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Category: Inside Circuits Views: 4394 Rank: 10 This small circuit is a Linear amplifier for driving small UHF TV transmitters. Its gain is 7dB and can amplify a signal between 450-800 MHz. You can drive the circuit with 1 to 1,5 Watts signal. Better use double layer PCB with the second layer connected to earth. Use a stabilized power supply 25 volts and at least 5Amps.  The transistor case is the SOT-122A and be careful because the transistor is very toxic for your health. Tuning can be achieved turning the two variable capacitors. Do not forget to use heat sink for both transistors, specially for the BLW89 and it would Datasheet file1: Click here to download 1N4148.pdf datasheet. Datasheet file2: Click here to download BLW98.pdf datasheet. Datasheet file3: Click here to download BD136.pdf datasheet.
Related circuits For the absolute measurement of temperatures, a thermometer is indispensable. However, in many situations, an The signal booster, built around a few transistors and support components, offers an RF gain of about 12 to 18 dB Unity-Gain Noninverting Amplifier Circuit Biasing methods for an N-channel MOSFET to form a unity-gain noninverting amplifier A typical circuit at 20 MHz is shown. The crystal, which has an internal series resistance Rs of 14ohm, oscillates at its third harmonic. The diode clamp Dl and D2 provides a constant amplitude control. The circuit is basically a 555 astable circuit that divides two LEDs, LEDl and LED2. LED2 is switched on when the output of Ul is high, and LEDl is activated when its output is low. When Ul oscillates, LEDl and LED2 switch on alternately as the output of Ul switches from state to state.... With the coupler biased in the linear region by the 10 mA dc bias on the IRED and the voltage divider on the phototransistor base, photodiode current flows out of the base into the voltage divider, producing an ac voltage proportional to the ac current in the IRED. The transistor is biased as an... This circuit indicates that a power outage occured for 1, 10, 100, and 500 seconds with the values given for R* and C* This precision current source has 10 µA to 10 mA ranges with output compliance of 30 V to -5V. Output current is fully adjustable on each range with a calibrated, ten-turn potentiometer How To BUILD The BEST HDTV ANTENNA!!!!
UHF Transmitter or Cellular Phone Jammer (12' range) up to 2GHZ
Comments
Andy wrote on Dec 19, 2008
Sadly this article has missed off some vital information.
The transistor should have a strip line load in the collector.
Also the output circuit needs a quarter wave line to effect an impedance transformation to the output 50 ohm load
.... wrote on Jan 5, 2009
input and output is RF ?..
pouchytech1012@yahoo.fr wrote on Jun 19, 2010
only this transistor is toxicing
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