[Elecraft] KPA500 RF output wiring

[Fred Jensen]

 > 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