I meant to point out another fact about the way the K4 handles power control. In addition to the usual ALC and our very clean CESSB-based compression, the K4 limits maximum drive in AF modes (audio-derived data and voice). This limit is calculated on a per-band basis, ensuring an upper bound on PA RF compression. The result is that it's very difficult to cause overdrive and splatter with a K4, even if you try to do it intentionally.
Wayne > On Jun 28, 2022, at 9:18 PM, Wayne Burdick <n...@elecraft.com> wrote: > > Like everyone else, we switched to 12 V VHF MOSFETs for our 10 and 100 watt > PAs. At the recommended supply voltage (~14 V), IMD for these transistors is > about the same as for bipolars, with 3rd order products averaging -35 to -40 > dBc and worst-case about -30 dB. These stats are borne out by an average of > QST review numbers going back over the last 30 years. > > It is true that at lower supply voltages, bipolars "gracefully degrade" with > more grace than MOSFETs. So if IMD is of primary concern when using lower > voltages, you may choose to reduce power somewhat. (Of course this is a > useful practice when running from batteries.) > > Reducing power while maintaining communications effectiveness recently became > a whole lot easier on the K4 with the addition of CESSB. In our tests, > average power went up by over 6 dB between settings of CMP=0 and CMP=30. > > 73, > Wayne > N6KR > > > >> On Jun 28, 2022, at 7:08 PM, jerry <je...@tr2.com> wrote: >> >> On 2022-06-27 15:23, Dynolab wrote: >> >>> Since the semi manufactures stopped making Bipolar RF Power transistors in >>> the middle of the last decade, most Ham HF transceiver manufactures were >>> forced into using ... 12 Volt MOSFETs in their finals. > > > ______________________________________________________________ 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
