BaoFeng Spectral Purity IMD Testing

[NearFieldOperator]

BaoFeng radios are well known to be lacking in front end filtering which results in high spurious harmonics that often fail FCC 97.307e standards. While they are popular for being extremely inexpensive to comparative models, they are often ridiculed as piles of junk and any respectable ham operator would find little use for them.

As an RF Engineer, I wanted to see how bad it really was failing instead of just taking the internet’s word for it. I have held a Technician license for 10 years and have recently convinced a few friends to get into ham radio. They all bought UV-5R radios from the “BAOFENG Store” on Amazon.com spanning from Fall of 2022 to Summer of 2023. I decided to test them on a Keysight PXA Spectrum Analyzer in my lab. This would also allow us to measure to overall output power and see if they are reaching the marketed 5 watts. I also had a BF-F8HP on hand that I could test.

To quote a portion of the test standard:

“For a transmitter having a mean power of 25 W or less, the mean power of any spurious emission supplied to the antenna transmission line must not exceed 25 µW (-16dBm) and must be at least 40 dB below the mean power of the fundamental emission...”

So the threshold for any spurious signal is -16dBm. I’m not sure how they determined that level of power was acceptable for spurious emissions, but that’s what we will be focusing on.

For the 5W radios, I included a 10dB attenuator to lower the signal enough to not damage the spectrum analyzer. The 8W radio also included an additional 3dB attenuator for additional protection. The attenuator(s) and cable loss to the analyzer were calibrated with a signal generator and the following results are showing the power levels at each radio’s antenna port in dBm. Test frequency was the 2m NCF (146.52 MHz).

Spectrum Testing Results

It was surprising to see that the only radios to fail were older ones bought over 4 years ago. None of the new radios failed and had at least 15dB of margin to the spurious threshold. Some had a 4th harmonic present and that may be due to ordering from a different supplier on the BAOFENG Store on Amazon. While this was a limited pool of radios, the trend is very telling that BaoFeng is taking EMC more seriously.

Main takeaways:

1. Recent BaoFeng UV-5R radios have upgraded front end filtering that is FCC 97.307e compliant.

2. The BF-F8HP having “better filtering” was not necessarily true 4 years ago. I cannot speak to the design now, but the current UV-5R design is more than adequate.

3. Average transmit power for current radios averages 4.5W on the 2m band.

I cannot speak to the overall quality of these radios in terms of sensitivity, front end loading, frequency precision, etc. especially compared to their competition. I have seen Kenwood HTs spectral purity tested that show all harmonic bands below -70dBm. I don’t doubt that the 3 main brands have better quality radios and if I were to design my own I would take a different approach than BaoFeng, but their performance-to-cost ratio is very high. There is no surprise why these radios are so popular for hams just getting started.

If anyone is considering one of these as a first-time handheld I would not hesitate to recommend them. And if anyone has the capability to measure their own models I would be interested to see if this trend of compliant radios is becoming the norm.

Spectrum Plot Results:
Radio Test
UV-5R Radio1
BF-F8HP Radio
UV-5R Radio2
UV-5R Radio3
UV-5R Radio4
UV-5R Radio5
UV-5R Radio6
UV-5R Radio7

 

[AK9R]

It was surprising to see that the only radios to fail were older ones bought over 4 years ago.

In 2017-2019, I went around to hamfests with a Rigol DSA815 spectrum analyzer and associated attenuators, cables, adapters and offered to test handheld radios for spurious emissions using equipment and methods similar to what the ARRL was doing at hamfests at the time. In my experience, the older the Baofeng, the worse it was when it came to spurious emissions. I particularly recall a UV-82 that showed its first spur at approximately 73 MHz and every multiple up to 1 GHz while transmitting on 146.52 MHz.

 

[kayn1n32008]

From numerous conversations, most hams don't give a **** about what's coming out of the antenna, they want the cheapest piece of **** radio, for the least amount of money.

They have no clue about spectral purity, and care even less.

It's all about their ****ty $20 radio and 'how great it is' because if they actually, maybe one day, go on a hike, or go for a paddle in their supposed canoe, they might drop that 'expensive big 3 brand radio' and it might break or sink. But their **** Chinese radio is only $20 so they will go but 10 of them so they have a fresh supply of **** radios that sound like **** and are barely functional. But hey. It's a ****ty cheap ass radio that 'works greeeaaaatttttt'

 

[MTS2000des]

Bowelturds are lowest common denominator radios based on low cost consumer grade SOCs that were designed by their maker (RDA) to be used in toy walkie talkies, bubble pack throwaway radios, and other low rent junk intended for casual consumer use. As such, even with front end filtering, and tx output filtering to remove the blades of grass, these chipsets lack performance amateurs expect such as useful band scan with fast scan rates, reliable CTCSS/DCS decoding without unmute failures, solid transmit audio that isn't muddy and muffled, and nevermind their glitchy and irritating firmware that makes programming and operating them in the field (VFO operation/keypad programming) a hassle for new and old hams.

A 25 year old Yaesu FT-50 that can be had for around a hundred bucks fully equipped mops the floor with these turds.

 

[G7RUX]

RF engineer here too.
All received and a nice bit of testing although what you have measured is the direct spurious emissions from the transmitter. Baofengs and similar sets have never been stellar in this regards but they are clearly just about OK.
However, I would suggest looking at the intermodulation distortion the transmitter generates when presented with reasonably strong in-band signals from other transmitters in the vic since this is the main problem with the very crude designs used in these sets.
I made measurements of Tx IMD during 2020 on a selection of radios, including handhelds, mobiles and base units and whilst few handhelds performed particularly well the Baofengs and similar were quite horrible, with very large IMD products all over the place, including squarely within VHF airband and low, mid and high-band VHF PMR. They were a little better in UHF but not by much.
I cannot post my report on these I’m afraid as it was done for my employer.