Antenna equivalent with power indicator. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Antenna equivalent with power indicator. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Antennas. Measurements, adjustment, coordination

Comments on the article

To set up a homemade shortwave power amplifier or transceiver, a radio amateur needs, among other measuring instruments, an antenna equivalent and a simple output power indicator (aka a wattmeter). Since purchasing branded instruments is not cheap, some simple measuring devices can be made independently. Moreover, if we combine structurally the equivalent of an antenna with a power indicator in one housing, this will save space in the amateur radio "shack" and eliminate additional connecting wires.

The output power indicator proposed in the article (Fig. 1) consists of an antenna equivalent, which is made on a non-inductive microwave resistor R1 RFP250N50TC from Anaren Microwave, a voltage divider on resistors R2, R3 and capacitor C1 and a simple RF voltmeter AC on the elements VD1, C1, C2, R4, PA1. Capacitor C1 performs frequency correction in the HF ranges and sets the uniformity of the frequency response of the voltmeter. The author has this capacitor homemade. It is made of a plate of fiberglass foiled on both sides with dimensions of 7x15 mm and a thickness of 1,5 mm. Its capacitance was selected experimentally by a gradual decrease on both sides of the foil areas. As a result, the dimensions of its plates were reduced to about 5x7 mm, and the capacitance measured by the MAS LC meter was about 0,7 pF. Switch SA1 determines the limits of power measurement - 200 or 500 W by connecting shunt R5 in parallel with the measuring device.

Equivalent antenna with power indicator
Rice. 1. Scheme of the proposed output power indicator

For long tuning sessions at the maximum output power of the amplifier, the design of the pointer provides for forced airflow of the antenna equivalent - resistor R1. The blower is controlled by a thermal switch (Fig. 2). When power is applied, the motor M1 rotates at a reduced speed at the minimum voltage for a sure start. This voltage is determined by the stabilizer DA1 and the diode VD4. When the heat sink temperature rises to +55 ^оWith the resistance of the thermistor RK1 decreases, the transistor VT1 opens and relay K1 is activated. The motor M1 receives the full supply voltage through the diodes VD2, VD3. These two diodes connected in series reduce the fan supply voltage from 13,8 to 12,6 V. At the same time, the HL1 LED lights up, signaling a noticeable heating of the antenna equivalent and that it may be necessary to pause the transmission.

Rice. 2. Thermal relay circuit

Most of the indicator parts are mounted on a board made of foil fiberglass 1,5 mm thick (Fig. 3). Mounting - hinged on the "patch". Resistor R1 is fixed (through KPT-8 thermal paste) on a ribbed heat sink measuring 90x65x35 mm from the Intel P4 series microprocessor cooling system.

Rice. 3. Mounting the board

The RA1 device is any microammeter with a large scale and a total deflection current of 100 μA. Miniature CMH incandescent lamps are mounted in the instrument to illuminate the scale. Connector XW1 - SO239.

The indicator scale (I deliberately do not call the design a "device") is graduated in watts. Preliminary calibration was carried out at a frequency of 50 Hz using LATR. Then it was checked in the middle and end of the scale with a VK7-9 RF voltmeter with a control signal from the output of the Kenwood TS-570 transceiver. The scale turned out, as expected, close to logarithmic. I believe that a reading error of 10 ... 20 W at a power measurement limit of 500 W in amateur radio practice is quite acceptable for most cases of using the pointer. The resistance of the shunt resistor R5 is selected experimentally in the process of setting up the device. Its required rating is determined by the characteristics of the RA1 microammeter used. The 200 W scale is calibrated in the same way.

The thermal relay is mounted on a breadboard. Thermistor RK1 - MMT-1, is installed on the heat sink of the antenna equivalent through the KPT-8 thermal paste. Relay K1 - RES49 for an operating voltage of 12 V. LED HL1 - with a diameter of 5 ... 6 mm of any type, red glow. The M1 electric motor is a standard cooler with dimensions of 120x120 mm from a computer power supply unit of the ATX form factor. The whole structure is assembled in the same case (Fig. 4).

Rice. 4. View of the assembled structure

The device is powered by the transceiver's power supply and consumes no more than 300 mA.

Author: Dmitry Inozemtsev (UA1ZKI)

See other articles Section Antennas. Measurements, adjustment, coordination.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

The existence of an entropy rule for quantum entanglement has been proven 09.05.2024

Quantum mechanics continues to amaze us with its mysterious phenomena and unexpected discoveries. Recently, Bartosz Regula from the RIKEN Center for Quantum Computing and Ludovico Lamy from the University of Amsterdam presented a new discovery that concerns quantum entanglement and its relation to entropy. Quantum entanglement plays an important role in modern quantum information science and technology. However, the complexity of its structure makes understanding and managing it challenging. Regulus and Lamy's discovery shows that quantum entanglement follows an entropy rule similar to that for classical systems. This discovery opens new perspectives in the field of quantum information science and technology, deepening our understanding of quantum entanglement and its connection to thermodynamics. The results of the study indicate the possibility of reversibility of entanglement transformations, which could greatly simplify their use in various quantum technologies. Opening a new rule ... >>

Mini air conditioner Sony Reon Pocket 5 09.05.2024

Summer is a time for relaxation and travel, but often the heat can turn this time into an unbearable torment. Meet a new product from Sony - the Reon Pocket 5 mini-air conditioner, which promises to make summer more comfortable for its users. Sony has introduced a unique device - the Reon Pocket 5 mini-conditioner, which provides body cooling on hot days. With it, users can enjoy coolness anytime, anywhere by simply wearing it around their neck. This mini air conditioner is equipped with automatic adjustment of operating modes, as well as temperature and humidity sensors. Thanks to innovative technologies, Reon Pocket 5 adjusts its operation depending on the user's activity and environmental conditions. Users can easily adjust the temperature using a dedicated mobile app connected via Bluetooth. Additionally, specially designed T-shirts and shorts are available for convenience, to which a mini air conditioner can be attached. The device can oh ... >>

Energy from space for Starship 08.05.2024

Producing solar energy in space is becoming more feasible with the advent of new technologies and the development of space programs. The head of the startup Virtus Solis shared his vision of using SpaceX's Starship to create orbital power plants capable of powering the Earth. Startup Virtus Solis has unveiled an ambitious project to create orbital power plants using SpaceX's Starship. This idea could significantly change the field of solar energy production, making it more accessible and cheaper. The core of the startup's plan is to reduce the cost of launching satellites into space using Starship. This technological breakthrough is expected to make solar energy production in space more competitive with traditional energy sources. Virtual Solis plans to build large photovoltaic panels in orbit, using Starship to deliver the necessary equipment. However, one of the key challenges ... >>

Random news from the Archive

ADATA SH14 Secure Drive 22.09.2011

ADATA has announced the SH14 secure drive. The body of the device is made of silicone and ensures the safety of components from shock, vibration and moisture. Inside is a 2,5-inch SATA HDD with a spindle speed of 5400 rpm and a capacity of 0,5 / 0,75 / 1 TB.

To connect to a PC, USB 3.0 is used, which also powers the drive with energy and allows you to increase the data transfer rate to 90 MB / s. Dimensions ADATA SH14 122,2x82,8x19,9 mm. weight - 210 gr. It is available in black and red colors.

Other interesting news:

▪ Multitasking reduces brain productivity

▪ Nanohousing for sun-loving bacteria

▪ Refractory clay supercapacitor

▪ Unexpected properties of yogurt

▪ A new way to control the speed of light

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Infrared technology. Article selection

▪ article Dove of Peace. Popular expression

▪ article Why is a computer program update called a patch? Detailed answer

▪ article Tuberous Ulluko. Legends, cultivation, methods of application

▪ article Security device on a microcontroller with telephone line notification. Encyclopedia of radio electronics and electrical engineering

▪ Article Experience with extinguished candle. physical experiment

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews