Thanks everyone for the answers, I suspected I had it wrong and I did. I have an output in dBm at 50 Ohms, using a transformer to convert the impedance from 50 ohms to 600 Ohms then output in DBU would be the voltage at 50 Ohms times the square root of the impedance ratio or 3.46 times higher than the 50 Ohm ?
+14 dBm = 1.1V at 50 Ohms convert to 600 ohms with a transformer and you have 3.8V at 600 Ohms or 10.7V PP +26dBm gain prior to that and I end up with -12 dBm input or higher will start getting you in trouble. Anybody know where I can find a sound card with 180 dB dynamic range for less than $200? At 03:40 AM 4/15/2007, Sami Aintila wrote: >Usually for audio applications dBm should be referenced to one >milliwatt into a 600-ohm load. (Your dBm figure is using 50 ohms). In >order to avoid confusion when we're measuring voltages, it's better to >not use dBm at all. For voltages, it's probably easiest to use dBV >referenced to one volt RMS. (There's also dBu which is equivalent to >dBm @ 600 ohms.) > >To answer your original question, while the Delta 44 may not be a >typical sound card, its input range (peak-to-peak) seems to be 11 Vpp. >That's about 5.5 Vpeak, 3.9 Vrms, +12 dBV (+14 dBu). > >The maximum input level is 6 dB lower when using the "consumer" >setting in D44's control panel. And using the lowest setting means >another -6 dB. That would be 0 dBV == 1 Vrms. Maybe that's pretty >close to a "typical" (cheap) sound card. > >73, Sami OH2BFO > > >On 4/15/07, k5nwa <[EMAIL PROTECTED]> wrote: >>What is the full scale input to a typical sound card? >> >>I'm thinking it's +10dBm or .7V, am I off my rocker? >> >> >>Cecil >>K5NWA >>www.qrpradio.com www.hpsdr.com >> >>"Blessed are the cracked, for they shall let in the light." > > >Cecil >K5NWA >www.qrpradio.com www.hpsdr.com > >Cum catapultae proscriptae erunt tum soli proscripti catapultas habebunt. >(When catapults are outlawed, only outlaws will have catapults!) _______________________________________________ FlexRadio mailing list [EMAIL PROTECTED] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
