Ramsey Electronics FT146 manual Microphone Considerations

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"hum-m-m-, that's not a .001 uf where a 100 pf should be is it?"

If there is a problem in getting the modulation working, a scope or audio amplifier will allow tracing down any problem in short order. The microphone audio is amplifier by about 350 times in U1:B. You should see at least a volt of audio at the output (pin 7) of U1:B. A low pass filter follows U1:B, you should still see at least a volt of audio at pin1 of U1. From there, the audio drives the varactor diode D1.

How about keying of the transmitter? Check to be sure that the microphone is switching to ground when keyed. This closure to ground causes PNP transistor Q7 to turn on, switching +12 volts to its collector. This +12 volts lights the LED and applies bias to the crystal oscillator.

If you hear a AC hum on the transmitted signal, usual causes are RF getting back into the power supply or a bad VSWR on the antenna.

These short checks in no way detail any and all problems that can rear their ugly head, but should get you on the way to solving most errors. We'd like to be able to forsee a problem a builder may encounter, but the sheer number of parts and the permutations and combinations of installing them makes an list of precise, exact solutions impossible. If you run into a roadblock, gather all your thoughts and information and give a call to the factory for some help. If you elect to enlist the help of a local expert, great - but be sure the expert is qualified - no need for having someone lead you down the wrong path! Remember you may always return the kit for factory service, and there's no charge if the problem is our fault. See the warranty on the last page of this manual.

MICROPHONE CONSIDERATIONS

During assembly, the FT146 was jumpered for using an Icom style microphone plugged into the mike jack J2. You may also use the rear panel 5 pin DIN jack, P1. If you decide to do so, change the "Audio In" wire jumper to go between A and B. When this is done, the transmitter cannot be keyed from the microphone and must be keyed from the PTT pin.

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Contents Meter FM 5 Watt Transmitter KIT Ramsey Transmitter Kits FT146 FM Receiver KIT Introduction FT146 Circuit Description Resistors and potentiometers FT146 2 Meter FM Transmitter KIT Parts ListCapacitors Required, not supplied Inductors and ferrite coresSemiconductor devices Special componentsRamsey Learn-As-You-Build KIT Assembly FT146 FT146 FT146 PC board Test point loopResisto Is 2 1/2 turns and will appear to be 3 turns if Winding L3 and L4 Use the same wireProcedure as used above for these coils. Each coil Enameled wireFT146 FT146 Wire jumper Wire sits flat FT146 Short lead here TESTING, Alignment and AdjustmentFT146 Verifying Transmitter RF Output Your Power Supply and RF Output PowerFT146 Troubleshooting Hints Maximizing RF Power OutputMicrophone Considerations Crystal Requirements Other Enclosure RecommendationsFT146 FT146 Parts Layout Diagram Ramsey Kit Warranty Time Estimated AssemblyRequired Tools Total Solder Points

FT146 specifications

The Ramsey Electronics FT146 is a versatile and compact FM transmitter that stands out for its user-friendly operation and impressive performance in both amateur and professional audio applications. Designed for hobbyists, educators, and small businesses alike, the FT146 offers a reliable solution for broadcasting audio signals over a short to moderate range.

One of the main features of the FT146 is its simple plug-and-play setup, which allows users to get started quickly without needing extensive technical knowledge. The device operates with a frequency range of 88.1 to 107.9 MHz, covering the entire FM broadcast band. This flexibility enables users to choose the best frequency for minimal interference in their transmission area. Additionally, with an adjustable output power of up to 2 watts, the FT146 can effectively cover distances ranging from a few hundred feet to several miles, making it ideal for a variety of broadcasting scenarios.

The FT146 utilizes advanced modulation technology to ensure high-quality audio transmission. It supports monophonic audio, which is perfect for clear voice and music transmission. The integrated audio limiter prevents distortion, ensuring that the sound quality remains consistent, even at higher volumes or varying audio signals.

Another notable characteristic of the FT146 is its robust construction. Housed in a durable metal enclosure, the transmitter is built to withstand everyday use. The compact design allows for easy portability, making it suitable for field applications, on-location broadcasting, or as a permanent installation in a small venue.

In terms of connectivity, the FT146 features multiple audio input options, including a 3.5mm jack and RCA inputs. This versatility allows users to connect various audio sources, such as MP3 players, computers, or professional-grade audio equipment.

Furthermore, the FT146 also includes an LED power indicator and a built-in antenna output for enhanced transmission efficiency. Users can either connect an external antenna for increased range or utilize the included telescopic antenna for convenience.

Overall, the Ramsey Electronics FT146 combines ease of use with professional-grade features, making it an excellent choice for anyone looking to explore FM broadcasting. Whether for personal projects, educational purposes, or small business promotions, the FT146 delivers reliable performance and adaptability in a compact package.
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