Just a little public service announcement that the Elecraft KAT500/KPA500 PowerCombo is only partially compatible with modern Kenwood radios. To whit… the PowerCombo works with VFO A, but not VFO B.
Most modern rigs come with dual VFO’s, of course. And many come with outright dual receivers. This ability to quickly monitor and move between bands/frequencies comes in handy in a variety of scenarios. And most of us happily bounce between these dual VFO’s without attaching any particular importance to one over the other. The problem lies with the KAT500, which reliably tracks VFO A… but which cannot track VFO B. The upshot being that if you’re operating VFO A, the KAT500/KPA500 PowerCombo will work as expected. But as soon as you toggle over to VFO B the KAT500 will manifest with clacking relays with every Tx on/off transition and the KPA500 will instantly fault with High Reflected Power if it is brought online in SWR conditions that required a tuned solution from the KAT500. Said differently, if you’re operating in conditions where native, un-tuned SWR is low – where you don’t need the KAT500, in other words - the KPA500 works perfectly. But as soon as you move to a frequency with a moderate-or-higher SWR – a situation where you need the KAT500 to insert its tuned solution – it cannot do so, and the KPA500 faults. The behavior is independent of the best practices usually espoused for the KAT500… always operate in ‘Manual,’ “train the tuner” to lock in inductor/capacitor settings in advance, and do that pre-tuning with 25-watts or more for greater accuracy. This VFO B problem applies to the Kenwood TS-590SG, TS-890S, TS-990S, and perhaps others. On their own, the KAT500/KPA500 PowerCombo are a remarkable addition to any shack. Profound is the word I’ve often used to describe their impact. However, the inability to use VFO B in conjunction with them is a pretty major failing. I have no information one way or the other, but I suspect the KPA1500 also suffers from this issue. Probably the thing that surprises me most is that this issue has apparently existed for years… and yet has not been socialized anywhere that I’m aware of. Neither the Kenwood TS-890S User Manual nor the Kenwood TS-890S In-Depth Manual make mention that their VFO’s A and B implement slightly different character streams. Elecraft’s KAT500 Automatic Antenna Tuner Owner’s Manual doesn’t mention that interfacing with Kenwood radios is a problem. Fred Cady, KE7X (RIP), doesn’t mention it in his KPA500 Amplifier and KAT500 Tuner manual. And it doesn’t appear to have made its way into any knowledgebase within Elecraft itself. One wonders how many hours have been spent by Elecraft staff and Elecraft customers – and how many KAT500 and KPA500’s have been shipped back for repair – because of this one issue. And that’s why I’m posting it here. I’d like to thank Bob and Dick from Elecraft for their prompt, professional, and thoughtful assistance in helping me to look at the anomalous behavior I’ve always seen, but never could quite pin down, with my KAT500/KPA500. And I’d especially like to thank Andy Durbin, K3WYC, for finally illuminating what was actually going on. Andy submitted a defect report last fall and hopefully Elecraft will prioritize it at some point. In the meantime, if you’re running a Kenwood rig and are contemplating adding the KAT500/KPA500 PowerCombo… be aware that there are issues. 73, Jeff K4EI ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
