SECRET TIPS AND TRICKS ON AUDIO POWER AMPLIFIER CIRCUIT

Amplilfier power circuit from the beginning until now not much changed. Some say this is good circuit, the circuit is good but fitting assembled and tested the result was not as we expected. The problem that there is usually treble is less smooth, less noise kenceng, broken voice, hum,

tested middle ground bass sound is lost. so you do not have to believe what people say 100%. Quality amplifier built-up must be different from the amplifier assembly, the circuit can be the same but the quality will depend on who assemble. Want to know the secret?

Here are a few tricks that need to be tried.

COPING hum :

Power amplifiers are often used in the field jacket. The circuit is said to Bell said people were assembled. But you do not immediately attracted to this power, the circuit is rather complicated & difficult to understand reflect the intelligence of the person who first mendisainnya. In my opinion a great power is the power of simple, inexpensive, easily assembled and rational. You do not need to use components with high prices such as tantalum capacitors, power mosfet and the other expensive. This does not determine the quality of the power amp once we raft. Power of sometimes causing buzzing, to overcome that is by holding the line on the ground socket input ground with 10-22 ohm resistor. So the ground is not directly take input from the ground but held first with the R 10 ohms.

SETTING HOW BIAS trimpot : 

Turn the bias trimpot (if any) until the drain current of 50-100mA on each power transistor, in order to avoid defects in the position treble volume over 10 hours. The risks are so hot heatsink! (This setting marks on plate A-AB)

LM3886 Amplifier Gain clone

according to the function / application at its data sheet, this amplifier is more suitable room to room with hi-fi quality with enough power such as OCL. Aplikasinnya exist in high-end TV and surround sound. both worked in class AB. TDA7294 has been using a pair of mosfet as a final, while the LM3886 are still using ordinary transistors.

pretty good! using the tone control treble tones seem to be more powerful, less kicking bass tones can be overcome by the addition of tone control and super galaxy. a special, almost / no signal transient "bump" when power is turned on so it does not need additional protector speakers. The secret is in Resisror around 22k which is connected to pin 8 and Vee plus Elko capacitors valued 1-100uF. The default value is used to value 100uf/10V Elko. I suggest using a 220uF to increase the time delay so that the noise "bump" can dicut. should thus power amplifier. Using good quality component is an option. I think using standard components is also great, the important thing is the active component of IC, route the PCB's ground track, and wiring. There are two types, LM3886T and LM3886TF. I think the TF is more elegant black and easier installation because it does not need insulators. Remember the metal body is connected to the negative supply.

ANTENNA FM VERTICAL 5/8 LAMBDA

Antenna system plays an important role in FM transmitter, Example:
Transmitter with a 150 Watt power output, SWR = 20: 1, 0 dB gain antenna. This antenna system has a performance / performance is worse compared to an FM transmitter with a power output of 25 Watt, SWR = 1: 1, and 6 dB gain antenna. This example shows how great the influence of the antenna system to the transmission of radio signals.

An important factor in the FM antenna system installation is the antenna height. In the VHF band, the requirement that communication can take place is a LOS (Line Of Sight). So ideally communications on VHF, both receiver and transmitter antennas both should be mutually visible. So that between them there should be no objects that can absorb radio energy. So that the amateur radio in the VHF band is often stated that it is better to have a small but gain antenna mounted antenna with a gain higher than a large but low mounted.

Vertical antenna 5 / 8 lambda below are very easy to make, and quite inexpensive. To "tune" enough lengthen or shorten pecutnya (whip). On the connections that can be mounted clamps tightened. These clamps are sold at auto parts store or motorcycle.

Comparison of the power amplifier assembly kit

1. Gain clone LM3886, TDA7294

In accordance with the functions / applications at its data sheet, this amplifier is more suitable room to room because of its power around 50watt's. Its application in the high-end TV and surround sound. Both work in class AB. TDA7294 has been using a pair of mosfet as a final, while the LM3886 are still using ordinary transistors. 

Testing 

With speakers from 6 "to 15" bass tone is pretty mediocre, using two bass speakers adds a new feel. This amplifier is low noise and low gain input signal so thirsty. Input signal must be amplified with a series of super galaxy plus tone control, if not this bass tones really mediocre. 

Low noise, almost as in power off condition. I tried it on the PCB stereo. CT 24v 24v power supply, the power output of the left-think of OCL. 

Problem frequency response do not doubt. The thing to remember is the case body is connected to the negative supply line, so do not forget to install the insulation.

Marantz 7C assemblies

Amplifier assembly is one way to be able to obtain a tube amplifier with a cost that is relatively much cheaper than the branded. We can search through the Internet diagram2 tube amplifier that is already known results and also a simple voice that uses minimal parts.

Today many parts for tube amplifiers that have been produced, among others, re Transformer Output and tubes of air macam2 famous brands. So also the other parts ie capacitor, kwalitasnya prisoners better than ever produced in the previous tahun2.

In my opinion the sound quality of amplifier assemblies will be good enough if the spare parts used are good too, especially Output Transformer and signal capacitors, while the lain2nya depends on our ability in expenditures.

Assemble SWR

In telecommunications, standing wave ratio (SWR) is the ratio of the amplitude of a partial standing wave at an antinode (maximum) for the amplitude at an adjacent node (minimum), in an electrical transmission line. SWR is usually defined as a voltage ratio called the VSWR, for voltage standing wave ratio. For example, the VSWR value 1.2:1 shows a standing wave of maximum amplitude is 1.2 times greater than the minimum value of standing waves. It is also possible to define the SWR in terms of flow, resulting in ISWR, which has the same numerical value. Strength of the standing wave ratio (PSWR) is defined as the square VSWR.

Practical implications of SWR

The most common one to measure and check the SWR is when installing and tuning the transmitting antenna. When the transmitter is connected to an antenna with a feed line, the impedance of the antenna and feed lines must be identical to the maximum energy transfer from the feed line to the antenna to be possible. Impedance of the antenna varies based on many factors including: the natural resonance frequency of the antenna on being transmitted, the antenna height above ground, and the size of conductor used to build the antenna.

UHF TV booster preamplifier with a transistor

Booster, preamplifier or signal boosters, maybe people have a lot to know, especially for TV Booster. usually much less satisfied if it is not equipped with a TV antenna with Booster. for those who like to experiment or hobby electronics, electronics projects please just try this one. the circuit is not too complicated. tolerable if so it can be used for UHF TV antenna at home. UHF antenna booster can be used for the purpose of better reception, especially if you are away from the TV stations / transmitter relay. UHF antenna booster works in the range 400-850 MHz.

Here is a UHF antenna booster circuit diagram : 

The circuit uses only one transistor, with the strengthening of between 10 to 15 dB, good enough for many situations. The most important part is that the transistor circuits must be protected from the input circuit, as shown in the schematic diagram by a dotted line (metal shield / protective metal). it aims to avoid interference. 

Circuit is supplied from a separate power supply via the signal cable (similar to the booster UHF systems that are sold in stores, the power supply inside the house or placed near a TV), because this booster circuit should be as close as possible to the antenna. This is very important because the amplifier must amplify the signal obtained by the antenna, not the noise being picked up by cable between the antenna and the circuit.

Large power RF Power Amplifier

To obtain a large RF power taken in the usual way to do that is installing the components to be duplicated into two four or even more to put together the output to produce the output power is doubled. There are several ways in which that is; Pushpull, combiner, and Balance. The first experience when beginning to try to double, I use became an increasing power transistor 2SC1970 doubled, definitely glad that successfully and naturally obsessed to try a more challenging again. The Homebrew too so yes! to not care about spending their money that important work. It is remarkable that a firm commitment, and that's what makes us succeed.

Figure 1. 150 Watt RF Power

Antena Colinear VHF

6 dB VHF Antenna Colinear.

It is not too difficult to make a VHF antenna with omni-directional properties and has the advantage of 6 dB *. A "Slim-Jim" antenna is quite popular but only about 1.7 dB of gain realized *. I have a problem with my radio station package and decided that the antenna gain is the solution. So now I have a 6 dB gain VHF colinear. I also managed to get another 6 dB or more than my old receiver VHF IC260A tired-out with a little tuning agile. (* - Referred by a simple 1/4-wave whip antenna)

This image shows the basic construction. There is nothing new about the technology, the installation of a half-wave on top of another is very common. Both Marconi and Franklin developed a similar technique, but Marconi is more interested in the capacitive coupling between antenna elements whereas Franklin proposed 1/4-wave stubs in a variety of simple and complex forms (Antenna Engineering Handbook by Jasic). I attended Franklin antenna approach, but using a 4mm hard drawn aluminum rod, supported by cutting bits of nylon cutting board "liberated" from the kitchen (when the wife is not there - of course). Each element and stub are all calculated 1/2-wave length (1030mm) but the pilot had to be about 2 "(5cm) longer stub is folded to form two parallel bars. 5cm apart joined together at one end of the Second. The remaining elements of radiation as a single straight element. the three elements are formed is supported by two pieces and shaped blocks nilon.6 dB VHF collinear VHF Antenna Mount Antenna Mounting 6 dB collinear. I have yet to show the dimensions of the block cut but put in the first picture shows you exactly how they are formed. It all depends on what size wooden mounting boom you have. This of course can be metal, but I got a bit of wood sitting doing nothing on the balcony. The only thing that matters is that the pilot should be 1/4-wave length, excluding end shorted (folded).