No doubt in 1991 they were using bipolar transistors, which in some cases could hit a "magic" combination that resulted in better than average performance. These days everyone uses MOSFETs, which are consistently in the -30 dBc range on at least one band. The K3S with the latest updates averages about -35 dBc at 100 W (see ARRL review).
Wayne N6KR On Oct 15, 2016, at 8:05 AM, Kevin <ksto...@ac0h.net> wrote: > Yaesu's secret was the ARRL. Unless things have changed they test at one > frequency and assume the other bands produce the same results. > > I'll reverse the question, what has Yaesu done to rigs since 1991 that they > can't reproduce those numbers? > > > On 10/14/2016 10:03 PM, Dave Hachadorian wrote: >> Yaesu FT-990, 12V finals >> 3rd order TX IMD -38dB >> ARRL Review 11/91 >> >> ARRL heaped glowing praise upon this rig way back in 1991 for its >> Tx IMD performance. So, what was Yaesu's secret, and why haven't >> manufacturers figured it out and capitalized on it ever since? >> >> Dave Hachadorian, K6LL >> Yuma, Arizona >> >> >> -----Original Message----- From: Kevin >> Sent: Friday, October 14, 2016 5:14 PM >> To: firstname.lastname@example.org >> Subject: Re: [Elecraft] K3S QST Article >> >> The cause for this is the use of 12V finals. It would be much >> improved >> by moving to 24 or 50V finals. >> >> Move the /K3s II/ to 50V finals, say a pair of MRF 150's, limited >> to 150 >> or 200W max output. Design/Sell an outboard 50V switching supply >> capable >> of 15-20A continuous current, with a 10A 12V switcher built in >> for the >> rest of the radio. >> >> >> On 10/14/2016 1:33 PM, Bill Leonard N0CU wrote: >>> I would not expect the synthesizer (old or new) to be a >>> contributor the IMD >>> issue. Hopefully someone will correct me if that is a bad >>> assumption. To me, >>> the primary issue appears to be the linearity of the two RF >>> power >>> amplifiers. >>> >>> >> > > -- > R. Kevin Stover > AC0H > ARRL > FISTS #11993 > SKCC #215 > NAQCC #3441 > > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > ______________________________________________________________ > 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 n...@elecraft.com ______________________________________________________________ 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