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 <[email protected]> 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 <[email protected]> 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:[email protected]] On Behalf Of Don >>> Wilhelm >>> Sent: Friday, November 20, 2015 5:55 AM >>> To: Scott Townley; [email protected] >>> 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:[email protected] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html Message >>> delivered to [email protected] >>> >>> >>> >>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[email protected] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to [email protected] >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
