I'd still like to see the test report because some certified transmitters are a nightmare in the spectrum analyzer. We have seen this in reports.
Morningdj, that's NANOwatts, or billionths of a watt.
Clearly, any manufacturer that advertises a transmitter with a 10/100mw power switch is not targeting the Part 15 market, despite any disclaimers that they might make (hey, you might as well try to go after as many sales as possible). In fact, their advertising is very similar to many 'Chinese junk' transmitters, that advertise being Part 15 'compliant'.
And what has to be understood in that disclaimer is that 200 feet range is NOT part of the Part 15 rules. Legality is determined by field strength only. Depending on the receiver that you use, and a whole host of other installation factors, the range of a legal Part 15 FM transmitter can be greatly under 200 feet. In other words, with a middling to poor receiver, you can get 200 feet range and still be well above Part 15 legal field strength limits.
The ONLY way to get legal field strength, even if you can tune the EDM down to 1mw output, is to attenuate the signal. At that point, and depending on the method used, you're really not dealing with the EDM any more, but a whole host of external factors (such as length of the antenna, lossy coax, changes to circuitry, etc.).
And even then, the ONLY way that you know for sure you're operating legally is to measure the field strength. Which virtually no purchaser is going to be able to do, without considerable expense and expertise - and if you had that knowledge and money, you'd be able to get a much better (and more expensive) transmitter, such as the Decade MS-100.
Of course, anyone can do whatever they want, but it just seems like a waste of time to me, particularly when there are so many other, much more useful (to the Part 15 world), reviews that could be done.
Rich said..
"In free space (no reflectors and no path obstructions), a Z-matched, 1/2-wave, center-fed dipole will generate the 250 uV/m maximum field intensity at a distance of 3 meters permitted by FCC 15.239 when radiating 11.43 nanowatts (0.000 000 011 43 watts)."
This applies if you are using the antenna mentioned.
In the Decade MS-100 tuned for BETS-1 the antenna is only 1/4 wave and just the telescoping antenna without the ground side. The max power on the Decade if you turn the RF adjust to max is 1.1 milliwatts and when adjusted to BETS-1 is about 4 turns back and the output power would be around .8 milliwatts.
Tuned to Part 15 would be(same transmitter) the output would be around .4 milliwatts. (with the antenna the right length for 1/4 wave length)
I agree with Artisan about the EDM as even with the 10mW and 100mW settings and continuosly adjustable how do you know when you are compliant? How do you know what the transmit power is unless you have a wattmeter that will measure in milliwatts which probably most people using this won't have.
If you go by the 200ft rule, that differs depending on the receiver, which determines range as much as the transmitter power or antenna.
If someone asks me how far I can go I tell them it depends on your radio...there's no set distance.
Mark
EDM defines "kit" as a unit that requires you to 1. Plug an IC into an already installed socket. 2. Solder the jack for the power source to the PC board. Then Tah-DAH! You've just completed your kit. Not really a lot of chance for you to do something wrong that would effect output power. Oh, and then you get to put it in the enclosure. Or not. It's optional.
TIB
I think it comes in a partial kit form to make it legal to purchase and import from outside the country as it's not as it comes a final functioning unit. EDM may have done their research here. But this wouldn't apply here in Canada.
Mark
How many Feet and inches is the antenna on the MS-100?
The Decade's telescopic antenna is 36 inches. They publish a table giving the proper length for each available frequency.
Mark, I'm not sure where you're getting the power output numbers for the Decade. I do know that it is specified as 1mw for RSS123 use, so the 1.1mw sounds about right. But BETS-1 not only specifies a field strength limit of 100uv/m at 30 meters, but it also states that power output for such certified transmitters is typically under 1 microwatt.
I do know, having owned one, that the EDM is much more powerful than the Decade. I thought it might be possible to adjust a telescopic antenna I was using so that it would meet BETS-1, but even then it handily beat the Decade (at least double the range, even when shortened considerably, and that's in stereo as well, while the Decade was in mono). I was reluctant to take the antenna down too low, as I was afraid of damaging the output transistors, as well as generating inteference - the EDM designed to take a 50 ohm antenna. So the EDM ended up in a closet, and eventually I got rid of it.
The only reason that I can see that this transmitter becoming as popular as it has is its relatively inexpensive price, combined with its powerful (and illegal) signal. It's not even all that great a transmitter. It bled strong inteference into adjacent frequencies, much more than the Decade, on the same car radio - you can't hear any remenants of the Decade's signal on the next channel over, even when located within a few meters of the transmitter. The EDM was prone to hum, even when using regulated power supplies - I never could get it completely out. The Decade is whisper quiet in terms of hum. And the Decade's sound quality was superior. The inexpensive C Crane transmitter sounds as good as the EDM, although it won't get nearly the range (hint, because it's legal!).
The only way the EDM can be sold in the U.S. is in 'kit' form, as it is definitely not Par 15 compliant (nor, according to the disclaimer, do they claim that it is).
Two comments based on earlier posts in this thread...
A) Kits
From FCC Part 15:
§15.23 Home-built devices.
(a) Equipment authorization is not required for devices that are not marketed, are not constructed from a kit, and are built in quantities of five or less for personal use.
Whether or not the FCC considers the EDM FM transmitter to be a kit, it IS "marketed," in that it is offered for sale on the Internet. Therefore its sale/delivery in the U.S. does not appear to be authorized by FCC §15.23(a).
B) Meeting FCC §15.239
Unless all of the conductors in the audio and d-c power supply cables connected to the transmitter are isolated (filtered) for conducted and radiated VHF signals, they will radiate, and add to the radiated signal of whatever conductor is connected to the antenna output.
That will produce an off-center-fed (OCF) dipole, which can perform nearly as well as a center-fed, 1/2-wave dipole.
Specifications for this transmitter show that the lowest r-f output power it can be adjusted to is 1 milliwatt.
But suppose due to impedance mismatching with this OCF antenna configuration, the system radiates only 10% that of a properly-matched 1/2-wave dipole antenna system -- or 0.1 milliwatt in tbis case.
That 0.1 milliwatt is 9,090 times greater than a matched 1/2-wave dipole needs to comply with FCC §15.239, and the free space field intensity produced by that EDM system at 3 meters would be about 95 times greater than the 250 µV/m limit of 15.239.
For the conditions above, radiated power would need to be attenuated by about 40 decibels in order to comply with FCC §15.239.
If the EDM is not pure on a spectrum analyzer it needs to be exposed as a POS transmitter. We need to let people know of these spectrum pollution problem children.
Rich said, "Whether or not the FCC considers the EDM FM transmitter to be a kit, it IS "marketed," in that it is offered for sale on the Internet. Therefore its sale/delivery in the U.S. does not appear to be authorized by FCC §15.23(a)."
Part 15 kits have been around for years, and the FCC appears to have no problems with them. They DO have problems with manufacturer's assembling those kits and selling them without authorization.
True kits are basically a bunch of parts, a circuit board and plans, often with suggested modifications. It would be pretty difficult to give out authorization for these things, considering that each finished product could be different.
At the end of the day, it's up to the FCC to interpret the rules. And I believe that history gives us the correct interpretation - that kits are allowed.
Finally, here is a response from the FCC regarding kits, found on the Rangemaster website (note - the Rangemaster is NOT a kit, so they would have no ulterior motives in publishing the response): "The kit does not require equipment authorization to be marketed (sold) but they would still need to comply with the limits set forth in corresponding sections of part 15. The responsibility of compliance lies on the user, or the person who assembles the parts together, not on the manufacturer."
Now, it's an interesting question as to whether the EDM is really a kit. It seems to be an assembled transmitter, with a few simple components left off, to get around the letter of the law regarding marketing transmitters. I recall the FCC having difficulty with such devices being sold, but I can't seem to find the reference. Any help on that would be appreciated.
"Part 15 kits have been around for years, and the FCC appears to have no problems with them. They DO have problems with manufacturer's assembling those kits and selling them without authorization."
Why is the Spitfire sold then? I am con-fooosed...
Doug
OMG it's still the operator who is responsible when running ANY transmitter. If you are technically ignorant you should NOT operate a transmitter certified or questionability out of compliance.
If the FCC wanted these transmitters to be annihilated they would NOT exist.
Even the Ramsey transmitter has a variable power from .1 milliwatts to 25 milliwatts and yet is still considered to be legally sold.
some of the transmitter antennas that are sold with some of these transmitter are really pieces of junk and most of the signal is lost before it even has a chance to get to the antenna. Also duly note that a horrible mismatched antenna is what causes interference in the first place.
Some experimentation has been done using Nanwatts and different types of antennas and you would be surprised at what you get from very little range less than 150 foot to a range of over a thousand foot with the same input power around 11 Nano Watts.
Then I've seen transmitters of more power into those Rubber Duckie antennas and they don't perform with beans. So with that said I still think we need to come up with a better way of measuring things. Plus from what I'm understanding just because a transmitter is certified doesn't get you out of a NOUO. You could fight it in court and say well I bought a certified transmitter and it was not modified but it's still up to the judge for the final outcome.
Telscoping antenna extends to 35"...1/4 wavelength
Mark
About the Decade I got the figures from the specs on the website and in conversation with Michael at Decade.
The max power the MS-100 goes to is about 1.1 mW with rf turned to max and this is certified for RSS-123. For BETS-1 it's approx 4 turns back.
Besides the one I got from you I also not to long ago purchased a new one in the metal cabinet as I was convinced that there were improvements made since those older ones and Michael gave me a good price that I won't mention here.
The 11 or so nanowatts to produce part 15 or BETS field strength is only with the most ideal antenna as Rich illustrated....a center fed HALF wave dipole in the right terrestrial location. The single element 1/4 wave telescoping antenna like on the MS-100 is still very inefficiant.
Since we are talking about the EDM here to illustrate if I had this transmitter and had it on full 100mW with a very inefficient antenna like a 12 inch piece of wire I probably wouldn't make it accross the street.
Mark
RE: Your statements -
The 11 or so nanowatts to produce part 15 or BETS field strength is only with the most ideal antenna as Rich illustrated....a center fed HALF wave dipole in the right terrestrial location. The single element 1/4 wave telescoping antenna like on the MS-100 is still very inefficiant.
Note that other things equal, "11 or so nanowatts" of r-f power from a transmitter at the feedpoint of an antenna system does not automatically produce the maximum field permitted BOTH by FCC §15.239 and "BETS," regardless of the configuration of that antenna system.
Also note that the power supply and program wires connected to the MS-100 will behave as I described in Reply 23 for those same wires/conditions when connected to ANY transmitter, which means that an MS-100 with those additional wires may NOT be using a "single element 1/4 wave telescoping antenna."
Since we are talking about the EDM here to illustrate if I had this transmitter and had it on full 100mW with a very inefficient antenna like a 12 inch piece of wire I probably wouldn't make it accross the street.
Sorry, but more study and experience would be useful before posting/accepting such a conclusion.