To be sure, your next test is to run the KPA500 into a dummy load and listen to yourself on another receiver.
This will help confirm if you have an equipment issue or an RFI issue. It is critical to start with a very basic setup and work your way up to more complicated. K3 and a hand mic into a dummy load. If that is ok, then add the KPA500, etc. Beyond that, you are can quickly be chasing your tail. After all that and you add an antenna, and you have the problem, you have to start dealing with common mode currents (aka RFI). Start install chokes (like Mix 41) on feedlines and powerlines. Both ends. At the antenna and at the radio. I read a document by the YCCC years ago and it became my bible on RF issues. The by product is that I started to hear more as I had less receiver noise as well. Let us know how you make out. Mike va3mw On Wed, Aug 1, 2018 at 10:03 PM, William C. Johnson via Elecraft < elecraft@mailman.qth.net> wrote: > Michael I also have the same problem. Worked on it with Elecraft Support > several times to no avail. > I have tried several different microphones, antennas, baluns. Still no > joy. I also use 18 watts drive, I had not thought of anything other than rf > feedback. I will play with different drive levels.In frustration I have > quit using the KPA-500. I hope you are on to something. > Bill J K7BRR Yuma > > Message: 2Date: Wed, 01 Aug 2018 10:19:04 -0400 > From: Michael Blake <k9...@mac.com> > To: Elecraft Mailing List <elecraft@mailman.qth.net> > Subject: [Elecraft] K3s+KPA500 SSB audio distortion > Message-ID: <312a3cd1-8c02-4b75-b39d-d93ecaf47...@mac.com> > Content-Type: text/plain; charset=utf-8 > > While on the air on 3710 SSB I receive audio reports that say my > transmitted audio is somewhat muffled or nasal. Making adjustments to mic > gain, compression levels, TX EQ seems to make no difference to this report. > These adjustments do change the sound of the audio but do not reduce the > reports of muffled or nasal characteristics. > > I normally run the KPA500 at 500 watts PEP output and the K3s is set to 18 > watts to achieve this output. > > This morning I suspected that this nasal sound might be related to running > the K3s at 18 watts as that uses both the 100 watt amplifier and the 12 > watt amplifier but in series at very low drive levels. As a test I cut off > the KPA500 and ran the K3s at 100 watts and the distortion was gone. As a > second test I dropped the drive to 11.9 watts which dropped off the 100 > watt amplifier module and runs the low power module at almost full power > and the audio was still clean with the KPA500 delivering about 300 watts > PEP. > > Is this something that anyone else has observed? Are there any built in > tests or adjustments that might help this issue? I have run the > transmitter gain calibration at all three power levels with satisfactory > results. > > Oh yes,?. The condition is the same using a dynamic mic (EV RE50), an > Electret Mic (MH4 & CM500) or mic audio from a USB connected computer (Blue > Yeti). > > Very 73 - Mike - K9JRI > > ______________________________________________________________ > 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 va...@portcredit.net ______________________________________________________________ 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
