Baofeng BaoFeng Spectral Purity IMD Testing

[redbeard]

Correction:
he can use them withOUT causing interference

Due to the higher power output he will probably cause interference to licensed GMRS users.

 

[a727469]

Another question(s). …has anybody here ever actually experienced real life interference from the radios mentioned? Has it impeded or impacted your or someone you know‘s ability to communicate?…Especially, has it affected public service communications? If so, then there is a big problem, if not, all we are looking at are figures on a chart. I know the FCC is supposed to regulate this and take action, but how many complaints have been filed and was any action taken? I am not asking to start a war but asking to gage the true seriousness of this in the real world.

 

[AK9R]

I am not asking to start a war but asking to gage the true seriousness of this in the real world.

The FCC's amateur radio rules specify spurious emission limits. Operating a transmitter that exceeds those limits is a violation of FCC rules.

The FCC's rules for GMRS, FRS, or Part 90 also require that transmitters used in those services have an FCC equipment authorization for those services.

Those of us who have amateur radio, GMRS, or Part 90 licenses agreed to abide by the FCC's rules.

If you think these rules are unfair or unrealistic, then you are free to petition the FCC to change them.

 

[prcguy]

Another question(s). …has anybody here ever actually experienced real life interference from the radios mentioned? Has it impeded or impacted your or someone you know‘s ability to communicate?…Especially, has it affected public service communications? If so, then there is a big problem, if not, all we are looking at are figures on a chart. I know the FCC is supposed to regulate this and take action, but how many complaints have been filed and was any action taken? I am not asking to start a war but asking to gage the true seriousness of this in the real world.

Probably none. If an out of spec radio is used on 2m amateur its second harmonic will fall in the UHF military band and the third harmonic will be in the UHF amateur band. If used on UHF amateur the second harmonic will fall mostly in the 800MHz cell phone band. GMRS second harmonic would fall in the 900MHz amateur and LMR band.

 

[dlwtrunked]

They've been exhaustively listed for years on this very site and others. I don't care to rehash them all, nor do I need to. Anyone with a brain not clouded by cheapness can see the quality. I also don't care if you agree or not. (nothing personal)
.;...

Not willing to look at current radios and rather than *possibly" outdated information? I was serious, I have seen posts over years, but those are stale. I remember when many said the same thing about Japanese cars. I own some recent models, along with ICOMs, Kenwoods, and Yaesu. All have advantages and disadvantages. I consider it very possible that without Baofeng and similar inexpensive radios that the the amateur radio service would die. (By the way, my most expensive radio was $13,000, so I am not cheap.) Also, I once attacked a certain brand receiver based on experience. Some claimed my experience was outdated. So I bought one to find it had the best audio I had ever hear on any radio even to today and some other nice features.

 

[a727469]

AK9R…why would I think the rules are unfair or unrealistic? I did not say that. I do not mean to degrade or ignore the rules since the radios mentioned comply. I have been a ham for many, many years and in spite of some other hams I know, I have obeyed and complied with every rule and even kept up to date.
Maybe it was not clear but my question was meant to be for me to gain knowledge and not based on ignoring rules but rather have there been any reports of type accepted radios causing the types of spurious interference referred to and what was done about it? It’s great to have an FCC with multiple rules, but without examples of enforcement where needed why have the rules?
I know for a fact when I got my license back in the 80s I had many examples of hams and others getting fines when the FCC actually went out on the road and monitored. There used to be a column in QST magazine with multiple enforcement examples, now occasionally I see something mentioned and it is usually a major issue.. I hope I am wrong and maybe I am just missing it.

Also, dlwtrunked, you are 100% right..in my local area at least 2 people I know got their B radio because they could not afford a $200 radio and they are great contributing, young hams which are needed. The radios are legal, they work and in this case help expand a somewhat dying hobby. Per your other comment, I too, have both $1000++ radios and $25 ones..the fun is not necessarily in the price but rather the radio!

 

[AK9R]

There used to be a column in QST magazine with multiple enforcement examples, now occasionally I see something mentioned and it is usually a major issue.. I hope I am wrong and maybe I am just missing it.

Routine issues are reported in the Volunteer Monitor Report posted in QST each month. You can see the last two months' reports here: Volunteer Monitor program

 

[a727469]

Thanks! Great, sorry I missed that, and a very good idea, but it would be nice to see all the final results along with actual fine amounts where applicable and I notice that no names or call signs are mentioned…if you break the rules/laws and it is proven then this information should be provided to possibly dissuade others.
Yes, I will stop since I know this is off topic..should go to amateur radio forum.

 

[dlwtrunked]

Probably none. If an out of spec radio is used on 2m amateur its second harmonic will fall in the UHF military band and the third harmonic will be in the UHF amateur band. If used on UHF amateur the second harmonic will fall mostly in the 800MHz cell phone band. GMRS second harmonic would fall in the 900MHz amateur and LMR band.

The 3rd harmonic of one the local VHF repeaters input frequencies when using a Yaesu FTM series radio routinely shows up interfering with the output frequency of one of the local UHF repeaters. This is also seen on a spectrum analyzer which I often leave running. This also prevents putting both repeaters on the "two sides" of such as Yaesu transceiver. That is the only time that I am aware of locally of any radio interference from an amateur radios harmonics.

 

[LogicalDave]

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

I have 3 older Baofeng radios (UV-82 and UV-B5) and none of them are compliant with 97.307e. On Baofeng's advice, I recently bought a pair of GT-5R PRO expecting them to be compliant, but they too were non-compliant in the 2m band with 2nd harmonic spurs around 0dBm. I tested on a Siglent SA with a 30dB attenuator. Your tests show harmonics better than -70dBc; that's really impressive, but nothing like the radios I tested.

 

[G7RUX]

Harmonics can often be a problem but are not the major issue,

I have 3 older Baofeng radios (UV-82 and UV-B5) and none of them are compliant with 97.307e. On Baofeng's advice, I recently bought a pair of GT-5R PRO expecting them to be compliant, but they too were non-compliant in the 2m band with 2nd harmonic spurs around 0dBm. I tested on a Siglent SA with a 30dB attenuator. Your tests show harmonics better than -70dBc; that's really impressive, but nothing like the radios I tested.

I would suggest that you should use more attenuation on the fundamental here. Whilst assuming 5W (37 dBm) output with a 30 dB attenuator gives 7 dBm which is well below the damage level (33 dBm) it is well *above* the specified level for 1dB compression (-5 dBm) so you will be affecting your measurement performance.

Ideally you would use an attenuator and then a notch filter to reduce the fundamental level significantly without affecting other frequencies too much.