumes everything is in perfect calibration. In the
real world, it's not unusual to see a greater error.  

That's why it's not normally considered important for owners to worry about
the K3's power calibration. Unless you have some laboratory standards to
compare to each other and to the K3, it's almost impossible to improve on
the default factory settings.

Ron AC7AC



-----Original Message-----

Gentlemen,

How accurate is the built-in watt meter indicator in the K3???

I'm asking because when I've used a supposed;y accurate "Bird 43" while
measuring the K3's various outputs on the various HF bands there seems to be
a slight discrepitancy between what the K3 is showing and what's actually
there according to the "BIRD!!!"  I'm particularly interested in the output
readings as concerns "6 metres!" Which is MORE ACCURATE???

Regards,

Jim/nn6ee
S/N 2406

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[w7aqk]

Hi All,

Over the years I've seen Bird Wattmeters for sale at dozens
of hamfests, as well as over the internet.  Typically these
are very "pricey", and require all sorts of accessories.  I
have no doubt that this is, more or less, "the standard"
when it comes to wattmeters.  However, my question is (and I
ask this seriously), just how often am I apt to really need
something that is so precise?  I have an Elecraft W1, and
several other wattmeters around the shack, including an OHR
W-1.  I think the two I specifically mention are relatively
accurate, although perhaps not quite up to "Bird" standards.
All wattmeters need to be calibrated, and need to be
re-calibrated if you change ranges significantly.  To be
honest with you, the only time I have any real concern about
being 99.9% accurate is if I'm crowding the 5 watt limit in
a contest.  My solution is to just set it for 4.5 watts, and
my conscience is clear!  Otherwise, whether it's 5 watts vs.
5.2 watts, or 100 watts vs. 101 watts, doesn't seem to make
much difference.  Should I care????

Dave W7AQK


----- Original Message -----
From: "Ron D'Eau Claire" <[hidden email]>
To: <[hidden email]>
Sent: Friday, May 29, 2009 9:10 AM
Subject: Re: [Elecraft] K3 Watt-meter question!

> Jim, you said "supposedly accurate". A Bird wattmeter is
> accurate only if
> it's been properly calibrated and handled carefully -
> especially the
> "slugs". Bumps and bangs can easily ruin the calibration
> (That's why all
> Birds used in critical applications carry calibration
> stickers showing when
> it was last checked - normally no less often than
> annually - and is
> carefully handled and stored in approved containers).
>
> Let's assume the Bird is recently calibrated and treated
> kindly:
>
> 1) Its calibration is then dependent upon using the right
> slug. You probably
> know better, but a surprising number of Bird owners think
> the frequency
> range on the slug isn't very important. I believe the
> proper Bird 43 element
> for 6 meters is the type A slug spec'd for 25-60 MHz.
>
> 2) Are you allowing for the normal error in even a
> perfectly-calibrated
> Bird? That's +/- 5% of *full scale*. IIRC the Bird 6 meter
> slugs have full
> scale ranges of 25 or 250 watts. If you're measuring 100
> watts with the 250
> watt slug, the possible error in a properly-calibrated
> Bird is +/- 5% of 250
> watts *anywhere* in the scale. So at 100 watts indicated,
> the actual power
> may be anywhere between 87 and 112 watts.
>
> That's plenty good enough accuracy for nearly all field
> use, including for
> showing that transmitter power levels comply with FCC regs
> (although when I
> demonstrate a marine transmitter to FCC engineers, it's
> *their* Bird that is
> the final word ;-)
>
> Now, the K3 has simply another wattmeter built in, so it's
> normal for the
> two wattmeters to disagree by the sum of their possible
> errors.
>
> You asked, "Which one is more accurate?" One of the
> Elecraft engineers would
> have to answer that, but let's assume the K3's built in
> wattmeter is as good
> as the Bird. In that case a perfectly calibrated Bird on a
> perfectly
> calibrated K3 may disagree by as much as 15 watts at 100
> watts giving you an
> indication of anywhere between 85 and 115 watts on the
> Bird when the K3
> meter says 100 watts.
>
> And don't forget that assumes everything is in perfect
> calibration. In the
> real world, it's not unusual to see a greater error.
>
> That's why it's not normally considered important for
> owners to worry about
> the K3's power calibration. Unless you have some
> laboratory standards to
> compare to each other and to the K3, it's almost
> impossible to improve on
> the default factory settings.
>
> Ron AC7AC
>
>
>
> -----Original Message-----
>
> Gentlemen,
>
> How accurate is the built-in watt meter indicator in the
> K3???
>
> I'm asking because when I've used a supposed;y accurate
> "Bird 43" while
> measuring the K3's various
> outputs on the various HF bands there seems to be a slight
> discrepitancy
> between what the K3 is
> showing and what's actually there according to the
> "BIRD!!!"  I'm
> particularly interested in the
> output readings as concerns "6 metres!" Which is MORE
> ACCURATE???
>
> Regards,
>
> Jim/nn6ee
> S/N 2406
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list:
> http://www.qsl.net/donate.html
>

... [show rest of quote]

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[WILLIS COOKE]

The Bird 43 watt meter is one of the few genuine antiques that are still available for use by amateur radio operators.  I am not sure but I would not be surprised if the 43 comes from being designed in 1943.  I know they are advertised in my 1964 ARRL Handbook and have not changed in appearance since.  They are still advertised to be +/- 5% of full scale accurate, the same as the $100 Daiwa.  For our purposes, such as not violating the 5 watt limit for QRP I would venture that the K2 or K3 wattmeter is plenty accurate enough for nearly all our purposes.

Other watt meters such as the Elecraft are probably more accurate and less expensive.  And that is assuming that you buy a factory new Bird 43 rather than one off the Buyer Beware table at a ham fest.

Willis 'Cookie' Cooke
K5EWJ


--- On Fri, 5/29/09, David Yarnes <[hidden email]> wrote:

> From: David Yarnes <[hidden email]>
> Subject: Re: [Elecraft] K3 Watt-meter question!
> To: "Ron D'Eau Claire" <[hidden email]>, [hidden email]
> Date: Friday, May 29, 2009, 10:01 AM
> Hi All,
>
> Over the years I've seen Bird Wattmeters for sale at dozens
>
> of hamfests, as well as over the internet.  Typically
> these
> are very "pricey", and require all sorts of
> accessories.  I
> have no doubt that this is, more or less, "the standard"
> when it comes to wattmeters.  However, my question is
> (and I
> ask this seriously), just how often am I apt to really need
>
> something that is so precise?  I have an Elecraft W1,
> and
> several other wattmeters around the shack, including an OHR
>
> W-1.  I think the two I specifically mention are
> relatively
> accurate, although perhaps not quite up to "Bird"
> standards.
> All wattmeters need to be calibrated, and need to be
> re-calibrated if you change ranges significantly.  To
> be
> honest with you, the only time I have any real concern
> about
> being 99.9% accurate is if I'm crowding the 5 watt limit in
>
> a contest.  My solution is to just set it for 4.5
> watts, and
> my conscience is clear!  Otherwise, whether it's 5
> watts vs.
> 5.2 watts, or 100 watts vs. 101 watts, doesn't seem to make
>
> much difference.  Should I care????
>
> Dave W7AQK
>
>
> ----- Original Message -----
> From: "Ron D'Eau Claire" <[hidden email]>
> To: <[hidden email]>
> Sent: Friday, May 29, 2009 9:10 AM
> Subject: Re: [Elecraft] K3 Watt-meter question!
>
>
> > Jim, you said "supposedly accurate". A Bird wattmeter
> is
> > accurate only if
> > it's been properly calibrated and handled carefully -
>
> > especially the
> > "slugs". Bumps and bangs can easily ruin the
> calibration
> > (That's why all
> > Birds used in critical applications carry calibration
>
> > stickers showing when
> > it was last checked - normally no less often than
> > annually - and is
> > carefully handled and stored in approved containers).
> >
> > Let's assume the Bird is recently calibrated and
> treated
> > kindly:
> >
> > 1) Its calibration is then dependent upon using the
> right
> > slug. You probably
> > know better, but a surprising number of Bird owners
> think
> > the frequency
> > range on the slug isn't very important. I believe the
>
> > proper Bird 43 element
> > for 6 meters is the type A slug spec'd for 25-60 MHz.
> >
> > 2) Are you allowing for the normal error in even a
> > perfectly-calibrated
> > Bird? That's +/- 5% of *full scale*. IIRC the Bird 6
> meter
> > slugs have full
> > scale ranges of 25 or 250 watts. If you're measuring
> 100
> > watts with the 250
> > watt slug, the possible error in a properly-calibrated
>
> > Bird is +/- 5% of 250
> > watts *anywhere* in the scale. So at 100 watts
> indicated,
> > the actual power
> > may be anywhere between 87 and 112 watts.
> >
> > That's plenty good enough accuracy for nearly all
> field
> > use, including for
> > showing that transmitter power levels comply with FCC
> regs
> > (although when I
> > demonstrate a marine transmitter to FCC engineers,
> it's
> > *their* Bird that is
> > the final word ;-)
> >
> > Now, the K3 has simply another wattmeter built in, so
> it's
> > normal for the
> > two wattmeters to disagree by the sum of their
> possible
> > errors.
> >
> > You asked, "Which one is more accurate?" One of the
> > Elecraft engineers would
> > have to answer that, but let's assume the K3's built
> in
> > wattmeter is as good
> > as the Bird. In that case a perfectly calibrated Bird
> on a
> > perfectly
> > calibrated K3 may disagree by as much as 15 watts at
> 100
> > watts giving you an
> > indication of anywhere between 85 and 115 watts on the
>
> > Bird when the K3
> > meter says 100 watts.
> >
> > And don't forget that assumes everything is in perfect
>
> > calibration. In the
> > real world, it's not unusual to see a greater error.
> >
> > That's why it's not normally considered important for
>
> > owners to worry about
> > the K3's power calibration. Unless you have some
> > laboratory standards to
> > compare to each other and to the K3, it's almost
> > impossible to improve on
> > the default factory settings.
> >
> > Ron AC7AC
> >
> >
> >
> > -----Original Message-----
> >
> > Gentlemen,
> >
> > How accurate is the built-in watt meter indicator in
> the
> > K3???
> >
> > I'm asking because when I've used a supposed;y
> accurate
> > "Bird 43" while
> > measuring the K3's various
> > outputs on the various HF bands there seems to be a
> slight
> > discrepitancy
> > between what the K3 is
> > showing and what's actually there according to the
> > "BIRD!!!"  I'm
> > particularly interested in the
> > output readings as concerns "6 metres!" Which is MORE
>
> > ACCURATE???
> >
> > Regards,
> >
> > Jim/nn6ee
> > S/N 2406
> >
> >
> ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list:
> > http://www.qsl.net/donate.html
> >
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

... [show rest of quote]

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[ww2r2]

The original military specification document, to which the bird43 was built
only requires 10% accuracy (to accomodate "field usage"?)

I did some checking

with a power attenuator and an hp436  power meter my k3 power meter agrees
within 1% on the hf bands

with the same 100H element in 2 different bird "bodies" i see errors of +3%
and -4%

Dave

ww2r

----------------------------------------------------------------------

Message: 1
Date: Fri, 29 May 2009 09:10:56 -0700
From: "Ron D'Eau Claire" <[hidden email]>
Subject: Re: [Elecraft] K3 Watt-meter question!
To: <[hidden email]>
Message-ID: <001001c9e078$0f538940$2dfa9bc0$@biz>
Content-Type: text/plain; charset="us-ascii"

Jim, you said "supposedly accurate". A Bird wattmeter is accurate only if
it's been properly calibrated and handled carefully - especially the
"slugs". Bumps and bangs can easily ruin the calibration (That's why all
Birds used in critical applications carry calibration stickers showing when
it was last checked - normally no less often than annually - and is
carefully handled and stored in approved containers).

Let's assume the Bird is recently calibrated and treated kindly:

1) Its calibration is then dependent upon using the right slug. You probably
know better, but a surprising number of Bird owners think the frequency
range on the slug isn't very important. I believe the proper Bird 43 element
for 6 meters is the type A slug spec'd for 25-60 MHz.

2) Are you allowing for the normal error in even a perfectly-calibrated
Bird? That's +/- 5% of *full scale*. IIRC the Bird 6 meter slugs have full
scale ranges of 25 or 250 watts. If you're measuring 100 watts with the 250
watt slug, the possible error in a properly-calibrated Bird is +/- 5% of 250
watts *anywhere* in the scale. So at 100 watts indicated, the actual power
may be anywhere between 87 and 112 watts.

That's plenty good enough accuracy for nearly all field use, including for
showing that transmitter power levels comply with FCC regs (although when I
demonstrate a marine transmitter to FCC engineers, it's *their* Bird that is
the final word ;-)

Now, the K3 has simply another wattmeter built in, so it's normal for the
two wattmeters to disagree by the sum of their possible errors.

You asked, "Which one is more accurate?" One of the Elecraft engineers would
have to answer that, but let's assume the K3's built in wattmeter is as good
as the Bird. In that case a perfectly calibrated Bird on a perfectly
calibrated K3 may disagree by as much as 15 watts at 100 watts giving you an
indication of anywhere between 85 and 115 watts on the Bird when the K3
meter says 100 watts.

And don't forget that assumes everything is in perfect calibration. In the
real world, it's not unusual to see a greater error.

That's why it's not normally considered important for owners to worry about
the K3's power calibration. Unless you have some laboratory standards to
compare to each other and to the K3, it's almost impossible to improve on
the default factory settings.

Ron AC7AC



-----Original Message-----

Gentlemen,

How accurate is the built-in watt meter indicator in the K3???

I'm asking because when I've used a supposed;y accurate "Bird 43" while
measuring the K3's various
outputs on the various HF bands there seems to be a slight discrepitancy
between what the K3 is
showing and what's actually there according to the "BIRD!!!"  I'm
particularly interested in the
output readings as concerns "6 metres!" Which is MORE ACCURATE???

Regards,

Jim/nn6ee
S/N 2406




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Post: mailto:[hidden email]

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