"Performance Numbers - What Do They Mean?" by Rob Sherwood NC0B
We were privileged to host Rob Sherwood, the renowned expert behind Sherwood Engineering's comprehensive receiver performance testing, for an eye-opening presentation on interpreting radio specifications and lab measurements.
For over 50 years, ham radio operators have relied on performance numbers to evaluate transceivers, but as Rob explained, many of us have been misinterpreting the data. The famous "Sherwood Table" - which ranks over 150 HF transceivers by their 2-kHz dynamic range - is often misunderstood. That ranking applies only to close-in dynamic range, not to every performance metric!
Rob's presentation cut through the confusion with practical insights:
- Don't choose a radio by one number alone. While 20+ modern transceivers now achieve the once-mythical "100 dB dynamic range," other factors matter just as much: user interface, ergonomics, and whether the radio feels right for your operating style.
- Sensitivity isn't always the issue. In today's RF-noisy urban environments, most radios are actually too sensitive on 160, 80, and 40 meters. Rob recommended using attenuation or reducing RF gain on lower bands to improve operating comfort.
- Pre-distortion technology matters. Rob demonstrated dramatic differences in SSB signal cleanliness between radios with adaptive pre-distortion (Apache PureSignal, Icom DPD, Flex SmartSignal) versus those without. The visual evidence was striking - clean signals versus significant splatter.
The bottom line? Modern transceivers from all major manufacturers offer excellent performance at reasonable prices ($1,000-$12,000). Rob successfully operated multiple CW contests with rigs in the $1,000-$1,500 range. His advice: try before you buy, talk to fellow club members about their experiences, and most importantly - choose a radio you enjoy using.
For those wanting to dive deeper into the Sherwood receiver data, visit http://www.nc0b.com. Rob welcomes questions at rob@nc0b.com.
Key Takeaway: Great performance is available across many price points today. Focus on finding the right radio for your needs, not just the highest number on a chart.
Thanks to Rob Sherwood for sharing his decades of expertise with NFARL!
Download the Presentation: PDF Slides Available Here
