I am designing a linking system for my repeaters using a couple of Astro Sabers. In the past I have just connected a audio transformer to the
speaker and the secondary side of the transformer to a audio input such as a TNC. This worked great, but now I need a COS. So it will key the repeater when the linking radio is receiving a signal.
I thought about using a LM328 inverting Op Amp. But I don't have any sample circuits to experiment with. Is there anyone that can show me how to build a circuit?
MARS
By the way: I am using some speaker mikes so I can easily program the radios.
COS Circuit for a Astro Saber
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I know it sounds like a big waste of a good piece of equipment. But, please keep in mind that this will be on a government frequency (MARS specifically) (narrowbanding may be required, issues are being worked), all work, equipment, and parts has to come out of my own pocket. My pockets are very shallow, and I can't afford to purchase radios. I was able to get a couple of radios (one VHF & one UHF Astro Saber, one VHF Range 2 and one UHF range 1 Quantars) thru government surplus channels.
The two repeaters that I want to link consist of one wideband repeater (138-144) and the other is a VHF range 2 Quantar. Which is still waiting for a frequency assignment (perferred in 148-150, for obvious reasons. This frequency assignment may be a digital assignment, I'm not sure what will be assigned).
Providing I get the seperation, I am looking at two options. 1) program the AS to communicate on the Quantar repeater pair and connect it to the wideband repeater. 2) Request a seperate frequency (406-420, narrowband), set up the AS for digital communcations and connect it to the wideband repeater. Then setup the UHF Quantar as a digital base station and connect it to the VHF Quantar.
Either way, I want to be prepared to go narrowband digital when setting up this system. It will only be a matter of time when everyone must go narrowband (including hams) and the old wideband equipment is not worth repairing.
Why have something collect dust when I can put it to use.
The two repeaters that I want to link consist of one wideband repeater (138-144) and the other is a VHF range 2 Quantar. Which is still waiting for a frequency assignment (perferred in 148-150, for obvious reasons. This frequency assignment may be a digital assignment, I'm not sure what will be assigned).
Providing I get the seperation, I am looking at two options. 1) program the AS to communicate on the Quantar repeater pair and connect it to the wideband repeater. 2) Request a seperate frequency (406-420, narrowband), set up the AS for digital communcations and connect it to the wideband repeater. Then setup the UHF Quantar as a digital base station and connect it to the VHF Quantar.
Either way, I want to be prepared to go narrowband digital when setting up this system. It will only be a matter of time when everyone must go narrowband (including hams) and the old wideband equipment is not worth repairing.
Why have something collect dust when I can put it to use.
If, like on other portables, the push-pull bridged audio output stage is turned on when the radio receives. Even the P200/HT600 do this. Connect a 20k resistor from each side of the external spkr line and the other end of the 2 resistors together and to a voltage detector which will "see" about 3-3.6 volts when the receiver unsquelches. Since the audio output is ballanced all you get is DC at the resistor junction.
