jwhite@com50.c2s.mn.org (Jeffrey J. White) (06/25/91)
Greetings, I need to build or aquire a rather odd power supply. I need a 24VDC 15-20 amp power supply for an older (early '70s) ham radio. I have been looking at some used power supplies, but none really meets those specs. Even new the best I could find was around 12amps (without spending more for the power supply than for the radio). After scoping out the National Semi linear data books and application book, I have considered building a power supply to meet my needs. (I am more a digital man than a linear hacker.) However none of the application notes really comes close to the high power I need. Any ideas?? -- Jeffrey J. White | ...!tcnet!com50!jwhite Com Squared Systems, Inc. | jwhite@c2s.mn.org 1285 Corporate Center Drive | (612) 452-9522 voice Eagan, MN 55121 | (612) 452-3607 fax
whit@milton.u.washington.edu (John Whitmore) (06/27/91)
In article <1991Jun25.010640.22405@com50.c2s.mn.org> jwhite@com50.c2s.mn.org (Jeffrey J. White) writes: > I need to build or aquire a rather odd power supply. I need a 24VDC >15-20 amp power supply for an older (early '70s) ham radio. > After scoping out the National Semi linear data books and application book, >I have considered building a power supply to meet my needs. > ... However none of the application notes >really comes close to the high power I need. Linear devices would have to dissipate a fair fraction of the total rated power (which is about 500W). It is axiomatic, therefore, that linear applications do NOT include this kind of power. What you will want to consider is a switching power supply. Unfortunately, build-it-yourself switchers are difficult (because the high-frequency high-current inductor is tricky to design/build). ACDC model RS24N13 is 24V, 13A; Powertec model 9K24-32-372-FG-3 will deliver 24V at 32A. Both these are ASTEC brands ('cuz that's the catalog I have handy); phone (619) 439-4243 to find out about local distributors or ordering. Expensive though it may be, the switcher might be your only real option, because large power transformers (which would be needed for the linear version) are becoming hard to find (and if you CAN find one, it'll be so expensive that maybe it's not worth it). The only cheap alternative is to put two car batteries in series and trickle-charge 'em after an hour or so of transmission. John Whitmore