Strange TS930S PA Fault

Discussion in 'Radio Circuits, Repair & Performance' started by G3YRO, Dec 2, 2017.

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  1. G4COE

    G4COE Ham Member QRZ Page

    I mentioned measuring R14 the current monitor just in case anything has happened to it due to the excessive current as a precaution.... I dunno how tough this resistor is.

    Dave
     
  2. G3YRO

    G3YRO Ham Member QRZ Page

    It's only had the excessive current for less than 2 seconds at a time, max ! (and even on receive, I turned the rig off straight away)

    So I presume that resistor is OK.

    But you're right - at some point when I have it apart it might be worth wiring a meter in series with the PA feed to check its calibration.

    Roger G3YRO
     
  3. G3YRO

    G3YRO Ham Member QRZ Page

    Well I've used the 930 for a couple of hours on CW the last couple of nights, to get the PA warm . . .

    I'm pleased to say there has been no sign of the problem re-occuring (I'm continually monitoring PA Current now, to see any signs of change!)

    So hopefully this problem WAS that dirty Bias pot changing contact when hot.

    However . . . I do now appreciate there MAY still be a problem with one of the PA transistors going leaky between Collector and Base when hot . . . so I will keep my eyes open. (and report back if it happens again)

    Thanks everyone who offered advice. (even if you end up self-diagnosing, I find it really useful to discuss faults on here . . . it makes you think things through properly)

    Roger G3YRO
     
  4. KA9JLM

    KA9JLM Ham Member QRZ Page

    I would be tempted to fuse the PA supply, Like many radios do.

    I hate when a RF out transistor becomes the main fuse protector.

    Have Fun.
     
  5. G3YRO

    G3YRO Ham Member QRZ Page

    Kenwood put a 20 amp fuse soldered inside the rig in the supply line . . .

    Roger G3YRO
     

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