Technical Chairperson

What Makes It Tick?

The entire radio, CPU is under the LCD on the other side. More pictures are available on the UV-3R Yahoo Group.

This radio is undoubtedly a SDR (Software Defined Radio) and has a relatively low part count. I will not cover every part used as a full list is available in the UV-3R Yahoo group file section (Thanks to PY2BBS), but will cover some of the major ones.

The heart of the radio is a RDA Microelectronics RDA1846 single chip transceiver for walkie talkies. This single CMOS chip provides frequency synthesizer, VCO/VFO, AFC, AGC, pre/de-emphasis (selectable and can be disabled), RSSI indicator, CTCSS/DCS encode/decode, DTMF, 8dBm PA (about 6mw), and more. Basically everything a radio needs is provided by a single chip. A programming guide can be found here. Personally, I think this is an amazing chip, and I'm thinking up some project ideas. If you read the spec sheet, you will note that this chip is also capable of 200-260 MHz.

Next up is the CPU to control the SDR. This chip is unmarked on the circuit board, but the MCU it is believed to be the Abov Semiconductors MC81F8816.

This radio contains two distinct RF pre amps, one for VHF and another for UHF. They are provided by NXP Semiconductors, and Hitachi respectively. As the firmware is presently programmed, their appears to be no way to control these preamps. Judging by my earlier findings, they might be automatically controlled and not on full time.

The final amplifier is provided by  Renesas RQA0009TXDQS MOS FET. This final seems to be capable of 6 watts of output at a 65% efficiency, something you are unlikely to obtain in a 3.7 volt operating environment.

The charge control is provided by a Linear Technology LTC4054-4.2 one of these little chips should have been provided in the docking stand but wasn't.

Next up we have a short disassembly type video from Brick O'Lore.

Next Page: How To Use It

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