[Elecraft] KPA1500 / K3 Mystery

[Fred Jensen]

I'll second Jack's observation Bruce.  "Most" of the time, the K3 
switches power levels properly ... but, the key lies in Jack's 
description of how it works.  The K3 gets notice of "events" from the 
KPA which treats the notices as "fire and forget."  The event causes the 
K3 to take some action(s) and go to some state.  It seems to be great at 
that. It also needs to remember that state [conceptually, "KPA in 
standby"] regardless of what goes on thereafter.  It seems there are 
things you can do after putting the KPA in off or standby that foul up 
this state memory.  With a background in aircraft systems for the 
military, the peripheral fire and forget mode is a non-starter for me.  
I just developed the habit of always checking the K3 PWR OUT setting 
before transmitting.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 10/20/2020 3:08 PM, Jack Brindle via Elecraft wrote:
> Bruce;
>
> Did you ever resolve the issue?
>
> The KPA500 and KPA1500 send events to the K3, not commands. The distinction is important - an event simply reports a state change in the amplifier. It is up to the K3 to decide what to do in response, if anything.
> Thus when tapping a and button the KPA simply sends an event indicate that the button had been tapped, the K3 receives that and decides to do a band switch (if needed).
> The fact that the K3 is indicating a response (in the VFO B display) says the K3 is indeed receiving the event properly. That means the KPA1500 is working properly, so the issue is in the K3.
>
> Since the K3 sets the correct power for the KPA OP mode, it should be expected the the K3 is also selecting the high power setting when the KPA indicates that it is in STBY mode. The is the same power level that would be used if the K3 is powered up with the KPA left turned off. From personal experience I have many times found the power not to be what I expected after some special operating activity, like Field Day where we run just 5 watts. Turning the Power knob usually fixes the problem quite nicely.
>
> 73!
> Jack, W6FB
> Elecraft Engineering
>