[Elecraft] W2 wattmeter

[John Marvin]

As you mentioned, the W2 utility shows greater accuracy, although just 
because it shows values in fractions of a watt, it doesn't mean that it 
is that accurate. However, the nice thing about the W2 is that it has a 
fairly nice calibration facility. So if you have or can borrow a higher 
accuracy meter then you can use that to improve the accuracy of the W2.

Also, I really like the fact that the SWR bridge sensor is remote from 
the unit. This allows a lot more flexibility for setup. In my case the 
cable was just a little too short, but I wondered if a CAT 5e patch 
cable would work. I did a little googling and saw an Elecraft employee 
recommending that option. I don't know how long you can go before it 
doesn't work or gives bad readings, but the patch cable I used was only 
2-3 feet longer than the cable supplied by Elecraft, and it didn't 
appear to affect the readings based on a simple before/after test.

Anyway, I think the W2 is a great product.  However, Elecraft recommends 
that it go between the amp and the ATU (Elecraft says that the accuracy 
really starts to suffer with high SWR). That means that it might not be 
very useful if I purchase a KXPA100 with the built in ATU.

John
AC0ZG

On 6/15/2013 9:34 AM, Donald Butler wrote:
> I have two W2 meters and I like them  .. But I do not rely upon them for
> accurate power readings.. My more practical use is to use my peripheral
> vision to keep tabs on what's going on while I'm on the air and be alert for
> unexpected changes.
>
> I think the Bird 43, when fully calibrated, claims plus or minus 5% accuracy
> at full scale on their analog dial.
>
> The W2 is probably close to that, but not quite (maybe 6% at best) ... there
> are 17 leds on the 0-20 watt meter scale  .. Doing the math, on the 2KW
> scale, that's about 118 watts per LED ... so the power has to increase about
> 118 watts before the next LED will light up, etc., etc.    Yes, you can get
> a reading of presumed accuracy to the nearest watt if you us the W2 software
> and keep a window running on your computer  . but the LED display itself is
> only capable of reading plus or minus 118 of actual wattage on the 2 KW
> scale.. And I've never bothered to calibrate to see what it takes for the
> next LED to light up .. Does it change when you (1) just cross the new
> threshold, (2) hit the midrange area of the next step, or (3) go the full
> distance.    Bottom line, it really doesn't matter, but I do not use a W2 to
> obtain accurate power readings just from the LED display.
>
> Don, N5LZ
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Fred Smith
> Sent: Saturday, June 15, 2013 8:28 AM
> To: 'NZ0T'; elecraft at mailman.qth.net
> Subject: Re: [Elecraft] W2 wattmeter
>
> Bill is 100% right on about the W2,it is most useful on screen for extreme
> QRP if you don't have a WM-2 QRP meter. But like I said earlier it is very
> close for all ranges both of my couplers are 2k's but still not bad for QRP.
>
>
> 73,
> Fred/N0AZZ
> K3 Ser #'s 6730/5299--KX3 # 2573--K2/100 # 6470-KAT100
> P3/SVGA--KPA500--KAT500--W2
>
>
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of NZ0T
> Sent: Saturday, June 15, 2013 7:16 AM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] W2 wattmeter
>
> Very happy with my W2.  I have the 2KW coupler.  Seems pretty accurate and
> the LED display is great for casual use.  I don't always keep the display up
> on the computer but it's very useful when greater resolution than the LED
> display is desired.
>
> 73 Bill NZ0T
>
>
>
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