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Post by thelegacy on Jul 21, 2017 7:20:43 GMT
The New Radio Revolution has been silent for a while during some important Interference testing on some of these transmitters using the BH 1404, 1415F chips. Some details of the tests are only available on the Elite section (For obvious reasons) but we'll point out the tests that can be posted on a public forum as Everyone should know this and the FCC should be happy we're testing and trying to put a stop to a would otherwise be a public endangerment.
There is a nasty 15.2 Mhz Image that plagues the Ramsey 100B and many of these transmitters. This also includes the CZE-7C (tested on a dummy load) as well and the image will either show up as a quiet dead carrier or has audio along with it. It can go quite far and seems to go further as the power gets past a certain point. It may not show until your power is above a certain level.
The tests does sort of reveal an issue with broadband amplifiers inside some of these transmitters. Some frequencies you transmit on like say 92.9 with its 15.2 Mhz image could wind up on 108.1 Mhz (The beginning of the Aircraft band). We really need to be diligent in testing and please report your findings and with what transmitter. Our NRR test person is going to try and find ways to eliminate this dangerous issue and we really need to have a meeting on this issue because all of us (Legal or not) needs to know the cure so we can fix it.
We have not tested the 1417 chip and there is a newer one too out that should be tested to see its abilities. The CZE-T200 also needs extensive testing to see if the interference issue occurs even at high power. For some reason it seems to be really clean and funny thing is that it is the cheapest TX. Some claim that at High Power it beats the 5 Watt TX with an outside antenna connected to it while this unit was just using a rubber ducky antenna (Nothing More). This is really something interesting.
In New Zealand your allowed 1 Watt so if any New Zealand member wants to test and report they sure could and let us know what you get. Also with the CZE-15B variable from 0-15 Watts. Does this TX do the 15.2 Mhz Image? If so we need to know.
We'd like to talk about this issue at the meeting and welcome real testers to join the Initiative and I'd give you Elite Access. WE need to reveal tests like we've found. Thanks to you all in advance for your interest in this.
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Post by Deleted on Jul 21, 2017 9:25:13 GMT
Looking For the Spurious Emissions
It is probably common to think that harmonics and other spurs coming out of a transmitter will tend to be above the main frequency carrier, but they can also happen at lower frequencies as TheLegacy has just demonstrated by finding the 15.2 MHz image, which is down in the shortwave band.
I know that my AMT3000 AM transmitter at 1550 kHz puts an image at 650 kHz, right on top of WSM in Nashville, but luckily I only hear it on one radio very close to the transmission antenna.
Radio8Z has explained that the 650 kHz "ghost" is not being generated by the transmitter, but actually is being produced by the receiver for some reason which he explained.
That may also be the case with the 15.2 MHz discovery, but it is too early to know for sure.
I will put several of my FM transmitters through the test and see what turns up.
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Post by thelegacy on Jul 22, 2017 1:47:37 GMT
Thanks Carl. Me and Station8 were in Different locations and used different Radio's and still every 15.2 Mhz above or below your frequency you can hear a dead carrier or audio. I was REALLY coming in on 27.405 (Channel 40 on CB). I could clearly hear what song I was playing and this happened for well over 75 feet from the transmitter antenna outside (And my antenna was a magnet mount CA-200) FM antenna. Imagine what interference would had been caused if I were to have bought the comet antenna or the Ultimate FM antenna sold by Radio Brandy.
I'm thinking that Veronica TX is looking better and better all the time to block that crap. It has far better filtering and is well built. Its NOT a toy so I'm sure it has got to do way better than this crap sold to the Hobby Radio community.
You should be able to Flycast with it for those of you who are into only that. Hell just use a dummy load for the antenna and keep your power down. Remember its variable 0-30 Watts so just creep the pot till you get the range you need and leave it.
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Post by Boomer on Jul 22, 2017 3:23:41 GMT
I'm glad you, thelegacy and Station8 are doing some tests, someone should do them with all of the current transmitters, it will just cost a lot of money to buy them all!
I used to see a site many years ago that covered the then-current crop of FM transmitters and did comprehensive reviews and scope analysis on the likes of Veronica, Panaxis, Broadcast Warehouse, Ramsey and possibly others.
Technology moves on fast though, a transmitter site should be updated every year at least.
For people wondering why to use a transmitter with more power than needed, then put a dummy load on it, it's because the transmitters with more power tend to be higher quality, use much better filtering, making you a better neighbor on the radio, even with the power cut back to what you can use properly in your situation. Not only that, they often have superiour sound quality, and audio filtering, pre-emphasis and separation, for a signal you can be proud of that's far better than the standard broadcast quality today, if you're a quality-conscious broadcaster.
As for your post there's the antenna factor that could allow more harmonics and spurs to get out. All the little desktop transmitters like CZ style ones come with Rubber Duck antennas. It's sheer luck if one of those is even near resonant.
RF filtering in the output of the transmitter, like low pass filters should see a resistive impedance around 50 ohms on the antenna jack. The Rubber Duck could be so far off that it will upset the output filter, and could cause more harmonics and spurs to be transmitted.
Most resonant antennas, like a dipole or ground plane, if tuned for a proper match to the transmitter, will naturally attenuate the second harmonic at least. It's resonant at the third harmonic again, but by harmonic 3, (example 300 mhz for a 100 mhz signal) the low pass filter should be doing some pretty strong filtering.
Glad to see your work at trying to keep stations safe and interference free, keep it up!
Boomer
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Post by thelegacy on Jul 22, 2017 5:08:08 GMT
Yes Boomer rather you decide to go over the limit or not interference is a problem.
I have seen this happen even on certified part 15 transmitters like the whole house 3. But keep in mind that the whole house three can also be turned up to higher power. At the higher power it will go a mile. I did notice on my whole house FM transmitter 3.0 that at high power I can cause the entire FM band to have a loud static sound in this pretty much wiped out the entire FM band. This occurs for a good 50 foot.
Keeping this in mind and being a good neighbor this could be a real problem in these type of complexes where there are four houses to one building.
I think the real reason why some people get busted even though they are transmitting on a fundamental frequency that is far away from any license station what they're not realizing is that their transmitter is causing Spurs and interference and people begin to complain about it. They might not complain to the person who's actually doing the transmitting one of the neighbors decides to call the police or the authorities about it. And then it's game on the person gets nailed often not knowing what is really going on.
I'm going to call a spade a spade and say that not everyone follows the rules and goes exactly the limit. Rather they want to admit it or not. This is another big reason that we at the new radio Revolution is trying to stomp out this interference problem. And don't think that hiding behind the false sense of security of certified transmitter is going to get you out of the interference problems. It seems like these transmitters are the ones that are doing it.
The funny thing is that transmitter like the Veronica and several others are far more Superior and don't cause this interference problems. I would like to see what the source FM transmitter does the one that is one Watt and is supposed to be part 73 certified.
The funny thing about that transmitter is that it does come with a rubber duck and it is a SMA connector on it. I would really like to see what type of interference issues that transmitter may or may not cause and I wonder if the power of that transmitter with less interference would actually get you out further.
Look I've always been the big FM guy in this bunch. And knowing all of these things and being a big FM guy I think it's time that we do try to come up with a good solid cure for this interference problem and one that would be something affordable for everyone.
I'm sure the FCC would rather you have a clean transmitter than a dirty transmitter. And it seems to me that some of these supposed certified part 15 transmitters are one of the worst noisemakers on the FM dial that there is. I wish I did have a spectrum analyzer because I would definitely show some of the transmitter that I own and what they actually are doing.
Maybe it's time to get more members of the new radio Revolution and maybe charge dues or something like that so that we could actually do more experimentation with these transmitters and then work on modifications that will stop the interference issues. That in itself will help everyone in the long run this I do believe.
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Post by thelegacy on Jul 22, 2017 5:30:51 GMT
For the ones who want to get out and you know what I'm talking about more than just a fly caster or they still want to be a flycaster because this one is also variable. The seat zet 200 is a transmitter that some of the members of the new radio revolution has used.
Range test of that transmitter by that member that owns it reportedly was around a mile. The good thing about this one is the member claims that it is almost as clean as the Veronica.
This is staggering news because that transmitter is only $40.
My step-mom owns the c z e t 200 and I can say I did notice a little bit of the effect that the whole house FM transmitter 3.0 has but it's not as prominent. I did notice a much cleaner signal at the high power level as well.
Because she lived 300 ft from a license station I was not able to really do some testing with that transmitter to find out what it's real capabilities was. I do know at the lowest power setting your transmission will only get out about 200 ft. That's at the .01 milliwatt level.
If anyone wants to do testing with a spectrum analyzer that would be the transmitter to really test with. Checking to see if that 15.2 Mhz image is still present is really important as well.
AgaAnd we would like to do some serious testing as a group of people to try and come up with good conclusions. Me being legally blind and have a fixed income makes it hard for me myself to do all sorts of testing with various transmitters unless I get donations from listeners.
I hope to see you guys at this emergency meeting that we're trying to set up. Because I think it is important to come up with better Solutions and hear the report from the actual person who did the major test.
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Post by Deleted on Jul 22, 2017 16:19:48 GMT
Transmitters are certified based on a number of factors. They must generate a legal field strength within the test environment of the lab, and they must have a clean signal AT THAT FIELD STRENGTH.
It's been shown in testing that even if a transmitter is certified in the lab, it may produce a field strength that is far above the legal Part 15 limits in the real world. But at least users can point to the certification as a justification for use (most don't have the requisite test equipment to check that).
You can't do that with these other transmitters. There's a reason for them not being certified (or even being able to be certified). They either produce more field strength than allowed (and are intended to do so), even in a test lab, or their signal is compromised. I'm sure that if they could be certified, the manufacturers would go through that process, as it would increase sales dramatically. So I'm not surprised at these findings.
As for the Whole House, it obviously meets Part 15 interference requirements at the legal field strength or it wouldn't have been certified (it is also RSS210 certified in Canada). Running it above those limits is just asking for trouble.
The only transmitters I'm interested in are those that are legal, and certified for a specific service.
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Post by thelegacy on Jul 22, 2017 19:01:28 GMT
BUT we've found out that even at the LEGAL power limit in some TX's it still is a issue. Now when the power is increased with that same TX it makes the issue worse. Using a filter will help and Station8 wants to talk about this on TeamSpeak tonight so if you can attend please do.
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Post by Deleted on Jul 22, 2017 22:51:54 GMT
I can understand it being an issue even at legal power with some uncertified FM transmitters (although it's difficult to tell if you're legal unless you have expensive test equipment). Part of the certification process is the lab ensuring that the transmitter has a clean signal.
That's why it's unwise to use uncertified transmitters unless you really know what you're doing.
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Post by Deleted on Jul 22, 2017 22:54:23 GMT
Big Hint
"Unless you really know what you're doing."
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Post by thelegacy on Jul 23, 2017 16:32:33 GMT
WE've found out after Carl left the meeting and Bob came on that there is a 7.6 Mhz crystac in the oscillator section of the Ramsey 100B TX. Giving that knowledge 7.6 X 2 = 15.2 Mhz (Tada Folks we may have a winner winner chicken dinner). Now what needs to happen next is to find a way to stop this second harmonic of the oscillator 15.2 Mhz from causing these image frequencies every 15.2 Mhz. Thank GOD I'm on 87.7 Mhz cuz 100.1 + 15.2 = 115.3 Mhz and where is that? The Aircraft band. Like I said THE CERTIFIED WHOLE HOUSE 3.0 DID THIS AS WELL and ALL OF THE TRANSMITTERS WE TESTED USED THAT BH1415F FM/compressor/limiter chip again some so-called certified TX's use.
Remember that the Decade is an expensive rip off of the CZE-05B(Same as Signstek CZE-05B, Fail-Safe CZH-05B with a bypass of the Hi Power capability and instead of the reverse TNC connector has a telescopic antenna). I can almost Guarantee this TX is doing the same thing that we experienced with several transmitters using that BH1415F Chip.
Now if I get enough donations I may prove a point and buy for testing that Source FM 1.2 Watt certified LPFM TX and see if it does the same thing as I'm willing to bet my bottom dollar it is using that BH1415F chip which again we see as a possible problem if their oscillator section is too using that 7.6 Mhz crystal. And I'm confident that our official engineer of the New Radio Revolution knows what he is doing as he has been in broadcasting for several years running.
Defeating this issue is now our goal before trying to ask for more power at this time. We had him do his authorized test and some findings were of alarming news that needs immediate attention FIRST! If we solve it we may post how to correct it.
One ALPB member mentioned he had a Ccrane FM1 and FM2 TX and said he never experienced any of what we have described. To what we want to know is what are they using to tune/transmit on FM? Is it the same Japanese Rohm BH XXXX chip set or did they use a proprietary chip no one else uses?
I guess if we can get folks to join and pay dues we could find out by purchasing a Ccrane and do our own investigation to see if indeed they may be using something different. Also they may use a different crystal in the oscillator section of that TX. We may have to test them to see if we get the image as well as crank them up since there are all kinds of images of the pot needed for that and then see if it starts to throw dead carriers or spurs at these multiples of 15.2 Mhz.
I think I'm gonna save for the Veronica TX that way I KNOW I'm clean. It is well filtered and has a nice clean sound as reported by many including a New Radio Revolution member. Yes its very expensive, but there is a reason its not cheap. They made sure that it didn't cause noise all over the spectrum unlike some other transmitters using the BH14XX chips.
I know there is a NEW BH1417 chip but we have not seen a manufactured transmitter using this one yet. The interesting thing about this NEW chip is that it has the 1 Watt capability right out of the chip (which makes me think that the 1.2 Watt SourceFM transmitter may be using) this is why I want to try this and see what it does but before I do I'll try and get the specs on it and see if they reveal if that is the case that they use the 1417F chip and indeed we can count on some cleaner transmitters in the future (Lets hope for the later).
We at the New Radio Revolution will be vigilant in solving this to help everyone in Radio from the Hobby Broadcaster to the listeners to public safety. This is a problem we'll not just sweep under the rug and forget about it and hope it magically goes away.
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Post by thelegacy on Jul 23, 2017 16:41:23 GMT
Oh I forgot don't forget the image at 27.405 Lower than 87.7 Mhz. This should be YET ANOTHER reason to request that 87.7 and 87.9 be considered as a LEGAL authorized frequency to broadcast on keeping that 15.2 Mhz image in mind. Yes someone asked what would convince the FCC to do just that? Our tests report will definitely do it.
New keep in mind that the experimental license MAY OFTEN require the posting of any data of the test to the FCC so I'm sure Uncle Charlie will now see what we found. I'm sure their not sitting on the fence on this one. I see a recall of some transmitters in the future as well as some new rule making that will make 87.7 and 87.9 your ONLY allowed frequency to broadcast to keep interference from the aircraft band.
Don't think CZERF won't get an Email telling them what we found either. They need to clean up their transmitters. Maybe Brian from Whole House 3.0 should get a ring a ding ding on the tele.
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Post by Deleted on Jul 23, 2017 17:14:40 GMT
Remarkable Day-After Development
At last night's SPECIAL MEETING called by Jeff Station8 to report on "New findings regarding FM transmitters" I was lost in fog because we were hearing about a problem that seemingly made no sense and had no estimated cause nor foreseeable solution.
But today comes this later news: "WE've found out after Carl left the meeting and Bob came on that there is a 7.6 Mhz crystac in the oscillator section of the Ramsey 100B TX. Giving that knowledge 7.6 X 2 = 15.2 Mhz (Tada Folks we may have a winner winner chicken dinner)."
All of a sudden things make sense and Jeff wasn't imagining things and there really was a problem in need of a fix!
This ALPB has the best members!
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Post by mark on Jul 23, 2017 22:53:13 GMT
The main transmitter chip used is not the only thing determining how "clean" it is, there's also the quality of the low pass or band pass filter before the antenna. The better transmitters don't use those BH1415 or related chips. The Broadcastvision, Decade models with the exception of the CM 10, The Veronica most likely not as it's a higher quality level. They use totally different chips and more discrete components. From what I've seen even the CCrane does not use that chip.
Mark
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Post by Druid Hills Radio on Jul 24, 2017 13:07:12 GMT
Carl's FM-30 also uses a 7.6 mHz crystal. It would be useful since he has an analyzer to see what he comes up with.
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