The TX SAMPLE output is supposed to be described in the owner’s manual. If it’s not there, it will be in the next update. It’s also mentioned in the FAQ, but re-reading it, I’m not sure it describes the signal level accurately. I’ll check on that.
> On May 28, 2018, at 10:46 AM, Jim Miller <[hidden email]> wrote:
> I've seen no documentation on this output. I assume it is a tap on the PA
> output before the ATU.
> Does anyone know the expected level here? Is is 30 or 40db or more down
> from the PA out?
> Is the attenuated level flat with frequency?
> jim ab3cv
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,
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
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 :)