[Elecraft] KPA500 RF output wiring

[Johnny Siu]

Thanks for all the replies from Don, Jim and Fred and some others

 73,


Johnny VR2XMC

從︰ Fred Jensen <k6dgw at foothill.net>
收件人︰ Elecraft Reflector <elecraft at mailman.qth.net>
傳送日期︰ 2011年09月8日 (週四) 9:57 PM
主題︰ Re: [Elecraft] KPA500 RF output wiring

> 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