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New K3 built - can I reset the 5w calibration?

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TJ Campie

New K3 built - can I reset the 5w calibration?

I finished building a K3 for the radio club at work and I thought I'd take
the bull by the horns and attempt to improve the factory setting for the 5w
calibration on the 100w Bird watt meter I had. I couldn't get it to go up
the the point that looked like 5w on the meter regardless of how much I
turned the knob on the K3. The setting ended up at 10 (the minimum) but I
think it must have been more correct from the factory. I *think* it was up
at about 37 but I don't remember - is there a way to reset it to the
factory setting? I don't have access to a 5w accuracy meter.

Otherwise, the build went great and was a blast :)

TJ W0EA
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Nate Bargmann

Re: New K3 built - can I reset the 5w calibration?

>From my experience, trying to measure 5W with a 100W element leads to
very inaccurate readings. The Bird is most accurate when the reading is
as near to full scale as possible. That means a 5W HF element (is that
even available?) would be ideal provided no more than 5W is put through
the meter. A 10W element would be less accurate but provide a safety
margin for the meter. Even better would be to have both elements and
use the 10W one to get in the ballpark and the 5W one for a final check.

73, de Nate N0NB >>

--

"The optimist proclaims that we live in the best of all
possible worlds. The pessimist fears this is true."

Ham radio, Linux, bikes, and more: http://www.n0nb.us
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Alan Bloom

Re: New K3 built - can I reset the 5w calibration?

A 100 MHz oscilloscope is an accurate way to measure RF power on the HF
bands. Just connect it in parallel with the dummy load and use W3FPR's
formula:

P = E^2 / 400

Where P is the power in watts and E is the peak-to-peak voltage read on
the oscilloscope.

Alan N1AL

On Thu, 2011-12-08 at 16:47 -0600, Nate Bargmann wrote:

> >From my experience, trying to measure 5W with a 100W element leads to
> very inaccurate readings. The Bird is most accurate when the reading is
> as near to full scale as possible. That means a 5W HF element (is that
> even available?) would be ideal provided no more than 5W is put through
> the meter. A 10W element would be less accurate but provide a safety
> margin for the meter. Even better would be to have both elements and
> use the 10W one to get in the ballpark and the 5W one for a final check.
>
> 73, de Nate N0NB >>
>

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Don Wilhelm-4

Re: New K3 built - can I reset the 5w calibration?

In reply to this post by TJ Campie

Tom,

OK, it seems now is a good time for me to insert my periodic "wattmeter
accuracy" rant! Sub-titled -- "Technician, know your tools but know
even better their limitations" OR - "No instrument can be relied on
until it has proven it is capable of telling the truth under the
conditions of use".

If you want quite good accuracy at the 5 watt level, I suggest you use
a 'scope with a 10X probe connected across the dummy load. The peak to
peak RF voltage can be easily measured by the vertical deflection of the
'scope. To convert that peak to peak voltage reading to power (when the
dummy load is 50 ohms), use your calculator - enter the peak to peak
voltage, square it, and divide by 400.

If you do not have an open dummy load that makes clipping the 'scope
probe across it easily, use a Tee adapter at the dummy load end so you
can gain access to the center conductor.

40 volts peak to peak is 4 watts - you might want to use that instead of
5 watts since it is even and easy to see on the 'scope face. If you
really need 5 watts, adjust for 44.72 volts peak to peak.

In fact, you can use the 'scope probe across the dummy load up to any
level permissible by your 'scope and probe. My probes will handle 100
volts peak easily, and that is the 100 watt level. The accuracy is only
limited by the accuracy of your dummy load (mine is within 1%) and your
ability to interpolate the voltage deflection on the 'scope. I might
suggest that you can come within 5% of the actual power level, which is
much better than analog power meters whose accuracy is expressed as a
percentage of full scale. So a freshly calibrated Bird wattmeter with a
100 watt slug is spec'ed for 5% of full scale - OK, that is a 5 watt
potential error - and that applies anywhere on the scale - so trying to
read a 5 watt power level with a Bird and a 100 watt slug is an exercise
in futility - use the 'scope, it is a LOT more accurate.
OTOH, many recent digital wattmeters will be spec'ed for accuracy
anywhere within its range rather that as a percentage of full scale used
with the analog wattmeters.

The (Vp-p)exp2/400 formula (actually [Vp-p]exp2/8R) does not seem to be
well know. I leave it "to the student" to derive it from standard
formulas for power, voltage and resistance. Hint - use SQRT2 rather
than the 1.414 or 0.707 approximations when converting peak to peak
voltage to RMS - it is an exact formula, the squares and square roots
cancel.

73,
Don W3FPR

On 12/8/2011 5:12 PM, TJ Campie wrote:

> I finished building a K3 for the radio club at work and I thought I'd take
> the bull by the horns and attempt to improve the factory setting for the 5w
> calibration on the 100w Bird watt meter I had. I couldn't get it to go up
> the the point that looked like 5w on the meter regardless of how much I
> turned the knob on the K3. The setting ended up at 10 (the minimum) but I
> think it must have been more correct from the factory. I *think* it was up
> at about 37 but I don't remember - is there a way to reset it to the
> factory setting? I don't have access to a 5w accuracy meter.
>
> Otherwise, the build went great and was a blast :)
>
> TJ W0EA
> ______________________________________________________________
> 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
>

Jack Smith-6

Re: New K3 built - can I reset the 5w calibration?

Don:

I would add a small caution. The maximum safe voltage rating of a 10x
probe is a function of frequency.

For example, Tektronix's model P6106A, a 250 MHz 10x probe, is rated at
450V below 1 MHz, but only 60V at 10 MHz and perhaps 50V at 30 MHz (hard
to read the graph accurately). All are RMS values.

100 watts is 70.7 V RMS, so the 10 MHz - 30 MHz voltage limits will be
exceeded at that power level. (100V RMS probe limit looks to be around
6.5 MHz.)

Of course, I'm sure there's a safety factor in the probe specs, but
before I measured 100 watts output with a 10X probe I would verify the
safe voltage rating in the probe manual.

Jack K8ZOA

On 12/8/2011 6:09 PM, Don Wilhelm wrote:

> Tom,
>
> OK, it seems now is a good time for me to insert my periodic "wattmeter
> accuracy" rant! Sub-titled -- "Technician, know your tools but know
> even better their limitations" OR - "No instrument can be relied on
> until it has proven it is capable of telling the truth under the
> conditions of use".
>
> If you want quite good accuracy at the 5 watt level, I suggest you use
> a 'scope with a 10X probe connected across the dummy load. The peak to
> peak RF voltage can be easily measured by the vertical deflection of the
> 'scope. To convert that peak to peak voltage reading to power (when the
> dummy load is 50 ohms), use your calculator - enter the peak to peak
> voltage, square it, and divide by 400.
>
> If you do not have an open dummy load that makes clipping the 'scope
> probe across it easily, use a Tee adapter at the dummy load end so you
> can gain access to the center conductor.
>
> 40 volts peak to peak is 4 watts - you might want to use that instead of
> 5 watts since it is even and easy to see on the 'scope face. If you
> really need 5 watts, adjust for 44.72 volts peak to peak.
>
> In fact, you can use the 'scope probe across the dummy load up to any
> level permissible by your 'scope and probe. My probes will handle 100
> volts peak easily, and that is the 100 watt level. The accuracy is only
> limited by the accuracy of your dummy load (mine is within 1%) and your
> ability to interpolate the voltage deflection on the 'scope. I might
> suggest that you can come within 5% of the actual power level, which is
> much better than analog power meters whose accuracy is expressed as a
> percentage of full scale. So a freshly calibrated Bird wattmeter with a
> 100 watt slug is spec'ed for 5% of full scale - OK, that is a 5 watt
> potential error - and that applies anywhere on the scale - so trying to
> read a 5 watt power level with a Bird and a 100 watt slug is an exercise
> in futility - use the 'scope, it is a LOT more accurate.
> OTOH, many recent digital wattmeters will be spec'ed for accuracy
> anywhere within its range rather that as a percentage of full scale used
> with the analog wattmeters.
>
> The (Vp-p)exp2/400 formula (actually [Vp-p]exp2/8R) does not seem to be
> well know. I leave it "to the student" to derive it from standard
> formulas for power, voltage and resistance. Hint - use SQRT2 rather
> than the 1.414 or 0.707 approximations when converting peak to peak
> voltage to RMS - it is an exact formula, the squares and square roots
> cancel.
>
> 73,
> Don W3FPR
>
> On 12/8/2011 5:12 PM, TJ Campie wrote:
>> I finished building a K3 for the radio club at work and I thought I'd take
>> the bull by the horns and attempt to improve the factory setting for the 5w
>> calibration on the 100w Bird watt meter I had. I couldn't get it to go up
>> the the point that looked like 5w on the meter regardless of how much I
>> turned the knob on the K3. The setting ended up at 10 (the minimum) but I
>> think it must have been more correct from the factory. I *think* it was up
>> at about 37 but I don't remember - is there a way to reset it to the
>> factory setting? I don't have access to a 5w accuracy meter.
>>
>> Otherwise, the build went great and was a blast :)
>>
>> TJ W0EA
>> ______________________________________________________________
>> 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
>>
> ______________________________________________________________
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> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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>

Don Wilhelm-4

Re: New K3 built - can I reset the 5w calibration?

Thanks Jack for that additional information and caution.

I believe that is an accuracy limitation for the probe specs, and not a
probe damage rating.

I routinely leave my 'scope probe connected to the dummy load at the
workbench and it is subjected routinely to powers up to 180 watts.

I use the RF voltage across the dummy load to accurately assess the
power output of the KX1, K1 and K2/10 transceivers that I repair. At
higher power levels, I use the LP-200 wattmeter which has been
calibrated at the 20 watt and the 80 watt levels to make quick decisions
on the power output of a transmitter. If I want a quick indication, I
just look at the LP-200. It is one of the digital wattmeters that is
good to within better than 10% of the actual reading (it is better than
5% at the 20 and 80 watt calibration points). If I need greater
accuracy or NIST traceability, I invoke the LP-100 which Larry (N8LP)
has calibrated with his NIST traceable standards. I use that wattmeter
as the "master" for calibrating all the others at higher power, but at
low power levels, I rely on the 'scope peak to peak readings and my 1%
50 ohm dummy load and punch the buttons on my calculator. With this
combination of tools, I can commit to better than 5% accuracy in power
measurement over the 1 to 100 watt range.

I also have accurate power measurement capability for low levels (-75
dBm through 100 watts), with the W7ZOI Power meter, but that is a
different subject - if anyone is interested, contact me off-list.

73.
Don W3FPR

On 12/8/2011 6:40 PM, Jack Smith wrote:

> Don:
>
> I would add a small caution. The maximum safe voltage rating of a 10x
> probe is a function of frequency.
>
> For example, Tektronix's model P6106A, a 250 MHz 10x probe, is rated at
> 450V below 1 MHz, but only 60V at 10 MHz and perhaps 50V at 30 MHz (hard
> to read the graph accurately). All are RMS values.
>
> 100 watts is 70.7 V RMS, so the 10 MHz - 30 MHz voltage limits will be
> exceeded at that power level. (100V RMS probe limit looks to be around
> 6.5 MHz.)
>
> Of course, I'm sure there's a safety factor in the probe specs, but
> before I measured 100 watts output with a 10X probe I would verify the
> safe voltage rating in the probe manual.
>
> Jack K8ZOA
>
>
> On 12/8/2011 6:09 PM, Don Wilhelm wrote:
>> Tom,
>>
>> OK, it seems now is a good time for me to insert my periodic "wattmeter
>> accuracy" rant! Sub-titled -- "Technician, know your tools but know
>> even better their limitations" OR - "No instrument can be relied on
>> until it has proven it is capable of telling the truth under the
>> conditions of use".
>>
>> If you want quite good accuracy at the 5 watt level, I suggest you use
>> a 'scope with a 10X probe connected across the dummy load. The peak to
>> peak RF voltage can be easily measured by the vertical deflection of the
>> 'scope. To convert that peak to peak voltage reading to power (when the
>> dummy load is 50 ohms), use your calculator - enter the peak to peak
>> voltage, square it, and divide by 400.
>>
>> If you do not have an open dummy load that makes clipping the 'scope
>> probe across it easily, use a Tee adapter at the dummy load end so you
>> can gain access to the center conductor.
>>
>> 40 volts peak to peak is 4 watts - you might want to use that instead of
>> 5 watts since it is even and easy to see on the 'scope face. If you
>> really need 5 watts, adjust for 44.72 volts peak to peak.
>>
>> In fact, you can use the 'scope probe across the dummy load up to any
>> level permissible by your 'scope and probe. My probes will handle 100
>> volts peak easily, and that is the 100 watt level. The accuracy is only
>> limited by the accuracy of your dummy load (mine is within 1%) and your
>> ability to interpolate the voltage deflection on the 'scope. I might
>> suggest that you can come within 5% of the actual power level, which is
>> much better than analog power meters whose accuracy is expressed as a
>> percentage of full scale. So a freshly calibrated Bird wattmeter with a
>> 100 watt slug is spec'ed for 5% of full scale - OK, that is a 5 watt
>> potential error - and that applies anywhere on the scale - so trying to
>> read a 5 watt power level with a Bird and a 100 watt slug is an exercise
>> in futility - use the 'scope, it is a LOT more accurate.
>> OTOH, many recent digital wattmeters will be spec'ed for accuracy
>> anywhere within its range rather that as a percentage of full scale used
>> with the analog wattmeters.
>>
>> The (Vp-p)exp2/400 formula (actually [Vp-p]exp2/8R) does not seem to be
>> well know. I leave it "to the student" to derive it from standard
>> formulas for power, voltage and resistance. Hint - use SQRT2 rather
>> than the 1.414 or 0.707 approximations when converting peak to peak
>> voltage to RMS - it is an exact formula, the squares and square roots
>> cancel.
>>
>> 73,
>> Don W3FPR
>>
>> On 12/8/2011 5:12 PM, TJ Campie wrote:
>>> I finished building a K3 for the radio club at work and I thought I'd take
>>> the bull by the horns and attempt to improve the factory setting for the 5w
>>> calibration on the 100w Bird watt meter I had. I couldn't get it to go up
>>> the the point that looked like 5w on the meter regardless of how much I
>>> turned the knob on the K3. The setting ended up at 10 (the minimum) but I
>>> think it must have been more correct from the factory. I *think* it was up
>>> at about 37 but I don't remember - is there a way to reset it to the
>>> factory setting? I don't have access to a 5w accuracy meter.
>>>
>>> Otherwise, the build went great and was a blast :)
>>>
>>> TJ W0EA
>>> ______________________________________________________________
>>> 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
>>
> ______________________________________________________________
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Vic Rosenthal

Re: New K3 built - can I reset the 5w calibration?

In reply to this post by Don Wilhelm-4

I learned the hard way that power handling capability of scope probes is
frequency-dependent. I blew TWO of mine trying to measure 100w on 28 mHz. (no, one lesson
is not enough for me). So check the ratings of your probes before you try this with more
than QRP power!

On 12/8/2011 3:09 PM, Don Wilhelm wrote:
> In fact, you can use the 'scope probe across the dummy load up to any
> level permissible by your 'scope and probe. My probes will handle 100
> volts peak easily, and that is the 100 watt level.

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/

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Ken G Kopp

New K3 built - can I reset the 5w calibration?

In reply to this post by TJ Campie

Trivia related to this thread ... The lowest power HF element
available from Bird is 50W FS.

Don's precautions are spot-on.

73! Ken - K0PP
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Eugene Balinski

Re: New K3 built - can I reset the 5w calibration?

In reply to this post by Nate Bargmann

The accuracy of Bird elements is typically +/- 5% of the
full scale value. For a 100 W Slug, that is +/- 5 Watts.
So theoretically speaking, with 5W in, and 0 registered
on the meter, the meter is still within its rated accuracy.

Additionally on the model 43 meter, there is meter scale
end compression. To get the most accurate reading, one
would want to have the 5W reading at the middle of the
meter range, which means that one would want a 10W slug.
Unfortunately I do not believe that Bird makes a 10W HF
slug any more. Perhaps they need an Elecraft W2 ??

73
K1NR

On Thu, 8 Dec 2011 16:47:27 -0600
Nate Bargmann <[hidden email]> wrote:

> >From my experience, trying to measure 5W with a 100W
> element leads to
> very inaccurate readings. The Bird is most accurate when
> the reading is
> as near to full scale as possible. That means a 5W HF
> element (is that
> even available?) would be ideal provided no more than 5W
> is put through
> the meter. A 10W element would be less accurate but
> provide a safety
> margin for the meter. Even better would be to have both
> elements and
> use the 10W one to get in the ballpark and the 5W one for
> a final check.
>
> 73, de Nate N0NB >>
>
> --
>
> "The optimist proclaims that we live in the best of all
> possible worlds. The pessimist fears this is true."
>
> Ham radio, Linux, bikes, and more: http://www.n0nb.us
>

______________________________________________________________
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> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Bill McDowell

Re: New K3 built - can I reset the 5w calibration?

In reply to this post by TJ Campie

Lots of great information in this thread, but no answer for TJ yet.

"is there a way to reset it to the
factory setting?"

73
Bill, K4CIA
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Don Wilhelm-4

Re: New K3 built - can I reset the 5w calibration?

Bill,

To set everything to factory defaults, do an EEINIT. I suggest saving
your configuration first using K3Utility just in case you want to go
back to whatever you had.

73,
Don W3FPR

On 12/9/2011 5:22 AM, Bill McDowell wrote:
> Lots of great information in this thread, but no answer for TJ yet.
>
> "is there a way to reset it to the
> factory setting?"
>
> 73
> Bill, K4CIA
>
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Mike Reublin

Re: New K3 built - can I reset the 5w calibration?

In reply to this post by Eugene Balinski

Wait.

Using a 100W slug, if you get a reading of 100 watts, the real power would be between
95 and 105 watts, right?
If you get a reading of 50 watts the real power would fall in a range of less than 45
to 55 watts?

Not if the 5% at full scale is the best accuracy. Or did I misunderstand what you said?

73, Mike NF4L

On 12/8/2011 11:59 PM, Eugene Balinski wrote:

> The accuracy of Bird elements is typically +/- 5% of the
> full scale value. For a 100 W Slug, that is +/- 5 Watts.
> So theoretically speaking, with 5W in, and 0 registered
> on the meter, the meter is still within its rated accuracy.
>
>
> Additionally on the model 43 meter, there is meter scale
> end compression. To get the most accurate reading, one
> would want to have the 5W reading at the middle of the
> meter range, which means that one would want a 10W slug.
> Unfortunately I do not believe that Bird makes a 10W HF
> slug any more. Perhaps they need an Elecraft W2 ??
>
> 73
> K1NR
>
>
> On Thu, 8 Dec 2011 16:47:27 -0600
> Nate Bargmann<[hidden email]> wrote:
>> > From my experience, trying to measure 5W with a 100W
>> element leads to
>> very inaccurate readings. The Bird is most accurate when
>> the reading is
>> as near to full scale as possible. That means a 5W HF
>> element (is that
>> even available?) would be ideal provided no more than 5W
>> is put through
>> the meter. A 10W element would be less accurate but
>> provide a safety
>> margin for the meter. Even better would be to have both
>> elements and
>> use the 10W one to get in the ballpark and the 5W one for
>> a final check.
>>
>> 73, de Nate N0NB>>
>>
>> --
>>
>> "The optimist proclaims that we live in the best of all
>> possible worlds. The pessimist fears this is true."
>>
>> Ham radio, Linux, bikes, and more: http://www.n0nb.us
>>

Mike Reublin

Re: New K3 built - can I reset the 5w calibration?

Meant to say:

If you get a reading of 50 watts the real power would fall in a range of less than 47.5
to 52.5 watts?

On 12/9/2011 9:08 AM, Mike wrote:

> Wait.
>
> Using a 100W slug, if you get a reading of 100 watts, the real power would be between
> 95 and 105 watts, right?
> If you get a reading of 50 watts the real power would fall in a range of less than 45
> to 55 watts?
>
> Not if the 5% at full scale is the best accuracy. Or did I misunderstand what you said?
>
> 73, Mike NF4L
>
>
> On 12/8/2011 11:59 PM, Eugene Balinski wrote:
>> The accuracy of Bird elements is typically +/- 5% of the
>> full scale value. For a 100 W Slug, that is +/- 5 Watts.
>> So theoretically speaking, with 5W in, and 0 registered
>> on the meter, the meter is still within its rated accuracy.
>>
>>
>> Additionally on the model 43 meter, there is meter scale
>> end compression. To get the most accurate reading, one
>> would want to have the 5W reading at the middle of the
>> meter range, which means that one would want a 10W slug.
>> Unfortunately I do not believe that Bird makes a 10W HF
>> slug any more. Perhaps they need an Elecraft W2 ??
>>
>> 73
>> K1NR
>>
>>
>> On Thu, 8 Dec 2011 16:47:27 -0600
>> Nate Bargmann<[hidden email]> wrote:
>>>> From my experience, trying to measure 5W with a 100W
>>> element leads to
>>> very inaccurate readings. The Bird is most accurate when
>>> the reading is
>>> as near to full scale as possible. That means a 5W HF
>>> element (is that
>>> even available?) would be ideal provided no more than 5W
>>> is put through
>>> the meter. A 10W element would be less accurate but
>>> provide a safety
>>> margin for the meter. Even better would be to have both
>>> elements and
>>> use the 10W one to get in the ballpark and the 5W one for
>>> a final check.
>>>
>>> 73, de Nate N0NB>>
>>>
>>> --
>>>
>>> "The optimist proclaims that we live in the best of all
>>> possible worlds. The pessimist fears this is true."
>>>
>>> Ham radio, Linux, bikes, and more: http://www.n0nb.us
>>>
>
> ______________________________________________________________
> 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
>

Don Wilhelm-4

Re: New K3 built - can I reset the 5w calibration?

In reply to this post by Mike Reublin

Mike,

You read it right. A newly calibrated Bird slug (how many hams have
recently calibrated Bird wattmeters and slugs?) is specified to have an
accuracy of 5% OF FULL SCALE. So yes, a 100 watt slug can be in error
by as much as 5 watts - anywhere on the scale. A reading of 50 watts
indicates a power somewhere between 45 and 55 watts. a reading of 25
watts indicates a power somewhere between 20 and 30 watts, and a reading
of 10 watts indicates a power somewhere between 5 watts and 15 watts.

In other words, use a Bird slug that is close to the power level that
you are trying to measure, and consider how long it has been since that
meter and slug have been calibrated before making any absolute
statements about the power accuracy.

BTW, you can use the "RF voltage across a precision dummy load" to
calibrate your wattmeter (at any power level). Doing that on a periodic
basis will give you faith in the integrity of your measurement tools.

73,
Don W3FPR

On 12/9/2011 9:08 AM, Mike wrote:

Eugene Balinski

Re: New K3 built - can I reset the 5w calibration?

In reply to this post by Mike Reublin

>From what I understand, the meter is rated at 5% of the
**full scale** rating according to Bird. Full scale
rating, is the rating on the slug.

That would mean that for a meter with a 100W slug, your
accuracy is +/- 5W (5%). So, if your wattmeter is reading
50W, the actual RF power could actually be 45 or 55 W....

73
K1NR

On Fri, 09 Dec 2011 09:08:55 -0500
Mike <[hidden email]> wrote:

> Wait.
>
> Using a 100W slug, if you get a reading of 100 watts, the
> real power would be between
> 95 and 105 watts, right?
> If you get a reading of 50 watts the real power would
> fall in a range of less than 45
> to 55 watts?
>
> Not if the 5% at full scale is the best accuracy. Or did
> I misunderstand what you said?
>
> 73, Mike NF4L
>
>
> On 12/8/2011 11:59 PM, Eugene Balinski wrote:
> > The accuracy of Bird elements is typically +/- 5% of
> the
> > full scale value. For a 100 W Slug, that is +/- 5
> Watts.
> > So theoretically speaking, with 5W in, and 0
> registered
> > on the meter, the meter is still within its rated
> accuracy.
> >
> >
> > Additionally on the model 43 meter, there is meter
> scale
> > end compression. To get the most accurate reading, one
> > would want to have the 5W reading at the middle of the
> > meter range, which means that one would want a 10W
> slug.
> > Unfortunately I do not believe that Bird makes a 10W
> HF
> > slug any more. Perhaps they need an Elecraft W2 ??
> >
> > 73
> > K1NR
> >
> >
> > On Thu, 8 Dec 2011 16:47:27 -0600
> > Nate Bargmann<[hidden email]> wrote:
> >> > From my experience, trying to measure 5W with a 100W
> >> element leads to
> >> very inaccurate readings. The Bird is most accurate
> when
> >> the reading is
> >> as near to full scale as possible. That means a 5W HF
> >> element (is that
> >> even available?) would be ideal provided no more than
> 5W
> >> is put through
> >> the meter. A 10W element would be less accurate but
> >> provide a safety
> >> margin for the meter. Even better would be to have
> both
> >> elements and
> >> use the 10W one to get in the ballpark and the 5W one
> for
> >> a final check.
> >>
> >> 73, de Nate N0NB>>
> >>
> >> --
> >>
> >> "The optimist proclaims that we live in the best of
> all
> >> possible worlds. The pessimist fears this is true."
> >>
> >> Ham radio, Linux, bikes, and more: http://www.n0nb.us
> >>
>
>
>

VE3GNO Daniel

Re: New K3 built - can I reset the 5w calibration?

The 5% accuracy of the wattmeter is not constant over the entire range from the 1st division of the scale coresponding to 1W or so to last 100W and can variate, they say is up to 5%. Now where is the best precision hard to say but might be in the middle range or full scale.

VE3GNO/YO3GJC Daniel

________________________________
From: Eugene Balinski <[hidden email]>
To: [hidden email]; [hidden email]
Sent: Friday, December 9, 2011 10:32:44 AM
Subject: Re: [Elecraft] New K3 built - can I reset the 5w calibration?

>From what I understand, the meter is rated at 5% of the
**full scale** rating according to Bird. Full scale
rating, is the rating on the slug.

That would mean that for a meter with a 100W slug, your
accuracy is +/- 5W (5%). So, if your wattmeter is reading
50W, the actual RF power could actually be 45 or 55 W....

73
K1NR

On Fri, 09 Dec 2011 09:08:55 -0500
Mike <[hidden email]> wrote:

Eugene Balinski

Re: New K3 built - can I reset the 5w calibration?

I did mention that in an earlier email. If you look at the
Bird 43 meter, the scale is not linear. There is scale
compression at either end. To get the most readibility,
one would want a slug that would place the expected
meassurement in the center of the meter...

73

Gene K1NR

On Fri, 9 Dec 2011 08:09:27 -0800 (PST)
VE3GNO/YO3GJC Daniel <[hidden email]> wrote:

> The 5% accuracy of the wattmeter is not constant over the
> entire range from the 1st division of the scale
> coresponding to 1W or so to last 100W and can variate,
> they say is up to 5%. Now where is the best precision
> hard to say but might be in the middle range or full
> scale.
>
>
> VE3GNO/YO3GJC Daniel
>
>
> ________________________________
> From: Eugene Balinski <[hidden email]>
> To: [hidden email]; [hidden email]
> Sent: Friday, December 9, 2011 10:32:44 AM
> Subject: Re: [Elecraft] New K3 built - can I reset the 5w
> calibration?
>
> >From what I understand, the meter is rated at 5% of the
> **full scale** rating according to Bird. Full scale
> rating, is the rating on the slug.
>
> That would mean that for a meter with a 100W slug, your
> accuracy is +/- 5W (5%). So, if your wattmeter is
> reading
> 50W, the actual RF power could actually be 45 or 55 W....
>
> 73
> K1NR
>
>
> On Fri, 09 Dec 2011 09:08:55 -0500
> Mike <[hidden email]> wrote:
> > Wait.
> >
> > Using a 100W slug, if you get a reading of 100 watts,
> the
> > real power would be between
> > 95 and 105 watts, right?
> > If you get a reading of 50 watts the real power would
> > fall in a range of less than 45
> > to 55 watts?
> >
> > Not if the 5% at full scale is the best accuracy. Or
> did
> > I misunderstand what you said?
> >
> > 73, Mike NF4L
> >
> >
> > On 12/8/2011 11:59 PM, Eugene Balinski wrote:
> > > The accuracy of Bird elements is typically +/- 5% of
> > the
> > > full scale value. For a 100 W Slug, that is +/- 5
> > Watts.
> > > So theoretically speaking, with 5W in, and 0
> > registered
> > > on the meter, the meter is still within its rated
> > accuracy.
> > >
> > >
> > > Additionally on the model 43 meter, there is meter
> > scale
> > > end compression. To get the most accurate reading,
> one
> > > would want to have the 5W reading at the middle of
> the
> > > meter range, which means that one would want a 10W
> > slug.
> > > Unfortunately I do not believe that Bird makes a 10W
> > HF
> > > slug any more. Perhaps they need an Elecraft W2 ??
> > >
> > > 73
> > > K1NR
> > >
> > >
> > > On Thu, 8 Dec 2011 16:47:27 -0600
> > > Nate Bargmann<[hidden email]> wrote:
> > >> > From my experience, trying to measure 5W with a
> 100W
> > >> element leads to
> > >> very inaccurate readings. The Bird is most accurate
> > when
> > >> the reading is
> > >> as near to full scale as possible. That means a 5W
> HF
> > >> element (is that
> > >> even available?) would be ideal provided no more
> than
> > 5W
> > >> is put through
> > >> the meter. A 10W element would be less accurate but
> > >> provide a safety
> > >> margin for the meter. Even better would be to have
> > both
> > >> elements and
> > >> use the 10W one to get in the ballpark and the 5W
> one
> > for
> > >> a final check.
> > >>
> > >> 73, de Nate N0NB>>
> > >>
> > >> --
> > >>
> > >> "The optimist proclaims that we live in the best of
> > all
> > >> possible worlds. The pessimist fears this is true."
> > >>
> > >> Ham radio, Linux, bikes, and more:
> http://www.n0nb.us
> > >>
> >
> >
> >
>

______________________________________________________________

> > 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
>
>

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TJ Campie

Re: New K3 built - can I reset the 5w calibration?

In reply to this post by TJ Campie

Well in light that I cannot get 4w requested power on the K3 to reach 40v
p-p, I'll try to do a full system reset and redo all of the calibration
procedures. How do I access the reset command?

TJ W0EA
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Post: mailto:[hidden email]

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Mike Reublin

Re: New K3 built - can I reset the 5w calibration?

In reply to this post by Eugene Balinski

5% of 50 watts is not 5 watts.

73, Mike

On 12/9/2011 10:32 AM, Eugene Balinski wrote:

> > From what I understand, the meter is rated at 5% of the
> **full scale** rating according to Bird. Full scale
> rating, is the rating on the slug.
>
> That would mean that for a meter with a 100W slug, your
> accuracy is +/- 5W (5%). So, if your wattmeter is reading
> 50W, the actual RF power could actually be 45 or 55 W....
>
> 73
> K1NR
>
>
> On Fri, 09 Dec 2011 09:08:55 -0500
> Mike<[hidden email]> wrote:
>> Wait.
>>
>> Using a 100W slug, if you get a reading of 100 watts, the
>> real power would be between
>> 95 and 105 watts, right?
>> If you get a reading of 50 watts the real power would
>> fall in a range of less than 45
>> to 55 watts?
>>
>> Not if the 5% at full scale is the best accuracy. Or did
>> I misunderstand what you said?
>>
>> 73, Mike NF4L
>>
>>
>> On 12/8/2011 11:59 PM, Eugene Balinski wrote:
>>> The accuracy of Bird elements is typically +/- 5% of
>> the
>>> full scale value. For a 100 W Slug, that is +/- 5
>> Watts.
>>> So theoretically speaking, with 5W in, and 0
>> registered
>>> on the meter, the meter is still within its rated
>> accuracy.
>>>
>>> Additionally on the model 43 meter, there is meter
>> scale
>>> end compression. To get the most accurate reading, one
>>> would want to have the 5W reading at the middle of the
>>> meter range, which means that one would want a 10W
>> slug.
>>> Unfortunately I do not believe that Bird makes a 10W
>> HF
>>> slug any more. Perhaps they need an Elecraft W2 ??
>>>
>>> 73
>>> K1NR
>>>
>>>
>>> On Thu, 8 Dec 2011 16:47:27 -0600
>>> Nate Bargmann<[hidden email]> wrote:
>>>>> From my experience, trying to measure 5W with a 100W
>>>> element leads to
>>>> very inaccurate readings. The Bird is most accurate
>> when
>>>> the reading is
>>>> as near to full scale as possible. That means a 5W HF
>>>> element (is that
>>>> even available?) would be ideal provided no more than
>> 5W
>>>> is put through
>>>> the meter. A 10W element would be less accurate but
>>>> provide a safety
>>>> margin for the meter. Even better would be to have
>> both
>>>> elements and
>>>> use the 10W one to get in the ballpark and the 5W one
>> for
>>>> a final check.
>>>>
>>>> 73, de Nate N0NB>>
>>>>
>>>> --
>>>>
>>>> "The optimist proclaims that we live in the best of
>> all
>>>> possible worlds. The pessimist fears this is true."
>>>>
>>>> Ham radio, Linux, bikes, and more: http://www.n0nb.us
>>>>
>>
>>
> ______________________________________________________________
>> 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
> ---------------------------------------------------------------------
> Web mail provided by NuNet, Inc. The Premier National provider.
> http://www.nni.com/
>

Don Wilhelm-4

Re: New K3 built - can I reset the 5w calibration?

Mike. but 5% of full scale for a 100 watt slug is 5 watts. That is
exactly the point being made. The error is a percentage of the Full
scale reading, and not a percentage of the actual reading.

A 250 watt slug can have an error of 37.5 watts - whether the power
reading is at 10 watts or 50 watts
al that can be concluded it that there is some power output - the
number displayed by the meter cannot be relied on if the power is
significantly lower than the power ratting of the slug .

73,
Don W3FPR

On 12/9/2011 7:11 PM, Mike wrote:

> 5% of 50 watts is not 5 watts.
>
> 73, Mike
>
> On 12/9/2011 10:32 AM, Eugene Balinski wrote:
>>> From what I understand, the meter is rated at 5% of the
>> **full scale** rating according to Bird. Full scale
>> rating, is the rating on the slug.
>>
>> That would mean that for a meter with a 100W slug, your
>> accuracy is +/- 5W (5%). So, if your wattmeter is reading
>> 50W, the actual RF power could actually be 45 or 55 W....
>>
>> 73
>> K1NR
>>
>>
>> On Fri, 09 Dec 2011 09:08:55 -0500
>> Mike<[hidden email]> wrote:
>>> Wait.
>>>
>>> Using a 100W slug, if you get a reading of 100 watts, the
>>> real power would be between
>>> 95 and 105 watts, right?
>>> If you get a reading of 50 watts the real power would
>>> fall in a range of less than 45
>>> to 55 watts?
>>>
>>> Not if the 5% at full scale is the best accuracy. Or did
>>> I misunderstand what you said?
>>>
>>> 73, Mike NF4L
>>>
>>>
>>> On 12/8/2011 11:59 PM, Eugene Balinski wrote:
>>>> The accuracy of Bird elements is typically +/- 5% of
>>> the
>>>> full scale value. For a 100 W Slug, that is +/- 5
>>> Watts.
>>>> So theoretically speaking, with 5W in, and 0
>>> registered
>>>> on the meter, the meter is still within its rated
>>> accuracy.
>>>> Additionally on the model 43 meter, there is meter
>>> scale
>>>> end compression. To get the most accurate reading, one
>>>> would want to have the 5W reading at the middle of the
>>>> meter range, which means that one would want a 10W
>>> slug.
>>>> Unfortunately I do not believe that Bird makes a 10W
>>> HF
>>>> slug any more. Perhaps they need an Elecraft W2 ??
>>>>
>>>> 73
>>>> K1NR
>>>>
>>>>
>>>> On Thu, 8 Dec 2011 16:47:27 -0600
>>>> Nate Bargmann<[hidden email]> wrote:
>>>>>> From my experience, trying to measure 5W with a 100W
>>>>> element leads to
>>>>> very inaccurate readings. The Bird is most accurate
>>> when
>>>>> the reading is
>>>>> as near to full scale as possible. That means a 5W HF
>>>>> element (is that
>>>>> even available?) would be ideal provided no more than
>>> 5W
>>>>> is put through
>>>>> the meter. A 10W element would be less accurate but
>>>>> provide a safety
>>>>> margin for the meter. Even better would be to have
>>> both
>>>>> elements and
>>>>> use the 10W one to get in the ballpark and the 5W one
>>> for
>>>>> a final check.
>>>>>
>>>>> 73, de Nate N0NB>>
>>>>>
>>>>> --
>>>>>
>>>>> "The optimist proclaims that we live in the best of
>>> all
>>>>> possible worlds. The pessimist fears this is true."
>>>>>
>>>>> Ham radio, Linux, bikes, and more: http://www.n0nb.us
>>>>>
>>>
>> ______________________________________________________________
>>> 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
>> ---------------------------------------------------------------------
>> Web mail provided by NuNet, Inc. The Premier National provider.
>> http://www.nni.com/
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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>