Mike Morris WA6ILQ wrote: > At 09:06 AM 06/17/08, you wrote: >>> I am building a large repeater system here in SE Kansas for SkyWarn >>> and I am wanting to use the RVS-8 Voter. >>> >>> Our system uses Motorola Maxtracs for pretty much every aspect >>> of our giant 15 county coverage repeater. >>> >>> Has anyone successfully used Maxtracs with this Voter? If so, >>> how did you interface them? >> Rear panel connections throught the 16 pin jack. Like most people. >> In the case of Kenwood TKR-820 Repeaters I had to make my own >> interface board. >> >>> The voter has room for up to 8 sattelite receivers. I have a >>> bank of UHF Maxtracs all tuned to different frequencies as the >>> link receivers. They are all identical, and have 16 pins on the >>> rear. I had planned to use PIN 8 COR and PIN 11 audio to feed >>> the voter. COR is in ACTIVE HI on the Maxtracs, as such in >>> the voter. >> Might be better to build and include a simple logic buffer >> circuit. One properly selected and applied fet or transitor >> circuit would probably work very nice. >> >>> The trouble I am having is getting PTT through the voter to be >>> consistant, and by this I mean, only light PTT when there is an >>> incoming COR signal from one receiver. It seems like the COR >>> light on the voter is pulsing all the time, and when a good COR >>> is detected, the COR on the voter goes solid and I can see the >>> SNR counter go up when I talk through it. >> You probably need to isolate the COR/COS output line (pin 8) with >> the simple buffer circuit I mentioned. The description reads like >> you're getting some type of logic pin dc interaction between the >> radios and the voter. >> >>> Anyone have any ideas? >> I try not to... >> >> >>> Thanks advance, >>> Tyler >>> K0FCQ >> Reply back to us if you need specific information about how to >> isolate the radio logic output line from the voter. I myself like >> active low logic lines where possible. >> >> cheers, >> s. > > Note that the LDG voter does NOT use TTL voltages on the COR inputs !!!!! > This bit me HARD a few years ago. > > Each COR input requires a voltage HIGHER than 6.5 volts (up to 20vDC) > and going down to ground (less than 1/2 volt) to work properly. > Yes, it's in the book ... see > <http://www.repeater-builder.com/tech-info/rvs.pdf> > > Go to page 8, and I quote: > > >Active HI means that your receiver COR must produce a positive-going > >voltage (6.5 to 20 volts) when the squelch is open (receiving a signal) and > >a low-going voltage (0.0 to 4.5 volts) when the squelch is closed > (no signal). > > >Active LO means that your receiver COR must provide a low-going > >voltage (0.0 to 4.5 volts) when the squelch is open and a high-going > >voltage (6.5 to 20 volts) when the squelch is closed.
That makes some sense too, since the GE voter needs 10V active high. And they mean 10; 9.5V won't work. > I ended up building an interface board that connected several Maxtrac > receivers to an LDG. The actual setup was to program the MaxTracs > for active high COR. The signal from each radio fed a 2N2222 transistor > base through a 4.7 K resistor. The collectors had 4.7K resistors to +12 > as a pullup resistor on each output. > > The actual radios were 36-42MHz Maxtracs that needed a home... nobody > wanted them so they were free.... the 30-36MHz ones end upon 10m, the > 42-50MHz ones end up on Red Cross or 6m. The guy that was building the > system used a converter from 430-440 and fed a TV splitter. Each output > port fed a Maxtrac. He didn't care about the 75ohm mismatch - the signals > were strong enough. The converter was set up so that 439Mhz channels > showed up on 39Mhz. End of problem. > > Mike WA6ILQ > Well, that's an interesting way to do it!
