[Elecraft] ALC and the K3

[Joe Subich, W4TV]

On 12/21/2017 2:34 PM, Bob McGraw K4TAX wrote:
 > Just tune and load the amp for maximum output and then reduce drive
 > power from the K3 to attain the level of power you desire to operate.

This assumes one has a (tube) amplifier with Tune/Load controls.

> If it is linear at 1500 watts, then reducing drive, it will be linear
> at 500 watts.

But *much less efficient*.  The output network will be adjusted for
peak current/minimum voltage conditions of maximum output while the
typical (average) voltage/current will be much different.

> If one re-tweaks at lower power it most likely won't be linear at
> 1500 watts or any lesser peak there of.

While it will not be "linear" at power levels above the level at which
the output network was tuned, it will certainly be "linear" up to that
point *and much more efficient* (less loss in the output network).

73,

    ... Joe, W4TV


On 12/21/2017 2:34 PM, Bob McGraw K4TAX wrote:
> As a rule ALC is not needed and is not recommended by Elecraft. The K3 
> power management system with the internal ALC is far superior to the 
> derived voltage from most all amps.   And, unlike many radios which when 
> operated with reduced power, they do have a propensity to overshoot, the 
> K3 series has firm ALC control at all power levels.
> 
> Just tune and load the amp for maximum output and then reduce drive 
> power from the K3 to attain the level of power you desire to operate. 
> And as a note, after tuning and loading to maximum output, do not 
> re-tweak the controls for or at the lower power operation.  This is a 
> common misunderstanding among hams.  If it is linear at 1500 watts, then 
> reducing drive, it will be linear at 500 watts.  If one re-tweaks at 
> lower power it most likely won't be linear at 1500 watts or any lesser 
> peak there of.  It will more likely be a "splatter generator".
> 
> 73
> 
> Bob, K4TAX
> 
> 
> On 12/21/2017 11:45 AM, Dave Cole (NK7Z) wrote:
>> I want to run ALC for my amp if for no other reason to protect the amp 
>> from overpower events.  I understand Elecraft does not recommend the 
>> use of ALC...
>>
>> Exactly why is that?
>>
> 
> 
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