My shack consists of 20 transceivers. I think [!!] only 4 run directly on AC power. The rest run from 12 VDC. My power supplies range from 35A Astrons to "El Cheapo" switchers. In the past 8 years the only power supply failure I had was an Astron. Do not over buy George, W6GF
________________________________ From: Edward R Cole <kl...@acsalaska.net> To: Elecraft@mailman.qth.net Sent: Wednesday, April 17, 2013 10:19 AM Subject: Re: [Elecraft] K3 power supply recommendation Wes, As that may be (it depends on ambient air temp), most hams are not transmitting key-down for extended time. In the communication industry the duty-cycle for Tx to Rx time is assumed to be 10%. Most FM equipment is equipped with time out timers that stop continuous transmission after 3-minutes. Since I will assume you are not talking about FM or AM or digital modes like WSJT, the class of service is ICAS and not CCS. The Astron 35 will handle 25amps quite nicely. 25a x 13.8v = 345w. This is probably way above the typical 100w RF CW/SSB radio dc load. If the amplifier runs at 60% efficiency it will draw 167w (about 12amps). Add the load of the radio this probably is not more than 17amps. You can probably add a VHF radio sitting in Rx and still not exceed 25amps (and that is only drawn in transmit 10% of the time of use). If you run any of the modes that are CCS then adding some air cooling is not a bad idea. I have fans on my high power VHF and UHF amps to just have a bit more tolerance to heat. I do use them for FM somewhat, and also are used as drivers for WSJT-eme for the 8877 final. Duty-cycle of WSJT (JT65) is 50% (one minute cycles of key-down followed by one-minute receive). This is hard-duty on ham equipment so lower the RF power if you run these. I run 55-60w on my 150w amp to drive the 8877 to 1300-1400w. My station Astron 50M is fused at the distribution panel for 30A so never exceeds this in any mode. I have a lot of equipment running at the same time. 73, Ed - KL7UW From: "Eugene Balinski" <euge...@nni.com> To: Wes Stewart <n...@yahoo.com>,elecraft@mailman.qth.net, garyk...@wi.rr.com Subject: Re: [Elecraft] K3 power supply recommendations Message-ID: <web-493727...@admin.nni.com> Content-Type: text/plain; charset="ISO-8859-1" Another vote for the RM-35. I have had mine for over 30 years. Not an issue. Note however that Astron over specs their power supplies. They claim that the RS-35 will do 25A continuous. It will not. It gets too darn hot. Given the heatsink, it should do about 20 continuous. This is with static air cooling, no forced air. ______________________________________________________________ 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 ______________________________________________________________ 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
