Analysing Quansheng UV K5(8) Harmonic Output

I'm still fascinated by these little Quansheng UV-K5(8) radios that I got recently, and have reached the conclusion that they are fantastic for what they are, which is... a £15 radio.

The obvious benchmark for comparison is the trusty Baofeng UV-5R, which is notorious for its spurious emissions.

So let's compare one to a UV5R. Below are some measurements taken with my TinySA, a cheap 10dB directional coupler, and some attenuators. The TinySA only goes up to 960MHz, so I measured at 145MHz and noted the power at the 2nd to 5th harmonics.


The TinySA has a LOW and HIGH input, which cover 0-350MHz and 240-960MHz respectively. Everything above the 2nd harmonic is in the higher range, so I measured the fundamental and 2nd harmonic in the LOW range, switched to the high range and the harmonics up to 725MHz.

Since I took measurements of the 2nd harmonic in both ranges, I can offset the upper harmonics by the difference between the 2nd harmonic measurement in both ranges to correct for each input's different characteristics.

Each set of measurements was taken for a Quansheng UV K5(8), a Baofeng UV-5R, and a Retevis RT-3S.


2nd Harmonic (290MHz)-45dBc-39dBc-57dBc
3rd Harmonic (435MHz)-23dBc-27dBc-25dBc
4th Harmonic (580MHz)-57dBc-43dBc-56dBc
5th Harmonic (725MHz)-52dBc-50dBc-57dBc
Plotslow / highlow / highlow / high

Ofcom's amateur terms state that not more than 1% of the mean emission power should be emitted outside of the nominal modulated carrier bandwidth, so the figure we are looking for is less than -20dBc.


The Quansheng is in spec, appearing to perform mostly better than the Baofeng, and not quite as well as the slightly more expensive Retevis.