OH1SDR CONTENT: PROJECTS: ANTENNAS: 5m vertical multiband GP antenna An 80 meter multiturn magnetic loop TX,RX: Computer controlled Mobira RC25 Telcom TE-157 - remove the beep
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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.
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. |