|3dB switched in for 50 mW from R-Pi|
I've known about the kits offered by K5BCQ for quite a while and am glad to report that a step attenuator is among them - the imaginatively named Attenuator Kit #13.
The kit was in my mailbox two days after ordering it. Assembly took under an hour and testing with my KX2 and OHR WM-2 wattmeter yielded impressively accurate results. I placed the attenuator inline and, with all switches off, power output was 10 watts. Switching in the 3 dB pad dropped power to exactly 5 watts. Other values of attenuation decreased the output to exactly what it should be.
There are two options available for switching in various levels of attenuation - slide switches or jumpers. I ordered the slide switches but should have ordered the jumper version since the slide switches don't perfectly fit the holes drilled into the circuit board. The slide switch pins (6 per switch, 9 switches) have to be bent into an ugly configuration to fit and the result doesn't look too good. As infrequently as changes in attenuation levels would be made, jumpers would have been adequate and would have made for a better-looking end result.
But it is dead-on accurate.
I am now (for the past 15 minutes) WSPRing on 20 meters with a ionosphere-scorching total of 50 milliwatts and am being heard in France and Switzerland.