AL-80B Metering Problem

Discussion in 'Amateur Radio Amplifiers' started by W2AAT, Jan 14, 2019.

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  1. W2AAT

    W2AAT XML Subscriber QRZ Page

    I own one of the earlier version AL-80B's. An issue has developed in the REF position of the MULTIMETER switch. At about 300 watts (key down), the meter (Forward(KW)) begins to creep up and ultimately ends up off scale.
    Yes, this happens when the amp is terminated into a dummy load.
    Power output indication on my external SWR/Watt meter does not change.
    There is new coax throughout my entire installation (problem happened prior to the new coax).
    The problem happens on all bands.
    I cleaned all contacts and relays.
    There isn't an swr issue between my 590 and the amp.

    Any comments and/or advise is sincerely appreciated.

    corky w2aat
     
  2. W1QJ

    W1QJ Ham Member QRZ Page

    As I recall the power circuit is amplified to the meter using a simple transistor amplifier circuit. It sounds like the transistor is saturating instead of amplifying. Something in that circuit is probably bad.
     
    N2EY likes this.

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