[Elecraft] ext ALC problem

[Don Wilhelm]

Howard,

You are correct, with nothing connected to  the K3 EXT ALC connection, 
there should be no power reduction for the K3.  Yes, you should contact 
k3support at elecraft.com to see if it can be tracked down and corrected.

I am sorry that we initially misinterpreted your email to the reflector.

73,
Don W3FPR

Howard K2HK wrote:
> Don,
>
> The output of the K3 decreases regardless of whether it is attached to amp or not when ALC is turned on. At this point I believe the problem to be in the area of the digital I/O board. If (when) I decide to use the external ALC I will check it out. 
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> Howard
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> HK
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> From: w3fpr at embarqmail.com
> Howard,
>
> It sounds like the ALC voltage coming out of your amplifier is much 
> greater than the K3 ALC input range.
>
> The ALC voltage from your amplifier is reducing the K3 power output. I 
> believe the problem is with the amplifier, not the K3.
>
> Remove the ALC connection to your amplifier, then using the K3 power 
> control, slowly increase the drive to your amplifier while measuring the 
> voltage being developed at the amplifier's ALC output. It should be 
> zero or very close to zero until the amplifier comes near its power 
> limit. If the voltage at the amplifier is in excess of the ALC 
> threshold you have set on the K3, then the K3 will reduce power.
>
> In other words, if you want to set the K3 ALC Threshold at -4 volts, 
> adjust the amplifier's ALC circuits to produce -4 volts when the 
> amplifier's power limit is reached.
>
> As others have pointed out, attempting to use the amp's ALC output to 
> control the power output of the K3 is bad practice and is likely to 
> produce distorted signals and splatter.
>
> 73,
> Don W3FPR
>
> Howard K2HK wrote:
> I am having a problem with the external ALC. I am trying a new amp that requires ALC feedback. When I set it in the config menu regardless of the value -2 to -8 my output is reduced to 60 watts. As I raise the drive it increases until about 60 watts then cuts back. In the tune position which I have set for 15 watts I get only 1-2 watts out. This occurs regardless of whether I am connected to the amplifier or not. The SWR is between 1.2and 1.5. I do have the mod installed.
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