After many comments, I checked all rigs also with my Spectran V6 and it proved that the spike at 3GHz is from the Spectrum Analyzer. So the RT85 and the IC-705 are clean, the Baofengs not
When I was staying more than 3 months in Switzerland I purchased a used Yaesu handheld on Ricardo. Shortly after 2 officials from Bakom knocked at my door at my temporary home in the Ticino. I explained that after 3 months I was using APRS via the Sunrise mobile network. They had all copies of the Ricardo transactions and explained that if I had bought a Baofeng they would confiscate it unless I could prove that it was permanently disabled from transmitting. They tried to sell me a Swiss license on the spot. They also had copies of my ham license exam of 1976 and my certificate of technical leader made in 1980. So much for "Big Brother".
Very interesting! Your spectrum analyzer is a scanning (swept) instrument, not a real time analyzer . Try to narrow the sweep to the frequencies close to the transmitter frequency. Or even to the suspicious harmonic or mix frequency. It will not be realtime, but it will sweep faster, and thus let you have a peek at what's going on . It may also shift your birdies off so they disappear from where they fooled you. Also try to add a "barrel" or piece of coax in your stack of pads. There may be a resonance in your stack. If the picture change, there you are. And the spike moving in the opposite direction is in my eyes just as you say a sign of a mirror image. I cannot think of anything else. I have been postponing measurements of my handies for some time. But you kicked me in my behind. And if a realtime SA passes by in our offices, I will not let it out immediately. ;-)
Adding an additional 10dB reduced the effect, but it did not disappear. The pre-amp is disabled and I played with the internal attenuation. But so far it did not disappear :-(
When you're directly connected to the radio, there could back stream radio connection by capacitance, ignoring the filterance. I have Baofeng BF-F8HPP.
I can confirm, my UV-5R puts out harmonics with 50dB attenuation at best case (70cm low power) and about 40dB worst (2m high power). I did not use that radio for transmitting for a long time since another ham gave me his old Kenwood TH-D7 for free which puts out harmonics with 60dB attenuation in the worst case.
I tested three which all were in this range as well
2 года назад
Kenwood TH-D7 for free? Wow. It's a great transceiver, only slighty beat by its successor, the TH-D72, by a little bit improved software and built-in serial adapter. To this day, I don't know of any other similarly equipped handheld transceiver on the market. Its terrible battery (NiCd with NiMH packs available from Germany) and its size was the reason why I went for TH-F7 as my daily driver and I keep the D7 for satellite work, portable and other scheduled activities. I made a barrel jack to XT-60 cable and it works great with 3S Li-Poly pack.
Very interesting problem! I wonder how difficult it would be to make an external low loss filter to fix the harmonics issues. I guess if you can bring the harmonics under the limit, it becomes "legal" again?
Unfortunately, we have to distinguish between „commercially available“ products and DIY. DIY is treated as an exception from the laws and is only allowed for licensed HAMs. The max. Number is 5 per design if I remember right. Here you must not harm others. If a supplier decides to sell a product it has to fulfill the law. Otherwise it is not aloud to be sold or imported. Technically, you are right. However the cutoff frequency is not easily to determine for a dual band handheld. P.S. nice to see you on this channel ;-)
@@HB9BLA I kind of enjoy you content here more :D I was thinking about this topic a bit, and you would need separate filters for the 2m and 70cm bands - no dual use - the 2m has a harmonic right in the 70cm band so that won't work. What do you mean by "max nr. 5 per design"? Also I fully agree a commercial product should be legal and compliant to begin with, however since this product is quite popular for beginner ham's, fixing it, by adding an output filter, could be a nice fun project.
@@FesZElectronics Somewhere I read that the max. number is 5 (maybe to distinguish between "commercial products). But unfortunately, I did no more find this text. It definitively would be an interesting project. However, it most probably would not be used because it seems nobody really cares...
@@HB9BLA I was reading about reviews and modifications for this handheld, and one topic that was mentioned was that a "better" antenna helps with emission but makes reception worse - I guess it picks up more noise and strong local transmitters (like FM); I'm thinking that the above filter, should help with reducing the out of band incoming signals and make the device work better. So it should not just help with harmonic emissions, it might improve reception - this is something users should definitely care about :D what do you think?
That would be a wonderful explanation! Because so far, I have not found the reason. But it seems to come from the analyzer, not the rigs. Which is good news :-)
I tried it with my Spectran V6 and did not see a signal. But it is not easy with these broadband SDRs. They also "see" the fundamental and easily can be overhelmed...
The Baofeng handheld is not allowed in Germany and as I learned now in Switserland but still no peoblem in NL. You found already that the spike you couldn't explain is coming from your SA. I just bought a Tiny SA for about 70 euro an amazing piece of work. You have to try it. BTW nice video
I think you may be overdriving the SA. Also I would, never connect a Tx directly to the SA (I have the lower bandwidth version on the siglent, so I don't see that spike) I use an RF sniffer that has a 20db attenuation between the main RF path and the sniffer output, then I add additional attenuation if needed to bring the signal down to about 0dbm In this test you are not really interested in absolute power, but just the difference between the main signal and any harmonics. If you don't have an actual sniffer ( I picked up mine on ebay for about 20 GBP) feed the output of the rig into a dummy load. There is usually enough leakage for a simple e field probe on the SA to pick up enough signal to work with. Andy
You are right. In the meantime, I added more attenuation, and the problem became smaller. I like more to work with attenuators than with a sniffer because I can check them out on all frequencies and usually, they are +/-1dB. And I checked the signal with my Spectran V6 and did not see anything.
So I am not sure if my experiance has any meaning for your measurement problem, but I was trying to do some audio THD measurements with some pretty expensive scopes at work and discovered that pretty much all oscilloscopes have pretty high THD. So the problem might be that you are measureing the distortion of your signal analyzer. This is why you use a notch filter on the fundamental in order to measure THD.@@HB9BLA
Interesting video thanks. Passive intermodulation spur at 3GHz maybe? Congratulations on the new channel I really like the technical side of Ham Radio. Perhaps you can take a look at the interesting project from Russia called Hfpager.. Possibly some scope to link our IOT sensors via HF radio/NVIS maybe? Best wishes from Cape Town! 73.
Interesting project! Maybe it would work with the new QDX of QRP-labs. But for a sensor, we would need an inexpensive and small transmitter like the "Walkie-talkies on a module" for VHF and UHF. I cannot imagine to use my IC-7300 just for one sensor ;-)
Here in HA land we are often recommended to get an UV-5R as our first handheld (or even first radio). Still illegal, but hardly ever enforced. (no, I did not get one. I'm waiting for my Yaesu, damn the chip shortage)
Looking at yours spectrum analyser, the dynamic range appears to be close to 60dB. You could be driving the first mixer quite hard. If you repeat the measurement with say an additional 10dB of input attenuation, does the artefact drop by the same amount? Ah. I didn’t read previous comment… You also don’t need to drive straight into the analyser. A loose coupling to a dummy load (or the antenna) will give you the fundamental and any radiated harmonics.
Its dynamic range can be higher, but not at this RBW. But I agree that it has to do with some internal mixer (s). I tried to add 10dB attenuation and it was better, but still not gone. I compared now all handhelds on my Spectran V6 with loose coupling and there was nothing on this 3GHz spot from the RT85 and the IC-705. The Baofengs had spikes on many harmonics ;-) I consider this as proof that the spike comes from the SA itself.
Those odd signals many harmonics away from the fundamental are always problematic. They can occur due to non-linearity in any part of the measurement system. Thus you have to calibrate everything in the signal path, like the cables, connectors, attenuators, etc. When I worked at a lab that did testing professionally, we spent 3-10 times longer calibrating all the parts of the system, than we spent actually measuring the system. Good Luck! :-)
@@HB9BLA - As far as I could tell, it’s caused by frequencies above the Nyquist limit creating aliases. The frequency of the 3GHz artefact moving lower as you increased the VFO frequency made me recall something similar that I’d read before. I’m keen to know what’s happening as I have an IC-705 too.
@@HB9BLA - I have definitely seen this issue described before in something I have read. I’ll have a further look today - I have four books on testing and the like that it may feature in.
I now checked if I find any info about the sampling rate of the SA. But I did not. If I recall right, it multiplies the signals to above 3GHz and mixed them down. Maybe something goes wrong there...
I have tried to "import" Retevis RT85 to Switzerland, and it was captured by BAKOM 🙂They wrote me that they will test it, and depending on the results of these tests I will get the device or an invoice... Keep your fingers crossed
@@HB9BLA SRC RYA- I was planning to use device on the boat (not in Switzerland). Yet BAKOM is testing the device, not license (I hope...). I'll report back with the result.
@@tomekdziekonski7478 So we will see what they say. These devices can be used on many frequencies outside the legal range and its power is also too high for non-licensed applications. Send me a Twitter or messenger message if you have the results.
I wonder if it is the length of the cable. 3ghz is 10 cm, and your cable looks like it could be a multiple of that? Try a few different cables if different lengths and see if that peak changes.
Another thought provoking video - Thank you Andreas. Regarding the attenuators - Have they been calibrated? As the objective is to measure the Db comparison between the primary frequency and the harmonics, this may be less of an issue for 1st harmonic, but have the attenuators been checked that they have the same attenuation across the range being measured ? G1GRW
And all of them Boafengs are still being sold on Amazon Germany and all of the other amazon stores. It bothers me a bit since a lot of non licensed people are interested in them to unknowingly 'play' with it as a sort of long range PMR.
Hello Andreas, THe IC-705 can be hacked for CB bands, Andy Kirby did this but his video was banned (or he removed it) after ANCOM in UK complained. Regarding LoRa Gateways for thingsnetwork, is the SX1302 a good fit? Thank you, DE1CTL (Swl)
40 years ago my FT-277 was also able to do 11m. Of course we never tried ;-) The SX1302 is one of the standard gateway chips. I think they have now a new one. But this one is still used everywhere. It is not for sensor nodes.
Was passiert eigentlich, wenn man wirklich mal ohne Freigabe sendet? Steht dann 10 Minuten später die Bundesnetzargentur vor der Tür? Ist es ok einen Impuls von wenigen Sekunden auszusenden?
Would really like to see how you can make your own 433mhz rf sender. And by that I mean imitate such a cheap module so that I can process it in my own pcb. I've tried several schemes online but can't seem to get it to work. I can't seem to find any info on how to troubleshoot this.
@@HB9BLA No, but I also just mean those simple transmitters that you can also find in your doorbell, for example. Or do you even need a degree for that?
@@HB9BLA oh really yes? thought this was just something harmless. Just wanted to make it as a lamp switch in my own project and own pcb to develop myself a bit.
@@matheokoning4456 AFAIK all/most countries requires a license for manufacturing of transmitters. This is to make sure the designer knows how to keep the device within legal limits - the harmonics showed in this video is one example on how easy faults can appear. (Disclaimer I'm not a HAM but interested and did my military service in "signals")
@@HB9BLA Thanks for responding. I'd like to restart but have not really found relevancy since cellphones have taken over the wireless communications scene. Although, it's a nice hobby. I wish you more power and 73s!
Baofengs aren't illegal. Hams are allowed to transmit in their own bands with any piece of homemade junk they like, and as long as the harmonics are in-band then no one cares. Ham radio is about experimenting and making things and not caring too much about the commercial rules - not what the self-appointed band police will tell you, but their hobby is policing, not "radio".
I agree, and I for sure am not against experimentation. But I think we have to comply with the law. This is also the reason that we are asked to pass a test and get a license. Otherwise this would not make sense for me.
Baofengs are only illegal for non-hams. Also on the ham bands no one really cares about the rules, and certainly no one cares about the band police. Do what you want on ham radio. It's only important to not interfere with someone else doing what they like.
Very good point. That’s why we have harmonically related bands available to us. Most of the licence relates to staying in band and how to deal with annoying non-hams as far as I recall.