User Manual for Ramsey Model No. FM100B Here’s the ultimate radio transmitter for all of you home brew DJs out there! This all-in-one stereo transmitter has all the features you will ever need for transmitting a school radio station, around your yard, or even around the block.
RAMSEY TRANSMITTER KITS • FM100B Professional FM Stereo Transmitter • FM25B Synthesized Stereo FM Transmitter • MR6 Model Rocket Tracking Transmitter • TV6 Television Transmitter RAMSEY RECEIVER KITS • FR1 FM Broadcast Receiver • AR1 Aircraft Band Receiver • SR2 Shortwave Receiver • SC1 Shortwave Converter RAMSEY HOBBY KITS • SG7 Personal Speed Radar • SS70A Speech Scrambler • BS1 “Bullshooter” Digital Voice Storage Unit • AVS10 Automatic Sequential Video Switcher • WCT20 Cable Wizard Cable Tracer • LABC1 L
Ramsey Publication No. MFM100B Price $10.00 USER MANUAL FOR FM100B PROFESSIONAL STEREO TRANSMITTER TABLE OF CONTENTS Introduction ......................................4 Using the FM100B ............................6 FCC Rules and Information ..............10 FM100B Specifications .....................19 Warranty ...........................................23 RAMSEY ELECTRONICS, INC. 590 Fishers Station Drive Victor, New York 14564 Phone (585) 924-4560 Fax (585) 924-4555 www.ramseykits.
INTRODUCTION TO THE FM100B First we will begin with a little history of stereo transmitters at Ramsey Electronics in order to give you an idea of how we arrived at the development of the FM100B as our latest stereo transmitter. We have many people call us each day asking questions about our earlier versions of transmitters such as the FM25B and the FM10A. Most are questions concerning drifting, sound quality, and transmitting distance.
ADJUSTING YOUR FM100B TRANSMITTER: Keep all tests very brief until you have carefully chosen an open operating frequency in the FM broadcast band. 1. Transmitting Frequency: After finding a suitable "open" frequency in the 88-108 MHz FM band, adjust the frequency by first getting the FM100B into setup mode by pressing both FREQ keys at the same time. Then use FREQ UP and FREQ DOWN keys until you hear the carrier frequency on a nearby FM radio.
USING THE FM100B WITHIN THE HOME: A most practical use for the FM100B would be to connect it to the main stereo system within a large home so that whatever is playing on the main system can also be tuned-in on portable FM radios in other rooms, the garage or in the yard. This connection consists of using shielded audio cables to connect the auxiliary "line audio" output of your cassette deck, CD player or other stereo device to the audio inputs of the FM100B.
ANTENNA IDEAS: Although use of the included whip antenna is recommended, you may want to use an external antenna to get a more uniform coverage. Use an external antenna mounted on the rear F connector to expand your coverage. Ramsey Electronics now offers an antenna called the “Tru-Match FM Broadcast Antenna”. This antenna has been specifically tested and designed for the FMseries of micropower transmitters and will help you get the most out of these products. When you call, ask for the TM100 antenna.
ANTENNA ALTERNATIVES: If your situation involves a single large building or multi-level home where reception from the FM100B antenna may tend to be uneven because of walls and other VHF path obstacles, you might set up the FM100B's output in a "carrier-current" configuration. If you know how, then do so safely.
• Turning on the microphone: [1] Make sure a microphone is plugged into the appropriate jack (3.5 mm). [2] Pre-set the gain level of the microphone before coming on the air. This will prevent the audio level of your voice varying every time you come on. [3] Use the MIC button to toggle between on and off as indicated by the MIC ON LED.. • Turning on AUTO AGC [1] Press the AUTO AGC button (when the MIC ON LED is lit) and it will blink rapidly to indicate that AGC mode is selected.
APPENDIX A: FCC RULES AND INFORMATION The Rules of the FCC (Federal Communications Commission) and your kit built FM Stereo Transmitter. An basic introduction of applicable FCC regulations. This basic introduction is just that: basic and introductory. A complete and thorough explanation of the FCC rules requires a reading of the regulations contained in the “Code of Federal Regulations, Part 15.
Here are the primary "dos and don'ts" picked from the current FCC Rules, as of May, 1990. This is only a brief look at the rules and should not be construed to be the absolute complete legal interpretation! It is up to you to operate within the proper FCC rules and Ramsey Electronics, Inc. cannot be held responsible for any violation thereof. 1. In the past, no "two-way communications" use of the 88-108 MHz FM broadcast band was permitted. This prohibition does not appear in the current edition of Part 15.
a. The transmitter must NEVER be tuned to a frequency above 108 MHz, specifically the band 108-121.94 MHz, FCC Rule 15.205 lists this band as restricted, due to potential interference with aircraft navigation equipment. b. The "bandwidth" of your transmission is limited to 200 KHz, centered on the actual operating frequency. Since 200 KHz is enough spectrum space for several different FM stations, this is a "generous" limitation designed to accommodate cruder FM devices.
DISTANCE FROM TRANSMITTER ANTENNA METERS FEET FIELD STRENGTH (µV) TOTAL RECEPTION AREA 3 10 250 314 FT 6 20 125 1256 FT 12 39 63 4800 FT 24 78 31 19113 FT 48 157 15 1.8 ACRES 96 315 7.5 7.2 ACRES 192 630 3.8 28.6 ACRES 384 1260 1.9 11.4 ACRES 768 2520 .95 458 ACRES 1536 5036 .5 1830 ACRES APPENDIX B: UNDERSTANDING LEGAL "FIELD STRENGTH" A "microvolt" is one-millionth of one volt and designated "µV" in the following explanations.
In all cases, the field strength of a signal decreases in direct proportion to the distance away from the antenna. Power decreases by the square of distance: for every doubling in distance, the signal power is quartered, but the field strength voltage is only halved. Using this theory, we can construct a simple chart to show the maximum permitted performance of a non-licensed FM band transmitter.
about 114 acres. A quick glance at stereo FM receiver specifications shows typical sensitivity of 1.7 µV before considering high-gain antennas or preamplifiers. Your non-licensed signal can provide serious competition to a public broadcast station fifty miles away, a station which someone in your neighborhood may have set up a special antenna to enjoy. Calibrated "field strength meters" such as described in the ARRL Radio Amateur's Handbook can detect signals down to about 100 microvolts.
SUMMARY The present edition of Part 15 of the FCC rules does not provide detailed guidance on ALL aspects of using a low-power transmitter such as the FM100B. The main point is that you may not cause any interference whatsoever to licensed broadcast services and that you must be willing to put up with any interference that you may experience. Lawful use suggestions for the FM100B 1. Build and adjust this kit strictly according to the published instructions. 2. Use the whip antenna supplied. 3.
intended for non-licensed operation under Part 15 Rules. You will find such notices written up for the front or back of the instruction manual for nearly any computer or video accessory that you have seen in recent months. Consult the Part 15 Rules for the exact wording of such notices.
Final comment A well-informed person will see today's FCC Rules to be evolving and progressively less-restrictive. Even though today's technology is far more complex than what was possible at the time of the Communications Act of 1934, the FCC rules are becoming more relaxed, giving radio experimenters more and more opportunities to explore many frequency bands, using many communications modes, with no need for a formal license of any kind.
FM100B SPECIFICATIONS AC power input: 85 - 264 VAC (47 - 63 Hz) @ 1 Amp Frequency coverage: Frequency steps: Bandwidth: Broadcast modes: Pre-emphasis: 88.0 -108.0 MHz 100 kHz +/- 75 kHz with built-in limiter Stereo / Mono 50 usec (Europe) / 75 usec (U.S.) selectable Audio input: Microphone input: Monitor output: 1 V p-p (line level), 2 channels, RCA connectors mono 3.
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WARRANTY INFORMATION FACTORY ASSEMBLED UNITS This warranty applies to original purchasers only. All factory assembled products are warranted to be free from defects in parts or workmanship for a period of 1 year from the date of purchase. Proof of purchase must accompany the unit. This warranty applies to units that have not been modified, misused, abused or repaired by unauthorized personnel. Repairs are to be accompanied by payment of the basic repair fee of twenty dollars ($50.00).
PROFESSIONAL FM STEREO TRANSMITTER KIT Quick Reference Guide Introduction ..................................... 4 Using the FM100B ........................... 6 FCC Rules and Information ............. 10 Specifications ................................... 19 Warranty .......................................... 23 Price: $10.00 Ramsey Publication No. MFM100B Assembly and Instruction manual for: RAMSEY MODEL NO. FM100B RAMSEY ELECTRONICS, INC.
