K3/KAT500/KPA500 integration question

[ANDY DURBIN]

Assume a  K3(S), KAT500, and KPA500 are all interconnected with cables to provide the maximum level of system integration.

Initial condition - KPA500 STBY, K3(s) transmitting key down 100 W RF output.  Now select OPER on KPA500.  What happens?

Is selection of OPER inhibited?  Does KAT500 open the key line or was it already open?  Is K3(s) power automatically reduced and, if so, does it happen fast enough to prevent KPA500 faulting?

My TS-590 / Elecraft interface handles this situation but I think I can improve how it does it.  Looking for the Elecraft baseline in the hope I can at least equal it.

Thanks and 73,
Andy, k3wyc


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[Elecraft mailing list]

Andy;

Here is what happens. Again, K3, KPA500 and KAT500. All are connected using AUX cables as described in the KPA500 and KAT500 manuals. KPA500 is STBY, and KPA500 NOT in any fault condition. K3 is transmitting at 100 watts, user taps the Operate button on the KPA500.

The KPA500 decodes the button, then if RADIO is set to K3, it sends an auxbus message to the K3 indicating it is transitioning to OP mode. When the transmission of the message is complete, it then proceeds into Operate mode  where it can process PTT input levels. The K3 will decode the auxbus message and set up to operate with the KPA.The KAT500 does not listen to KPA500 auxbus traffic; it does nothing (unless it see high SWR, of course).

If RADIO is set to BCD (or something other than K3), then the auxbus message does not apply, and the KPA500 will immediately transition to Operate mode.

When placed in operate mode the KPA500 is allowed to process PTT levels. Continuing your scenario, the KPA will then start sequencing the internal controls to switch to full transmit. This is a process that takes several milliseconds to complete (I’ll stop short of saying how many) and puts us in full transmit at the end of the sequence. I would expect that the K3 would have the time needed to drop its power to the requested level and we would keep going. This, of course assumes the K3 is set for Power per Band as described in the K3 manual.

The KAT500 will not open the key line unless it sees high reflected power and needs to do something about it.

I will have to test this to see exactly what happens, whether the KPA will fault or not. It is possible that the K3 processes the command quickly enough to drop power and things just keep going. My experience has been that Wayne is _really_ good at getting high performance out of the K3’s processor.

I would not suggest trying this if at all possible. The stress the high power places on the input network will eventually cause damage to those components. While I enjoy visiting my friends in Watsonville, I don’t like bringing my radios down for them to be repaired (and thus not having their use)...

And, Andy, I haven’t forgotten your other questions, I’ll get to them as soon as I can.

73!
Jack, W6FB

> On May 30, 2019, at 7:29 AM, Andy Durbin <[hidden email]> wrote:
>
> Assume a  K3(S), KAT500, and KPA500 are all interconnected with cables to provide the maximum level of system integration.
>
> Initial condition - KPA500 STBY, K3(s) transmitting key down 100 W RF output.  Now select OPER on KPA500.  What happens?
>
> Is selection of OPER inhibited?  Does KAT500 open the key line or was it already open?  Is K3(s) power automatically reduced and, if so, does it happen fast enough to prevent KPA500 faulting?
>
> My TS-590 / Elecraft interface handles this situation but I think I can improve how it does it.  Looking for the Elecraft baseline in the hope I can at least equal it.
>
> Thanks and 73,
> Andy, k3wyc
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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[ANDY DURBIN]

Jack,

That for taking the time for your detailed reply.   It seems there is some risk that a fully integrated K3, KAT500, and KPA500 could experience a power spike for the scenario I proposed.

Up to this morning I had been opening the KAT500 key line anytime my TS-590 was set to 40 W or more regardless of KPA500 mode.  This is the pro-active overdrive protection I had previously told you about.  With that implementation I saw a 600 W power spike when I selected OPER during an FT8 transmission with 37 W set for STBY but 8 W set as OPER band power.   My setting of OPER band power will be much slower than the K3 response to the Aux bus signal.

This morning I changed my controller code so KAT500 key line is always open when KPA500 is STBY.  When I see KPA500 change to OPER I wait a second to allow OPER band power to be set and then enable the KAT500 key line.   This greatly reduces the risk of a power spike at the STBY to OPER transition.  Here is the diagnostic output for the transition 37 W STBY to 8 W OPER:

 2:39:22.997  New KPA_mode  - ^OS1;
 2:39:22.998  STBY_OPER_time set
 2:39:23.145  Sending PC008; to Kenwood
 2:39:23.388  New PC - PC008;
 2:39:23.999  power_prot_limit=40
 2:39:24.000  Power protection cleared
 2:39:24.001  KEN power verified
 2:39:24.003  Sending AMPI0; to KAT500
 2:39:24.062  New AMPI  - AMPI0;

My power management code is not all that complex but it has taken a while to understand and accommodate the various "corner cases".     Your willingness to share your insights has been helpful.

73,
Andy, k3wyc




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