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April 11th 05, 02:28 AM
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From: Telamon Organization: Internet Argonaut Newsgroups: rec.radio.shortwave Date: Sun, 10 Apr 2005 18:58:57 GMT Subject: Power Supples In article , Greg wrote: Okay, thanks to all who replied. The people at http://www.innovatronix.com/cgi-bin/...alog/index.asp are marketing these power inverters to run studio strobes on location, which implies, though they don't actually say so, that they run off a vehicle battery and supply ample VDC for the studio strobes, which require recycling large capacitors as rapidly as possible. My interest would be in using an 12VAC inverter to supply 13VDC voltage for my NRD-525, in hopes of eliminating power line noise (as well as powering several potable, battery-operated radios). From what you guys are telling me, either a linear or switching power supply would work, but filtering is the critical factor. (This isn't a big priority - most noise at my location is radiated noise.) I'll sum up my previous response. Linear or switcher could work in practice but it would be unlikely and expensive for a switcher supply to not interfere with radio reception. Not only do you need to use a linear supply but I would make sure that supply is radio friendly. Just because it is a linear supply it does not mean that the designer has gone through the trouble to provide an RF bypass around the rectification diodes, which still create switching noise even at lower voltages. +++++++++++++++++++++++ You can find out if your reception noise floor is affected by EMI by disconnecting the antenna and tuning slowly through all the bands you want to listen too. This will allow you note down any birdies the radio may have and at what level along with whether any conducted noise is coming through the power cord. You should terminate the antenna terminals 50 ohm input with a short lead 50 ohm resistor in practice but it probably won't make a difference in this test. You can then reconnect the antenna and note the difference in noise. In this way you can determine the difference in EMI and RFI at your location instead of guessing. -- Telamon Ventura, California Good advice. Thanks Teledude! Greg |
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