Scott, I don’t know if this helps much but several of the locals have constructed BLF-188 amps (singles and pairs) in the past two years. The W7, Israeli and Russian boards were used and they all suffered the same fate in various degrees. They would cease being very linear at about 75% of their CW output. Careful selection of bias and feedback levels would allow some improvement but in none of the cases were the devices even close to acceptable IMD wise at their data sheet output levels. The only one that am aware of that worked well was a W8 friend who is driving it (EB-104 water cooled Russian amplifier) with an Anan and used Pure Signal to effectively clean it up. On all of the others when the output came up to the target level you could immediately start seeing them in the opposite sideband.
All of the data sheets that we saw at the time talked about CW/FM applications and none provided specs for SSB linear service. These have been my observations of the BLF-188 amps. Very 73 - Mike - K9JRI > On Jun 9, 2018, at 9:08 PM, K9MA <k...@sdellington.us> wrote: > > I did look at the K3 output, and it's much, much better than the KPA1500 > output. I also checked that the KPA1500 supply voltage was not dropping > much: 53 V in standby, 52 V at 1500 W. > > 73, > Scott K9MA > > ---------- > > Scott Ellington > > --- via iPad > >> On Jun 9, 2018, at 7:26 PM, Wes Stewart <wes_n...@triconet.org> wrote: >> >> I don't have a KPA1500 or enough power attenuators to test my KPA500, but I >> have spent many dozens of hours looking at TX IMD on my two K3s. >> >> I will simply say, if you haven't already, check the IMD of the bare K3 >> before blaming the KPA1500. Garbage in, garbage out. That of course doesn't >> pardon the KPA for dropping gain. >> >> Wes N7WS >> >> >>> On 6/9/2018 2:21 PM, K9MA wrote: >>> I recently ran a two-tone test and measured CW power gain. (SN1078) It >>> doesn't look good. The two-tone waveform shows distinct "flat-topping", >>> and the power gain drops 25 percent from 1000 to 1500 Watts. My old 3-500Z >>> amplifier is much better. Has anyone measured IMD or linearity, or seen >>> any test results? >>> >>> While I'm primarily a CW operator, I'd be very reluctant to use the >>> amplifier on SSB. >>> >>> 73, >>> >>> Scott K9MA >>> >> >> ______________________________________________________________ >> 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 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 k9...@mac.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
