[Elecraft] [P3] Power measurement with the P3

[Brett Howard]

I have done the mods and I'm running 00.30 and I'm still a bit off.
My XG2 puts out ~-74dBm give or take a few tenths last time I measured
it on our 80K spectrum analyzer and my combination reads -81dBm on the
K3 with the ATU in bypass and no pre or att.  PRE or ATT are correctly
accounted for and the signal does not change if either are activated
individually.  Activating both at the same time causes the signal to
increase by 1dB but operating in this condition would just be plain
silly so I don't consider that a real world scenario.  Engaging the
tuner which is setup for my antenna at that particular frequency
actually makes a change of 3dB.  Again thats no fault of any of the
equipment just something of interesting note...

~Brett (N7MG)


On Fri, Aug 13, 2010 at 3:56 AM, Bill W4ZV <btippett at alum.mit.edu> wrote:
>
>
> Al Lorona wrote:
>>
>> I note my P3's amplitude readings are about 6 dB low-- that's with the IF
>> output
>> switched off. I'm not sure how to calibrate it.
>>
>
> Have you done the IF OUT Gain Mod mentioned at the top of page 5 in the
> manual?
>
> http://www.elecraft.com/K3/mods/IF_Output_Buffer_Gain_Mod_Rev_A.pdf
>
> Earliest P3 firmware versions had a gain error of ~10 dB but the latest
> version (beta 00.30) is better.  My P3 now reads -74 dBm for all
> combinations of PRE/ATT on and off (using the XG1's -73 dBm setting).  Once
> Alan implements Amplitude Calibration  we should be able to correct the
> remaining errors.
>
> 73,  Bill
>
> --
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