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Are switch-mode powers supplies suitable for receivers?
"Richard" wrote in message ... I have an ex AM PMR radio that I wish to use on 144Mhz. I need a PSU feeding 24V @ about 300mA. Are switch-mode powers supplies alright or are they too noisy to be used for receivers? TIA. Many years ago I designed a switching power supply for aircraft Nav and Com VHF radios. The switcher was 100% shielded and line filtered to get the radio to pass FCC and FAA TSO certification. Even though the Com and Nav radio's are VHF, they were placed next to an ADF radio (low frequency) without problems. Testing was performed not only for electro magnetic emissions, but also for line current emissions, with a line stabilization network, into the radio from the aircraft power. Even if the switcher is 100% shielded, this will not prevent radiation along the input power line. You need to consider methods to eliminate pulsed current along the input power line caused by the switcher. This may be hard to achieve, especially for high efficiency switchers. A good choke will help, but it will also introduce additional switching losses. So yes, a switcher can be used; but, IMHO it must be designed for use in an RF environment. |
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