Baofeng UV-5R+ Harmonics
It seems that the ARRL and a number of individuals have been taking a serious look at harmonics and other spurious emissions from various ham transceivers, including the ubiquitous Baofeng range of handheld transceivers. So, a while ago, I decided to take my Baofeng UV-5R+ to work and see what mine looked like.
I don’t want to play the “radio police” here. That is not my goal. I think these radios do a great service to amateur radio by making it affordable to people who have an interest, but would otherwise not be able to afford to get on the air. With these radios, you’re on the air for a <$40 commitment, and that includes your technician license fee.
There seems to be some general confusion as to whether you can use the Baofeng UV-5R type radios on the ham bands in the USA, since they’re certified under FCC part 90. I am not a compliance or EMC engineer, so I don’t have a fantastic grasp of the rules, but what I have figured out is that there is no requirement for FCC certification or type acceptance involving the use of FCC part 90 commercial radios on the amateur radio bands, so long as it meets the spectral purity limits set forth in FCC part 97 (amateur radio). If it is certified under part 90, but meets FCC part 97 – you may use it legally. It is the operator who responsible for making sure the radios you use are compliant to FCC part 97.
Taking the spurious limits for Part 90 and Part 97 as follows:
|Part 90 (Private Land Mobile Radio):
Handheld Conducted Power Limit: 2W
|Part 97 (Amateur Radio Service):
Power Limit: License Dependent
With that said, this is what I found emanating from my UV-5R+:
Disregarding the restricted bands, (I didn’t do a radiated spurious test anyway) it looks like this particular Baofeng UV-5R+ is compliant with the FCC part 90 limits, which makes sense since it’s designed as a part 90 radio. It doesn’t appear to be compliant for use in the amateur radio bands, since it exceeds the FCC part 97 limits. If you look at the measurements I took of the fundamental, you’ll see that it was generous. Over 5 Watts on both bands. Perhaps I just got a “hot” one. If this is the case, it is possible that the RF amplifier is pushed well out of its linear region, past P1dB, and is generating excess harmonics.
I should mention also that I did not use a high pass filter or a notch filter to reduce the level of the fundamental when doing these tests. The analyzer could well be generating some of these spurious signals itself due to mixer or amplifier saturation. However, if mixer overload does happen, the analyzer will indicate it, which during this test, it did not.
Anyway, this was just a cursory look at the conducted harmonic emissions from the UV-5R+. If you want to see the measurement screenshots of the above, and more, including RF output power on 2m and 70cm, occupied bandwidth (not a scientific test, but illustrative), and antenna measurements, grab the download below.
Download a PDF of the measurements here: