The Broadcast Hardware
RF Transmitter Technical Guide | AM-FM-TV Transmitter
Articles
Harmonic Absorbing Filter for FM RF Amplifier
2009-11-21 01:20:57
All RF amplifiers will "react" in some way when a low pass filter is attached. This reaction is mainly caused by reflected harmonics. All RF amplifers generate harmonics. When a low pass filter is attached to the amplifer most of the harmonic energy is reflected back to the transistor causing reduced efficency and output power. The transistor will also run hotter. The new LDMOS transistors have higher harmonics and more bandwidth; therefore, they are more sensitive to the low pass filter. For this reason we have developed a state of the art low pass filter to match the state of the art transistors. This filter terminates all harmonics up to 550MHz with a 50 ohm 250W termination. This filter will improve the performance of all FM amplifiers. This low pass filter is designed for use with the BLF574 and BLF369 modules operating up to 1200W. Silver Plated #8 AWG inductors. Teflon circuit board. 0.1dB Insertion loss typical. -30dB Return loss typical. 1/4 inch aluminum base. 3 inch
2009-11-21 01:20:57
All RF amplifiers will "react" in some way when a low pass filter is attached. This reaction is mainly caused by reflected harmonics. All RF amplifers generate harmonics. When a low pass filter is attached to the amplifer most of the harmonic energy is reflected back to the transistor causing reduced efficency and output power. The transistor will also run hotter. The new LDMOS transistors have higher harmonics and more bandwidth; therefore, they are more sensitive to the low pass filter. For this reason we have developed a state of the art low pass filter to match the state of the art transistors. This filter terminates all harmonics up to 550MHz with a 50 ohm 250W termination. This filter will improve the performance of all FM amplifiers. This low pass filter is designed for use with the BLF574 and BLF369 modules operating up to 1200W. Silver Plated #8 AWG inductors. Teflon circuit board. 0.1dB Insertion loss typical. -30dB Return loss typical. 1/4 inch aluminum base. 3 inch
FM Power Amplifier 88-108 MHz 600W BLF574
2009-11-21 01:18:46
BLF574, 50V, push-pull transistor using NXP’s High Voltage 6th generation of LDMOS technology was introduced recently and makes this FM amplifier possible with a single transistor. This eliminates the need for combiners and associated losses. The BLF574 is the latest high performance technology from NXP. These new 50 volt LDMOS transistors are ideal for that 1KW amplifier project. 600W BLF574 48V FM Pallet info. The two push-pull sections of the device are completely independent from each other inside the package. There is an internally integrated ESD diode protecting the gates of the device. The device is unmatched and is designed to be used for applications anywhere below 600 MHz where very high power and efficiency are required. Common applications would be FM and VHF broadcast, or in laser or ISM applications. Great care has been taken during the design of the high voltage process to ensure that the device achieves high ruggedness. This is a critical parameter for successful
2009-11-21 01:18:46
BLF574, 50V, push-pull transistor using NXP’s High Voltage 6th generation of LDMOS technology was introduced recently and makes this FM amplifier possible with a single transistor. This eliminates the need for combiners and associated losses. The BLF574 is the latest high performance technology from NXP. These new 50 volt LDMOS transistors are ideal for that 1KW amplifier project. 600W BLF574 48V FM Pallet info. The two push-pull sections of the device are completely independent from each other inside the package. There is an internally integrated ESD diode protecting the gates of the device. The device is unmatched and is designed to be used for applications anywhere below 600 MHz where very high power and efficiency are required. Common applications would be FM and VHF broadcast, or in laser or ISM applications. Great care has been taken during the design of the high voltage process to ensure that the device achieves high ruggedness. This is a critical parameter for successful
Elliptical RF Low-Pass Filter 88-108 MHz
2009-11-21 01:08:58
Here's a reference circuit for building Elliptical FM Low-pass Filter (from Cauer) for Power Amplifier 88-108 MHz. A ninth-order, elliptic, low-pass filter attenuates harmonics generated in the power amplifier. The capacitors for the filter are circuit board pads. The directional coupler (reflectometer) uses printed circuit board traces for micro-strip transmission lines. Transmission line segments (with an impedance of about 82 ohms) on either side of a 50 ohm conductor provide sample voltages representative of the square root of forward and reverse power. 9th Order Cauer RF Filter Typology 9th Order Chebyshev RF Filter Typology Source: Elliptical RF Low-pass Filter-Reflectometer
2009-11-21 01:08:58
Here's a reference circuit for building Elliptical FM Low-pass Filter (from Cauer) for Power Amplifier 88-108 MHz. A ninth-order, elliptic, low-pass filter attenuates harmonics generated in the power amplifier. The capacitors for the filter are circuit board pads. The directional coupler (reflectometer) uses printed circuit board traces for micro-strip transmission lines. Transmission line segments (with an impedance of about 82 ohms) on either side of a 50 ohm conductor provide sample voltages representative of the square root of forward and reverse power. 9th Order Cauer RF Filter Typology 9th Order Chebyshev RF Filter Typology Source: Elliptical RF Low-pass Filter-Reflectometer
RF Amplifier Broadband 88-108 MHz 100W
2009-11-21 01:06:52
This RF amplifier for FM 88-108 MHz with no tune (broadband) needed to cover all the FM Band. This RF Power amplifier is equiped with a bipolar transistor, the famous MRF317. As lots of FM amplifier application ,the power transistor is in a C class bias. All the impedance networks (Input-Output) of this RF amplifier have been determined by using the softwares: Mimp.EXE. This RF Amplifier need a 9 elements low pass filter ensures that its harmonic frequency meet at least a 60 dB rejection from the carrier.(RF Simulation with RFSIM99) This RF FM amplifier has a a 10 dB gain with a 60 to 65% efficiency. The Input VSWR is around 1.4 and there's no problem to reach the maximum power in all the FM band.. RF Power Amplifier PCB Layout Source: 100W FM AMPLIFIER
2009-11-21 01:06:52
This RF amplifier for FM 88-108 MHz with no tune (broadband) needed to cover all the FM Band. This RF Power amplifier is equiped with a bipolar transistor, the famous MRF317. As lots of FM amplifier application ,the power transistor is in a C class bias. All the impedance networks (Input-Output) of this RF amplifier have been determined by using the softwares: Mimp.EXE. This RF Amplifier need a 9 elements low pass filter ensures that its harmonic frequency meet at least a 60 dB rejection from the carrier.(RF Simulation with RFSIM99) This RF FM amplifier has a a 10 dB gain with a 60 to 65% efficiency. The Input VSWR is around 1.4 and there's no problem to reach the maximum power in all the FM band.. RF Power Amplifier PCB Layout Source: 100W FM AMPLIFIER
RF Power Amplifier 144 MHz 50W 2N6084
2009-11-21 01:06:24
This RF Power Amplifier for 144-146 MHz. It uses a 2N6084 RF transistor with power output 50w max. It is a class C amplifier design, and therefore good for FM mode only. RP Power Amplifier Schematic RF Sensing Schematic Source: 2N6084 144MHz FM Power Amplifier
2009-11-21 01:06:24
This RF Power Amplifier for 144-146 MHz. It uses a 2N6084 RF transistor with power output 50w max. It is a class C amplifier design, and therefore good for FM mode only. RP Power Amplifier Schematic RF Sensing Schematic Source: 2N6084 144MHz FM Power Amplifier
Two Way Radio-Microphone Connections
2009-11-21 01:05:37
Are looking for internal cable connection of your rig microphone? Here is the right place of your choice. This site collects any info about microphone connections and sockects. If you have any Microphone information You would like to add to help other radio amateurs or two way radios. Check this out!. Kenwood Most Popular Microphone Connections If you wan to know more about your rig microphone connections or your two way radio external microphones visit this best site g4wpw
2009-11-21 01:05:37
Are looking for internal cable connection of your rig microphone? Here is the right place of your choice. This site collects any info about microphone connections and sockects. If you have any Microphone information You would like to add to help other radio amateurs or two way radios. Check this out!. Kenwood Most Popular Microphone Connections If you wan to know more about your rig microphone connections or your two way radio external microphones visit this best site g4wpw
Simple AM Transmitter with BC109
2009-04-25 19:05:43
Here's a simple Amplitude Modulation (AM) transmitter. This circuit is deliberately limited in power output but will provide amplitude modulation (AM) of voice over the medium wave band. The circuit is in two halfs, an audio amplifier and an RF oscillator. The oscillator of this AM transmitter is built around Q1 and associated components. The tank circuit L1 and VC1 is tunable from about 500kHz to 1600KHz. These components can be used from an old MW radio, if available. Q1 needs regenerative feedback to oscillate and this is achieved by connecting the base and collector of Q1 to opposite ends of the tank circuit. The 1nF capacitor C7, couples signals from the base to the top of L1, and C2, 100pF ensures that the oscillation is passed from collector, to the emitter, and via the internal base emitter resistance of the transistor, back to the base again. Resistor R2 has an important role in this circuit. It ensures that the oscillation will not be shunted to ground via the very low int
2009-04-25 19:05:43
Here's a simple Amplitude Modulation (AM) transmitter. This circuit is deliberately limited in power output but will provide amplitude modulation (AM) of voice over the medium wave band. The circuit is in two halfs, an audio amplifier and an RF oscillator. The oscillator of this AM transmitter is built around Q1 and associated components. The tank circuit L1 and VC1 is tunable from about 500kHz to 1600KHz. These components can be used from an old MW radio, if available. Q1 needs regenerative feedback to oscillate and this is achieved by connecting the base and collector of Q1 to opposite ends of the tank circuit. The 1nF capacitor C7, couples signals from the base to the top of L1, and C2, 100pF ensures that the oscillation is passed from collector, to the emitter, and via the internal base emitter resistance of the transistor, back to the base again. Resistor R2 has an important role in this circuit. It ensures that the oscillation will not be shunted to ground via the very low int
What is AM Stereo?
2009-04-24 10:33:07
AM Stereo is the technology that allows AM radio stations to broadcast with high-fidelity Stereophonic sound, far exceeding the quality normally associated with regular monaural AM radio. AM Stereo provides clear full-dimensional Stereo sound that envelops the listener with fidelity usually thought of as something only found on the FM band. AM Stereo has been used all around the world for over two decades and is employed by hundreds of stations on every continent. Since its introduction, millions of AM Stereo receivers have been sold for home, car, and portable listening enjoyment. AM Stereo is a robust analog system that has been optimized for high performance reception and audio quality even with weak, distant signals. The greater long-distance range of AM signals, especially at night, regularly brings forth stations from hundreds or even thousands of miles away featuring true Stereo sound, something the FM band is incapable of. And yet, AM Stereo is fully compatible with all regula
2009-04-24 10:33:07
AM Stereo is the technology that allows AM radio stations to broadcast with high-fidelity Stereophonic sound, far exceeding the quality normally associated with regular monaural AM radio. AM Stereo provides clear full-dimensional Stereo sound that envelops the listener with fidelity usually thought of as something only found on the FM band. AM Stereo has been used all around the world for over two decades and is employed by hundreds of stations on every continent. Since its introduction, millions of AM Stereo receivers have been sold for home, car, and portable listening enjoyment. AM Stereo is a robust analog system that has been optimized for high performance reception and audio quality even with weak, distant signals. The greater long-distance range of AM signals, especially at night, regularly brings forth stations from hundreds or even thousands of miles away featuring true Stereo sound, something the FM band is incapable of. And yet, AM Stereo is fully compatible with all regula
80 Watt FM Stereo Transmitter
2009-04-24 10:31:52
This transmitter circuit was designed from the ground up to provide very high sound quality, coupled with excellent frequency stability, reliability, etc. It can be used as a standalone transmitter to serve a medium-sized town, or as an exciter to drive a kilowatt-class power amplifier to serve a large city. It is designed to work from 13.8V nominal voltage, so that it can be run from a common communications power supply in parallel with a backup battery. In the event of a power cut, the transmitter can keep operating from the battery, at slightly reduced power as the voltage drops. It consists of four modules, the three most important of which are ready, tested, and described below. The fourth module has not yet been built, and might never be built, but I will describe its basic functions so that you can design it, if you want. The audio processor and stereo encoder The textbook way of processing and encoding a stereo signal for FM transmission goes like this: 1) Take both channels
2009-04-24 10:31:52
This transmitter circuit was designed from the ground up to provide very high sound quality, coupled with excellent frequency stability, reliability, etc. It can be used as a standalone transmitter to serve a medium-sized town, or as an exciter to drive a kilowatt-class power amplifier to serve a large city. It is designed to work from 13.8V nominal voltage, so that it can be run from a common communications power supply in parallel with a backup battery. In the event of a power cut, the transmitter can keep operating from the battery, at slightly reduced power as the voltage drops. It consists of four modules, the three most important of which are ready, tested, and described below. The fourth module has not yet been built, and might never be built, but I will describe its basic functions so that you can design it, if you want. The audio processor and stereo encoder The textbook way of processing and encoding a stereo signal for FM transmission goes like this: 1) Take both channels
TV Transmitter for VHF Low Channel
2009-04-24 10:30:26
This transmitter circuit transmits your VCR or camera signal to any nearby TV set with great audio and video quality. Please be aware that this kit is a real transmitter and can be received by others - whether they want to or not! The TV transmitter can be tuned for channel 3-6 (frequency 61.25-83.25 MHz). The signal of the tansmitter is very stable. Remember since we are transmitting locally, your TV set should have a nearby antenna connected such as a pair of rabbit ears or a short dipole style antenna. You cannot operate the TV with the outdoor antenna or the local cable TV system hooked up to it - after all, their master antenna may be located 30 miles away! Finished TV transmitter can be installed in a variety of enclosures of your own design and choosing. Link Source: www.ramseykits.com
2009-04-24 10:30:26
This transmitter circuit transmits your VCR or camera signal to any nearby TV set with great audio and video quality. Please be aware that this kit is a real transmitter and can be received by others - whether they want to or not! The TV transmitter can be tuned for channel 3-6 (frequency 61.25-83.25 MHz). The signal of the tansmitter is very stable. Remember since we are transmitting locally, your TV set should have a nearby antenna connected such as a pair of rabbit ears or a short dipole style antenna. You cannot operate the TV with the outdoor antenna or the local cable TV system hooked up to it - after all, their master antenna may be located 30 miles away! Finished TV transmitter can be installed in a variety of enclosures of your own design and choosing. Link Source: www.ramseykits.com