Remote Radio Unit RF board.
An FM repeater in a milled aluminum chassis. Built around a pair of CC1200 chips from Texas Instruments and an RF power amplifier module. Revision A with CC1200 RF front-ends supports various FM-based modes, including M17 and AFSK.
RF power module - RA60H3847M1
RF output power - 1..60W continuous, up to 80W with lower duty cycle
Frequency range - 420..450MHz
Frequency error - <0.5 ppm over -40 to +85°C range
Supply voltage - 13.8V DC
Power consumption - <150W at 60W RF out
Load mismatch immunity - continuous over the whole VSWR range (built in RF isolator)
Harmonic content - 2nd <-40dBc, 3rd <-55dBc (435MHz at 48.3dBm)
Mode support: analog FM, M17, (A)FSK
Circulator: WH3538X-1, 400..470MHz (microstrip)
Dummy load: Anaren J100N50X4B
A basic, "crash-test" frmware template is available here.
- Build the firmware using CubeIDE
- Copy the .bin file over to Raspberry Pi
- Run
stm32flash -v -R -i "-539&-529&539,529,:-539,-529,529" -w rru-rf-fw.bin /dev/ttyAMA0
In case of problems, see this for some additional explanation.
Milled aluminum chassis is required. A reference design can be obtained from a separate repository.
Initial revision.
- Switched mode voltage regulators have been replaced with linear.
- Added a buffer between the 40 MHz reference TCXO and transceiver ICs.
- Added bleeder resistors at the RF PA and 13.8V power supply.
- Slightly improved ALC circuit.
- Reduced N-connector cutouts (4.5mm down to 2mm).
- Added decoupling capacitor arrays at both RF PA's supply and VGG pins.
- DA15 connector now has MCU's BOOT0 signal available at pin 13.
- Bodge wire mod is no longer required, as both baseband trigger signals are now routed to the MCU.
- Added a lowpass filter after the RF PA stage
- Added a bandpass filter at the RF input
- TX and RX blocks are now clocked independently
- Pull-down resistor at TP2 (BOOT1)
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
