how to increase range of ASK 433Mhz transmitter and receiver ?

hello all,
i'm using ASK 433Mhz tx and rx for wireless transmission, 've made use of HT12E and HT12D and i'm hardly getting output at the receiver when tx and rx are 1meter apart. How can i increase this range ? plzz help

Can you describe RX and TX modules, their powers (mW), battery source and status of batteries, module internal antenna or external antennas ?

HT12E and HT12D are encoder/decoder and not RF transceivers which make actually the wireless link connection.

I presume the OP knows. As HT12x won't bridge a single cm without a RF transmitter/receiver pair.

Even with a short piece of wire acting as antenna, a standard ASK or FSK transmitter/receiver pair can be expected to achieve at least several 10 m range, even indoor. So there must be a special problem like wrong tuning or strong interference sources in the vicinity.

wrong tuning in what sense ? i've used 1M ohm at transmitter side and 51K at reciever side .. is there any other points to be considered ? i'm not getting any solution......

here is the circuit diagram of tx in this i've used 1M ohm resistor instead of 750k
../imgqa/eboard/Antenna/rf-nsjd4g5mpsu.gif

and here is the circuit diagram of rx, 've used 51k instead of 33k .. in one website 've read tht using 1M and 51k wil get better response so used those..
../imgqa/eboard/Antenna/rf-n4to4anyead.gif

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how to increase ange using these encoder and decoder ?

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how to increase range using these encoder and decoder ?

Some RF modules have RF tuning elements. You tell anything about the used modules.