Two years ago I built the "Damn Reliable Attenuator" from Kees K5BCQ and have used it periodically. So why another step attenuator?
While the K5BCQ attenuator is fine for the job I bought it to do - attenuating the signal of various QRPp WSPR transmitters - its 1-watt resistors limit its use for power levels of above 3 or 4 watts.
I noticed this when I wanted to feed the output of my old KX2 into the RSPduo (operating in spectrum analyzer mode) and, with 5 watts in, the attenuator's resistors became quite warm after just a few seconds.
The attenuator from QRPKits uses 2-watt resistors to form its pads and is rated for 5 watts continuous and 10 watts intermittent. This makes it more suitable for QRP (as opposed to QRPp) applications.
With the RSPduo now able to function as a spectrum analyzer, the need for a suitable attenuator has now been met. FWIW, the maximum continuous input to the RSPduo is 1 mW; 10 mW intermittent. 37dB of attenuation from a 5 watt QRP rig takes the power down to 1 mW and, with this new attenuator, will do so without overheating the resistors.
I also like the bypass switch which gives the ability to switch in or out any attenuation level with a single switch.
In addition to being a worthy piece of test equipment this would make a great "first" kit for a new builder. And for anyone who has a compatible SDR receiver from SDRPlay and desires to use spectrum analysis software with it, this new step attenuator is more than worth its $25 price.