I learned a lot about power supplies since I bought an Astron RM-35A. Rated for 35 amps intermittent and 25 continuous, this linear supply is heavy. They sell for over $300 and I got it at a bargain, $100. It’s very clean and the previous owner even added an analog current meter and digital voltmeter to the front panel.<\/p>\n\n\n\n
I noticed it was running at 14.4 volts. Although the radios connected to it weren’t complaining, I wasn’t comfortable running them with a high voltage long-term. I opened up the case and found the trimmer I needed, a 1k pot, R5. I gave it a tiny turn in one direction and the supply immediately shut off, sort of. It was only putting out 1 volt. I moved it back and nothing. I called the previous owner who referred me to repeater-builder.com as they have some excellent, very thorough write-ups on these very power supplies. It turns out that I had gone over the voltage limit and the power supply’s crowbar circuit kicked in. Thank God the current-limiting circuit was good as my transistors were not fried.<\/p>\n\n\n\n
I turned the pot back and it turned on but the voltage was very unstable and it shut off again. I turned the pot a few times back and forth and set it right about where I remembered it was to begin with. The supply came back to life and has been putting out a nice, steady 14.1 volts ever since. I can live with that.<\/p>\n\n\n\n
I added an external fan to the heat sink that runs on the same 14.1 volt output and my transistors are nice and cool. I plan to drill a hole to attach a ground strap but after that, I’ll just leave this bad boy alone and let it power my radios.<\/p>\n\n\n\n
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I learned a lot about power supplies since I bought an Astron RM-35A. Rated for 35 amps intermittent and 25 continuous, this linear supply is heavy. They sell for over $300 and I got it at a bargain, $100. It’s very clean and the previous owner even added an analog current meter and digital voltmeter…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-60","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/n0xmz.com\/blog\/wp-json\/wp\/v2\/posts\/60","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/n0xmz.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/n0xmz.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/n0xmz.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/n0xmz.com\/blog\/wp-json\/wp\/v2\/comments?post=60"}],"version-history":[{"count":1,"href":"https:\/\/n0xmz.com\/blog\/wp-json\/wp\/v2\/posts\/60\/revisions"}],"predecessor-version":[{"id":61,"href":"https:\/\/n0xmz.com\/blog\/wp-json\/wp\/v2\/posts\/60\/revisions\/61"}],"wp:attachment":[{"href":"https:\/\/n0xmz.com\/blog\/wp-json\/wp\/v2\/media?parent=60"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/n0xmz.com\/blog\/wp-json\/wp\/v2\/categories?post=60"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/n0xmz.com\/blog\/wp-json\/wp\/v2\/tags?post=60"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}