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How to replace 6400 fuse

“Just remove the top cover and it’s right by the powerpole connector”. Except the filter board covers it! What is the procedure for removing the filter board?


  • AG4Q
    AG4Q Member ✭✭

    I have the same question. Is removing the rear panel from the chassis the easiest way to get to the fuse?

  • NI0K
    NI0K Member
    I got the job done. Here is what I did:
    Remove top cover
    Remove screws from ANT1 and ANT2 connectors
    Remove screws from filter board
    Unsolder wire from ANT2 connector
    Using an L-shaped tool lift the corner of the filter board closest to the ANT2 connector
    Pull the filter board away from the rear panel then raise the board to reveal the fuse

    The fuse is a 30A ATO (mini blade)
  • KD0RC
    KD0RC Member, Super Elmer Moderator

    No unsoldering is necessary. Remove the top cover with a T9 Torx bit. On the 6400, remove the two coax cables (very gently pull straight up) and make note of where they go back (LPF X2, RXA X7). Gently unplug the ribbon cable (PA X4). Remove the four phillips-head screws from the filter board. Remove the four phillips-head screws from the SO-239 antenna connectors. Gently ease the board back and out. The rivets holding the coax connectors can hang slightly on the mounting studs, so a little wiggling may be necessary.

    Now the fuse is in plain view and can be replaced, if needed.

    Put the filter board back in (making sure that all cables are accessible) and put all the screws back in only finger tight. Then tighten the SO-239 screws first so that there is no stress on the board. Finally, tighten the screws holding the board down followed by plugging in the ribbon cable and two coax cables.

    I don't have an ATU or a 6600, so there may be more connections and another board to deal with, but I would think the process is generally the same.

    I didn't need to change my fuse but did this exercise to understand what I need to do in the field should anything bad happen requiring a fuse replacement. My truck and camper both use this same fuse size, and I have plenty of 30 A replacements on hand, therefore I will never need to replace it...

  • Tim K9WX
    Tim K9WX Member ✭✭✭

    One bit of advice for anyone trying this: the fuse in my 6600 is an mini fuse. It is not the larger style fuse used in RigRunners or other power strips common to the hobby. The terminology for these fuses is somewhat confusing and the 6600 hardware reference manual simply says, "The power input has a protective 30 Amp automotive “blade type” fuse inside the radio case." Make sure you have the right size replacement fuse on hand before you start. Here is a table of automotive fuse styles from Wikipedia. Lots of different ways of referring to the same fuse.

    Tim K9WX

  • Cleaning the fuse blades and adjusting the clip springs on the fuse holder appears to have fixed a problem I was having with low power output. Before making the adjustment, I was getting less than 80W out on all bands, now over 100W at max power.

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