Radio Amateur N5GE wrote: > To make sure I have understood correctly. Am I correct in saying each > of the control wires going to the switch box should be connected to > the SOURCE and the ground connected to the SINK? > > Thanks again, > > Tom, N5GE > K3 #806, K3 #1055 > XV144, XV432 > W1 and other small kits. > http://www.n5ge.com > > Tom,
While following this thread, I was thinking that someone would ask that question. The answer is "not quite". In your particular case, the ground wire from your relay box connects to one of the KRC2 "G" connectors (and the power supply common for the relays must also connect to a "G" connector) - your relay box requires power directed to the relay to be operated.. For some antenna relay boxes one terminal of the relay coil is connected to a voltage that matches the relay coil requirements (12 volts is usual for amateur equipment) - and the operating switch connects the other side of the relay coil to ground when that relay is to operate. If your antenna relay box is of that type, then you would connect the relay coils to the appropriate SINK in the KRC2. In other words, the relay box contains the power for the relays, and the switch in the shack connects the ground for the relay to be operated (the power provided by the relay box goes "down the SINK drain"). Don't forget that the relay power supply common must also connect to the KRC2 (at one of the "G" connectors). Other relay boxes contain no power, and all the relays in the box have one of the relay's coil connected to ground - and the relay positive coil terminal must have power delivered to it (SOURCED) to operate. This is the case with the Ameritron RCS-8VX switch. The relay that is to operate must be provided with 12 volts, all the relays are connected to ground. So you would connect the relay power supply to the KRC2 "V" connector (and power supply ground to "G:) and the wires to the relays to the appropriate band (SOURCE or high side) outputs - those are the ones silkscreened on the board *without* the bar across the top of the label. Since in this case the relay power required is 12 volts, you can connect the relay (and KRC2) power to the coaxial power jack instead of to the "V" and "G" connectors. If the relay voltage is greater than 15 volts, you *must* use the "V" and "G" connectors when using the SOURCE drivers in the KRC2. Be certain the relay common is connected to the KRC2 "G" connector to complete the common path. In this case, the power for the relays comes from the relay power supply (that is equivalent to the city water supply in Jack's analogy) and is controlled *to* a particular relay by the source driver (that particular faucet) connected to the relay coil. While one *CAN* use both the source and sink drivers together, normal usage will use one or the other. As an aside, I might mention, that those familiar with relay logic might see a vast variety of possibilities for doing relay control using both the source and sink drivers, since the drivers may be "wire ORed" together. Add a few diodes to help with the isolation and a lot of logic functions can be performed with the KRC2 outputs and some relays. This was intended to be informative, not confusing. If you found it confusing, ask about it and I will try again. 73, Don W3FPR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
