[CQ-Contest] Which Coax Jumpers Reduce SO2R Interference

[Ken Widelitz]

Although both my radios have stubs (double stubs on 40 meters) and bandpass
filters, I still suffer from more interstation interference than I would
like when operating SO2R from my city lot. Thinking some of the problem
might stem from my coax jumpers, I first went to all RG-214 jumpers from
RG-213. I didn't notice much difference. I then went to Andrews F4 (1/2")
hardline jumpers. It seemed to get worse. I just finished exhaustive testing
of the RG-214 vs. the hardline jumpers, and the numbers show, with one band
combination exception, the RG-214 is better. The only place the hardline
came out better was transmitting on 80m and receiving on 40m. All other
combinations favored the RG-214.

I would have thought the better shielding of the hardline would have made it
better. The only factor that might have affected the hardline's results is
that all the hardline came with N connectors, so I used adapters to PL-259s
on each end. These were new and the best quality I could buy.

Any thoughts on why this is?

73, Ken, K6LA / VY2TT