I don't think the diode isolation will work in this case. Scott K9MA
On Feb 16, 2011, at 2:36 PM, Paul Christensen wrote: >> You might have a problem when only one rig is powered up, with the >> unpowered one pulling down the key/control line. The K3 is OK, as both >> outputs are open drain/collector. If that's also the case with the ICOM, >> the "Y" connector should work. If the ICOM has a pull-up resistor, or >> anything except an open drain/collector connected to that control line, >> there could be a problem... > > In that case, a Schottky steering diode can be used on the Icom key line. A > 1N914 or 1N400X series may be fine but I've seen instances where the higher > diode junction voltage prevents the line from going low enough to circuit > ground potential. Not sure how sensitive the Alpha 9500 is to that effect. > I agree with Scott that the K3 should be fine with its open-drain on the > MOSFET switch. > > I don't see this issue very often on the amp key line -- I do see it often > when trying to use a single CW keyer, feeding multiple transceiver's in > parallel, due to the use of pull-up resistors on the paddle key line. > Again, Schottky steering diodes used for isolation at the input to each > transceiver's CW key line solves the problem. > > Paul, W9AC > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html Scott Ellington Madison, Wisconsin USA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
