I've experienced some of these same issues with my KPA-1500. In addition, sometimes the amp will switch to stand-by for no apparent reason, on 6 meters the AT won't tune a 1.7 to 1 SWR under 1.5 to 1, and one of the exhaust fans got a good deal noisier after about 25 hours of operation. My amp is back at Elecraft for service as I write. 73, Dick- K9OM
On Mon, Nov 26, 2018 at 5:15 PM K9MA <k...@sdellington.us> wrote: > This was my first serious contest effort with the new amplifier. It is > paired with a K3. It survived about 24 hours of operation, though it > faulted a few times, as described below. Clearly, the protection > circuitry did its job. Firmware is 1.87. > > A couple glitches: > > The power gain drifts downward as the transistors heat up. If I start > out at 1500 W, it will drift down to about 1100, without changing > frequency or SWR. Conversely, if I turn the drive up after the amp is > warm, and forget to turn it back down, the amp will fault when cold. > Since the amp is talking to the K3, couldn't some clever software fix this? > > Despite setting tune power to 40 W, the ATU sometimes just won't get the > SWR below 1.4:1 or so. This is with antennas below 2:1, and the ATU stop > set to 1.0. This happens on 40 meters, so it's probably not an ATU L/C > resolution limit. This 1.4:1 SWR is sometimes high enough to limit > output to well below 1500 W due to high drive power or high current. I > have not yet tried manually tuning the ATU to see if I can get the SWR > lower. > > Finally, after "training" the ATU across the band, I sometimes find that > the SWR has gone up significantly at some frequencies. I don't believe > this is due to changing antenna SWR. It seems more like the ATU has > "forgotten" the settings, or tried to retune itself without permission. > (HiSWR RETUNE OFF) > > Has anyone else seen similar issues? > > 73, > > Scott K9MA > > -- > Scott K9MA > > k...@sdellington.us ______________________________________________________________ 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
