I have posted if it has a certification a user doesn't have to know anything else other than it's legal to use. BUT...we, or the majority of us that do this hobby are more electronically/mechanically inclined then most and we do know the certification of this even as it comes out of the package with stock rubber duck antenna on "low" power has a question mark.
It is really very easy to bring this into ball park compliance as it is really a decent transmitter with good audio and all harmonics as I tested on the TR-508 are far below the max allowed out of band. I only had it for a day when a music store here was selling them.
You can use a spectrum analyzer as a field strength meter. The TinySA hand held model measures signals over the air and is accurate. The analyzer can be used with the 12" antenna it comes with.
It is very simple to open the case of the transmitter and remove the top cover. You are looking to put a 50 to 75 ohm(experimentation will tell) 1 watt resistor across antenna to any ground point on the board.
The Tiny SA is measuring in dbm and at 3 meters from the transmitter antenna with the transmitter antenna and analyzer antenna vertical and with no audio, carrier only, you want to see maximum -60(minus 60) dbm which will bring you into ball park legal in the USA.
Experiment with a few resistors and see it's effect on the radiated power to get the reading at no more than -60dbm. With this measurement the higher the number the lower the field strength. Centre the frequency you are doing this with and have a start stop of 400kLz above and below selected frequency.
Don't use a Tecsun radio for this. Also have open space no objects in between the transmitter and the analyzer. It's already certified and you are just being safer using it.
This isn't certified for Canada but if it was I would do this procedure.
It appears that at least one so-called 'expert' over at Hobbybroadcaster (why not call a spade a spade) has insinuated that you had nefarious intentions when you purchased your TR-508. There were some dubious thoughts prior to this one, and I'm sure others will chime in after the fact. Obviously they 're making these comments with only partial information, either not reading or perhaps understanding previous posts here about the TR-508 (and similar transmitters) and the discussion on differences between Part 15 certification and compliance. As well as who is ultimately responsible (as defined by the FCC rules) if a certified transmitter is not compliant.
I guess we have to count our blessings, however. Luckily they're not so paranoid and biased against Part 15 FM that they're driving around measuring stray signals they come across to see if they're compliant. Oh, wait....
@artisan-radio I didn't see that, I should check this out. It seems that the other forum's "experts" over there are spending a lot of time reading this one so maybe this one is the real reference for hobby broadcasting!
But if they read everything I post those experts would know I had it for one day and returned it as it was not legal here but while I had it I checked it out to see how it operated. The store info said part 15 AND Canada RSS-210 which I found out after was not true and wrong info and I told the store about it and they changed the description and stopped selling them. If there's a question about certification why don't the wannaby agents there contact the FCC and go after them, not criminalize the user that sees FCC certified part 15. The fact is it did get approval and you can't fault anyone for using it assuming it is legal. The onus is on the lab and the company that got it approved, not the end user.
I was also, as I know this is being read over there, giving some info on how to bring this transmitter into compliance without needing a $20,000 piece of equipment. I was telling people how to be legal, with any transmitter for that matter, but you didn't read that part.
Also if you read my posts you will read that I am in Canada and I use a certified Decade MS-100 not the Retekess TR 508 and I have this posted in the section "my station" just that.
I wouldn't worry about what those guys say (and they're saying more).
I also personally find it amusing when I'm called illiterate by someone who can't spell and doesn't know enough to use a spell checker.
And as far as I'm concerned, this Forum is the real reference for legal, unlicensed broadcasting. Those guys aren't interested in helping others. They're just in it to feed their own egos.
I just went into the Canadian REL to see if the Retekess TR-509 is in there (Retekess claims that it is IC certified on their web page).
I could not find it, and I also discovered that the TR-508 has been removed. So, at least theoretically, it can no longer be used even for RSS123 in Canada. I say theoretically, because it was in there, and likely some purchased the transmitter because of it. I don't know where the onus is if a device has been certified, and then it's not. Is it the responsibility of the end user to keep checking? That doesn't seem right.
There's really something wrong when a device is certified, and then that certification is rescinded without notification. There should at least be a section in the REL or the ISED website which gives the reasons why. In the case of the TR-508, it can't be because of the multiple power levels, as other RSS123 certified devices have adjustable power levels as well.
I can certainly understand why the TR-508 isn't RSS210 or BETS certified. How it could be Part 15 certified is beyond me, but then, maybe it's gone from there as well (I haven't checked recently - which again, shows a real problem, as that check has to be done manually).
I'm also not totally discounting that it (and the TR-509) might still be in the Canadian REL, but under a different name, or a different company name.
I think a change has been done in the USA as well.
Look at this carefully, The lab was in California and it says here part 73 not 15. Look at the company's FCC certification# and the number is dash 73 for the last part.
I will check the number that is there for IC if I can get a picture good enough to see it clearly.
Amazon won't let me copy/paste link here but check on Amazon.com CZH 05B and the info is there.
Here's the picture from Amazon for the CZH 05B
Definitely not approved for Part 15 use. If you look at the current lab report in the FCC database, it also doesn't mention Part 15 approval.
So the question becomes - is the onus on the purchaser and user to keep up to date with the certification status of these devices? And shouldn't there be a better way to find out that status other than to scour through reams of detail? And what about those devices that were sold with Part 15 certification stickers?
I can see the argument for user responsibility for licensed broadcast devices, where you typically have engineers responsible for their correct operation. But we're talking about consumer-oriented devices here, or at least, we were. Now they're classified as broadcast devices.
It was only by accident that I came across this information, and started to ask questions.
@artisan-radio OK here's the original FCC #2ASVO05B7CT200 which was FCC ID part 15
on the FCC ID page with the documents so seems to be two certifications or the other has been cancelled Haven't checked. Can't find a readable picture of the IC number still there on any of them.
Ok checked the original FCC # and here it is with info.
https://fccid.io/2ASVO05B7CT200
Confusing! Seems to be a lot of numbers! This actually shows the CZH 07B 7 watt one!
one big screw up if you ask me.
FCC IDENTIFIER: | 2ASVO05B7CT200 |
Name of Grantee: | Guangzhou Chuanzhou Electronic Technology co., Ltd |
Equipment Class: | Part 15 Low Power Communication Device Transmitter |
Notes: | FM transmitter |
Grant Notes | FCC Rule Parts | Frequency Range (MHZ) |
Output Watts |
Frequency Tolerance |
Emission Designator |
15C | 88.1 - 107.9 |
Now here's another number for the TR-508....part 15!
Crazy! All info is here so to answer your question if it still says certified part 15 you can rightly assume legal to use.
https://fccid.io/2AAR8TR508
Yeah I found the IC number on the FCC photos of the label. 23503-TR508 and that's all you should have to put in and as you found it's gone!
So the question is, what is the responsibility of the transmitter user if the transmitter suddenly disappears from the certification list. Particularly in Canada, where it has to be certified to be used..
In the case of RSS123, a licensed service, it's obvious. You can't use it, as ISED won't issue a license for the device.
But what happens with an RSS210 or a BETS user? They likely won't even know that it is no longer certified.
It would also be a concern in the U.S. with these questionable transmitters that are Part 15 certified. As long as they are certified, it should be OK to use them (unless an FCC agent tells you otherwise, of course). My take is that as long as they have that certification sticker, it should be OK to use, but who knows?
I better take a look at the certifications! The Decade was certified in 1998 and the BVE was certified if I remember early 2000s issue 7 when RSS-210 had the two field strengths allowed and is there in the REL but I will check Decade today! I wouldn't think certifications expire.
This thread has got me wondering about transmitters that contain a certification number (at least in the U.S.) but have come to be considered uncertified by whistle-blowers without proof of whether the FCC has withdrawn their certification number. I have four Scosche transmitters that are marked certified but contain FM frequencies not permitted under Part 15, namely 87.5 to 87.9 MHz. I bought these at Walmart for $10 each. I use one of them to transmit stereo audio from my analog turntable to a digital work station, which takes under an hour every few weeks.