[Elecraft] Elecraft gear relative IMD

[Wes (N7WS)]

I have some of those data, but not all.  This conversation had already given me 
the idea that I should remeasure the two radios' IMD at different voltages, as 
well as vs power vs. frequency.

But you are asking for two different things, IMD and spurious signals.  With a 
nominal "12 V" radio, absent some fancy feedback, IMD products will never be 
down 50 dB in this lifetime, even when using the "cheating" (IMHO) 
dB-relative-to-PEP method.

Looking for and measuring spurs, other than harmonics, is a job for a spectrum 
analyzer, something I lack.


On 12/30/2015 8:09 PM, ac5p at sbcglobal.net wrote:
> Who has some measured 2 tone IMD test figures for an actual  K3/K3S at full and reduced power levels and at supply voltage levels between 12-15 volts?Must assume the Harmonic and Spurious Outputs exceed 50dB below carrier @ 100W within ham bands as per Elecraft manual specs.  HOW  much better than 50dB with above variables is the question?   Can someone share these figures?
> 73,Mike  AC5P
>   
>
>      On Wednesday, December 30, 2015 6:39 PM, Don Wilhelm<w3fpr at embarqmail.com>  wrote:
>   
>
>   I think it is time to change the subject line (and I did).  The original
> question was about increased IMD with lower power supply voltages.
> It has now morphed into the relative IMD at different power levels with
> higher (normal) power supply voltages.
>
> Whatever the actual IMD of the K3/K3S at any power level, the
> information I have heard from contesters and DXers is that the Elecraft
> gear is has lower IMD than most other transceivers.  We have heard
> testimony to that repeatedly from Field Day setups and DXpeditions where
> there are multiple transceivers operating in close proximity to other
> stations.  When station A cannot hear anything interfering when station
> B transmits, that is a good thing. Elecraft gear can do that while many
> other manufacturer's transceivers cannot say the same thing.
>
> What we do know is that higher power supply voltages provide better IMD
> figures, and since the Elecraft gear is rated for up to 15 volts, we
> will achieve better IMD performance if the power supply is cranked up to
> provide a voltage just a bit below 15 volts.
>
> 73,
> Don W3FPR
>
> On 12/30/2015 6:52 PM, Fred Jensen wrote:
>> Ummm ... I don't think that was what was suggested at all.  I read the
>> post to be an observation of a *relative* condition.  All amplifiers
>> [at least that I've ever encountered] exhibit increasing distortion
>> near their rated power limits.  I've always assumed that's why
>> distortion numbers are almost always accompanied by the power when the
>> measurements were taken.
>>
>> My K3/100 is a K3/10 below about 15 watts ... the 100 W amplifier
>> switches out of the circuit.  I think all that the post was trying to
>> point out is that, from 100 W downward, the distortion will decrease
>> *until* the KPA3 cuts out.  At that point, the LP amplifier/exciter is
>> near it's max power, and it's distortion will probably be higher than
>> the values from the KPA3 operating just above that power.  In any
>> case, absolute distortion from a K3/<anything> is still among the
>> lowest in the marketplace.
>>
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