> On 9/7/2011 10:53 PM, Johnny Siu wrote: >> The connection between the RF deck to the RF SO239 output is a pair >> of twisted wires instead of a coaxial jumper. Is there any reason >> for such a design?
Twisted pair is a highly effective transmission line, and easier to work with than coax in tight quarters. That TP in the KPA500 is short. A suitable size piece of coax would be pretty stiff. I don't have any quantitative data [ask Jim, K9YC, I'm sure he does], but I've also found balanced twisted pair to often be less susceptible to RFI than shielded cable. In the early 70's, I was working on a process control system hosted on a Data General Nova mini-computer. The boards were about 40cm square. For unexplainable reasons, the CPU stopped when the FORTRAN compiler encountered a DO statement [don't ask me how it knew that :-)]. DG finally brought in the guru, wearing what appeared to be the same clothes for a week, and he finally said, "cut these two traces in two places and replace them with a piece of tightly twisted pair." Problem solved. Obviously, he wasn't being paid the big bucks because of his wardrobe, but twisted pair did the trick. 73, Fred K6DGW - Northern California Contest Club - CU in the 2011 Cal QSO Party 1-2 Oct 2011 - www.cqp.org ______________________________________________________________ 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
