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Ramsey FM25B review posted on Epinions

vandiik's Full Review:
Ramsey FM25B Synthesized FM Stereo Transmitter Kit

I had no idea when I bought my Ramsey FM25B that it would become the centerpiece of audio programming in my house. But in a matter of weeks it did.

The finished transmitter is wired between the sound card of our computer and the computer speakers. Then on any FM radio in the house, we can listen to what's streaming on the computer. I listen to New Orleans music from, eclectic Radio Heartland from Minnesota, classical feeds from all over the world, Pandora, a whole summer of baseball play-by-play from for $15 per season. Who needs XM?

This is not flashy technology with remote control at the speakers. If you want to change what you're listening to, you have to go to the computer and do it, but the inconvenience is not burdensome for us. I don't get tripped up by 'digital rights management' quirks as I might if I used one of the little Internet radio appliances that talk directly to your network router. Also, it doesn't cost an arm and a leg like most of those little Internet radios do. The transmitter's signal is rock solid, and it also allows us to continue using the FM radios we already own.

So if you bought this unit, what could you expect?  Well, expect it to be a hobby, at least for a few months while you figure it out. If that statement just turned you off, check out the CCrane FM transmitter. It's ready to play out of the box, and is fully street legal. With the CCrane though, you may not have sufficient range to cover your entire house or yard.

Because FCC regulations don't allow transmitters this powerful (up to 25 milliwatts) to be sold assembled, the Ramsey FM 25B is a kit. You will get a bag of electronic components, a circuit board, a plastic case, a whip antenna and a power pack. Some dealers assemble the kit and then sell it, which is strictly illegal, and enforced by the FCC. Do yourself a favor and avoid these shady businesses.

To build the kit you'll need to get comfortable with a soldering iron. The excellent assembly instructions take you step by step through the build, assuming you're a total beginner.

Tools/supplies you will need:
*soldering iron
*rosin core solder and maybe soldering wick in case you have to undo something.
*wire cutter and maybe a needle nose pliers
*digital multimeter or an analog volt/ohm meter

Solder and soldering iron can be had at Sears or Radio Shack for $10-$15, the meter can be had for as little as $10 but spend a little more if you can.

Assembly takes a few hours if you're careful and double check your work (please do), but it is also very rewarding.  Be sure to work in a very well lit space.  There are three things you should do first as last to get the best sound possible from the transmitter, and minimize hum.

1. Don't use the supplied whip antenna, the transmitter has a socket for external antenna.  Use it. Rabbit ears set up like this will work fine:
Rabbit Ears or Google: 'folded dipole antenna' and set up one of these. They're cheap to buy or easy to make and work great. Take care to feed the antenna loop with shielded coax, don't use 300 ohm ribbon cable which is not up to the job. There are many other more involved antenna options, but they'll give you too much range.

2.) Instead of mounting the circuit board in the supplied plastic case, mount it in a steel box on threaded metal risers (available from electronics stores such as Radio Shack) that make electrical contact with the case. Ready-made kit boxes are available, but be creative: Mine is in a surplus ammo box which cost me nothing and works very well.

3.) If you do steps 1 and 2 and still hear unacceptable noise in the signal, power it with a regulated 12-13.VDC power supply, also available from electronics stores such as Radio Shack.

Still with me? Congratulations, you're the kind of DIY geek I like. While I'm thinking of it, Ramsey Electronics has a very active bulletin board of FM transmitter users who are happy to help you get your transmitter running.

What about the competitors? In business terms, Ramsey is probably the largest, and most legit of the kit suppliers. There are other FM transmitter kits around that have their devotees. And owing to Ramsey's transmitters being the most established, other transmitter suppliers who want a piece of the market sling a lot of mud at Ramsey. Since people rarely have the chance to hear multiple transmitter designs side by side for comparison, most will likely never really know if the competitors have better products, or if they're a bunch of liars.

My opinion of the Ramsey sound quality is that it's not perfect, there's room for improvement. But it's more than adequate if you take into consideration its low price, and the clock radio/ boom box devices on which you'll probably listen to it. If you expect to be wowed by the FM 25B using a great stereo, you won't be. But I'd suggest, you not get too hung up on fidelity with this purchase, it's about opening your home and your ears to audio programming you couldn't possibly get on your FM dial any other way (and without the headaches of using a wireless network device such as an Apple airport which can be subject to interference from cordless phones and microwave ovens).

On the topic of design: All these little FM transmitters, whether they're Ramsey units broadcasting to an external antenna, or $10 fobs dangling off your iPod, are possible because of silicon chips.  The chips have two functions: 1.) take two-channel stereo input, and create a single FM multiplex source signal (the multiplexed signal can be decoded as stereo in the receiver), and 2.) take the multiplex source and creates the antenna ready transmitter signal. These chips are all made by the same company, Rohm. Rohm has a few different series of these chips that offer different design features, and newer series chips will likely offer greater refinement and fidelity. I know the Ramsey FM 25B uses the Rohm BH1415F chip, and this is not the newest, which a South African supplier, EDM is quick to point this out. (They and their loyal devotees sling so much mud at Ramsey, it makes me a little suspicious of them. I'd love to hear one of their transmitters sometime and make up my own mind.)

The work of Ramsey engineers and other transmitter designers is to tweak their circuits around these chips to best effect. One obvious example: circuitry around the chip amplifies and filters the FM signal after it leaves the transmitter chip so the unit has more than a 24 inch broadcast range and a clean signal. Designers also have the choice of not using portions of the chip's function set if they think they can set up a better performing circuit themselves, and it's in all of these design decisions that the different transmitters take on an identity beyond what's on the Rohm spec sheet.

Lastly, the FCC and you [and I am not a lawyer, this is one layman's opinion, not legal counsel]: Read all the boiler plate that Ramsey has about FCC Part 15 broadcasting, and behave accordingly. Find an open frequency, and keep your broadcast range just large enough to cover your yard.

In the US, the FM radio band is closely guarded by the National Association of Broadcasters. Their members bear the burden of compliance with Federal regulation, and expect to operate on the clear frequencies those Federal regulations ensure. I can't blame them for that. If you interfere with a licensed broadcaster's frequency, and they get a complaint from one of their listeners, you can expect they'll turn that complaint over to the FCC and you'll find yourself in their cross-hairs. You will have absolutely no rights. Immediate compliance with the FCC and total capitulation is in order.

I've run my transmitter 24/7 for a few years now, and haven't ever heard any on or off frequency interference. None of my neighbors have ever bothered to try and find it on their radios, which is good as far as the FCC is concerned, and a dose of reality for anyone who thinks he or she is going to create a broadcast radio station with this unit.

Good luck, have fun.

Ramsey FM25B Transmitter
Ramsey FM25B Transmitter Review

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