Kenwood TS-850 Cooling Fan

Discussion in 'Radio Circuits, Repair & Performance' started by W4LAC, May 20, 2019.

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  1. W4LAC

    W4LAC Ham Member QRZ Page

    Does the fan only run when the RF box gets hot? According to the service manual, its controlled by the PTT line and the RF Final board (specifically a transistor on the RF final, which is controlled by TH1 thermistor. When the unit is cool, with the case off, the fan doesn't run at all until I key the mic, and then it's really slow, and even has trouble starting to spin. This normal?
  2. KA5IPF

    KA5IPF Ham Member QRZ Page

    Yep, it will speed up as the temp goes up.
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    It is funny how some complain because of the fan noise. And some complain that there is no fan noise (Me).

    Many do mods to the radio, Then it never works properly.

    A Q-Tip is great for cleaning the fan. Then it moves max air flow. I have use Endust on fan blades, Q-tip applied.

    I hope you are enjoying retirement Clif, Nice to see your great info posts. :)
    Last edited: May 20, 2019
  4. W4LAC

    W4LAC Ham Member QRZ Page

    What about on key down with a cool unit? Should the speed still be reduced?
  5. W4LAC

    W4LAC Ham Member QRZ Page

    Thanks Cliff. I talked to you on the phone last week concerning the capacitor issues. Still finding bad caps on this radio. Thanks for the help.

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