[Elecraft] P3 Phase noise/HighSignal Response?

[Jim Brown]

On Tue,3/14/2017 8:19 AM, K5MWR via Elecraft wrote:
> Jim
>
> Really appreciate this information and going over it now to make sure 
> I understand the limits.  The presentation is well done.

Thanks. But it's not really a presentation, just an easy way to display 
the data.
>
> How did you capture the SVGA images?

I plugged a USB memory stick into the P3 USB port. There's a menu 
selection to do the capture. I assigned it to one of the soft buttons.

73, Jim K9YC
>
> Dave K5MWR
>
>
>
> On 3/13/2017 10:53 PM, Jim Brown wrote:
>> Hi Dave,
>>
>> The P3 is quite good for measurements, and the SVGA card is even 
>> better.  Here's a collection of work I've done with whatever rigs and 
>> amps I could get my hands on to measure.
>>
>> http://k9yc.com/P3_Spectrum_Measurements.pdf
>>
>> In my experience, if you keep the K3 within its linear region, you'll 
>> get good data from the P3 if you understand the measurements you're 
>> making.  Limitations -- the dynamic range is 100 dB, but you can only 
>> display 80 dB on screen. For all of the operation I do, I use the P3 
>> with a lot of averaging and a slow waterfall, fairly large 
>> waterfall.  For measurements, I use the P3 in Peak reading mode and 
>> let it accumulate peaks for a while. I make the amplitude display 
>> pretty large, set it for 80 dB, and adjust levels to fill the 
>> amplitude screen.
>>
>> When I'm checking CW bandwidth, I send a series of dits in the range 
>> of 35 WPM for at least 20 seconds I reset the peak a second or so 
>> after I've started sending dits so I don't see any initial transient 
>> that might be present. Notice that I set the span for a fairly narrow 
>> bandwidth.
>>
>> The annotations you see for bandwidth are obtained by moving the 
>> cursor to each data point and writing down the readings, and they are 
>> the DIFFERENCE between the high and low points.
>>
>> If you want to show data more than 80 dB below the peak of the 
>> signal, you can repeat the measurement with the reference level 
>> reduced by 20 dB.  More than that and the P3 will overload.
>>
>> 73, Jim K9YC
>>
>> On Mon,3/13/2017 6:03 PM, K5MWR via Elecraft wrote:
>>> I am trying to use my P3 to evaluate signals from other hams here in 
>>> my community.  While I know the K3s is excellent, I am not sure what 
>>> to expect out of the P3 in terms of phase noise or response under 
>>> high signal conditions. I can always pad to lower the signal but 
>>> that will not help with any P3 internal phase.
>>
>>
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>
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