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Christopher
There's nothing strange there, 12V Vs 18V output on a laptop PSU if it's designed for a laptop of a very recent gen (last 4-5 years) or an older netbook, as they tend to use 12V input. It's older laptops, especially 'desktop replacement ' items that often ran desktop PC CPUs (not low consumption) instead of low consumption 'mobile' edition CPU's.? Those often used an 18v supply. But even an 18V example can be fixed to 12V one if one happens to be spare or an 18V replacement is found. But, and especially more modern examples, whilst SM PSU's are inherently EM noisy, the modern ones do seem to be more compliant with the EMC requirements Vs the older stuff. In fact, on my fairly modern Legion5 laptop, it generates more EM garbage than the PSU itself (original OEM item).? In fact I had the PSU on a synthetic load test setup and sat the 6100 next to it and there's little notable lift in band noise or birdie type transients notable - not 100% absent but very low order where there are any occurances.? But I will assume that's not universal as I do seem to be lucky with equipment in getting stuff with better than average EM compliance. But even if a laptop PSU (OEM or aftermarket replacement) is a bit noiser than you'd want, you could mount it in a metal box, add a vent or two and a box mounted intake and exhaust fan pair running a fairly low RPM and that'll lose a bit of any stray EM.? But again, a modern OEM or aftermarket replacement of a recent-ish design for recent/current laptops should be usable without re-casing and maybe at best a couple of ferrite cores in the DC lead as a precaution won't do any harm. But regardless, they are way more fit for original purpose and repurposed use for radio than those horrible PD type USB-C adaptive variable output items.? And as I probably said, there's little saving over a laptop item cost in buying a substandard unfit for radio use purpose USB-C item. There are HH's, VHF and UHF, which have USB-C charging capability and can be powered for RX on a PD type charger whilst charging, but there's often way more noise than say repurposing a laptop item to (with appropriate mods where needed output wise) with a dummy USB fitting to provide a psuedo USB-C charge source.? It's very noticeable on FM only items, less so on DMR/DPMR items unless the radio is configured to auto switch between FM & DV in the occurances of FM mod sigs on the preset frequency. On Sun, 26 Mar 2023, 10:05 federico.giampietro, <federico.giampietro@...> wrote: I use an old laptop power supply which strangely had an output voltage of 12V (5A) instead of the usual 18V. The performance of the radio is excellent on all bands (having 9W of peak power instead of 10W is completely irrelevant in terms of dB) and the heat is significantly lower than that generated when using 13.8V power supplies... not low but still tolerable. |
