Transmitter Solutions

SECRET TIPS AND TRICKS ON AUDIO POWER AMPLIFIER CIRCUIT

2011-10-23T11:40:00.000+07:00

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)

SETTING OFFSET trimpot :

At the time of the input with no signal, turn the trimpot so that the voltage offset at the speaker actually read 0 volts. If you do not want to bother, use and rely only circuit with ic type of Hitachi HA17741 or other quality brand IC! This is the heart of the circuit, 90-95% of the quality of the circuit is determined from the IC!

OVERCOMING THE VOICE lackluster / LESS :

Use a pre-amp circuit to raise a minimum of 2 times the signal. normally and should be pre-amp circuit using IC op-amps with minimal supply +12 V-12V. Raise his mid tone! you do not want to just use the tone control circuit IC that there is a mid-her! The secret is not in the tone of his mid-course but the output signal of the IC op-amps are usually large.

TREBLE SPLITS:

Excessive treble will damage the power amp, power instead of out even. Handle, attach the filter capacitor at the input power amp 1NF to ground to ensure the signal is not disabled. Always use a quality active components such as ICs and transistors, 500 price difference will also be different results. Use a large and short as possible, especially for leg power transistors and these transistors should be directly soldered to the pcb.

BASS LOST IN THE FIELD :

Typically power for field use supply 50V CT 50V transformer, or at least 42V 42V ct. The greater the supply voltage is greater wattage channeled though the series was just written 300-400 Watt only. This course uses Elko capacitor with a voltage 80-100V. 10.000 uF/100V capacitor will be equal to 4X10.000uF/50V and of course the voltage of the capacitor is filled with full / almost full.

Try to use a strong Elko at temperature 105 'C. These robust capacitors in the supply of more than nominal voltage written on the body. For example 4700uF/50V 85'C capacitor will quickly explode in voltage 51V 85'C. And Elko 4700uF/50V 105'C going strong more than 50V voltage supplied at a temperature of 85'C. Elko is not so quickly explode if given the full voltage, keep the temperature as cold as possible, dikipas with the cool air.

FOR SPEAKER

Try using a driver speakers that have a large diameter spool fitted with a suitable size bok. Usually included examples of the parameters / dimensions bok. Bok size is usually larger than bok2 sold in the market. if you force using the bok of this market, use driver type G12-80 (sorry no fear campaign called brand) speakers with bass tones to the size of a small bok. Bok wall should be thick, strong and do not forget glued! Bok who will not be glued with a different sound, especially bass tones, prove it!

HEAT SENSOR

The form of transistors, these transistors can usually type MJE340 or BD139 also located there in the middle, flanked by a pair of transistors that newfangled same. These transistors must be mounted on the main heatsink to detect the heat generated by the power transistor. It acts to lower the bias current at the time of the hot heatsink. So what power transistor heatsink and heat must be set in position? Yes the goal nothing to prevent the signal from the defect (in class A or AB), with the consequence of heat. This class does not need and will not be felt if you just want a bass tone alone. Goal setting on. AB grade is the sound remains clear despite maximal volume rotated in position (center field).

It is unlikely, but it's closer.

LARGE heatsink VOLT

Electrolytic capacitors are not only more explosive at high temperatures, power transistors can also break far below the original break voltage. For example 2SC5200 transistor has a voltage of 230Vdc break, but if temperaturya break higher then the value of its voltage will drop well below this value, resulting in faster transistors damaged. The use of heatsink and cooling fan is very important not only to reduce the heat, more than it can prevent the transistor from break / damaged and weakened output. Increasingly hot temperatures it will be increasingly less ability. The use of cooling components is expected to remain fresh, fit and durability.

COMPONENT SELECTION :

TRANSISTOR POWER

There are so many types and models of these transistors, for example MJ15003 & MJ15024-4-5 from Motorola, but unfortunately this component is no longer manufactured by Motorola but from ON Semiconductor. Transistor model jengkol usually stronger at high temperatures, perhaps because it is more airtight. 2SC5200 from Toshiba, this transistor dalamannya Sanken 2SC2922 as large as the Koreans, and they will break if the temperature is too hot. Sanken 2SC2922 issued tin granules when heated, this weakness. 2SC3281, this transistor is the most popular, most linear and often used in professional amplifier, but Toshiba does not produce much, if still on the market, then it most likely is a fake!

TRANSFORMERS

There are two models of the transformer is often used, namely EI model (box / conventional) and the model toroid (ring / donuts). Some say toroid transformer model is better because it has a smaller kobocoran fluk, in fact just the same, or perhaps a larger toroid radiation. Circuits are sensitive to this flux is a series of high berpenguatan as head pre-amp and mic pre-amp. The circuit is usually installed horizontally / flat parallel to the arrangement of a conventional transformer wire email so that the circuit receives a bigger buzz. Unlike the model toroid transformer is arranged in a vertical wire email so that the wires are perpendicular to the circuit kits. The effect is that the received kit fluk pre-amp head is smaller. To overcome this fluk not to go into the circuit is by downloading shelding / fortified with solid aluminum plate made of oxygen impermeable. Plate is of course connected to ground via the cable. To match fluk vertical transmission, a conventional transformer need to be in pairs side (the side used as the bottom side) so that the composition of the transformer wire stand upright, this method often used in built-up power2. Voltage 50V 50V CT can be obtained by combining two transformers 25VCT25V, CT is not used, the leg so the foot 25V 50V only be used as a CT, so the total number is 100V or 50VCT50V. It's worthy to pwr on 400Watt power amp.

RESISTOR 5W

Resistor at the legs of the power transistor is usually worth 0.5 ohm 5 Watt white box-shaped. If we dismantle in it appears there was a circular aluminum wire. It resembles the inductor, the inductive reactance inductor will be high if fed a high-frequency sinya so that treble tone will be weakened and deformed. Power required for high tones (treble) certainly larger, the problem is here. Use of the power amplifier R 0.5/5W home its ok-ok only. But often do not realize the cause of damage to the speakers and power amplifiers is the high treble tones. Treble is not out but was hit by pwr amp so that arises is hot and damaged. We recommend using 2 Watt resistor regular 0:47 - 1 parallel 2 ohm so counted 4 Watt. Or if using ohm 2 Watt resitor 0:22 diparalel unnecessary because the voltage is pretty half-flops (one R 0.5/5W replaced one R 0.22/2W) its ok.

FUSE

Breakdown properties of semiconductor materials / transistor power amplifier is short, if you use a supply that is high enough then the destruction of one of these transistors will invite their partners to be damaged as well. In order for the destruction of transitor is no need for mounting fuse congregation. 1.5A per power transistor is considered sufficient.

LM3886 Amplifier Gain clone

2011-10-23T11:34:00.000+07:00

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.

To drive a lot of speakers, these kits can we add to the power transistors such as the Sanken transistors. we can now own the circuit.

ANTENNA FM VERTICAL 5/8 LAMBDA

2011-10-23T11:29:00.002+07:00

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.

Loading Coil can use a single electric wire of 1.2 mm HIS and need not be discarded insulation. After the match, in each and every screw and give the loading coil with waterproof glue (again on a motorcycle parts store).

Comparison of the power amplifier assembly kit

2011-10-23T11:22:00.002+07:00

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.

2. OCL

The circuit is quite popular. Even many people who exclude this power, I still use this power. They said a rough voice 2N3055 transistor. if you look at the data sheet and compare it with MJ2955 probably yes. But the test results actually good. Fine treble voice, clear medium, super, bass tolerable. My test page that wide use ACR C1230, good sound, the bass notes are lacking, this deficiency is in the speaker is not in power. Speaker replace it with black magic and a little modification on the box of his new bass tone out. To date I have not found the power amplifier assembly is better than this amplifier. The series of the most simple and cheap prices. Output power can be adjusted to supply its value, less than approximately 70 Watts with 32V supply ct. Input supply ranging from 18V to 32V. PA is lauched heat until the solder melts and loose wires. Replace the cable, again Ok. This excess PA transistorl OCL. PA is optimized to drive a speaker 12 ". For more than 12 speakers", we can use the air-supply amplifier is more than 32 volts.

Marantz 7C assemblies

2011-10-23T11:12:00.001+07:00

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

2011-10-23T10:59:00.000+07:00

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.

When the antenna and feedline do not have a matching impedance, some of the electrical energy can not be transferred from the feedline to the antenna. Energy is not transferred to the antenna is reflected back to the transmitter. It is the interaction of the wave is reflected by the forward wave that causes the standing wave pattern. Reflected power has three major implications on radio transmitters: Radio Frequency (RF) energy loss increases, the distortion at the transmitter because the reflected power from the load and damage the transmitter can occur In telecommunications, standing wave ratio (SWR) is the ratio of the amplitude of a partial standing wave at a 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

Matching the impedance of the antenna to the impedance of the line feed is usually done using an antenna tuner. Tuner can be installed between the transmitter and the feed line, or between the feed lines and antennas. Both installation methods will allow the transmitter to operate at a low SWR, but if the tuner is installed in the transmitter, feed line between the tuner and the antenna will still operate with a high SWR, causing additional RF energy to be lost through the feedline.

Many amateur radio operators consider the problem serious impedance mismatch. However, this does not happen. Assuming the mismatch is within the limits of operation of the transmitter, radio operators only have to worry about power loss in transmission lines. Power loss will increase with increasing SWR, but this increase is often less than amateur radio may assume a lot. For example, a dipole antenna tuned to operate at 3.75MHz-center 80-meter amateur radio bands will exhibit approximately 6:01 SWR at the band edges. However, if the antenna is fed with 250 feet of RG-8A coax, loss due to standing waves only 2.2dB. Feed line losses usually increases with frequency, so antenna VHF and above shall be adjusted closely to the feedline. Mismatches at 06:01 for 250 feet of RG-8A coax would experience losses on 146MHz 10.8dB.

UHF TV booster preamplifier with a transistor

2011-10-23T10:44:00.000+07:00

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.

Antenna and booster circuit can be mounted on the roof of your house. 75 ohm coaxial cable length can be used from this booster circuit output to the power supply unit is located close to the TV.

Construction is very simple power supply, use a 50-100 uh inductor or RF choke between the output and power supply cables. Small ceramic capacitors 100pF are used to block DC voltage from the power supply. Adjust P1 to get the best reception, and this is to set the current consumption during use which is about 5-15 mA.

Large power RF Power Amplifier

2011-10-23T10:34:00.000+07:00

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

Transistors are commonly used to build this project can be 2SC2782, or 2SC2094, or 2SC2630. Keep in mind that in building the RF power in this way to be able to exit the output as expected, it is necessary also to consider in the input. So here, for a 2SC2782 RF power will be able to power out 80 Watts using 2SC1946 power driver. Now we expect in the way in Pushpull, Combine, or Balance, RF power can go out as much power two 160 Watt. Was only able to drive with a 2 X 2SC1946 2SC2782 get out to achieve the power of 160 Watts? Could be less. Ideally also need 2 x 2SC1946. Yes it is enough for 2SC1946 because it was able to enlarge the output power to almost two folding, but 2SC1946 pity works because it has to be pumped all-out to maximum, He also still use. That sounds good if you want to try a power driver 2SC2630 even though it is not practical. Wow steady results! Ko-Ko Full Power. 2SC2630 issued its relaxed as small as needed, then simply driven with 2SC1947, and the output is pumped into 2 x 2SC2782A

Antena Colinear VHF

2011-10-23T10:14:00.000+07:00

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).

Enter the central spacer first then simply push-fit everything together (using a little violence). The holes are vertical / horizontal in the block-end should have the electrical connection between the stub and the driven element. I use a bit of iron (to be attached to the magnet) wire from the lead component, threaded through the holes so that there is good contact between the two. Copper well separated from the aluminum in an atomic scale that, given time, you will find corrosion between the anode and cathode metals such as copper. If you do not know it, most of the resistors and capacitors using an iron wire, just take a magnet and test them. Nylon cut block more than enough to support the elements, even in the wind kencang.6 dB VHF collinear VHF Antenna Mount Antenna Mounting 6 dB collinear. Connections are made 15cm (6 ") from the closed end of this stub stub eat with 50-200 ohm coaxial balun that is not balanced to unbalanced. By using RG58 or URM76 length necessary to form a loop balun 0.33 x wavelength of wave A 1 / 2 to 145 MHz radiation element 1030mm and length of coaxial balun should be about 690mm, folded to form a circle of 345mm. You can, of course, simply roll it up.

I have just seen some articles that were published using this type of antenna is made of copper pipe, but I think that my method is much easier to make and cost almost nothing in both money and effort (if the wife does not catch you). VSWR? I never even customized mine, but do not need it!