[Elecraft] W1

[Robert Nobis]

Just wondering. Why is an accuracy within less than 1dB important?

Happy New Year.

73,

Bob Nobis - N7RJN
n7rjn at nobis.net


> On Dec 31, 2015, at 09:42, Ed Lambert <g_e_lambert at comcast.net> wrote:
> 
> John,
> 
> Thank you for your response.
> My original K3s test setup was per the manual: good quality dummy load (not
> the DL1 because of its 20 watt upper limit) with the ATU off. My high
> quality dummy load does not have a test point.
> After reading your results, I decided to take the DL1 as my "truth model". I
> found that the W1 display was 0.8 dB high and the K3s power display was 0.9
> dB low. Each one was at the opposite end of the error budget. (sort of like
> winning the "losers" lottery).
> So, I set up the W1 to match the DL1 up to 20 watts and, surprise, the W1 TP
> voltage is now 4.87 volts.
> I don't have the W1 software and cabling installed yet. At that time I can
> fine tune all of this.
> It seems as though a consensus is building that the W1 manual specification
> of 4.5 volts is no longer correct, unless there is something "off" with the
> W1 internal algorithm.
> Good stuff. Thank you everyone for your comments and help.
> 
> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of John
> Oppenheimer
> Sent: Thursday, December 31, 2015 7:22 AM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] W1
> 
> Hi Ed.
> 
> The W1 DC voltage calibration resulted with incorrect reading with my W1. My
> hunch is that components have changed since Elecraft established the TP1 DC
> calibration voltage almost a decade ago.
> 
> I have a KX3F with unchanged factory power calibration. Based on comments
> from Wayne, the KX3 is calibrated at 7.0 watts.
> 
> My W1 TP1 voltage is 4.812 using a Fluke 87V
> 
> Setting up a test bench with KX3 -> W1 -> DL1
> 
> Using W1 Utility to display W1 power:
> http://www.elecraft.com/software/W1/elecraft_w1_software.htm
> 
> TP1 V = 4.812
> KX3 power = 7.0 W
> W1 power = 7.02
> DL1 V = 12.91 = 6.93 watts
> 
> The W1 20 dB directional coupler does absorb power, at 7 watts, the
> directional coupler will absorb 0.07 watts. Adding 0.07 to the DL1
> measurements equals 7.00 watts.
> 
> John KN5L
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