[Elecraft] K2/100 - Power investigation

[Vic K2VCO]

Don Wilhelm wrote:

> I find that with a good 50 ohm dummy load and an 100 MHz oscilloscope 
> with a 10X probe (probe rated for 100 MHz), I can calibrate the KPA100 
> wattmeter to less than 5% accuracy on bands below 20 meters - at higher 
> frequencies, the 'scope and probe rolloff will indicate lower than 
> expected results. 

Be careful if you use this method!  I learned the hard way (destroyed 
THREE probes) that the voltage rating for scope probes goes down as 
frequency goes up. There is a little piece of paper that comes with the 
probes; look at it, compute the voltage across your dummy load at the 
power levels that you will be testing (100 watts is about 70.7 volts), 
and make sure that the probe can handle it at the frequency of interest.
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco