Modulasi OT426

Modulasi OT426
Until the mid 80'an, AM mode still dominates the 80m band radio communication. AM transmitters are easy to make, and very suitable for beginners who want to explore the techniques of radio communication. With the enactment KEP-065/OP/KU/2009, the AM mode can be reused by the level of alert. Allocations in the 3550-3560 MHz frequency (10khz ???), with audio bandwidth not exceeding 6Khz. The easiest way to make the AM mode, is to use a transformer modulators (series modulator). Used to be very easy to find transformer capacity OT426 from 10W to 100W. But now the heart of an AM transmitter is already difficult to find. The alternative? using a transformer in the market? yes, the transformer power supply ...... Alternative model 1: Using 1 pc power supply transformer secondary with identical. Transformer power supply that is used must have two identical secondary, eg 0-12V, 0-18V, and so on. If the final transistor taking a current of 1A with a voltage of 12V, then the transformer power supply that is used must also have a secondary with 1.5x current 1A = 1.5A and 12V voltage. 1.5x multiplier, because the assumption of additional power modulators for half of the power needed by the final transistor transmitter. Capacitors for 10000uF, used for amplifier protection against wild currents. BE CAREFUL with its primary section (0-110-220), nyetrum .... Alternative model 2: Using 2 pieces of transformer power supply. If you are having trouble finding an identical transformer with the secondary, you can use 2 pieces of the primary transformer (0-220V) connected to each other. Secondary one associated with the final transistors, other secondary modulator. BE CAREFUL with its primary section (0-110-220), nyetrum .... Alternative model 3: Using 2 pieces of transformer power supply that are far apart. Sometimes we need a separation of part of his transmitter with audio, with 2 of the transformer, not a problem, stay connected with cable twinpair. In this way, the transmitter can be separated with an audio modulator of 10m-100m, without fear of losing power in its audio amplifier. BE CAREFUL with its primary section (0-110-220), nyetrum .... Using the transformer modulator, is a way of generating the most simple AM ​​mode is made (for beginners though). Other types of series modulator is to use transistors (not transformer). Series modulators suitable only for low power. Generation cara2 AM other than the above is to use PWM (pulse width modulation), PDM (pulse duration modulation), and so forth. In principle, the audio is inserted into the OWN / PDM, so that the output voltage will move from half Vcc to Vcc in sync with the audio amplitude (linear). Both are commonly used as modulators for AM transmitters powered.