[Elecraft] KX1 Power Measurements by band

[Phil Wheeler]

Ron,

Comment re the cap noted.  I did recheck both TX toroids (L and 
transformer) and they both look just right, so it may be the capacitor.  
I could remove it and check with my AADE meter -- but I'm not about to!

The other thing is that I have yet to build and install the atu, and 
that could make a slight difference in measurements.  That is my next 
priority and I will redo all measurements after that.

I found the manual for the meter I am using,  It is the KD1JV "0-10 Watt 
RMS RF Power Meter Kit" and I built it in Summer of 2001.  Stated 
accuracy is (worst case) 3% of reading.  It is based on an Analog 
Devices AD8361.  Apparently this kit is no longer on the market -- so 
I'm glad I got one when I did.  One plus is a very low inductance (1 
nHy) 51 Ohm 10 W thick-film load resistor.

Back to melt some more solder!

73, Phil

Ron D'Eau Claire wrote:

>I don't know what causes the variations with frequency, but yours does meet
>the "3 to 4 watt" spec. I'm suspicious of possible variations in the values
>of the cap in the output network since it appears that the differences you
>are seeing look like the result of a slightly different frequency response
>characteristic. 
>
>That said, your readings are within about 10% of mine, and I'd not expect
>any better accuracy out of my watt meter alone. 
>
>Ron AC7AC
>
>-----Original Message-----
>
>Ron D'Eau Claire wrote:
>
>  
>
>>40: 4.1 watts
>>30: 4.8 watts
>>20: 3.8 watts
>>
>>    
>>
>
>Ron,
>
>Here are the power levels I just measured with the 30 m module installed 
>and a 13.8 V supply voltage (note: R30 is changed from 22 to 36 ohms and 
>R4 is fully CW);
>
>40: 4.5 W
>30: 5.0 W
>20: 3.4 W
>
>So mine are in the same relationship as yours (30 highest, 20 lowest, 40 
>in between) but I have a larger range (1.6 W vs 1.0 W from highest to 
>lowest).
>
>Measurements done with a precision digital qrp wattmeter into a very 
>precise dummy load inside the meter.  ATU is not yet installed.
>
>Aside from wishing 20 m were a tad higher (say 4.0 W), these results do 
>not seem all that bad.  However, I will play with T1 a bit (check no of 
>windings and respace ite prmary tomorrow (oops, later today) and see if 
>I can reduce the power range.
>
>73
>
>
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