Harris SX1 and MW1

[HadYourPhil]

I am trying to help a guy who has the luck of engineering an AM station with one each of the above. The MW-1 is making 440 watts, but it at least works fine at that power. But... the main transmitter is an SX1. The first attempts to start it showed much arcage at the HV contactor. I burnished the removable contacts and now it works without arcing. The transmitter still won't turn on, though. Control voltage is there (buttons light up, display works) but nothing else. The contactor will click several times and then nothing. The "step start" resistor has been eliminated by a previous engineer. Nothing appears damaged or stressed. The HV diode bridge is fine.

The only other SX1 I've ever played with has been trouble free (it's used as a backup) in its current life, so I've not had the opportunity to troubleshoot one. I'm sure one or more of you has...

The MW1? That will be next.

 

[frankberry]

Replace the step-start resistor! It was put there for a reason. If the contactor is clicking several times and then shutting down, something is drawing excessive current. Probably a failure in the PA stage.

 

[HadYourPhil]

Turns out the controller's batteries were dead, which reduced the power to zero!

 

[Kent T]

The controller batteries are a good thing to replace every so many years.

 

[boiseengineer]

Harris & BE seem to like batteries in their controllers.
Why?
Non-volatile memory has been available for many years.

 

[BobRadil]

One thought...

Try cleaning the contacts on the 3rd pole on the main contactor.

It connects to the controller and signals to it that the contactor is on. If those contacts are dirty contact won't be made and the controller thinks it's still off and dumps.