DMR Repeater F1ZSX
DMR repeater in UHF band
![](https://f1atb.fr/wp-content/uploads/2020/01/F1ZSX-DMR.jpg)
Characteristics:
- TX frequency: 439.8875 MHz
- RX frequency: 430.4875 MHz (-9.4 Mhz)
- TX Power 25W
- Collinear Antenna
- Location: JN33NP
- ID CSS7: 208146
- Colour code: 1
- Sysop: F1ATB
- Transmitter: GM360 Motorola (Ebay)
- Receiver: GM360 Motorola
- Hardware MMDVM Pog
- Firmware MMDVM
- Master DMR: BM France 2082
Hardware
![](https://f1atb.fr/wp-content/uploads/2020/01/MMDVMpog.jpg)
The MMDVM pog modem mounted on a Raspberry pi 3 B allows direct interconnection with the Motorola GM360s used for transmission and reception. The 2 adjustable resistors on the card allow the adjustment of audio input and output levels.
![](https://f1atb.fr/wp-content/uploads/2020/01/GM360.jpg)
The transmitting GM360 is cooled by a fan started with the PTT control via a relay.
The connection of the transmitter and the receiver on the same antenna is done via a UHF duplexer bought in China via Ebay. When ordering you give the 2 frequencies and it is delivered to you set.
![](https://f1atb.fr/wp-content/uploads/2020/01/Duplexeur.jpg)
Software
On the Raspberry Pi, the Pi-Star software manages the whole.
![](https://f1atb.fr/wp-content/uploads/2020/01/Modem.jpg)
To program the 2 Motorola GM360s, use the CPS version R03.11.16. The F1ZSX GM360 programming file can be downloaded here.
![](https://f1atb.fr/wp-content/uploads/2020/07/Cable_Motorola-2-1024x576.png)
Calibration
To correctly adjust the modulation index in transmission, the MMDVMCal software can be used with an RTL-SDR key used as a spectrum analyzer. Many blogs explain the procedure.
Note that under the callsign F1ZSX there are 2 relays, one DMR in UHF which is described above and one analog in VHF.
Recent Comments