[PPRAANet] transmission line question

[james.f.gibson at gmail.com]

Transmission line experts, I have a question.

 

After installing a MFJ-2389 antenna (currently used only for 2M operation) I
temporarily connected a 120 ft RG8X cable between the rig and the short ( <
10 ft ) span of RG8U attached to the antenna.  The measured SWR was 1.48.

 

Then I removed the RG8X cable and attached the intended permanent cable
which is 50 ft of MPD400 (LMR400 equivalent) to the RG8U.  Surprised to get
a SWR of 2.8.

 

These are all 50 ohm coax cables.  Any idea why the MPD400 swap-in would
give me an unacceptable SWR?

 

Jim KS4F