View Single Post
  #12 (permalink)  
Old 11-02-2011, 4:55 PM
loumaag's Avatar
loumaag loumaag is offline
Silent Key - Aug 2014
Join Date: Oct 2002
Location: Katy, TX
Posts: 13,132

Let me make a comment here.

I think that there may be a bit of a language barrier thing going on here. I think that the Wouxun folks may have a hard time explaining why the heat is being generated; although, I can certainly understand how it could be done, so they said it is transferred by the cable.

And I guess technically that is correct, and before someone thinks I have gone around the corner in my old age, stop and think for a moment what voltages appear on a RS232 signal path. Nominally both a -12v and a +12v appear on on the port. A bad design of either (or both) the port on the radio and the software can cause those voltages to be constantly pulled (assuming the computer doesn't crash the driver). For short periods, that shouldn't cause problems, but based on my limited experience with SMD it doesn't take much heat to start causing havoc. Ah, for the good old days of wire components inside electronics. Oh wait, that was when stuff was expensive...never mind.

ETA: Well, someone sent me a message pointing out that the Wouxun cable incorporates a level converter to change the RS232 voltages to TTL voltages (~ +5v/0). I don't own one of these radios and really don't have a dog in this fight but I figured that I would pass on the information. Interestingly enough this would lead me to believe that the cable has a MAX232 type chip in it and if designed correctly should work. However, just something in the way the information was passed on makes me wonder if they designed this as a single ended TTL interface as opposed to a differential TTL interface. Without getting into the technical aspects, a single ended TTL requires current to be returned on the ground connection which has proven in the past to allow other common ground connected components to be affected. In any case the above is for consideration and information of those that might be interested.

Last edited by loumaag; 11-04-2011 at 9:56 AM.. Reason: Adding information
Reply With Quote