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Old November 15th 04, 02:17 AM
righteous-jude
 
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Default Auction ends in 1 hour! 2 Watt FM Stereo Broadcast 88-108 MHz LCDDigital PLL Transmitter

2 Watt FM Stereo Broadcast 88-108 MHz LCD Digital PLL Transmitter

Auction ends in 1 hour!

Ebay item #: 5730774971

Ends Nov-14-04 19:13:56 PST

My Ebay Feedback rating is 100% positive.

Ebay user ID: righteous-jude

Direct link:

http://cgi.ebay.com/ws/eBayISAPI.dll...m=57307749 71

This transmitter is an assembled and tested unit -- not a kit.

This FM Stereo transmitter is well-known among Ebayer's as being the best
transmitter you can get for the money. You'd have to buy a commercial brand
FM exciter (such as a Harris) to exceed the specs of this unit. On virtually
all FM receivers you would not hear the difference.

You could hook up and transmit any sound source you want, such as:

1. The sound output directly from your computer (to play MP3's) using iTunes
or any software you like.

2. Directly connect an iPod, CD Player, tape deck, an XM Satellite Radio
etc. right to the transmitter.

3. Use a professional mixer board if you want to "DJ" live. A decent
Behringer UB802 Mixer is only $49. Then you could mix and cross fade between
two different stereo sources LIVE. Add a decent microphone ($19) so you can
talk and people won't know you aren't a commercial station until they
realize "Hey, why aren't there any advertisements?"

This FM transmitter is DIGITAL (not analog) and can equal the sound of
commercial FM stations. It can transmit anywhere between 88-108 MHz. It
outperforms ANY of the Ramsey or other so-called "kit" transmitters,
including the "export" version of the FM-100B which Ramsey sells for $429.99
- which is WAY more than the cost of the transmitter I'm selling.

Depending on the quality of the antenna you connect to it* (see "NOTE"
section below) and how high up in the air it is, it is possible to get about
a 1.5 mile range using a simple homemade outdoor wire antenna, or over 5
miles of range with a $70 pre-made omni directional roof-mounted antenna.

This transmitter has a filtered RF output which means it puts out a clean
signal. RF filtering is important to avoid interfering with other FM
stations, or if you intend to add an RF Power Amplifier* to increase your
range. Most other low cost FM transmitters have bad RF harmonic suppression
which means they cause a lot of interference to TV's and radios in your
neighborhood, which will attract attention to you from people like Cable TV
technicians (something you definitely want to avoid).

For the technical stuff:

This transmitter uses 16-bit Direct Digital Synthesis (D.D.S.) modulation of
PLL carrier using 16-Bit digital oversampling, just like the Harris and
other Digital-type professional FM Exciters do.

This transmitter is a new design and DOES NOT use the "BA" or "Rohm" analog
chip - ANYWHERE IN IT AT ALL. Which is a good thing.

The heart of the transmitting circuit uses a DSC (Digital Signal
Controller). This is a 16 bit DSP microcontroller with on-chip Flash, RAM,
A/Ds, PWM, and 200k of EEPROM.

D.D.S. modulation technology is used to generate and modulate the carrier
signal of higher quality FM Broadcast exciters.

I can't reveal the complete design, but the heart of it uses a Cypress
Semiconductor DSC.

A Motorola-designed Class-A linear wide-band amp module (originally designed
for use by cable-company operators as line transmission amplifiers) results
in virtually no unwanted spurious harmonic output, high reliability and
EXTREME SWR ruggedness. The RF output of this transmitter will withstand
greater than a 30:1 SWR mismatch without failure. Which means if your
antenna shorts-out or dies, this transmitter will not fail.

The transmitter has a LCD digital display, an on-screen menu system with two
buttons for adjusting operating parameters such as transmitting frequency,
modulation level, MPX pilot level, etc. It can transmit in mono or stereo
and runs on 12-24 volts DC input.

Here are the specifications for this transmitter (from the manufacturer):

Transmission Frequency: Adjustable between 87-108 MHz
Tuning Steps: 10 kHz
RF Power Output*: Typ 1Watt @ 13V or 2 Watts @ 24V
Spurious RF Emissions: Better than -45 dB ref. to carrier
Frequency Stability: PLL Typ +/-1KHz
SWR Ruggedness: Withstands 30:1 SWR mismatch
RF Output Connector: BNC type
Audio Input Sensitivity: 0.8V rms for +/- 75 KHz deviation
Signal To Noise Ratio: 60 dBu
Frequency Response: Flat from 20 Hz to 15 KHz
Stereo Separation: 40 dB
Pre-emphasis: 75 uS (standard FCC spec for U.S. FM radio)
Audio Distortion: Better than 0.2 % THD
Audio Input Connectors: RCA Phono Jacks
Power Jack: Coaxial type, 5.5mm O.D. 2.1mm I.D. center positive
DC Power Input: 12 to 24 Vdc Regulated 600mA

I won't list all the details here, you can learn them all by going to
http://www.Ebay.com and entering item # 5730774971 using Ebay's "Search"
Feature.

This item will be available for only 1 more hour:
auction ends Nov-14-04 19:13:56 PST

"Yeah, OK all that stuff is great, but how can I tell how good this
transmitter will sound before I buy it?"

The Ebay auction listing gives instructions for downloading MP3 sound files
of recordings made of the FM transmitter signal received live, on-the-air.
You can judge for yourself.

** Please read the section of the auction explaining how I got the best
sound quality from this transmitter, and how the live off-the-air MP3
recordings were made. **

*NOTE: If you are concerned about gov't compliance regarding the unlicensed
use of this transmitter within the United States (or elsewhere), an "RF
Attenuator" (also known as a T-pad) may be attached to the output of this
transmitter. This is a simple screw-on device which will reduce the
transmitter's RF output power to a level within the guidelines mandated by
the country in which you intend to operate this transmitter. Guidelines vary
from country to country. In the U.S. unlicensed operation of this
transmitter is permitted under the mandate of the FCC's guidelines for
"Unlicensed Operation of Part 15 Transmitters", provided you do not exceed
certain restrictions such as RF output level or type of antenna. Compliance
guidelines may be viewed at:

www.fcc.gov/mb/audio/lowpwr.html


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