This looks pretty nice.
$60 & free shipping
This looks pretty nice.
$60 & free shipping
100mW/ 500mW (Power adj.) 76-108Mhz Home FM TRANSMITTER
Dear Who, Thanks for fixing that image
However, this one, same model but different style, looks pretty cool too!
http://cgi.ebay.com/100mW-500mW-Power-adj-76-108Mhz-Home-FM-TRANSMITTER-/110607705416
(I can't figure how to get the picture her)
Same price, free shipping, different seller
It is nice for the price, but i just hope it isn't a Hlly Chinese Transmitter in disguise. The Hlly are prone to throwing harmonics across the FM band.
Be careful.
DANGER:Uncertified junk! Frequency range and power output are not legal in the USA!!! That means you wont know if it has met the spectral purity required to keep it from shutting down your local PD or Airport. It is sure to attract the attention of the FCC in a hurry!!!
Adjustable power is one of it's features.. 100mw to 200mw
But yeah it could be junk
It is from Hong Kong, maybe it is one of the "Hlly"s
Looks Promising But looks can be deceiving,
At first glance It looks amazing.
But as it is un-certified and does cover more of the band than it should leads me to believe this could be a dangerous buy.
Plus the fact that half a watt could easily go over the limit.
Given the reputation of these cheap, uncertified transmitters form the Far East, it would be wise to steer clear of them.
A device like that, connected to an external antenna, could easily attract unwanted attention.
You could probably use it in your basement, on low power, without any trouble though.
The FCC doesn't care whether you use a certified on non-certified transmitter. They only care about your operation if there is a complaint filed. Then they will check to see if your FM operation complies with section 15.239:
Section 15.239 Operation in the band 88 - 108 MHz.
(b) The field strength of any emissions within the permitted 200 kHz band shall not exceed 250 microvolts/meter at 3 meters.
This field strength limit typically results in a range of 200 ft. Your only responsibility as a user of a certified or uncertified transmitter is to ensure it doesn't exeed the field strength limit.
OK, so you buy any certified or uncertified transmitter and turn it on. Now use a really good portable radio or a car radio and go to 200 ft and beyond. If the signal is listenable beyond 200 ft. go, back and reduce the power (if that is an option) or shorten the antenna. Do this until you comply. Logic and common sense say you won't get a complaint.
It seems that every time anyone posts a link to an uncertified FM transmitter on any forum, there is a barrage of posts warning about "possible" legality issues. On the other hand, there are many posts asking how to increase the range of certified FM transmitters. Sanity check here. What is expected?
If you are a part 15 FM broadcaster, you need to decide if you want to stay STRICTLY legal, or push the limits a bit.
Phil
I for one genuinely want to stay strictly legal. What I'm attempting is an basically an elaborate tourist information station ran for profit.
The pitch to local advertisers will involve receiving radio ad spots, and ads in a local monthly printed newspaper, as a sister to the station (which I am well verse in doing), and.. a basic 2 or 3 page website, designed and constructed individually. A great exposure package deal.. Might try to make it some kind of membership thing.
Nothing is ironed out, this whole venture is such an iffy venture to begin with. But there's a real potential. If I can cover a solid mile with one transmitter, legally, then everything will be primed for success. At which point a second transmitter to cover the other mile will have to come into the picture.
But back to the original topic...
I got curious and googled the "CZH-05B" shown on the front, and the first results in google gave me this page http://www.elecsky.com/index.php?main_page=product_info&cPath=4&products_id=41
I tell ya, everytime I look at it the more intriqued I get, and I have no interest in getting one. Its an Elesky PLL FM Transmitter. This one is incased aluminium, and more attractive than the other two.
This page also provides a pdf manual to it, which I skimmed over...
--It has the FCC compliance paragraph, and in the intruduction it claims:
--"the transmission frequency is highly stable".
--In bold letters: ".transmission distance more than 300 meters (In line of sight, field, open land)".
-- "will not drift between stations because of our advanced stereo PLL Digital Tuner Technology"
--"The FM Transmitter is designed to operate non-stop 24/7
The manual has 8 pages nicely detailed, and in the appendix right after the Transmitter covering Distance chart, it concludes with this statement in bold: "Electron_Sky(elecsky), it's owners, and employees accept no responsibilty whatsoever for any consequences arising from the use or misues of unliced or unapproved equipment. We suggest that you check local laws before operating or purchasing transmitting equipment. Again, it is your responsibilty not to break the law."
I'm just saying it's intriquing, they present it as quality (to a laymen like me), and it's sharp looking.
As long as it's kept on the legal 100mw setting.
As long as it's kept on the legal 100mw setting.
Rich, let me help you a bit with this. The 100 mW limit in the part 15 rules is for the input power to the final amplifier of an AM transmitter, not an FM transmitter.
The legal limit for FM on part 15 is based only on field strength and not transmitter power. The best a hobbyist can do to try to be legal is to follow Phil's advice posted above regarding the range. There is no way to tell in advance what power setting will result in a legal operation, and in fact the lowest power setting may be too high and would require attenuation at the antenna.
Neil
WARNING: The FCC also states it is illegal in the USA to posess,transport,sell,market,own or operate any transmitter that is not a kit that does not comply with and bear an FCC certification ID tag. They are certified with the supplied antenna and are illegal to modify. A kit need not be certified but is still expected to meet field strength limits,which is the users responsibility.
FM transmitters are not specified to a power input or output level,they are restricted to a field strength limit which can be exceeded at a power level of a few microwatts,again it is the users responsibility to insure compliance.
The best way to insure FM compliance is to use the FCC estimate of range expected from a legal transmitter which works out to about 300 feet maximum. If you are getting more than that,you are probably in violation. If you want more range,try the AM band.
On another note,I heard about a company in California who has portable AM and FM stations mounted in vans they park at malls and stores with banners on the van and advertising on the air,giving specials and discounts for listeners. They even had a live remote in the mall or parking lot. They were making big money at it too. YMMV
The mobile vans are a great example of the commercialization of low power radio and a tantalizing opportunity. I hope RichPowers will continue to keep us updated on his remarkable efforts!
Here is a link to a study done in Oregon about the opportunities
Oregon SeaGrant Low Power Radio Study
WARNING: The FCC also states it is illegal in the USA to posses, transport, sell, market, own or operate any transmitter that is not a kit that does not comply with and bear an FCC certification ID tag.
There certainly are restrictions on transmitters that are not certified - maybe not quite these restrictions, however.
As TAW Global, marketer of the Whole House unit learned the hard way, it is definitely prohibited, and actively enforced against, to market or sell an assembled transmitter that is not certified.
If the transmitter you are operating exceeds the field strengths in the regs then it is prohibited to operate it.
As far as possess, transport or own, well, not so much...
Were that the case, the NOUOs, NOVs and NALs in our FCC Field Notices RSS feeds would include seizure and impound actions for each field strength violation rather than limiting those actions to extreme and repeated rules violations.
I stand corrected.
By the way Neil, I'm listening to you and Carl right now! I've listened to all the Low Power Power Hours a couple times.
WARNING: The FCC also states it is illegal in the USA to posess,transport,sell,market,own or operate any transmitter that is not a kit.. I actually recall something about that, and was wondering about it.
The van story is great, I always love hearing about people having success and/or making a dollar with Part15... It really worried me when I heard about KenC (?) getting shut down by the FCC - it still bothers me.
Regarding the 100mW - 500mW adjustable power, earlier comments about confusion around 100 mW are spot on.
I will add to that my experience of connecting a 10 mW FM unit to a well matched dipole and getting 3000 feet range - not 300' - so 100mW is way beyond the needed RF output to well exceed the field strength limits with any kind of antenna attached.
I want to sound the alarm on this transmitter and give some real world comparisons to us all.
My FM station is using a Ramsey FM-30B running at around 3 milliwatts output into an end-fed coaxial-rat-tail dipole antenna. Even in the car, I can here the station about 200 feet in all directions. I WAS running approx. 10 milliwatts and covering way to much real estate. I can't imagine getting away with 100 milliwatts or more on the FM band.
For comparison, licensed FM stations consider their broadcast area to include the 1 millivolt or 60 dbu contour, otherwise known as the inference free contour. For Class A FM stations (3KW at less than 100 meters HAAT) this would extend out to about 15+ miles or so; LPFM 100 watt stations out to about 3-1/2 miles.
When you reduce a 1 millivolt/m signal by -6 db you arrive at 250 microvolts per/meter or the legal Part 15 limit at approximately ten feet from the antenna for an FM transmitter. That's right, at 10 feet Part 15 gets 1/4 the usable signal of a license FM in its interference free signal contour miles from the transmitter.
This unit is a citation looking for the opportunity to happen. If you live in Canada, or outside the U.S., this unit might be usable. In the good ol' U.S.. I wouldn't.
Remember that an LPFM filing window is coming up soon. If you are cited for an unlicensed violation the possibility of getting a construction evaporates entirely. Read the LPFM rules. Is $60 worth your future as a broadcaster? I think not.