[Elecraft] KAT500 investigation results (WAS KPA-1500 issues)

[ANDY DURBIN]

"As far as calculating bin size, I suspect that K3WYC’s solution of sending FA; response frequencies into the KAT500’s serial port might actually yield a better solution since those frequencies can have 1KHz (or better) resolution. In this case the relays should switch very close to the actual boundary instead of at 8KHz boundaries. What I don’t know is if the KAT500 uses RF counted frequency for its bin determination or if it can use the externally reported frequency. I suspect it is the former."

Not quite how I implemented the frequency interface.  What I do is use the values of IF, FA , and FB to determine the frequency my TS-590 would transmit on if it went into TX at that instant.  This calculation to done each time I get a new value of IF, or FA, or FB.   I send that frequency value to the KAT500 using the F command but I only send it if the calculated transmit frequency differs from the KAT500 last observed frequency by more than 8 kHz.   Sending the raw FA value to the KAT500 is not a useful solution for several reasons - The TS-590 may not be using VFO A for RX or TX;  if the TS-590 is using VFO A then FA alone is not enough information to know if A is the TX or RX VFO for split;  Even if A is the TX VFO, FA does not include XIT offset; FA is not meaningful for memory channel operation; etc. )

The KAT500 follows the TX frequency I send it and sets the proper tuning solution for that frequency with no RF transmission required.   The only issue with my implementation is that RF detection can override the frequency I provided and move it to an adjacent, incorrect or less accurate, value.  The fact that the last observed frequency is changed by RF does not necessarily  mean a new tuning solution will be selected.  That depends on how the 8 kHz increments of last observed frequency overlay the tuning segment boundaries (and other factors that are likely Elecraft proprietary).

73,
Andy k3wyc