[Elecraft] TX Sample level on KPA1500?

[David Box]

Jim

I have done a little characterization of the TX Sample.  Testing I did 
was into a dummy load running CW and using the KPA1500 reported powers.  
Ran K3s barefoot measuring the TX Sample level terminated with 50 ohms 
from 20 - 100W in 10W steps .  Then ran with KPA1500 operating up to 
about 1700W.  With the KPA1500 inline I ran the K3s from 5 W - 35W in 5W 
steps.  Max power reported at 35W was 1720W by the KPA1500.  Tuners in 
K3s and KPA1500 were bypassed in this data acquisition, the load was a 
Bird Termaline 1KW Dummy Load.

TX Sample voltage is same with or without powering up the KPA1500, so 
pretty sure it is just a torroid with passive scaling.

With the TX Sample terminated by 50 ohms I find   POpep= (V^2)*55. Where 
V is the P-P TX Sample Voltage.  The constant 55 is from trying to do a 
linear regression.  Expect it is off a little based on accuracy of 
KPA1500 reported power and my scope has not been officially calibrated, 
but close.

With an accurate RF voltmeter this could be refined by actually 
measuring power in dummy load but right now do not have the hardware to 
do that.

Be interested if anyone has found a better fit.

Be interesting to see what the manual reveals when they get caught up.

Now I can justify scrounging some more test equipment and build a few 
more test jigs :)

Also learned the list does not like for you to use formatting of 
superscripts and subscripts :)

73 Dave K5MWR


On 6/2/2018 10:01 PM, David Box wrote:
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