[BC] Platinum-Z problem

[Allen Sherrill]

Hey folks:

 

We are getting ready to help out one of the local non-coms with an intermittent foldback or muting problem on a Harris Platinum-Z10 (analog, no HD).  Several times a day the exciter is apparently muting.  The fault indications seem to be VSWR trips.  The problem occurs at any power level above about a kilowatt.  Station frequency is 88.1.

 

The contract engineer does not suspect an actual VSWR problem, although it can't be ruled out.  The antenna and transmission line (approximately 100' of 1 5/8") have been visually inspected (externally) and appear fine.  The line is holding pressure with no problems and has been pressurized since installation.  I'm going to suggest he get a TDR and make sure it's OK, and get a tower guy to check the antenna fitting.

 

The contract guy has swapped in a different exciter (Digit) and changed controller/life support boards in the Z, and the problem persists.  If it's not an actual VSWR trip I might suspect RF getting into the ribbon cables between the exciter and the Z controller.

 

We're going over tomorrow to look at it.  Other than an actual antenna problem, does anyone have suggestions?

 

Thanks,

Allen Sherrill