Bob,
The answer is - It all depends ... -- read on if you want the rest of
the story.
I constantly rely on the RF voltage produced across a known accurate 50
ohm resistor for my power measurement calculations, so that is the
method I depend on.
The W1 is quite accurate, but there is one
Ed,
Yes, the formula in the DL1 manual is off a bit - there was some discussion
about that on the reflector about 6 months ago.
As I calculate, the correct formula is P(watts)=(1.414(V(volts)+0.15))^2/50
Or easier expressed as P=2(V+0.15)^2/50 (I am not certain why the square
root of 2 (1.414)
Larry Phipps wrote:
You can also fine tune the formula based on DC measurement of the
resistance of the bottom half of the load. The formula assumes an
exact 25.0 ohms for the bottom half of the load.
Also, measure the resistance at the temperature you will be using for
testing. You can
Fran,
You have the calculations correct - I use Vp-p^2/400 all the time for a 50
ohm load. I use the 'scope probe connected directly across the dummy load
(the 'scope probe has a short grounding lead).
It is quite unlikely that the power output really climbs with power, so
there must be
All,
Thanks to all who answered me either direct or on the list.
Based upon the answers I would guess that I need to pay better attention to
lead length. I did not make any attempts to keep things short.
I will also think about Ron's suggestion to bypass the KAT2.
I'll post the final results
Yes, you have the right formula, Fran.
Power = (Vpk-pk)^2/8R
Where R is the load resistance.
It is *not* frequency sensitive, but hardware often is.
Either your scope probe is not properly frequency-compensated or your load
is not a good, solid 50 ohm non-reactive dummy load. Note that it's
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