Jim, The marine divisions of Kenwood, et.al. already have low cost, low voltage, PA solutions with better IMD specs, primarily due to channel spacing for the marine band.
Jim W6AIM -----Original Message----- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Jim Brown Sent: Thursday, October 29, 2015 11:58 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] IMD and supply voltage On Thu,10/29/2015 12:06 PM, frank wrote: > Also, you did not answer my questions. Maybe I should ask them one at a time. I thought Wayne answered them quite well, but I'll try to rephrase his answers in terms that are easier to understand. 1) Contemporary ham rigs are designed to operate from automotive DC voltages as a matter of convenience. 2) The output transistors used in these rigs produce less distortion at higher supply voltages. 3) Most rigs are optimized for 13.8 - 14 VDC, and are tested at that level by ARRL. 4) Most commercial power supplies marketed to hams are regulated to 13.8 - 14.5 VDC, and that voltage is internally adjustable. 5) Most rigs will work at lower DC power supply voltages. 6) When operated at lower DC power supply voltage, their distortion will increase. 7) When operated above their design output power, distortion will increase. 8) Doing both 6 and 7 will increase distortion even more. 9) Distortion in the K3 and K3S output stage is specified for full power output at 13.8 - 14 VDC, and distortion is greatly reduced when run at lower power levels. My own comments: Distortion causes the most QRM when running high power. Many of the best power amps reach full power with drive power in the range of 50-60 W -- the KPA500 needs about 28W, my Titans (I have three) need between 40-60W, depending on condition of the tubes and the operating frequency. An ACOM 1010 needs between 50 and 70 watts, again depending on the operating frequency. > This is state of the art? How much do you want to pay for "state of the art?" How about the infamous pentagon $800 hammer? According to ARRL measurements, the K3 produces the cleanest CW signal of any current rig. See my summary of their published data in the following link k9yc.com/TXNoise.pdf See my measurements of my K3 and several other rigs in this link http://k9yc.com/P3_Spectrum_Measurements.pdf 73, Jim K9YC ______________________________________________________________ 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 jbol...@outlook.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
