Also note that the Astron 20A rating is actually the ICS or "Intermittent Commercial Service" rating. OTs recognize this as the former ICAS rating when "Amateur" was included in the designation.
IIRC, ICS is based on five minutes at full current and five minutes on standby. Running SSB, CW and *some* digital modes, the actual load is much, much less. SSB, for example, draws peak current only on voice peaks and, of course, CW draws peak current only so long as the key is closed. Now, hammering out a digital mode such as RTTY at 100% power for long transmission is a different story - and often well beyond the capabilities of the transmitter anyway. Airflow and environment are important too. In commercial repeater service we seldom crowded the specs, especially when the system was in a building full of repeater gear where the temps around the power supply might exceed 100F in spite of air conditioning. Even so, dozens of Astrons ran year after year without a hitch. I cannot recall finding one dead. And then there's the Ham station I saw one time where the power supply was sitting on the floor - directly on top of a heating vent! I've been running the home station from an Astron 20 for about 10 years now - a K2/100 and then the K3/100. It handles either rig to full output with current to spare. I am a 99.9% brass pounder. Ron AC7AC -----Original Message----- Another example of "reading the manual" or in this case the "info sheet". I have run Basecom20 for a 50w VHF-FM radio for up to ten years onboard 200-foot oil field work boats. I did have one "croak" but that might have been due to the highly regulated (joke) ships generator: 115vac +/- 50vac! Ten years in continuous duty is not bad. These look to be re-labeled Astron RS-20 PS and have been supplying multiple radios on a boats. 250w => 18 amps. A 150w marine SSB will have a dc load of about 250w. I use a 50A Tait PS (14.1 vdc) to power my home station 12volt needs. The No. 6 welding wire supply line is fused at 30A at the radio table distribution point. Been in service for about 9 years. This is a re-labeled Astron VM-50. So, yes, I derate them about 60% for long-term service. Ed - KL7UW At 06:16 AM 7/3/2011, Eugene Balinski wrote: >All, > > Please be advised that Astron supplies are generally >over rated. The RS-20 is rated at 20A peak and 16A >continuous. It is more like 12 -14 continuous. I have >seen people try to use them at their "continuous" ratings, >only to have them fail. The heat sinking is just not >there. Be careful when using any of the supplies at their >top ratings. If you need to use one at rated, then put a >good fan on the heat sink. > > >73 >K1NR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
