[Elecraft] KPA500 Power In Digital Modes

[Joe Subich, W4TV]

Jim,

> Recent measurements I've done of a K3 driving a KPA500 both with pink
> noise on USB and keyed CW show that not to be the case.

Your measurements are not of the conditions I describe.  You are using
*filtered and band limited pink noise* (slide #3 - EQ settings) not the
specific digital signals I mention *and* your measurements are at PEP
not average power (slide #2 - LP-100A set to peak).  In addition,
unfiltered pink noise has a crest factor (peak to average ratio) of 3
dB which you are further reducing by compression in the K3 - not the 6
to 10 dB crest factors of the specified digital modes which *can not*
be compressed without significant distortion and IMD.

Your measurements, while interesting, do not accurately simulate the
specified digital modes are not applicable in this case.

73,

   ... Joe, W4TV


On 2014-11-11 2:20 AM, Jim Brown wrote:
> On Mon,11/10/2014 4:30 PM, Joe Subich, W4TV wrote:
>> *DO NOT* try running
>> PSK, MFSK, etc. modes at 600W average power from a KPA-500 as you
>> will be generating serious IMD and garbage.
>
> Recent measurements I've done of a K3 driving a KPA500 both with pink
> noise on USB and keyed CW show that not to be the case. Yes, bandwidth
> increases a few dB from 400W to 600W, but I would NOT call it serious.
> This is preliminary work and a preliminary report. At its current stage,
> it's a proof of concept.As I have time (and the radios to test), I plan
> to look at lot of others. I've just lined up a couple in the FT1000MP
> family.
>
> P3SprectrumMeasurementsSlides.pdf
>
> 73, Jim K9YC
>
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