I have long wondered why some manufacture did not think of it. That is a amp with built in 12 VDC boost PS. With all of the new switching tech, it should be a KISS solution and make the amp SOUND GREAT all of the time.... Just my opinion hi. Mel, K6KBE
From: Bill Frantz <fra...@pwpconsult.com> To: elecraft@mailman.qth.net Sent: Monday, February 20, 2017 2:08 PM Subject: [Elecraft] Boost power supplies for RF amps The short answer is they can. It is only a matter of engineering time, cost, resulting price, number of customers and competing projects. In other words, the usual business considerations. Lets work the idea through for several of the Elecraft RF amplifiers: The 10-15W K3(s) amp: This amp can have significant IMD at low voltages as we have discovered with our QRP, all Elecraft, field day operation. The KX3 seems to do better, so reengineering the amp may be a better solution. For field day, we try to have fresh batteries available. The 100W K3(s) internal amp: This amp also has low voltage IMD as we found during our 100W California QSO party expeditions. But, consider the K3(s)'s construction. The front of the radio is the digital portion, including the DSPs and the front panel computer. All of this digital noise is isolated from the analog circuits in the back of the radio. If Elecraft were to include a boost power supply with the internal amp, that high-current switcher would be in the analog section, and probably impossible to quiet. Solution: Get an external boost power supply. The KXPA100 external amp: This form factor would be an ideal place to include a boost power supply. The use profile includes portable battery operation and designing isolation for the power supply into the package seems straight forward. The KPA500 external amp: The amp setup procedure sets the voltage to to 65v to 85v and the specifications call for about 1000 VA of power or about 13A at 75v. That would be nearly 75A at 13.5 volts assuming 100% efficiency, so it would be a good idea to put the boost power supply next to the battery and run 75v to the amp. It would make a nice high power mobil rig. 73 Bill AE6JV In thread "Re: [Elecraft] Chinese ebay amps for KX3", on 2/20/17 at 5:47 AM, pin...@erols.com (Charlie T, K3ICH) wrote: >So now, tell me why a mid-sized radio can't have a built in 12 V to say, 50 >V converter to drive some HV FETs for cleaner output specs like the Yuge >radios. ----------------------------------------------------------------------- Bill Frantz |The nice thing about standards| Periwinkle (408)356-8506 |is there are so many to choose| 16345 Englewood Ave www.pwpconsult.com |from. - Andrew Tanenbaum | Los Gatos, CA 95032 ______________________________________________________________ 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 farrerfo...@yahoo.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