[Elecraft] W2 wattmeter not reading xv50 output

[John Marvin]

I'm not sure I can explain this. But it's possible the problem is a 
combination of two possible error sources:

1) I believe the XV50 leds are displaying power based on the voltage at 
the final stage, and is not using a SWR bridge to measure forward power. 
The W2 is measuring forward power, so if the SWR is greater not 1:1 then 
it will measure a lower value than what the XV50 is displaying. Did you 
take note of SWR and reverse power using the W2 utility? Since you are 
driving another amp I wouldn't expect a really high SWR though.

2) Did you build your XV50 or did you get a factory built version? If 
factory built then Elecraft would have properly calibrated it. If you 
built it, did you perform all the calibration steps? Since you already 
mentioned you don't have a lot of test equipment, you may not have been 
able to calibrate the XV50 properly. In particular, if calibrated 
properly, 1mW drive should produce 20 watts output, not 30.  Also,  you 
should try to avoid sending more than 1mW to the XV50.

Final question. How were you generating the test signal and what mode 
were you using?

John
AC0ZG

On 1/23/2014 8:10 AM, Bob KD7YZ wrote:
> On 1/22/2014 02:05, John Marvin wrote:
>> Bob,
>>
>> You should try installing the W2 utility
> Just went and D/L. Thanks .
>
> XV-50 into a dummy-load:
> K3-Drive        W2-UTil         XV50 Bars        W2-Box-LED
>
> 0.1mW drive     0.50W on W2     2 bars ((2W)     0
> 0.2mW drive     0.83W on W2     4 bars ( 5W      0
> 0.3mW drive     1.42W on W2     5 bars   7W      1 1watt
> 0.4mW drive     1.90W on W2     6 bars  10W      1 1watt
> 0.5mW drive     2.41W on W2     6 bars  10W      2 2watt
>
> 0.6mW drive     3.02W on W2     7 bars  15W      3 3watt
> 0.7mW drive     3.66W on W2     8 bars  20W      3 3watt
> 0.8mW drive     4.23W on W2     9 bars  25W      4 4watt
> 0.9mW drive     4.81W on W2     10bars  30W      4 4watt
>
> 1.0mW drive     5.35W on W2     10bars  30W      5 5watt
> 1.5mW drive     8.80W on W2     10bars  30W      8 8watt
>
> So, as you see, nothing agrees with anything. Note: I am not a test-lab
> and have little in the way of measurement equipment. Coaxial-Dynamics in
> the PA output. However, 500/1000 watt slugs.
>
> But, the XV50 drives the 180w 6m brick to an acceptable low limit (based
> on XV50 drive).
> The Brick drives the PA to 1250W .. so I can't complain in that regard.
> Just wanted to monitor/see the output of the XV50 and can't seem to do it.
>