[Elecraft] Question K3 ALC w/SPE Expert 1.3K-FA amp

[Wayne Burdick]

Hi Darrell,

Nearly all ALC systems cause splatter, and some are horrible. Letting the amp control a radio's drive level is pretty much worst-case. This just about guarantees clicky, distorted ALC response as well as poorly shaped CW keying.

Instead, we recommend adjusting the K3's drive level per-band (see CONFIG:PWR SET) to just reach the desired power level at the amp's output. This way, little if any ALC is used. The per-band levels are stored at the K3 and recalled as you change bands.

The K3 has its own very clean internal, slow ALC to compensate for minor gain variations. We also apply ALC and compression within the DSP, at the audio stages--again with intent to minimize splatter. All gain-controlled stages are pre-crystal filter, ensuring that any dynamics are entirely band-limited before they ever get to an output stage.

This goes counter to instructions for some amps. They assume you are not capable of properly adjusting the drive to compensate for per-band variations, so they instruct you to crank it to the max at the rig. But the proof can be heard on the air. A K3 properly adjusted per-band will be exceptionally clean.

73,
Wayne
N6KR




On Apr 2, 2015, at 7:34 PM, AB2E Darrell <ab2e at hotmail.com> wrote:

> Hello all,
>       I am the proud new owner of a new K3. I am also the proud new owner of an SPE Expert 1.3K-FA solid state amp, and I have a question for the group regarding interfacing the K3 to the amp.
> 
> My current setup is using my Icom 756 Pro III with the SPE Expert 1.3K-FA. The recommended setup for Icom was to connect both the Relay and ALC cables between the rig and amp. This is because the software in the amp automatically reduces the power in the rig to the best output level for the amp (on the amp LOW=500W out= 3W drive, MID= 1000W out= 6W drive, HIGH = 1500W out = 9W drive). It works flawlessly. Actually, I could leave the power on the Pro III untouched, and the amp reduces the power accordingly.
> 
> My question for the group is, is there a way to allow the K3's output to be controlled by the amp? I see the note on p27 about not using an amp to control the K3's output, but wonder if there is a safe way to do it. For instance, could the K3 be set to say 15W out on all bands via the menu, then allow the amp to control the output via ALC for optimum drive? 
> 
> Any info and comments appreciated. 
> 73 Darrell AB2E
> 
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