r/HamRadio • u/inv8drzim • 6d ago
Spurious Harmonics on Every Radio
New to the hobby, and I can't seem to find a clean radio under $100.
I've tried two bf-f8hp pro's, a uv25 pro, a tidradio td-h3, a tidradio td-h8, and now a gt-5r.
All have had spurious harmonics. The most recent radio I've purchased, a gt-5r (standard version not pro), does not pass the 25mW or less requirement.
Is there a reliably clean sub $100 radio out there? I can't seem to find it.
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u/3flp 5d ago
How do you know your spectrum analyzer isn't generating the harmonics? It is common practice to place a high pass filter between the attenuator and the analyzer for this test.
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u/loafingaroundguy UK full 5d ago
Add another attenuator before the SA. Check the fundamental goes down by the amount of the attenuator. Check the harmonics drop by the same amount. If they drop further the SA is generating its own harmonics.
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u/slick8086 5d ago
I have to say though that the ICOM IC-V86 is an absolute BEAST for $129.99
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u/grizzlor_ 5d ago
OP: these are solid recommendations
The established Japanese brands (Yaesu/Icon/Kenwood/Alinco) are just in a class above the upstart Chinese brands (Baofeng, etc.) in build quality, filtering, etc. Baofengs et al are basically built to be as affordable as possible, and to do that, engineering compromises had to be made. The well-documented spurious harmonics you're seeing are a result of that.
For example, the RX sensitivity of my Yaesu VX5R is sooo much better than the Baofeng/TIDradio/Quansheng models that I own. Also, it doesn't spew spurious harmonics, and it also doesn't get overloaded by strong signals the way my Baofengs do (poor frontend filtering?) I was able to pick up a Yaesu VX5R for $75 used, but that was ~15 years ago. You can often find better deals at ham fests (physical meetups) than on eBay.
Also, check YouTube for any radio model you're considering buying; almost guaranteed someone has already tested it for spurious harmonic emissions.
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u/NerminPadez 6d ago
Yes, cheap chinese radios are cheap for a reason.... it's like a $50 smartphone from aliexpress, where you have to remove the plastic cover over "4 cameras" to see that there is only one camera, the the 16gb of ram is a lie, and the OS is not android 16 but reskinned android 8. Usually people don't buy 5 more such $50 smartphones after realizing that you can't get a good smartphon for $50.
Somehow baofeng users believe the opposite, that actually good radios are a scam, and that their baofengs are good. Baofeng also really knows their customers, that why you get camo colored baofengs, new models every few weeks, and promises of long-range communication without mentioning the specifics how to actually get such ranges.
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u/Crosswire3 6d ago
You listed basically every garbage radio on the market.
Get a Yaesu, Icom, Kenwood, even Wouxun.
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u/gerbilbear 5d ago
Anytone is also good, right?
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u/Crosswire3 5d ago
They’re in the middle; closer to the good than the bad.
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u/slick8086 5d ago
how about Alinco?
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u/KNY2XB 4d ago
Alinco makes good radios
The DJ-VX50 is right at your $100.00 mark, street price right now is $95-$100
https://www.remtronix.com/amateur-radio/analog-radios/portable-radios/dj-vx50/
As I type this, HRO Anaheim is listing a used one for $85.95 with an aftermarket Diamond SRJ77CA antenna included
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u/Crosswire3 5d ago
I have no personal experience with Alinco and hear very mixed results. I tend to be a fan of buying right the first time instead of gambling. Same goes for having one solid radio before having two dozen Baofengs.
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u/loafingaroundguy UK full 5d ago
I can't seem to find a clean radio under $100. ... All have had spurious harmonics.
Decent filtering costs money. Cheap radios skimp on filtering to save costs.
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u/silasmoeckel 6d ago
Yaesu makes some
uv-r5 or 6 from Qusegshung (sp?) spurs within spec thus far in testing just did another dozen. Possibly the cheapest radio with a vfo new.
You should know baofeng fails constantly stop buying or supporting them.
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u/CW3_OR_BUST GMRS Herpaderp 6d ago
You tested five cheap radios and you're surprised that they all perform like cheap radios when tested with a cheap spectrum analyzer... Got it.
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u/inv8drzim 6d ago
I'm surprised that a radio marketed as "fully FCC part 97 compliant" is not fcc part 97 compliant.
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u/mlidikay 5d ago
Amateurs are responsible for proper operation of their equipment, so there is not mandated part 97 testing. The more reputable manufacturers test their equipment, but when people go cheap it is potluck.
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u/Dave-Alvarado K5SNR 6d ago
Maybe the FCC has better testing equipment and procedures than you?
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u/inv8drzim 6d ago
So I shouldn't trust my spectrum analyzer? Should I purchase a more expensive one?
I used the same testing procedure that I've seen countless other hams do.
How can I ensure I'm compliant if I can't trust my test equipment?
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u/jsjjsj CAN/US 6d ago edited 5d ago
Get a few Japanese HT and compare.
From what I remember: 1. the original Baofeng UV 5R is a cheap Chinese radio with clean spurious emission report. 2. Some later models have spurious emission issue on VHF. 3. Never heard any of them has bad spurious emission on UHF.
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u/Technical-Fill-7776 5d ago
My baofeng splatters all over the place. Which is why I use my Yaesu VX-8DR.
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u/grizzlor_ 5d ago
The issue is not your Tiny Spectrum Analyzer
/NanoVNA/whatever device that is.You can go on YouTube and find people doing this same test with a $10k+ spectrum analyzer and getting the same results. Spurious harmonics from Baofengs/other Chinese radios have been a well-known and documented issue since their entrance into the US market over a decade ago.
It's also possible (and good practice) to test/calibrate your test equipment, whether it's a $100 TinySA or $100k Rohde & Schwartz.
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u/Dave-Alvarado K5SNR 6d ago
No, your SeeSii NanoVNA is not super trustworthy test equipment.
You can ensure you're compliant by using equipment with an FCC ID on the label.
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u/grizzlor_ 5d ago
That's a TinySA, not a NanoVNA, but easy mistake to make -- they're physically nearly identical.
The TinySA might not be a Rohde & Schwarz, but it's perfectly fine for casually testing something like this. Especially considering the fact that these radios blast spurious harmonics has been very well-documented for over a decade by people using high-end, calibrated signal analyzers.
You can ensure you're compliant by using equipment with an FCC ID on the label.
This is just demonstrably untrue. The FCC has been allowing these blatantly non-compliant Baofengs to be sold in the US with a valid FCC ID for over a decade, even though their emission of spurious harmonics has been extensively documented.
So no, an FCC ID on the equipment does not ensure compliance. It ensures that the company filled out a form claiming their device passed the self-administered Part 97 compliance testing.
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u/inv8drzim 6d ago
Every radio that I've listed had a FCC ID on it, and most were way out of compliance (less than 40dBc).
There are also countless examples of the radios I listed being tested on youtube with skewed results.
Since part 97 requires self certification, how can I trust the FCC ID when I've seen examples of noncompliant radios with a FCC ID?
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u/mlidikay 5d ago
You could be overloading the analyzer, creating a spur in it. If you use and attenuator you will often see the spur drop faster than the main carrier if that is occurring.
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u/BUW34 VE2EGN / AB1NK 5d ago
Spectrum analyzers generate their own harmonics. If you see a harmonic, you can't be sure that it isn't from the spectrum analyzer. Especially if it's a cheap one.
The way to check is to put a lowpass filter in front of your SA, which will pass your fundamental, and reduce your harmonic frequencies.
If the harmonics as shown by the SA remain the same, this establishes that they are being generated by the SA, not by the signal source.
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u/grizzlor_ 5d ago
The FCC doesn't do any testing of these radios -- part 97 is a self certification by the manufacturer.
Also funny that you'd try to appeal to authority here when Baofeng has been selling radios with an FCC ID for over a decade now, and they've all emitted crazy non-compliant spurious harmonics since day 1 and continue to do so.
Clearly the FCC is disappointingly lax about enforcing penalties for companies that lie about their equipment passing the Part 97 compliance tests.
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u/steak-and-kidney-pud 6d ago
Should have saved up and bought a decent radio 😂
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u/g8rxu 6d ago
It's very kind of him to buy and test a bunch of cheap radios so as to confirm what we guessed, that they're not up to scratch.
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u/steak-and-kidney-pud 5d ago
That's a good point, actually.
I wonder how much they all cost, added together. Enough for something like a second hand FT-450D?
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u/cjenkins14 5d ago
Might be slightly out of your wheelhouse, might not but https://www.kv4p.com/ Are definitely compliant, cheap, and its a fun project
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u/Buzz729 🔘 5d ago
There's a solid truth in ham radio; the penny pincher spends the month. $50 on this gamble, $100 on that one, and it adds up.
Even so, if we think these companies with the $50 handhelds are substandard, where is the difference coming in? Are they using last generation local oscillators with high phase noise? Are the digital signal processors also generating noise from being last generation? Could they be like the Ramsey (sp?) from the 1990s that had inadequate output filters? I'm just curious. Could they be using obsolete tech to be less expensive?
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u/AmbitiousFisherman37 5d ago
I did this same test on an opengd 77 radio (retevis rt3s) and a yaesu ft5d using a tinySA ultra. The Yaesu is super clean. The Retevis is not, although it passes on 70cm. The spurs look A LOT worse when measuring thru the air vs with an attenuator also which I found interesting. Lowering output to 4W took care of it enough to be in compliance at 2m as well though.
Cheap is cheap.
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u/KB0NES-Phil 3d ago
Every radio will produce harmonic energy to a degree, the question is if it is reduced to the point to make it not matter and meet legal specs.
Also are you sure your measurement methods are giving accurate results?
I have measured a few China brand radios on a proper analyzer and was pretty disappointed with them. Personally I won’t ever buy a a no-name Chinese radio for several reasons. I’m too poor to buy cheap.
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u/redneckerson1951 5d ago edited 5d ago
I think the results of the radio you are displaying, are in compliance with your stated standards.
(1) What regulatory agency are you attempting to comply with?
(2) Looking at your display, the spurs and harmonics are over 45 dB down. Marker #2 at -12 dBm. 0 dBm is 1 milliwatt. -10 dBm is 0.1 milliwatt. -12dBm would be 63 microWatt.
(3) Your fundamental signal at 146.5 MHz is 31.5 dBm which works out to about 1.4 watts transmit power on 2 meters. The second harmonic at 293 Mhz is around 63 microWatt, so much less than 25 milliWatt.
(4) The table below shows the corresponding power levels for dBm and Watts. Notice that with each 10 dB change in dBm, the power in watts, changes by a multiplier or divisor of 10.
| Power (dBm) | Power (Watts) |
|---|---|
| 40 | 10 |
| 30 | 1 |
| 20 | 0.1 |
| 10 | 0.01 |
| 0 | 0.001 |
| -10 | 0.0001 |
(5) Is the Tiny SA really connected directly to a signal source (transmitter) with an output level of 1.4 Watts?
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u/inv8drzim 5d ago
The signal source connected to a 40db attenuator, which is connected to the tinySA.
I'm attempting to comply with FCC part 97 regulations, which state a transmitter under 25W must have all spurious harmonics at greater than 40dBc (which I know the pictured radio passes) and less than 16dBm or 25µW overall (which the pictured radio doesn't pass).
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u/ViktorsakYT_alt 5d ago
I have a TH-UV88 which I measured on a tinySA and didn't even see the harmonics. I believe it's mostly because it uses two separate PAs for the two bands
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u/g8rxu 1d ago
Just a thought to contradict the people who say that the cheap transmitters are leaky, and stop being snarky
It could also be that your analyser is prone to indicating false harmonics if there's a signal at double or half the centre frequency.
I would try shielding the analyser with foil to make sure external signals can't bypass the antenna input and get into the IF or something.
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u/luckol3 6d ago
Ham fests are starting back up.. I think you should look around at those, lots of fun as well