Craig Smith wrote: >I certainly understand the impracticality in terms of cost and size of >designing the basic KAT500 with a large number of output ports. My >personal wish is that an optional external Elecraft unit will >eventually be available that will allow for port expansion based on the >user's desire for number and configuration. It should be waterproof >(or easily made so) and controlled by the same bus as the external KAT500. >
"Waterproof (or easily made so)" is very important because the optimum location for an ATU is remote from the shack, as close as possible to the antenna(s) so that the main feedline is operated at low SWR. Waterproofing requirements vary hugely around the world, and any design errors will have very expensive consequences, so a designer in California shouldn't even try to guess what is needed in Scotland, for example :-). On the other hand, customers in Arizona shouldn't have to pay for heavy-duty waterproofing that they don't need. Please let us hope that one version of the KAT500 will be a bare board-level module that users can package to meet their own environmental requirements. If anything goes wrong, I'd much rather blame myself than blame Elecraft. Returning to antenna switching, most stations will also have a number of antennas that don't need an ATU. These users may be content with only two switched outputs on the KAT500 itself, and instead will want to use a normal 50-ohm remote switch *ahead* of the KAT500. But look where this discussion is headed... the more antenna switching possibilities we envision, the less realistic it becomes for the KAT500 to meet them all. However, there is a half-way solution which could be implemented at relatively low cost. That is to provide a number of open-collector relay drivers within the KAT500, remotely configurable through the control bus. These relay outputs could then be used to create custom antenna switching arrangements outside of the KAT500. When the KAT500 is commanded to energize one of its external relay ports, it would know that a different antenna is being connected to the output of the tuner, and could then switch to a different bank of stored settings. This system would greatly expand the flexibility of the KAT500 at very little hardware cost (no RF-rated parts required, only an addressable relay driver array and a pin header; all the rest is done in firmware and the configuration utility). It would also be completely transparent to anyone who didn't want to use it - they wouldn't even know it was there. The key to making this work is to incorporate the external relay drivers *within* the KAT500 control system. Independent external switching wouldn't work because the KAT500 wouldn't be aware of it, and would be continually forced to retune. -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek ______________________________________________________________ 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
