**KX4AZ**. He searched the net with "WSPR 10 milliwatt" and found the page on "WSPR with 10 milliwatt" on my PA1B website. hi.

Bruce

**KX4AZ**is a operator that makes very interesting WSPR spots with just

**10 milliwatt**.

Believe it or not, but a WSPR station with

**10 mW**will ONLY be spotted, when the

**propagation**is very good. Please study the

**diagrams below**, to convince your self.

**Lowest Possible Power diagram**

To show the propagation, I developed the Lowest Possible Power diagram. You can immediately see how good or how lousy the propagation is, for each individual spot.

The

**better**the propagation, the

**lower**the Lowest Possible Power.

2019-04-19 I visited the WSPR old database and collected some interesting spots.

**Time slot 1**

In the time slot of 17:46 UTC

**ND7M**spotted 7 stations.

4 stations with 5 W, 1 station with 1 W,

**W6CLB**with 100 mW and

**KX4AZ**with 10 mW.

Luckily for Bruce, the propagation from the stations with 5 W and 1 W, to

**ND7M**was not that good, so Bruce's signal was not over shouted by the 1 W and 5 W signals. Something that can easily happen,

**even**with a power of 100 mW.

In the first diagram Bruce was spotted by

**ND7M**with a SNR of -29 dB. It's the spot in yellow, on the line of -29 dB and the line of 10 mW. So in this time slot Bruce needed the

**full 10 mW**. Hi.

In this time slot the best propagation is shown by the spot of

**W6CLB**with 100 mW and a SNR of -15 dB. This spot has a Lowest Possible Power of 5 mW. Thus about 3 dB better than the spot of Bruce.

KX4AZ with 10 milliwatt spotted by ND7M over 3100 km |

**Time slot 2**

The second diagram shows the next spot of

**KX4AZ**by**ND7M**.
In this time slot the signals of

**W6CLB**with 100 mW has a SNR of -12 dB.
The signal of

**KX4AZ**has a SNR of -22 dB. please notice that both spots, show the same propagation, which is**very good**. The Lowest Possible Power of both stations is**2 mW**. The signal of Bruce is even about 7 dB stronger, than in the first time slot.KX4AZ with 10 milliwatt spotted by ND7M over 3100 km |