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: Procom
CXL 70-8HD, installed at 95 m ASL

 




 
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
 
 

 

 



 
UHF Repeater
Antenna tower, height 40 meters
Repeater antenna at the top
 
 

 

 



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, 3 for RX and 3 for TX.
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