KWM-2 Low Power Out

Discussion in '"Boat Anchor" & Classic Equipment' started by W3TA, Oct 17, 2021.

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  1. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Sorry!

    Doesn't the KWM-2 PA screen voltage come from the LV power supply (normally the 5U4 in the 516F-2) which is independent of the HV supply (normally the 5R4 in the supply)?

    I think it does, although haven't looked lately.

    But if it does and you pull the HV rectifier (5R4 or its solid-state plug-in replacement) and don't also pull the LV rectifier, and try to transmit, that should destroy the 6146 screen grids almost instantly (once cutoff bias is disabled and control grid operating bias plus RF drive is applied).
     
  2. W3TA

    W3TA Ham Member QRZ Page

    You are correct. I suppose I neglected to say that I also disconnect the PA screen voltage. There is a jumper that gets cut between the "PA Disable" connectors on the rear panel of the radio. I then make a jumper (phono to phono) to use for reconnecting the voltage until I'm done tinkering. The manual calls out the instructions to cut this jumper along with removing the HV rectifier to perform several tests.

    Tom
     

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