. right Glen! That's the reason why advanced SDR technologies use ,envelope tracking' for best efficiency.
73, Helmut, DC6NY Von: Glen English [mailto:[email protected]] Gesendet: Freitag, 19. Juni 2020 02:18 An: [email protected] Betreff: Re: [Freetel-codec2] FreeDV Tx power the bias doesnt change, but any PA pushed into its supply rails generally operates at maximum efficiency . this is because there is no potential between the supply rail and the active device. in undersaturated, quasi linear conditions , there is the additional dissipation because the supply voltage exceeds the output voltage. On 19/06/2020 10:02, Al Beard wrote: Hi guys, I've never seen any ham rigs, HF or VHF with the bias changed depending on modes. Not one. FT620, FT-221, FT897D FT-450, IC-910H and I've looked at the circuits of many others: FT-200, TS-520, TS-820 and commercials, Codan, Crammond and Racal. Alan VK2ZIW On Fri, 19 Jun 2020 08:54:17 +0930, Mark Jessop wrote > Heat issues might be the case for 'shack in a box' rigs like IC-7100s, FT-857s etc... > > However, rigs like the IC-7300, IC-7610 will quite happily sit there putting out 100W of FSK (e.g. FT8) pretty much continuously. It helps that they have decent cooling. Since I'm feeding in that FSK signal via an audio input, the amp isn't biased differently... > > Can't really speak for Yaesu rigs, as I don't own any. > -- Diese E-Mail wurde von AVG auf Viren geprüft. http://www.avg.com
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