Another issue not explicitly mentioned is using an external antenna switch with different conjugate matches already trained withing the KPA1500 ATU. Those different matches mean when one selects a "new" (different) antenna than already selected on a particular frequency (same band or not), the KPA1500 doesn't know this fact until power is applied. Then, due to a high VSWR, the amplifier faults.
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. As alluded to in previous messages on this topic, perhaps the solution, unfortunately, is an external box that could contain the appropriate data so that, when a new frequency/antenna combination, that has a previously tuning solution, is selected, the external box will tell both the KPA1500 ATU to select the appropriate solution and transceiver to make appropriate power level adjustments, both PRIOR to actually transmitting. This is done (approximately, but with no power level changes) by the KAT500 in selecting one of the three antenna ports and the appropriate tuning solution. This assumes no other antenna choices on each of the three ports for the same frequency. The KPA1500/K3S combination is (currently) not sufficiently "smart" to accomplish this. Of course, if we had "perfect" antennas that provided resonant matches on all bands/frequencies, we wouldn't be discussing this. If we had those, we wouldn't need the KPA1500 ATU either. 73, Bill, K8TE -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
