VU2BBB -matheran repeater

VU2BBB Location:- Matheran, Maharashtra, Near Mumbai

VU2BBB

Freq. 145.000Mhz +600 Khz Shift

LOCATION:- MATHERAN , MAHARASHTRA

HEIGHT 2467 Feet,

Cordinates N 19. 00.500 , E 73. 17.013.

CURRENT STATUS- ON AIR

This blog gives an idea of an initial experimentation done with PIC MCU based homebrew repeater interface to control repeater in a very remote location. After serving for a while interface and repeater were damaged by lightening.

At present repeater is fully functional without remote interface.

DTMF Interactive(morse code) Interface-Telemetry.

DTMF # 1, returns outside temp.
DTMF # 2, returns battery voltage.
DTMF # 8, returns system status,'A' for AC & 'B' for bat
DTMF 6 digit code for remotely switching ON and OFF repeater.

VU2BBB repeater was started by Bombay Repeater Society in late 1980s. Licence to the repeater was issued on 1st November, 1988. It was in service for many years. But in recent years due to technical and locational problems it was not on air. We are happy to put it back on air, at a better location, Matheran, a small hill station near Mumbai. This repeater site is given to us by the Collector's office, Thane.

This repeater is regularly accessed by VU2HOC from Valsad (182km), from Pune by VU2UPQ (little noisy) and from Nasik by VU2CVD (little noisy). Some signals may be noisy due to topography of the region.

Repeater is accessible all over Mumbai with a good signal strength.

Known problems:- Repeater gets irregular power from main power line, which is more or less normal for that area and may become severe in monsoon, which may keep it off air for some time. Future plan includes installation of solar panel.

SIMPLE PIC INTERFACE

I homebrewed interface based on Microchip PIC16F628 for controlling the repeater. Just few lines of coding was required and the interface worked very well.

CLOSE UP - TELEMETRY INTERFACE

As a remote location it was necessary to tackle different problems like long hours of load shedding , battery charging etc. I wrote another program for Microchip microcontroller PIC16F72 and made interactive interface which could reply about various parameters in Morse code, a simple telemetry. Complex program consumed 80% of flash memory of pic16f72. Program does everything right from reading voltage, reading temperature , driving display, math's, generating Morse , ptt, Morse tone and reading BCD data from MT8870.

Parameters includes battery voltage, system running on AC or Battery, outside temperature , low battery warning and low battery cut-off. By simply pressing DTMF key #1 you can get out side temp in Morse code, by pressing #2 gives battery voltage, by pressing #8 gives you "A" for a AC or "B" for battery. While having QSO if battery voltage falls below 11.7vdc , small beep is given every 10 seconds, alerting users about battery status. If battery voltage falls below critical level 11.4 vdc, relay disconnects power (not used any more, due to inverter).

Recently I have updated the program and it includes remotely switching ON -OFF repeater. It uses DTMF six digit code to do the operation in a specific sequence, there are 2 different codes for ON and OFF. It has to be incorporated to prevent fishermen entering in to input frequency of the repeater, as the 2m band highly infested by fishermen in Mumbai.

COMPLETE INTERFACE

Both PIC mico-controllers are linked together and monitor the entire repeater system. Pic16f72 ADC port monitor 12/180AH battery voltage. It has its own 5v smps adaptor (cell phone charger), to check if mains supply is present or not.

TX, BATTERY AND INVERTER

Entire setup may look ugly, but everything will be neat and tidy shortly

To deal with long hours of load shedding a 12v/ 180AH battery was installed. Branded Microtek inverter can charge the battery efficiently even in low AC voltage (100-300VAC). Inverter gives uninterupted ture sinewave powers to SMPS power supply , which powers both the radio. Tx Radio, Icom 2200H is kept cool by AC operated cooling fan.

REPEATER RX

Homebrew max232 programing interface was constructed and radio was programmed to 145.6mhz as Rx, its accesory port was also configured.

CLOSE UP OF DUPLEXER

Since duplexer was not used for few years, it required retuninng. It took 2 session and almost 3-4 hrs to get it perfectly working, while doing on air test. We are using Heliax coax about 37 meters in length. Stack 5/8, 6db gain antenna is on the 100 feet height Tower