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RF power amplifiers. Schemes, articles, descriptions

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RF power amplifiers

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Power amplifier KB transceiver



Section RF power amplifiers. The described device allows linear amplification of power in the frequency range from 1,83 to 29,7 MHz. Its input and output impedance is about 50 ohms. The maximum input signal level is 150 mV (effective value). When it was tested by the two-frequency method, the power at a frequency of 14,1 MHz in the peak of the envelope on a load with a resistance of 50 Ohms reached 75 W, and the level of mutual modulation did not exceed 30 dB. In this case, the terminal stage consumed a current of 27 A from a voltage source of 5 V. The efficiency of the terminal stage when operating with a telegraph and power in a load of 40 W is 40%. The circuit diagram of the amplifier is shown in fig. 1 ... >>

Indicator for charging a screwdriver 14,4 volts



Section Chargers, batteries, galvanic cells. I bought a cheap Chinese SKIL-2007 screwdriver, a 14,4 V - 1,2A / h battery, in principle, you can work normally, but it turned out to have two drawbacks. First - there is no rotation speed adjustment, I dealt with it quickly, put a switch with a speed controller. Second, there is no indicator for the end of charging. The kit comes with two batteries and a simple charger, made in the form of two separate parts. In a small case, which is plugged into a socket, there is a transformer with a rectifier, it produces 18 V 200 mA at the output, a piece of wire with a connector extends from it. The second part is the charger itself with indicators, here is its diagram - Fig. 1 ... >>

Negative Feedback Amplifier



Section Nodes of amateur radio equipment. To increase the dynamic range of the amplifier, negative feedback (NFB) is used. Everyone knows the usual amplifier with transformer OOS, which is successfully used by many. Its only drawback is the low decoupling between the input and output: if the load is different from 50 ohms, then the input impedance is not equal to 50 ohms. N6NWP described a high isolation amplifier that is used between a passive mixer and a crystal filter in a high dynamic receiver. However, it is rather complicated. The amplifier described below is quite simple and has high dynamics, low noise figure, input impedance of 50 ohms, which depends little on the load impedance. ... >>

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Articles on RF Power Amplifiers

Articles on RF power amplifiers; RF power amplifier circuits; descriptions of RF power amplifiers: 53 articles

 


 

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Random news from the Archive

NEC LaVie Hybrid Zero family of lightweight convertible ultrabooks 21.01.2015

NEC officially introduced the LaVie Hybrid Zero line of ultrabooks, which replaced the LaVie Z series models. The main difference between the new products and their predecessors is a modern hardware platform (Intel Haswell replaced by Broadwell) and a different case that transforms a laptop into a tablet due to the large angle of rotation of the lid (in models HZ750 and HZ650).

The HZ550 is the lightest in the series at 779 grams. Its equipment includes a dual-core processor Intel Core i5-5200U (2,2-2,7 GHz), a 13,3-inch screen with a resolution of 2560 x 1440 pixels, 4 GB of RAM, and a 128 GB SSD. Claimed battery life in this case is 5,9 hours.

In the configuration of the HZ750 model - a touch screen with exactly the same characteristics and a 128 GB SSD, but the processor is already Intel Core i7-5500U (2,4-3,0 GHz), and the amount of RAM is 8 GB. Autonomy and weight of this model - 9 hours and 926 grams.

As for the middle model HZ650, it differs from the HZ550 in having a lower resolution touchscreen (1920 x 1080 pixels), more weight (926 grams) and autonomy (up to 11,6 hours).

Every LaVie Hybrid Zero comes standard with 802.11n Wi-Fi and Bluetooth 4.0, an SD card slot, a 0,9MP webcam, two USB 3.0 ports and HDMI video out, 2W speakers, a sound processor Yamaha AudioEngine.

The dimensions of the HZ750 and HZ650 models are 319 x 217 x 16,9 mm. The HZ550 differs only in its smaller width - 212 mm.

The laptops will go on sale in February.

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