UHF Repeater
All photos are Copyright SM7GYT
 
 
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UHF Repeater
RX: Motorola MC Micro, 432.8125 MHz
TX: Motorola GM350, 434.8125 MHz
Locator: JO65PU
Antenna: Arial Oy, AV1915-300, installed at 85 m ASL

 




UHF Repeater
Mobile coverage

 




 
UHF Repeater
Duplex Filter RX: BpBr, rebuilt from 450-460 MHz, 70 dB Notch
Duplex Filter TX: BpBr, rebuilt from 66-88 MHz, 75 dB Notch
 
 

 

 



Modification of Motorola MC Micro for PTT output.
1. Opto 4N35 "belly up", pin 4 to GND.
2. Connect 4N35 pin 2 to pin 9 on U704.
3. Connect 4N35 pin 1 to 9.6 VDC via 1K resistor.
4. Cut connection to VR651.
5. Cut link L--M, and connect 4N35 pin 5 to L (pin 9 on J5).
 
This PTT-output (open collector) is controlled by the microprocessor, and detects if a valid PL-tone is received, and will not open with only a carrier, if PL-squelch is enabled.
 

 

 



Repeater Controller
Microprocessor:  PIC16F648A


 
 

 

 



UHF Repeater with VHF Crosslink
RX UHF: Motorola MC Micro, 432.6375 MHz
TX UHF: Motorola GM350, 434.6375 MHz
RX/TX VHF Link: Motorola GM350, 145.675/145.075 MHz
Remote control with DTMF, 6 channels with password protection
Repeater controller: PIC 16F648A
Antenna: Procom, CXL 70-8HD

 
 

 




UHF Repeater with VHF Crosslink
Thermostat controlled heater


 

 




UHF Repeater with VHF Crosslink
Duplex filters
Heat Cable for temperature control

 

 




UHF Repeater
New project with VHF Crossband link
Repeater controller: PIC 16F648A


 

 




UHF Repeater
New project with VHF Crossband link
Repeater controller: PIC 16F648A
Beta version, with "Beeper" in Audio when Crosslink is active

 

 



DTMF Controller
New project with VHF Crossband link
Remote control by DTMF, 6 channels with password protection
 
 

 




UHF Repeater (Test setup)
RX: Motorola MC Micro, TX: Motorola GM350
Repeater Controller: PIC 16F648A
CTCSS Decoder with Display
Remote control by DTMF, 6 channels with password protection
 
 

 




UHF Repeater (Test setup)
RX: Motorola MC Micro, TX: Motorola GM350
Output: 30 Watts after Duplex filters
Duplex filters: Rebuilt from 66-88 MHz bandpass filters
Repeater Controller: PIC 16F648A
CTCSS Decoder with Display
Remote control by DTMF, 6 channels with password protection
 
 

 




UHF Repeater (Test setup)
Power Amplifier, Motorola MRF646
Gain: 3 dB (25 Watts in = 50 Watts out)
 
 

 




Voting Project
RX 1 and 2: Motorola MC Micro
Voter: LDG RVS-8

 

 




Voting Project
Remote receiver
RX and TX: Motorola MC Micro
Duplex filter: Storno