[Elecraft] The amp I would like to see Elecraft build.

[Ken K6MR]

While making these changes would help, they pale in comparison to a SDR implemented pre-distortion system like Pure Signal. The big advantage will be that the entire transmit chain will be cleaned up as a system, rather than trying to deal with each box separately.

Time to move into the 21st Century.

Ken K6MR



From: Wes Stewart<mailto:wes_n7ws at triconet.org>
Sent: Monday, August 1, 2016 21:41
To: elecraft at mailman.qth.net<mailto:elecraft at mailman.qth.net>
Subject: Re: [Elecraft] The amp I would like to see Elecraft build.

I'm not always on the same page as Joe, but this time I could not agree more.
As someone who has measured the TX IMD of both my kit K3/100 and a factory built
K3S/100 I can attest to this.  First of all, they like every other manufacturer
and the ARRL fudge the numbers by 6 dB (in their favor of course) by comparing
one distortion product to the sum of the two tones.

EIMAC and MIL-Specs say, "The standard method of specifying the magnitude of the
distortion products is to specify the reduction in decibels of
one product from one tone of a two-equal-tone signal."

Elecraft isn't to be singled out for this, they are just doing what the ham
industry is doing.

One of several motivations for replacing a perfectly working K3 with the K3S was
the hope that the FET PA would be cleaner than the bipolar PA in the K3.  Big
disappointment.  One factor is the fact that it's still a nominal "12 V" PA.
Another is that it's still driven by a bipolar "10 W" exciter.  If some of you
are using a bare K3/10 and running at greater than 10 W, shame on you.  And
shame on Elecraft for letting you do it.  Based upon my measurements (which BTW
correlated to 1 dB or less with Elecraft measurements) the IMD of the 10W PA
above 10W is abysmal.

So, no higher power "12 V" PAs please!

Wes  N7WS


On 7/31/2016 6:43 PM, Joe Subich, W4TV wrote:
>
>> Then Elecraft can build us a 12 volt version of the KPA500.
>
> Heaven help us, NO!  The 12V amplifiers are marginally clean enough
> at 100W.  A 500W 12V amplifier is likely to have IMD be much poorer
> than -30 dB PEP.  What we really need is a 48V final for the K3/K3S
> (maybe at 200W) so we can see IMD in the -45 dB to -50 dB PEP range
> where it really should be.
>
> It's time to make a stand for cleaner signals ... not signals in the
> same class as the "no name" Italian and Chinese amplifiers.
>
> 73,
>
>    ... Joe, W4TV

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