I just recently uploaded a YouTube video on my homemade SQUELCHED TRIGGERED REPEATER SYSTEM using the Radio Shack 2052 radio scanner as a receiver, and ICOM V68 as the transmitter. It uses a squelched trigger relay switch to enable a handheld or base transceiver. It is so simple that you might want to try it if your out of budget on a commercially made repeater or COR.
Watch my DIY video at
PROJECT FACTS AND DETAILS:
Though you can hack and add squelch trigger devices to any scanner receiver or 2 way radios of your choice (yes, you can tap the squelch circuit on the receive section of that ICOM 28H for a cleaner repeater performance on 2 meter!), I strongly suggest that you first study how the squelch circuit of your radio works. You must secure a schematic diagram of your radio. You must identify the squelch IC and see if a specification/ data sheet for that part number is available on the web.
Next identify the logic +5 volt pin of that IC. From what I read, it is a voltage comparator section of the circuit which outputs a +5 volt when a signal is present or when the squelch is closed, or 0 volt when it is open (silent) or vice versa. 5 volt is nominal, but in some radios like my Radio Shack Pro-2052 it is 3 volts. Even if you doesn't have a pin-out diagram of the squelch IC, you can try looking for that voltage logic pin using a digital tester and varying the squelch control (opening and closing the squelch). Just be careful not to short anything on those pins or you'll damage that squelch IC. Connect the negative test prods of your multimeter to negative ground or any metal part of your radio, and carefully tap the pins one by one with the positive tip of your tester while the squelch is open. If your digital tester reads something between +3 volts to +5 volts, then bingo! You got the right squelch tap.
Then you had to make a relay trigger switch. Search for an appropriate schematic on the web. You must be familiar with the relay switch connection. It must be able to activate the transmitter (your handheld transceiver or base radio) when a signal is present on the receiver.
A good working relay trigger device should activate even by merely touching the input with your finger. You should hear series of clicking sound on the relay while touching the input terminal (usually, one of the amplifier transistor pin)
If your receiver has a CTCSS (Tone Squelch), you can use this feature to safeguard your homemade repeater from unauthorized use or triggering which might hinder your operations.
You can do all these through experimentations like what I did. But be extra careful.
Good luck, and enjoy the hobby!!!
MANNY DE GUZMAN, JR.
SoundMagik Home Studio
Site Creator, TEENMODELS2007http://teenmodels2007.wetpaint.com/
Watch my YouTube video "HOMEMADE REPEATER USING RADIO SHACK PRO-2052 AND ICOM V68" here: