[Elecraft] KAT-500 + KPA-500 / SWR Thresholds

[Jeff Wandling]

W7BRS> comments in-line below.



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73, Jeff  W7BRS
https://blog.w7brs.com



On Monday, January 1st, 2024 at 1:21 PM, Andy Durbin <a.durbin at msn.com> wrote:


> "Actual Results: The ATU-500 clicks between Bypass and MAN (by "clicks", I mean only what I can infer from the behavior -- it is as if the ATU-500 is either using the memory-based ATU settings of the previously tuned settings and switching between that and what seems like a Bypass mode) -- the clicking is rapid and persistent at the onset of the CW message."
> 
> How does your KAT500 know what frequency to use? Does it have a serial data interface or does it depend only on the internal RF counter?
> 

W7BRS>  AUX cable between K3 to KAT-500 and KAT-500 to KPA-500.  They are in serial communication per Elecraft protcol(s), whatever those are.

> What KAT500 mode (AUTO, MAN, BYP) is selected when you observe this anomaly?

W7BRS> Per manual for KAT-500/KPA-500 the stated "nominal" mode is MAN.  So I leave the KAT-500 in MAN *after* tuning the antenna to 1.1.

> 
> I ask these questions because I doubt the problem has anything to do with SWR thresholds.
> 

W7BRS> Interesting. I am only guessing that the excessive clicking in the KAT-500 was the KAT-500 going in/out of BYPASS.  (This isn't the clicking associated with the Tune-search for L/C.  It's a different kind of click.   I don't know how else to describe it other than a single kind of click as if it was a single relay in operation in the KAT-500 -- that same kind of 'click' sound that would occur if you switched between MAN and BYPASS on the KAT-500. Same sound.  But that's not definitive enough I suppose.  I don't have any Serial Log data from the Utility to base that guess.

W7BRS> Thanks for the questions.  I've got a few other replies to sort through with other suggestions:

1.  Try dummy load vs. real antenna
2.  Carefully listen if clicks are syncopated with CW (they aren't but I can listen again to make sure).
3.  RF/RFI - Not likely except that Serial AUX cable might be picking up some RF.. I could attach some ferrite cores around it to rule out.  Otherwise the shack is weighted down with ferrite in all the right places -- Everywhere. /hi/

W7BRS> Thanks again for the questions, very good.

> Andy, k3wyc
> 
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