(Not finished, currently under prototyping, this page will be updated soon)

Features:

• Covering 1260 to 1300Mhz
• VFO for simplex and repeater
• Output power up to 4 watt
• CTCSS available
• Shift -6Mhz

Transceiver is based on a DRA818 VHF module, and TR2021-S transverter (UR3LMZ), DRA818 range is 134 to 174Mhz, so we will add 1126Mhz OL to have 1260/1300Mhz output, transverter must be little bit modified, is designed for 1296Mhz, so IF filter (1) must be changed to be more wide, (2) SAW filter is on 1295 centered so should be remove because Bw is 32mhz, and replaced by a LPF, LFCN1450. (see schematic bellow).

LO frequency is generated by ADF4350, 1152 or 1246 MHz (switchable), so we need to remove (3) Attiny13 R22/23/24, and set ADF frequency (1126) by the Arduino.

Power output from DRA818V is  attenuated with a LAT-15+, transverter does not accept more 10mw input.

The RF reference is 10mhz OCXO.

uC:

A Arduino NANO run the software, UART connection via the SerialSoft library is done through a resistive divider (3.3k/1.8k) to respect the level of the module which is 3.3v , a micro switch allows a “programming” mode in order to isolate the connection. The Arduino is powered via a 7805 regulator.

DRA818 is programmed by default when the Arduino starts up, output power is approximately 500mw at 4.5v, control is done via AT+ commands.

The BF is amplified by a 3W audio amp, LM4871.

Mic preamplifier is a MAX4466 module.

PA amplifier is EME214-23CM KIT, 4W Amplifier +36dBm

Output relay is EME226-KIT , DC-1.3GHz 50W RF G6K-2F-Y +12v Relay Kit

Bugs, experiences and improvements: