hf gendet
The HP33290A wave generator was utilized for radio building projects, serving as an excellent instrument for generating various signals up to 15 MHz. Due to budget constraints and the need for reliability, a decision was made to construct a personal HF generator. Although it would not match the performance of the HP33290A, it was inspired by its features, with an emphasis on a crucial HF detector section. The device operates in two modes: transfer mode and reflection mode, allowing for both generator and detector functionalities. It can function as a standalone HF generator or an HF power meter, with capabilities for sweeping frequency bands and FSK modulation, adhering to ham radio standards. The user interface is composed of a rotary encoder switch, two buttons, and a 4-line by 16-character LCD. Additionally, it has a COM port interface for outputting comma-separated values for frequency and power estimations. The circuit is divided into three parts: the microcontroller, the HF generator, and the HF power estimator. The first part of the circuit diagram includes the controller and power supply, while the second part encompasses the HF generator and detector. The microcontroller, an Atmega16 in a 40-pin DIL package operating at 12 MHz, manages the serial interfaces of the DDS and ADC chips, the LM041L LCD module with a HD44780 driver, the user interface, relay drivers, and the COM port. A 5-pin header, several resistors, diodes, and a transistor are integrated for in-situ programming of the Atmega16 using the PonyProg application. The HF generator section features an AD9835 DDS chip clocked at 48 MHz by an external crystal oscillator, with control lines managed by the microcontroller. The output is set to 850 mVpp into a 220 Ohm load. The signal is then amplified by an AD8099 high-speed operational amplifier, reaching 1.25 Vpp at the output, which translates to 0 dBm into a 50 Ohm load at the BNC connector. The HF detector section employs two AD8310 logarithmic broadband detectors connected to a Stockton SWR bridge. The bridge incorporates a mechanical design for shielding and symmetry, utilizing two FT50-43 toroids with a 1:10 turns ratio for a 20 dB attenuation. The load resistors are designed to maintain close to 50 Ohm resistance using standard 1% components. RG58 coax is used in the transformers to provide Faraday shielding, with the shield connected to ground on one side only. The choice of logarithmic amplifiers over traditional Germanium diodes is due to their superior linearity at low signal levels, though their maximum input of +10 dBm limits the power in the SWR bridge.
The HF generator circuit is designed to provide versatility and functionality for various radio applications. The Atmega16 microcontroller plays a pivotal role in managing the overall operation, interfacing with the DDS and ADC chips to generate and measure signals accurately. The use of a 12 MHz clock ensures that the microcontroller can handle real-time processing of frequency and power measurements, allowing for precise control and modulation of the output signal.
The AD9835 DDS chip is a key component in the HF generator section, providing frequency synthesis capabilities with high accuracy and stability. By clocking the DDS at 48 MHz, the circuit can generate a wide range of frequencies, essential for testing and experimentation in radio applications. The 850 mVpp output ensures compatibility with various loads, while the subsequent amplification stage using the AD8099 operational amplifier enhances the signal strength for effective transmission and measurement.
The HF detector section, featuring the AD8310 logarithmic detectors, is crucial for assessing the output power and ensuring proper functionality of the generator. The use of a Stockton SWR bridge allows for accurate reflection and forward power measurements, enabling users to monitor the performance of their antenna systems. The design considerations for shielding and symmetry in the bridge help minimize interference and ensure reliable readings.
Overall, this HF generator instrument combines advanced components and thoughtful design to create a reliable tool for radio enthusiasts. Its ability to operate in multiple modes, coupled with features such as frequency sweeping and FSK modulation, makes it a valuable asset for both hobbyists and professionals in the field of radio communications.I was lucky to use an HP33290A wave generator for my radio building projects, a fantastic instrument for generating all kind of signals up to 15MHz. Since I could not always rely on it and buying one would by far exceed my yearly hobby budget, I decided to build an HF generator instrument myself.
It would not come close to the HP332 90A in terms of performance, still it was the source of inspiration. I didn`t bother about the features I never used, but added a few of my own, the HF detector part being the most important. The instrument has two basic modes of operation: transfer mode and reflection mode, where the generator and the detector part are both used.
It can obviously be used as a stand alone HF generator or HF power meter. It is moreover capable of sweeping a frequency band and of FSK modulation (hamradio standard). Its user interface consists of a rotary encoder switch, two buttons, and a 4 line by 16 character LCD. It as a COMport interface, to output a string of comma separated values for the frequency and power estimations.
The circuit consists of three parts: the micro-controller, the HF generator and the HF power estimator. See here for the first part of the circuit diagram (controller and power supply) and here for the second part (HF generator and detector part).
The micro-controller, an Atmega16 (see Atmel AVR 8-Bit RISC Homepage ) in a 40 pin DIL package and clocked at 12MHz, will serve the serial interfaces of the DDS and ADC chips (3 I/O lines each), the LM041L LCD module which includes a HD44780 driver chip (10 I/O lines), the user interface (rotary encoder and 2 buttons: 4 I/O lines), the relay drivers (2 I/O lines) and the COMport (2 I/O lines). A 5pin header, a few resistors, diodes and one transistor are permanently build into the circuit for the in situ programming of the Atmega16 with the PonyProg application (taking another 3 I/O lines + the reset).
The use of this technique is really amazingly easy, just connect the COMport to the circuit (using an adequate cable), launch PonyProg and manipulate whatever part of the micro-controller`s memory, the firmware will even spontaneously restart afterwards. The HF generator part consists of a AD9835 DDS chip clocked at 48MHz by an external crystal oscillator.
The SDATA, SCLK, FSYNC and FSEL lines are controlled directly by the micro-controller, the latter being used for the FSK modulation. The DDS chip is set to output 850mVpp in a 220Ohm load. Then comes the output/power amplifier based on the AD8099 high speed video operational amplifier. This circuit can amplify into the 100MHz region, it is tamed somewhat to behave from DC to 25MHz. The signal is amplified to 1. 25Vpp at the output of the operational amplifier, which yields 0dBm into a 50Ohm load at the BNC connector behind a 50Ohm source impedance.
The HF detector part consists of two AD8310 logarithmic broadband detectors connected to a Stockton SWR bridge. The bridge is a quite elaborate mechanical construction for the shielding, and care is taken to keep all things as symmetrical as possible.
Two FT50-43 toroids are used, the ratio of turns is 1 to 10 which yields an attenuation of 20dB (or 1%) between the power at the input of the bridge (forward or reflected) and the power at the load resistors. The resistance of which are designed to keep as close to the nominal 50Ohm as possible using standard 1% components.
The use of RG58 coax as the primary of both transformers in the bridge creates a Faraday shielding separating the primary from the secondary (at least from electrostatic coupling), care should be taken to connect the shield only on one side to the ground. The choice of the logarithmic amplifiers as detectors elements over the traditional Germanium diodes is quite obvious in view of their far better linearity at low signal levels.
Their maximum input of +10dBm on the other hand limits the power in the SWR bridg 🔗 External reference
The HF generator circuit is designed to provide versatility and functionality for various radio applications. The Atmega16 microcontroller plays a pivotal role in managing the overall operation, interfacing with the DDS and ADC chips to generate and measure signals accurately. The use of a 12 MHz clock ensures that the microcontroller can handle real-time processing of frequency and power measurements, allowing for precise control and modulation of the output signal.
The AD9835 DDS chip is a key component in the HF generator section, providing frequency synthesis capabilities with high accuracy and stability. By clocking the DDS at 48 MHz, the circuit can generate a wide range of frequencies, essential for testing and experimentation in radio applications. The 850 mVpp output ensures compatibility with various loads, while the subsequent amplification stage using the AD8099 operational amplifier enhances the signal strength for effective transmission and measurement.
The HF detector section, featuring the AD8310 logarithmic detectors, is crucial for assessing the output power and ensuring proper functionality of the generator. The use of a Stockton SWR bridge allows for accurate reflection and forward power measurements, enabling users to monitor the performance of their antenna systems. The design considerations for shielding and symmetry in the bridge help minimize interference and ensure reliable readings.
Overall, this HF generator instrument combines advanced components and thoughtful design to create a reliable tool for radio enthusiasts. Its ability to operate in multiple modes, coupled with features such as frequency sweeping and FSK modulation, makes it a valuable asset for both hobbyists and professionals in the field of radio communications.I was lucky to use an HP33290A wave generator for my radio building projects, a fantastic instrument for generating all kind of signals up to 15MHz. Since I could not always rely on it and buying one would by far exceed my yearly hobby budget, I decided to build an HF generator instrument myself.
It would not come close to the HP332 90A in terms of performance, still it was the source of inspiration. I didn`t bother about the features I never used, but added a few of my own, the HF detector part being the most important. The instrument has two basic modes of operation: transfer mode and reflection mode, where the generator and the detector part are both used.
It can obviously be used as a stand alone HF generator or HF power meter. It is moreover capable of sweeping a frequency band and of FSK modulation (hamradio standard). Its user interface consists of a rotary encoder switch, two buttons, and a 4 line by 16 character LCD. It as a COMport interface, to output a string of comma separated values for the frequency and power estimations.
The circuit consists of three parts: the micro-controller, the HF generator and the HF power estimator. See here for the first part of the circuit diagram (controller and power supply) and here for the second part (HF generator and detector part).
The micro-controller, an Atmega16 (see Atmel AVR 8-Bit RISC Homepage ) in a 40 pin DIL package and clocked at 12MHz, will serve the serial interfaces of the DDS and ADC chips (3 I/O lines each), the LM041L LCD module which includes a HD44780 driver chip (10 I/O lines), the user interface (rotary encoder and 2 buttons: 4 I/O lines), the relay drivers (2 I/O lines) and the COMport (2 I/O lines). A 5pin header, a few resistors, diodes and one transistor are permanently build into the circuit for the in situ programming of the Atmega16 with the PonyProg application (taking another 3 I/O lines + the reset).
The use of this technique is really amazingly easy, just connect the COMport to the circuit (using an adequate cable), launch PonyProg and manipulate whatever part of the micro-controller`s memory, the firmware will even spontaneously restart afterwards. The HF generator part consists of a AD9835 DDS chip clocked at 48MHz by an external crystal oscillator.
The SDATA, SCLK, FSYNC and FSEL lines are controlled directly by the micro-controller, the latter being used for the FSK modulation. The DDS chip is set to output 850mVpp in a 220Ohm load. Then comes the output/power amplifier based on the AD8099 high speed video operational amplifier. This circuit can amplify into the 100MHz region, it is tamed somewhat to behave from DC to 25MHz. The signal is amplified to 1. 25Vpp at the output of the operational amplifier, which yields 0dBm into a 50Ohm load at the BNC connector behind a 50Ohm source impedance.
The HF detector part consists of two AD8310 logarithmic broadband detectors connected to a Stockton SWR bridge. The bridge is a quite elaborate mechanical construction for the shielding, and care is taken to keep all things as symmetrical as possible.
Two FT50-43 toroids are used, the ratio of turns is 1 to 10 which yields an attenuation of 20dB (or 1%) between the power at the input of the bridge (forward or reflected) and the power at the load resistors. The resistance of which are designed to keep as close to the nominal 50Ohm as possible using standard 1% components.
The use of RG58 coax as the primary of both transformers in the bridge creates a Faraday shielding separating the primary from the secondary (at least from electrostatic coupling), care should be taken to connect the shield only on one side to the ground. The choice of the logarithmic amplifiers as detectors elements over the traditional Germanium diodes is quite obvious in view of their far better linearity at low signal levels.
Their maximum input of +10dBm on the other hand limits the power in the SWR bridg 🔗 External reference