Hi Wayne
" We're mindful of the negative > impact ALC can have on > transmit signal purity, a subject of recent debate > within testing > organizations." Is it then safe to assume that the issue of ALC overshoot and ALC induced wideband IMD has been addressed in the K3's design? I was also wondering about the transmit IMD performance data of the K3/10. I can find no official IMD data for the RD16HHF MOSFET. Although i do believe at low power outputs the IMD performance is indeed good. Have you made any 2 tone measurements at various power level settings for the K3? Craig VK3HE --- wayne burdick <[EMAIL PROTECTED]> wrote: > Hi Enno, > > Transmit power control via the ALC input (AUX I/O > pin 15) is planned, > but not finalized. We're mindful of the negative > impact ALC can have on > transmit signal purity, a subject of recent debate > within testing > organizations. > > External amplifiers vary widely in their loop gain, > causing problems > with distortion. Many amplifiers, like the Alpha > 87a, specifically say > not to use external ALC. A properly operating, > internally ALC > controlled rig like the K3 does not need external > ALC input to connect > to an external amp. In general, external ALC should > -not- be used as a > way to control rig power. > > As for the voltage range, this is not a typo: the > ALC input handles 0 > to +5 V. Once ALC is working to our satisfaction, > we'll provide simple > interfacing information that will allow the use of > negative control > voltages (probably a resistive divider pulled up to > a positive supply, > or at most an op-amp circuit). > > Meanwhile, the K3's DSP-based early-stage ALC is > very effective at > preventing amplifier overdrive, and should suffice > in nearly all cases. > > 73, > Wayne > N6KR > > > Scanning through the manual I saw that the ALC > voltage to be applied > > on pin > > 15 of the ACC connector needs to be in the 0 - +5V > range. This worries > > me a > > bit because many (if not virtually all) linear > amps output a NEGATIVE > > ALC voltage for > > feedback to the transceiver. > > > > Is the +5V maybe a typo (i.e. should it be -5V) ?? > > > > -- Enno, PF5X > > > --- > > http://www.elecraft.com > > _______________________________________________ > Elecraft mailing list > Post to: [email protected] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > ____________________________________________________________________________________ Looking for a deal? Find great prices on flights and hotels with Yahoo! FareChase. http://farechase.yahoo.com/ _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
