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Rescaling the W2?

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Scott Townley

Rescaling the W2?

I know the W2 can be "dialed in" to match one's personal standard,
but...can it be completely rescaled?
I use the K3/KPA500/W2 mobile, and the KPA500 is mounted in my pickup
bed so the W2 is the only system meter available at the operating
position. However, the 2's scaling doesn't give me much display dynamic
range...the KPA500 will only light 5 of the 17 LEDs at full power.
It would be far more useful for me to have the meter scaled to 600W
say...then the 15th LED would be 450W. Even scaling it to 1000W would
give me more than half the display range.

--
Scott NX7U

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Don Wilhelm-4

Re: Rescaling the W2?

Scott,

I believe that would require a new sensor and firmware to support it.
Popular scales on wattmeters are 200 watts and 2000 watts full scale, so
you are not going to get much better with another brand product.
The W2 used with its utility program can give you more resolution, but
then using the Utility when mobile would not be advisable.

73,
Don W3FPR

On 11/20/2015 8:32 AM, Scott Townley wrote:

> I know the W2 can be "dialed in" to match one's personal standard,
> but...can it be completely rescaled?
> I use the K3/KPA500/W2 mobile, and the KPA500 is mounted in my pickup
> bed so the W2 is the only system meter available at the operating
> position. However, the 2's scaling doesn't give me much display
> dynamic range...the KPA500 will only light 5 of the 17 LEDs at full
> power.
> It would be far more useful for me to have the meter scaled to 600W
> say...then the 15th LED would be 450W. Even scaling it to 1000W would
> give me more than half the display range.
>
>

Cliff Frescura

Re: Rescaling the W2?

I find the scaling awkward as well. My W2 is placed on the input side of my
KPA500 and it seems that dividing the scale by two might do the trick. I've
not looked at the schematic, but wonder if it could be tricked by a resistor
divider in the sensor line.

73,

Cliff K3LL

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Don
Wilhelm
Sent: Friday, November 20, 2015 5:55 AM
To: Scott Townley; [hidden email]
Subject: Re: [Elecraft] Rescaling the W2?

Scott,

I believe that would require a new sensor and firmware to support it.
Popular scales on wattmeters are 200 watts and 2000 watts full scale, so you
are not going to get much better with another brand product.
The W2 used with its utility program can give you more resolution, but then
using the Utility when mobile would not be advisable.

73,
Don W3FPR

On 11/20/2015 8:32 AM, Scott Townley wrote:

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Alan Bloom

Re: Rescaling the W2?

I just tested it. The maximum you can set the W2 calibration value to
is 650. (Using the ">" and "+" RS-232 commands) That causes the
wattmeter to read about 60% high on my W2. So with the W2 set to read
2000W full scale, the actual full scale would be about 1250W.

Or you could go in the other direction. The minimum calibration value
is 350, which causes the power to read about 47% (on my unit). With the
W2 set to read 200W full scale it would actually be about 425W full scale.

Alan N1AL

On 11/20/2015 07:15 AM, Cliff Frescura wrote:

> I find the scaling awkward as well. My W2 is placed on the input side of my
> KPA500 and it seems that dividing the scale by two might do the trick. I've
> not looked at the schematic, but wonder if it could be tricked by a resistor
> divider in the sensor line.
>
> 73,
>
> Cliff K3LL
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Don
> Wilhelm
> Sent: Friday, November 20, 2015 5:55 AM
> To: Scott Townley; [hidden email]
> Subject: Re: [Elecraft] Rescaling the W2?
>
> Scott,
>
> I believe that would require a new sensor and firmware to support it.
> Popular scales on wattmeters are 200 watts and 2000 watts full scale, so you
> are not going to get much better with another brand product.
> The W2 used with its utility program can give you more resolution, but then
> using the Utility when mobile would not be advisable.
>
> 73,
> Don W3FPR
>
> On 11/20/2015 8:32 AM, Scott Townley wrote:
>> I know the W2 can be "dialed in" to match one's personal standard,
>> but...can it be completely rescaled?
>> I use the K3/KPA500/W2 mobile, and the KPA500 is mounted in my pickup
>> bed so the W2 is the only system meter available at the operating
>> position. However, the 2's scaling doesn't give me much display
>> dynamic range...the KPA500 will only light 5 of the 17 LEDs at full
>> power.
>> It would be far more useful for me to have the meter scaled to 600W
>> say...then the 15th LED would be 450W. Even scaling it to 1000W would
>> give me more than half the display range.
>>
>>
>
> ______________________________________________________________
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>
>
>
>
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Cliff Frescura

Re: Rescaling the W2?

Very cool Alan! Did you verify the power with another reference meter?
...wondering if the scale adjustment is linear over the calibration setting
range.

73,

Cliff K3LL

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Alan
Sent: Friday, November 20, 2015 9:07 AM
To: [hidden email]
Subject: Re: [Elecraft] Rescaling the W2?

I just tested it. The maximum you can set the W2 calibration value to is
650. (Using the ">" and "+" RS-232 commands) That causes the wattmeter to
read about 60% high on my W2. So with the W2 set to read 2000W full scale,
the actual full scale would be about 1250W.

Or you could go in the other direction. The minimum calibration value is
350, which causes the power to read about 47% (on my unit). With the
W2 set to read 200W full scale it would actually be about 425W full scale.

Alan N1AL

On 11/20/2015 07:15 AM, Cliff Frescura wrote:

> I find the scaling awkward as well. My W2 is placed on the input side
> of my
> KPA500 and it seems that dividing the scale by two might do the trick.
> I've not looked at the schematic, but wonder if it could be tricked by
> a resistor divider in the sensor line.
>
> 73,
>
> Cliff K3LL
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of
> Don Wilhelm
> Sent: Friday, November 20, 2015 5:55 AM
> To: Scott Townley; [hidden email]
> Subject: Re: [Elecraft] Rescaling the W2?
>
> Scott,
>
> I believe that would require a new sensor and firmware to support it.
> Popular scales on wattmeters are 200 watts and 2000 watts full scale,
> so you are not going to get much better with another brand product.
> The W2 used with its utility program can give you more resolution, but
> then using the Utility when mobile would not be advisable.
>
> 73,
> Don W3FPR
>
> On 11/20/2015 8:32 AM, Scott Townley wrote:
>> I know the W2 can be "dialed in" to match one's personal standard,
>> but...can it be completely rescaled?
>> I use the K3/KPA500/W2 mobile, and the KPA500 is mounted in my pickup
>> bed so the W2 is the only system meter available at the operating
>> position. However, the 2's scaling doesn't give me much display
>> dynamic range...the KPA500 will only light 5 of the 17 LEDs at full
>> power.
>> It would be far more useful for me to have the meter scaled to 600W
>> say...then the 15th LED would be 450W. Even scaling it to 1000W
>> would give me more than half the display range.
>>
>>
>
> ______________________________________________________________
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>
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> list: http://www.qsl.net/donate.html Message delivered to
> [hidden email]
>
>
>
>
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Michael Blake

Re: Rescaling the W2?

In reply to this post by Alan Bloom

Alan, while I do not own a W2 it would seem that the pickup coils in the sensor could be reduced in turns by the correct amount to lower the coupling loss loss by 3 dB. Would not the rest of the W2 work correctly at the 3 dB (or whatever you choose) lower power level?

Michael Blake - K9JRI

> On Nov 20, 2015, at 12:07 PM, Alan <[hidden email]> wrote:
>
> I just tested it. The maximum you can set the W2 calibration value to is 650. (Using the ">" and "+" RS-232 commands) That causes the wattmeter to read about 60% high on my W2. So with the W2 set to read 2000W full scale, the actual full scale would be about 1250W.
>
> Or you could go in the other direction. The minimum calibration value is 350, which causes the power to read about 47% (on my unit). With the W2 set to read 200W full scale it would actually be about 425W full scale.
>
> Alan N1AL
>
>
> On 11/20/2015 07:15 AM, Cliff Frescura wrote:
>> I find the scaling awkward as well. My W2 is placed on the input side of my
>> KPA500 and it seems that dividing the scale by two might do the trick. I've
>> not looked at the schematic, but wonder if it could be tricked by a resistor
>> divider in the sensor line.
>>
>> 73,
>>
>> Cliff K3LL
>>
>> -----Original Message-----
>> From: Elecraft [mailto:[hidden email]] On Behalf Of Don
>> Wilhelm
>> Sent: Friday, November 20, 2015 5:55 AM
>> To: Scott Townley; [hidden email]
>> Subject: Re: [Elecraft] Rescaling the W2?
>>
>> Scott,
>>
>> I believe that would require a new sensor and firmware to support it.
>> Popular scales on wattmeters are 200 watts and 2000 watts full scale, so you
>> are not going to get much better with another brand product.
>> The W2 used with its utility program can give you more resolution, but then
>> using the Utility when mobile would not be advisable.
>>
>> 73,
>> Don W3FPR
>>
>> On 11/20/2015 8:32 AM, Scott Townley wrote:
>>> I know the W2 can be "dialed in" to match one's personal standard,
>>> but...can it be completely rescaled?
>>> I use the K3/KPA500/W2 mobile, and the KPA500 is mounted in my pickup
>>> bed so the W2 is the only system meter available at the operating
>>> position. However, the 2's scaling doesn't give me much display
>>> dynamic range...the KPA500 will only light 5 of the 17 LEDs at full
>>> power.
>>> It would be far more useful for me to have the meter scaled to 600W
>>> say...then the 15th LED would be 450W. Even scaling it to 1000W would
>>> give me more than half the display range.
>>>
>>>
>>
>> ______________________________________________________________
>> 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 Message
>> delivered to [hidden email]
>>
>>
>>
>>
>> ______________________________________________________________
>> 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
>> Message delivered to [hidden email]
>>
> ______________________________________________________________
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Jack Brindle-2

Re: Rescaling the W2?

In reply to this post by Alan Bloom

Note that this affects all Power measurements in the W2 (but not SWR). This means that the serial data will be scaled by the same amount.
It will have affects on the auto-switching in the unit, as well as the alarm function. This means that if you set the alarm for 1000 watts and set the scaling so that 1000 watts is read as 500 watts, you won’t get an alarm. Conversely, if you scale so that 500 watts is indicated as 1000, you will see an alarm.

I would not recommend modifying the connections into the pickup unit - you would have to modify all of the sensor connections, and it would have adverse affects on our ability to detect characteristics of the unit.

Changing the scaling might be interesting for your use, though. If you try it, let us know how it works out for you.

73,

- Jack Brindle, W6FB

> On Nov 20, 2015, at 9:07 AM, Alan <[hidden email]> wrote:
>
> I just tested it. The maximum you can set the W2 calibration value to is 650. (Using the ">" and "+" RS-232 commands) That causes the wattmeter to read about 60% high on my W2. So with the W2 set to read 2000W full scale, the actual full scale would be about 1250W.
>
> Or you could go in the other direction. The minimum calibration value is 350, which causes the power to read about 47% (on my unit). With the W2 set to read 200W full scale it would actually be about 425W full scale.
>
> Alan N1AL
>
>
> On 11/20/2015 07:15 AM, Cliff Frescura wrote:
>> I find the scaling awkward as well. My W2 is placed on the input side of my
>> KPA500 and it seems that dividing the scale by two might do the trick. I've
>> not looked at the schematic, but wonder if it could be tricked by a resistor
>> divider in the sensor line.
>>
>> 73,
>>
>> Cliff K3LL
>>
>> -----Original Message-----
>> From: Elecraft [mailto:[hidden email]] On Behalf Of Don
>> Wilhelm
>> Sent: Friday, November 20, 2015 5:55 AM
>> To: Scott Townley; [hidden email]
>> Subject: Re: [Elecraft] Rescaling the W2?
>>
>> Scott,
>>
>> I believe that would require a new sensor and firmware to support it.
>> Popular scales on wattmeters are 200 watts and 2000 watts full scale, so you
>> are not going to get much better with another brand product.
>> The W2 used with its utility program can give you more resolution, but then
>> using the Utility when mobile would not be advisable.
>>
>> 73,
>> Don W3FPR
>>
>> On 11/20/2015 8:32 AM, Scott Townley wrote:
>>> I know the W2 can be "dialed in" to match one's personal standard,
>>> but...can it be completely rescaled?
>>> I use the K3/KPA500/W2 mobile, and the KPA500 is mounted in my pickup
>>> bed so the W2 is the only system meter available at the operating
>>> position. However, the 2's scaling doesn't give me much display
>>> dynamic range...the KPA500 will only light 5 of the 17 LEDs at full
>>> power.
>>> It would be far more useful for me to have the meter scaled to 600W
>>> say...then the 15th LED would be 450W. Even scaling it to 1000W would
>>> give me more than half the display range.
>>>
>>>
>>
>> ______________________________________________________________
>> 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 Message
>> delivered to [hidden email]
>>
>>
>>
>>
>> ______________________________________________________________
>> 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
>> Message delivered to [hidden email]
>>
> ______________________________________________________________
> Elecraft mailing list
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> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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Jack Brindle-2

Re: Rescaling the W2?

In reply to this post by Michael Blake

The inductors in a directional coupler are not linear. The response to the turns count is actually a squaring function, so it would be difficult to remove turns and have the effect you want. The other problem is that the W2 firmware has a lot of data tables that depend on the values that are set in the sensor - changing the sensors means changing the tables. I believe that using the scaling factor that is already built in to the W2 would be the best way to achieve what Scott wants. It does have a down side, though. If someone else were to look at the scaled W2 and see the 10 LED light up, we would naturally think it was indicating 10 (or 1 or 100 or 1000) watts instead of whatever value Scott has scaled for.

- Jack, W6FB

> On Nov 20, 2015, at 10:08 AM, Michael Blake <[hidden email]> wrote:
>
> Alan, while I do not own a W2 it would seem that the pickup coils in the sensor could be reduced in turns by the correct amount to lower the coupling loss loss by 3 dB. Would not the rest of the W2 work correctly at the 3 dB (or whatever you choose) lower power level?
>
> Michael Blake - K9JRI
>
>
>
>> On Nov 20, 2015, at 12:07 PM, Alan <[hidden email]> wrote:
>>
>> I just tested it. The maximum you can set the W2 calibration value to is 650. (Using the ">" and "+" RS-232 commands) That causes the wattmeter to read about 60% high on my W2. So with the W2 set to read 2000W full scale, the actual full scale would be about 1250W.
>>
>> Or you could go in the other direction. The minimum calibration value is 350, which causes the power to read about 47% (on my unit). With the W2 set to read 200W full scale it would actually be about 425W full scale.
>>
>> Alan N1AL
>>
>>
>> On 11/20/2015 07:15 AM, Cliff Frescura wrote:
>>> I find the scaling awkward as well. My W2 is placed on the input side of my
>>> KPA500 and it seems that dividing the scale by two might do the trick. I've
>>> not looked at the schematic, but wonder if it could be tricked by a resistor
>>> divider in the sensor line.
>>>
>>> 73,
>>>
>>> Cliff K3LL
>>>
>>> -----Original Message-----
>>> From: Elecraft [mailto:[hidden email]] On Behalf Of Don
>>> Wilhelm
>>> Sent: Friday, November 20, 2015 5:55 AM
>>> To: Scott Townley; [hidden email]
>>> Subject: Re: [Elecraft] Rescaling the W2?
>>>
>>> Scott,
>>>
>>> I believe that would require a new sensor and firmware to support it.
>>> Popular scales on wattmeters are 200 watts and 2000 watts full scale, so you
>>> are not going to get much better with another brand product.
>>> The W2 used with its utility program can give you more resolution, but then
>>> using the Utility when mobile would not be advisable.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> On 11/20/2015 8:32 AM, Scott Townley wrote:
>>>> I know the W2 can be "dialed in" to match one's personal standard,
>>>> but...can it be completely rescaled?
>>>> I use the K3/KPA500/W2 mobile, and the KPA500 is mounted in my pickup
>>>> bed so the W2 is the only system meter available at the operating
>>>> position. However, the 2's scaling doesn't give me much display
>>>> dynamic range...the KPA500 will only light 5 of the 17 LEDs at full
>>>> power.
>>>> It would be far more useful for me to have the meter scaled to 600W
>>>> say...then the 15th LED would be 450W. Even scaling it to 1000W would
>>>> give me more than half the display range.
>>>>
>>>>
>>>
>>> ______________________________________________________________
>>> 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 Message
>>> delivered to [hidden email]
>>>
>>>
>>>
>>>
>>> ______________________________________________________________
>>> 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
>>> Message delivered to [hidden email]
>>>
>> ______________________________________________________________
>> 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
>> Message delivered to [hidden email]
>
> ______________________________________________________________
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>
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Alan Bloom

Re: Rescaling the W2?

In reply to this post by Cliff Frescura

I just read out the power via RS-232 with the calibration at the nominal
value of 500 and then again with the bogus calibration value to see how
much it changed. The calibration value is not linear - I think it is
proportional to the detector voltage, which is roughly proportional to
power squared. (650/500)^2 = 1.69 and I measured 1.6.

Alan N1AL

On 11/20/2015 09:44 AM, Cliff Frescura wrote:

> Very cool Alan! Did you verify the power with another reference meter?
> ...wondering if the scale adjustment is linear over the calibration setting
> range.
>
> 73,
>
> Cliff K3LL
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Alan
> Sent: Friday, November 20, 2015 9:07 AM
> To: [hidden email]
> Subject: Re: [Elecraft] Rescaling the W2?
>
> I just tested it. The maximum you can set the W2 calibration value to is
> 650. (Using the ">" and "+" RS-232 commands) That causes the wattmeter to
> read about 60% high on my W2. So with the W2 set to read 2000W full scale,
> the actual full scale would be about 1250W.
>
> Or you could go in the other direction. The minimum calibration value is
> 350, which causes the power to read about 47% (on my unit). With the
> W2 set to read 200W full scale it would actually be about 425W full scale.
>
> Alan N1AL
>
>
> On 11/20/2015 07:15 AM, Cliff Frescura wrote:
>> I find the scaling awkward as well. My W2 is placed on the input side
>> of my
>> KPA500 and it seems that dividing the scale by two might do the trick.
>> I've not looked at the schematic, but wonder if it could be tricked by
>> a resistor divider in the sensor line.
>>