I did a computer supply conversion here. the one I did was a 150W supply so only good for about 10A. I followed the QST article for the conversion. This one had a pot for adjusting the voltage. I had to change one resistor value to get 13.8 VDC out. The output wave form looked like the early commercial switching power supplies tested by QST. Those showed some RF noise in the QST tests.
I added a torrid with several turns on it, a big electrolytic cap, a.01uf, and a .001uf to the output. After that, the waveform on the "o" scope looked like the 2nd round of switching supply reviews in QST. Those showed much less RF noise. Unfortunately I didn't have a spec ana. to check it but it hasn't caused any RF problems for the low power repeater that it has been running for the last 6 months.. John Lock kf0m at arrl.net -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] Behalf Of Gmail - Kevin, Natalia, Stacey & Rochelle Sent: Sunday, August 03, 2008 11:05 AM To: [email protected] Subject: [Repeater-Builder] Power Supply from a PC. Slightly OT Hi All, This request is slightly OT but still for Amateur and possible Repeater use. I read an artical about using a PC power supply as a 12 and 5 volt/ high amp atable power supply for the bench. Looking over the specs it looks good for 12v at 19A and 5v at over 30A. Was interested and due to the size of the PC power supply takes up a lot less room on the bench then my standard Ham power unit. Before I go and use one of these (Have a couple of spares), I would like to know if anyone has already tried this, and if so what problems has it caused? Being a switch-mode is it very nosiey on HF or even the upper bands? Thanks Kevin. Get Skype and call me for free.
