"With just two antenna ports on the KPA1500, there are only two quickly 
accessible tuning solutions per frequency if using both ports. If using only 
one port and an external antenna switch, a common choice in many stations, 
finding the correct tuning solutions can't be done fast enough to prevent a 
fault."

The KAT500 remembers the most recent 6 tuning solutions for each frequency 
"bin".  The saved solution includes the antenna port in use when that solution 
was stored.  I would guess that the tuner in KPA1500 does the same thing.  This 
means that the tuner already has enough non volatile memory allocated to cope 
with more than one antenna on each port.  The problem would be letting the 
tuner know which antenna is in use on the current port before RF is applied.

If the tuner had the option to tag each tuning solution with antenna port and 
also external antenna selection, then up to 6 switched antennas could be 
accommodated on 1 port with little, or no, increase in NVM overhead.   If the 
external antenna switch provided a position signal then that signal could be 
provided to the tuner by a new serial command or AUX bus command, or by 
extension of the existing antenna selection commands.

There would be lots of details to sort out and I suspect it would be easier to 
store the multiple tuning solutions for different externally selected antennas 
in a separate controller.  The idea is the same though - if the system knows 
what what port is in use, and it knows what antenna has been selected on that 
port, then it can instantly recall and apply the last remembered tuning 
solution for that switching combination for the current TX frequency.

Andy, k3wyc




















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