Saturday, May 6, 2017

WSPRing at 5 milliwatts

For almost a week I operated my R-Pi WSPR transmitter on 20m through a step attenuator for 1 milliwatt to the antenna. I was hoping to cross the Pond at that power level since it was so easy to do at 100mW and even 10mW.

But, alas - no WSPR DX with a single lonely milliwatt.

So today I upped the power slightly to 5 milliwatts and was heard by three European stations in short order.

The level at which they heard me tells me I wouldn't have made it with one milliwatt - and that's the beauty of thinking of these power levels in terms of dBm rather than milliwatts. My 5mW power level is 7 dBm. One milliwatt is 0 dBm. The stations that decoded my 5mW/7dBm signal heard me at -25 and -27 dB, meaning that at 1 mW I would have been -32 and -34 dB - too weak even for WSPR.
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