Cheap Good FM Transmitter
- Thread starter Baron
- Start date
JohnsRdChristmas
Full time elf
Depends what you need it to do,
I use a cheap ebay FM transmitter - Gives a good 100mtr range which is enough for what i need. Just had to solder a length of wire and good to go.
I use a cheap ebay FM transmitter - Gives a good 100mtr range which is enough for what i need. Just had to solder a length of wire and good to go.
DSP PLL 87-108MHz Digital Wireless Microphone Stereo FM Transmitter Module Board | eBay
The use of advanced digital audio signal processing (DSP) technology and FM modulation phase-locked loop (PLL) to make sound more realistic, more stable performance, long working hours without frequency offset.
www.ebay.com.au
Those cheapy $5 FM transmitters work okay.
I used one in 2019/2020. On board USB audio card isn't that bad either. FPP and Windows recognises the USB audio.
I have noticed a difference in quality between my new SignsTek unit. The quality difference is something I would sneeze at given the huge price difference.
I'd easily go back to it as a backup (now that I have a more powerful unit).
Biggest complaint for me was the signal didn't travel well, even with the recommended wire length for antenna.
The signal goes almost 140m on my new SignsTek unit in 0.1W mode. Stock antenna is short.
On the cheapy $5 unit, the recommended 70cm bit of wire got me 30m outside the house.
For the price, go with the cheap $5 one off eBay/Aliexpress. Nothing to lose here.
If you've got $80 (been on sale for less than $50 at times) then get a SignsTek (also rebranded under CZE).
[*USD]
I used one in 2019/2020. On board USB audio card isn't that bad either. FPP and Windows recognises the USB audio.
I have noticed a difference in quality between my new SignsTek unit. The quality difference is something I would sneeze at given the huge price difference.
I'd easily go back to it as a backup (now that I have a more powerful unit).
Biggest complaint for me was the signal didn't travel well, even with the recommended wire length for antenna.
The signal goes almost 140m on my new SignsTek unit in 0.1W mode. Stock antenna is short.
On the cheapy $5 unit, the recommended 70cm bit of wire got me 30m outside the house.
For the price, go with the cheap $5 one off eBay/Aliexpress. Nothing to lose here.
If you've got $80 (been on sale for less than $50 at times) then get a SignsTek (also rebranded under CZE).
[*USD]
TerryK
Retired Elf
Be careful how cheap you go. During development of FM radio transmission in the 1900s, the US choose a 75uS (micro-second) transmitter pre-emphasis while just about everyone else choose 50uS pre-emphasis. Most of the cheaper FM transmitter units on Amazon and just about everything coming out of China will be the 50 uS units. Non-US transmitters when listened to with US receivers will sound 'bassy'. Treble frequencies will be low actually. To obtain a 75uS pre-emphasis unit one is probably looking at the $100 range or higher.
You did not ask but unlicensed FM transmission in the US is limited by Part 15 of the FCC regulations. They keep tweaking the rules but presently the limit is a field strength of 250uV/M @ 3M (250 micro/Volt per Meter measured at 3 Meters). They loosely translate this to a receive distance of an approximate 200 foot radius.
The CZE-05B model is mentioned rather often and there are units very similar to it. I suspect with nearly identical electronics. You might look at the "Whole House Transmitter" on Amazon. It is 'supposed' to have switchable 50uS and 75uS pre-emphasis built in and be not only FCC certified but also FCC Part 15 compliant.
You did not ask but unlicensed FM transmission in the US is limited by Part 15 of the FCC regulations. They keep tweaking the rules but presently the limit is a field strength of 250uV/M @ 3M (250 micro/Volt per Meter measured at 3 Meters). They loosely translate this to a receive distance of an approximate 200 foot radius.
The CZE-05B model is mentioned rather often and there are units very similar to it. I suspect with nearly identical electronics. You might look at the "Whole House Transmitter" on Amazon. It is 'supposed' to have switchable 50uS and 75uS pre-emphasis built in and be not only FCC certified but also FCC Part 15 compliant.
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As Terry mentioned the CZE-05B is a very popular transmitter. I used one for years until I upgraded to an EDM. The EDM at 3-4 times the cost wasn't worth the money in my opinion. I think I paid about $40 for my CZE05B but thats been a few years. They arent "cheap" but less than $100 USD on Amazon
I'll mention that there is a CZE version with an output of 7 watts. This is over-kill and breaches transmitting distance/power.
The 0.5 watt version is what we are referring to.
I don't know anything about your US rules about this 75uS vs 50uS. It's been mentioned many times in presentations for these cheap eBay $5 units. I haven't heard anyone have a problem.
This is the one I am referring to and have used with success. As far as I can see, it is the same as the one posted above from eBay.
FM transition is stated in here with this cheapy unit.
View: https://www.youtube.com/watch?v=9-vYg82kdIQ
Given that many use this type. It's probably legal to use in the United States.
[Happy DMX. 512th post].
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HoHoHo stick. What a difference between the word 'this' and 'there'. Serves me right when writing something then changing a whole sentence without proofreading again!
Intension was saying that there is a version that exists.
TerryK
Retired Elf
A few comments not in any particular order; pre-emphasis and de-emphasis technically are standards rather than rules and while not certain are I think maintained by the NAB (National Association of Broadcasters). The standards are in place to minimize high frequency noise in what one hears in broadcast systems. As FM technology improved and to help keep the world somewhat on the same page, I would think the ITU (International Telecommunications Union) has a role in those as well.
The US FCC rules dictate how transmission devices 'must' operate within the US borders and as it pertains to this thread, Part 15; unlicensed FM transmissions. Part 15.203 states that the antenna must be of a design either permanent or with a unique connector as such that no antenna other than one of original design can be attached. That means the very low cost PC Board no antenna transmitter is illegal. It also means that as soon as one changes (different in any way: cable, length, or type) the original antenna the transmitter looses its legality.
Part 15.239 pertains to unlicensed FM band (88 to 108 MHz) transmitters and states the 250 uV/M @ 3M limitation. There's a bit more in that one too dealing with bandwidth. At one time, the FCC defined low power as 100 mW input to the final RF amp of a transmitter and for some services still do I think. Somewhere in the past, the FCC realized that various efficiencies of RF amps from different manufacturers and types/designs of attached antennas put the radiated power (and transmission distance) all over the map.
All interesting reading if ones eyes do not glaze over. For those interested, the FCC also has a Bulletin OET-63 for your reading pleasure.
I watched the video and agreed with nearly all of it. Points where I did not: quality of some of the sound chips in PCs. Some are quite decent, others as mentioned produce decent noise. The parts where FM transmission distances were discussed and the dipole antenna change. And finally, SWR which came from a question at the end. Thinking a bit more about SWR as such. I am inclined to think that if the FCC part 15 is followed and if the manufacturer of the transmitter designed the RF amp and antenna properly, the user does not need to be concerned about SWR. SWR (Standing Wave Ratio) by the way is a measure of how close an antenna is design to operate on the desired frequency. The rubber duckie antenna on the CZE-xx (and other) transmitters are likely designed for the low 90MHz frequency; somewhere in the near middle of the 88 to 108 band.
Apologies for the novel. Quite a bit of this applies US only but I am fairly certain other countries have regulations similar in place. I also had to refresh the memory on some of this and while I think everything I said is accurate, please correct me if not. Cheers.
The US FCC rules dictate how transmission devices 'must' operate within the US borders and as it pertains to this thread, Part 15; unlicensed FM transmissions. Part 15.203 states that the antenna must be of a design either permanent or with a unique connector as such that no antenna other than one of original design can be attached. That means the very low cost PC Board no antenna transmitter is illegal. It also means that as soon as one changes (different in any way: cable, length, or type) the original antenna the transmitter looses its legality.
Part 15.239 pertains to unlicensed FM band (88 to 108 MHz) transmitters and states the 250 uV/M @ 3M limitation. There's a bit more in that one too dealing with bandwidth. At one time, the FCC defined low power as 100 mW input to the final RF amp of a transmitter and for some services still do I think. Somewhere in the past, the FCC realized that various efficiencies of RF amps from different manufacturers and types/designs of attached antennas put the radiated power (and transmission distance) all over the map.
All interesting reading if ones eyes do not glaze over. For those interested, the FCC also has a Bulletin OET-63 for your reading pleasure.
I watched the video and agreed with nearly all of it. Points where I did not: quality of some of the sound chips in PCs. Some are quite decent, others as mentioned produce decent noise. The parts where FM transmission distances were discussed and the dipole antenna change. And finally, SWR which came from a question at the end. Thinking a bit more about SWR as such. I am inclined to think that if the FCC part 15 is followed and if the manufacturer of the transmitter designed the RF amp and antenna properly, the user does not need to be concerned about SWR. SWR (Standing Wave Ratio) by the way is a measure of how close an antenna is design to operate on the desired frequency. The rubber duckie antenna on the CZE-xx (and other) transmitters are likely designed for the low 90MHz frequency; somewhere in the near middle of the 88 to 108 band.
Apologies for the novel. Quite a bit of this applies US only but I am fairly certain other countries have regulations similar in place. I also had to refresh the memory on some of this and while I think everything I said is accurate, please correct me if not. Cheers.