Re: ext ALC problem

Posted by Don Wilhelm-4 on
URL: http://elecraft.85.s1.nabble.com/ext-ALC-problem-tp2989650p2991848.html

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
[hidden email] 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.
>
>  
>
> Howard
>
>  
>
> HK
>
>  
>
>  
>
>
> From: [hidden email]
> 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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