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Telcom TE-157 - remove the beep


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Last update 9.9.2009

Telcom TE-157 - remobe the beep

Telcom TE-157 is awesome little PMR radio that can easily be modified for 70-cm amateur radio band. Because the "band modification" is widely covered on the web, I won't bother to explain it here. For a lisence free operation the beep might be usefull, but I think that most ham radio operators want to get rid of it. I spent few minutes to study the circuit and found that it can be removed just by taking one resistor off. This will also move the capability to use sub channels (not needed on 70-cm anyway), call and will take the keypad beeps off.

Just open the radio: Remove the front mask, open the four screws, take the front panel off, unsolder the antenna connection from the PCB and take lift the two stacked PCBs off. Turn the unit around and remove the 22k SMD resistor marked in the picture.

Additional notes: I have several units of TE-157 and have noticed that few of them have different bandpass filter. These radios have SAW filter after the 1st (preamp) stage - not the best design but works. The dynamic range could be easily improved by adding some sort of bandpass filter in the front of the preamp. When modifying to 70-cm operation, I suggest to order suitable SAW filter and replace the original one. Suitable ones can be found at least from digikey.

After the filter mod, I was able to get sensitivity down to -137 dBm. With fresh set of batteries and over all voltage being 6V, the RF output was 440mW.