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Index 37

1W RF Power Amplifier for iPOD Stereo FM transmitters

Published:2012-11-11 20:08:00 Author:muriel | Keyword: 1W, RF , Power Amplifier, iPOD , Stereo , FM transmitters

1W RF Power Amplifier for iPOD Stereo FM transmitters
This project explain how you can build and connect a powerful 1W amplifier to your FM transmitters. A perfect solution for those wishing to listen to their favorite tunes in the car, house, garden, school, campus, party, you name it.... Why not share your music with every one else in your city!   (View)

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100W Transmitter RF Power Amplifier 2SC2782

Published:2012-11-11 19:57:00 Author:muriel | Keyword: 100W , Transmitter , RF, Power Amplifier, 2SC2782

100W Transmitter RF Power Amplifier 2SC2782
This is a 6m band transmitter RF power amplifier (50 MHz) with 100W output. It used with my FT-736R and drive from 10W for the 6m SSB DX. The Building information comes from Japan CQ Magazine. The Toshiba RF bipolar power transistor is used in it. If you want to construct this rf amplifier, it's the better way if the double side PCB use for increase the grounding and current transfer. The TX power can be tune to 120W.   (View)

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100W Transmitter Amplifier for 2200m

Published:2012-11-11 19:56:00 Author:muriel | Keyword: 100W , Transmitter, Amplifier, 2200m

100W Transmitter Amplifier for 2200m
This particular transmitter was later shipped up to VY1JA in the Yukon where, thanks to Jay's excellent antenna system, it was heard in Europe as well as in New Zealand during one of the Trans-Pacific Tests! Running 24 volts on the final will produce 100 watts into a 50 ohm load. The transmitter utilizes a 4060 binary counter IC chip as both the crystal oscillator and frequency divider. I used a 2200 kHz crystal along with the 'divide-by' sixteen output to produce a signal at 137.5 kHz. Other combinations of crystal frequencies and 'divide-by' combinations may also be used since the 4060 features divided outputs for f/32 (pin 5) and f/64 (pin 4), among others. You may have a 4MHz crystal or an 8MHz crystal in your junk box that will put you in the band using these output pins. I used a crystal oven from a very old taxi cab fm radio to mount the crystal but do not use the 'oven' feature. I discovered that the thermostat-controlled heating / cooling cycle produced more drift than simply leaving the oven off. I have however, lined both the inside and the outside of the oven with styrofoam in hopes of keeping the crystal's temperature change to a minimum. Initial tests indicate that it is entirely adequate for QRSS30 speeds. I have not yet tested it at QRSS60, where even the slightest drift shows up very quickly. The transmitter is simple and inexpensive to construct. The IRF540 FET final runs very cool, although it should probably be heat sinked. I have also used IRF640s with little or no change noted. All coils and transformers are wound on ABS or PVC tubing. TRANSMITTER SCHEMATIC I used the Manhattan Style of construction on pc board. TRANSMITTER PCB Output Transformer (T1) - wound on 1.5 tubing ~ 5 inches in length. Wind the secondary first which consists of 80 turns of ~ #20 enamel wire. Wind the primary centered on top of the secondary with 15 turns of ~ #16 enamel, close spaced. Before winding the primary, wrap the center part of the secondary with PVC electrical tape or heavy plumber's teflon tape. Output Filter (L1) - wound on 2 tubing ~ 5 inches in length. Wrap 80 turns of #20, close spaced with taps at 40 turns and every 5 turns until the end. The capacitor used at the drain of the FET should be of high quality such as polycarbonate or mica. Although the original design indicated a 1 uF capacitor at the top end of T1's primary, I found that the 2.2uf gave a better waveform across the FET's drain. Look for the typical class-e type waveform at the drain. CLASS-E WAVEFORM Operation - Mitch's version of this amp appears to be operating at greater efficiency than the one I built. Running the final at 24VDC, the FET draws around 6.5-7 amps for an input of approximately 160W. With a measured output of 95W, the efficiency is around 60%. A properly designed class-e amplifier should realize much higher efficiencies so there is still plenty of room for improvement on this design. One of the things I would like to do is experiment with the output transformer in order to optimize its performance. Perhaps rewinding it on a ferrite core would help. The output transformer develops a lot of heat, indicating a substantial power waste. Perhaps that is where the missing 30% efficiency can be reclaimed. Operate the transmitter into a 50 ohm dummy load or your resonant (50 ohm) antenna system. You might want to 'tune-up' at a lower voltage and then increase the drain voltage when adjustments are completed. Start with the antenna tapped at the coaxial end of the filter coil. As you tap closer to the center, power output will increase, as will final amplifier drain current. You will reach a point where the output does not increase any further, even though drain current has increased. Tap at the point of best efficiency. The output waveform should be a clean sine-wave.   (View)

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1.5W VHF Amplifier

Published:2012-11-9 21:05:00 Author:muriel | Keyword: 1.5W , VHF Amplifier

1.5W VHF Amplifier
This project will explain the basic function of a class-C transmitter. I will explain how to dimension a transmitter and the purpose of the different components. I will also explain how you can build a 1.5W PA transmitter. The project will include PCB, components and instructions how to make coils, assembly and testing.   (View)

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1.3W VHF RF Amplifier 2SC1970 88-108 MHz

Published:2012-11-9 21:01:00 Author:muriel | Keyword: 1.3W, VHF, RF Amplifier, 2SC1970, 88-108 MHz

1.3W VHF RF Amplifier 2SC1970 88-108 MHz
This RF power amplifier is based on the transistor 2SC1970 and 2N4427. The output power is about 1.3W and the input driving power is 30-50mW. It will still get your RF signal quit far and I advice you to use a good 50 ohm resistor as dummy load. To tune this amplifier you can either use a power meter/wattmeter, SWR unit or you can do using a RF field meter. RF Amplifier Assembly Good grounding is very important in a RF system. I use bottom layer as Ground and I connect it with the top with wires to get a good grounding. Make sure you have some cooling at the transistor. In my case I put the 2SC1970 close to the PCB to handle the heat. With good tuning the transistor shouldn't become hot. RF Amplifier Printed Circuit Board You can download a pdf file which is the black PCB. The PCB is mirrored because the printed side side should be faced down the board during UV exposure. To the right you will find a pic showing the assembly of all components on the same board. This is how the real board should look when you are going to solder the components. It is a board made for surface mounted components, so the copper is on the top layer. I am sure you can still use hole mounted components as well. Grey area is copper and each component is draw in different colors all to make it easy to identify for you. The scale of the pdf is 1:1 and the picture at right is magnified with 4 times. Click on the pic to enlarge it. Low-Pass Filter Some of you might want to add a low-pass filter at the output. I have not added any extra low pass filter in my construction because I don't think it is needed. You can easy find several homepages about low pass filter and how to build them.   (View)

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1 Watt Universal RF Amplifier

Published:2012-11-9 20:59:00 Author:muriel | Keyword: 1 Watt , Universal, RF Amplifier

1 Watt Universal RF Amplifier
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Homemade mini - amplifier and speaker circuit diagram

Published:2012-11-9 19:28:00 Author:Ecco | Keyword: mini - amplifier, speaker

Homemade mini - amplifier and speaker circuit diagram
The amplifier part uses fidelity Manifold TDA1521, and its peripheral integrated circuit is extremely simple, and it has overheating, squelch, short circuit and other protection circuits, and it is suitable for homemade beginners. The first class uses the NE5532 for 10 times line amplifier. The coupling capacitor can use domestically CBB capacitors or tantalum capacitors. The previous level power can be gotten by 7815,7915 regulator, and the power transformer should use more than 30W. Bridge rectifier can use 3A full bridge. Amplifier part is shown in Figure 1, the power part of the circuit is shown in Figure 2.   (View)

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30 Nanosecond Settling Time Measurement for a Precision Wideband Amplifier

Published:2012-11-9 0:21:00 Author:muriel | Keyword: 30 Nanosecond, Settling Time, Precision Wideband Amplifier

30 Nanosecond Settling Time Measurement for a Precision Wideband Amplifier
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Ultra low noise op amp

Published:2012-11-9 0:16:00 Author:muriel | Keyword: Ultra, low noise, op amp

Ultra low noise op amp
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LTC1050 chopper op amp

Published:2012-11-9 0:15:00 Author:muriel | Keyword: LTC1050 , chopper op amp

LTC1050 chopper op amp
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Last stage power amplifier circuit diagram

Published:2012-11-1 22:28:00 Author:Ecco | Keyword: Last stage, power amplifier

Last stage power amplifier circuit diagram
V1, V2 form a single-ended input, single-end output differential amplifier, V3 constitutes a voltage amplifier. In order to ensure that there is sufficient gain and distortion improvment, V4 is used for temperature compensation. V5, V6 are current push tubes which mainly provide the necessary current for the power amplifier tube to reduce the input impedance of the power amplifier tube. The high-power tube uses the recently popular ZSC5200/2SA1943 pairing tube. R18 is the negative feedback resistor, the closed-loop gain of the machine is determined by R18, R17, C6 is the bootstrap capacitor.   (View)

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Push-Pull Class A Amp using type 5687 dual triodes

Published:2012-10-29 21:51:00 Author:muriel | Keyword: Push-Pull Class A Amp, 5687 dual triodes

Push-Pull Class A Amp using type 5687 dual triodes
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Push-Pull Class A 2A3 Stereo Amp

Published:2012-10-29 21:50:00 Author:muriel | Keyword: Push-Pull Class , A 2A3, Stereo Amp

Push-Pull Class A 2A3 Stereo Amp
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diode-connected MOSFET with buffer amplifier output

Published:2012-10-29 21:45:00 Author:muriel | Keyword: diode-connected MOSFET , buffer amplifier output

diode-connected MOSFET with buffer amplifier output
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CMOS Logic Inverter Amplifier

Published:2012-10-29 21:44:00 Author:muriel | Keyword: CMOS, Logic Inverter Amplifier

CMOS Logic Inverter Amplifier
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Buffer Amplifier circuit

Published:2012-10-29 21:42:00 Author:muriel | Keyword: Buffer Amplifier circuit

Buffer Amplifier circuit
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All-directly-Heated Pushpull Amp

Published:2012-10-29 21:41:00 Author:muriel | Keyword: All-directly-Heated, Pushpull Amp

All-directly-Heated Pushpull Amp
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20-W Bridge Audio Amplifier

Published:2012-10-29 1:48:00 Author:muriel | Keyword: 20-W , Bridge Audio Amplifier

20-W Bridge Audio Amplifier
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16-W bridge amplifier circuits

Published:2012-10-29 1:47:00 Author:muriel | Keyword: 16-W, bridge amplifier circuits

16-W bridge amplifier circuits
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Practical LT1010 Based Boosted Op Amp

Published:2012-10-29 1:45:00 Author:muriel | Keyword: Practical LT1010, Based Boosted , Op Amp

Practical LT1010 Based Boosted Op Amp
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