You gotta love the RS232 "standard" :-) In addition to Don's explanation below, you can't rely on any manufacturer to label the signals according to the standard DTE/DCE nomenclature. Some folks think it is just plain wrong to label a signal TXD (transmit data) when it really is a receiving signal line. Or RXD when it is actually transmitting data. That is what pin 3 and pin 2 on the RS232 connector on your K3 are.
About the only sure way to figure out what is an active source is to look at a schematic or measure the pins with a volmeter/scope or get one of the RS232 blinky boxes. For some more information, have a look at http://www.ke7x.com/home/miscellaneous-k3-information/unexpected-agc-behavior/rs232-interfaces-1 For even more fun and games, read up on the history and use of the handshaking signals RTS, DTR, CTS and RTS. Cheers, Fred KE7X ________________________________________ From: Elecraft <elecraft-boun...@mailman.qth.net> on behalf of Don Wilhelm <w3...@embarqmail.com> Sent: Monday, December 14, 2015 1:25 PM To: char...@k5ua.com; elecraft@mailman.qth.net Subject: Re: [Elecraft] K3S RS232 "Y" Connector causing port conflict Charles, You should find the amp has a driver connected to pin 2. To make sense of the signal directions, you have to know whether the device is configured as DCE or a DTE. Data Communications Equipment or Data Terminal Equipment. The 'transmit' and 'receive' signals are relative to the DTE. In other words, the signal on pin 2 (RXD) will have a receicver in the DTE and a Driver in the DCE. The PC is the DTE and devices like the K3 and your amplifier are DCE type. I know that the DTE/DCE designation for the PC does not make sense, but the serial port of the PC started out to be a port which allowed the PC to behave as a terminal. 73, Don W3FPR On 12/14/2015 2:50 PM, char...@k5ua.com wrote: > > > Thanks for the detailed explanation Don. It seems like that is what is > happening, the OM2500 may be sending info back on the line into the "Y" > connector, confusing Na3P on the computer end on making the OM2500 jump > frequency rapidly back and forth between the correct frequency and the > out-of-band phantom frequency. From the responses, there may be 3 > possible solutions: > > ______________________________________________________________ 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 Message delivered to fc...@montana.edu ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
