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How do you change the fuse in a 6600M?

Don-KB6TSQDon-KB6TSQ Member
I was running FT8 digital mode.  I moved the power output to 100 watts out to finish a QSO.  On the RR73 transmit sequence, the radio died.  I think the fuse went.  Has anyone changed the fuse on a 6600M?  When I removed the top cover I see the ATU board and another board below it.  The fuse doesn't appear to be easily reachable.

Kind regards and 73,Don


  • Roger,  W6VZVRoger, W6VZV Member
    edited May 2019
    Could it be the power supply rather than the radio?  That would be my guess.
    de Roger W6VZV
  • N9VCN9VC Member ✭✭
    edited July 2018
    Taken from the manual downloadable 6600 hardware  on the website

    The power input has a protective 30 Amp automotive “blade type” fuse inside the radio case. In the event you ever need to replace the internal fuse, remove the top cover and locate the fuse in the rear corner of the PA board just inside the case adjacent to the Anderson Powerpole connector.
    73, Jim N9VC
  • Bill -VA3WTBBill -VA3WTB Member ✭✭✭
    edited July 2018
    I would contact Flex and ask..  If it was the fuse, something must have gone wrong. Simply replacing it may not be a good idea.
  • Don-KB6TSQDon-KB6TSQ Member
    edited July 2018
    Power supply is still working.  It also runs relays that are active.  I read that part of the manual...there are two boards above the Anderson Powerpole connector.  Wouldn't it have been simpler to put a fuse on the hot wire coming into the radio...:)
    Thanks for your comments.  Think I will try your approach Bill.Kind regards and 73,Don-WY6T
  • Bill -VA3WTBBill -VA3WTB Member ✭✭✭
    edited July 2018
    Don, they are having phone trouble now
    you can email...  [email protected]

    or start a help desk support...
  • DougDoug Member ✭✭
    edited March 19
    I really don't care for this design starting with the Anderson Powerpole connector and the power cord is short and no inline fuse. Looking at the wonderful power cord that is supplied with my Icom 7600 it is very cheap to say the least. My powerpole connecter on my 6400M is bad it won't lock the cord in. Flex makes a wonderful radio don't get me wrong but I feel the entire design with there connectors need redesigned. The screwy mic connector and on the rear is a poor design.......... SO let the flames begin .
  • edited July 2018
    Are You sure the fuse is **** - Take an ohmmeter to check it if you can

    I had a problem with the PowerPole itself, if the Blades are not sitting correctly, a voltage 
    drop occurs and causes a higher resistance - had to change out Power Poles to make 
    sure their connection is good on Cable - but can happen on Radio side also 

    73 Mike
  • Lionel Lionel Member ✭✭
    edited July 2018
    Yes, the mike connector seems like it could be a problem one day, but I made an umbilical for headphones, mic, and key. It works fine. For non Flex reasons I made another power cable with suppression. Power poles always leave me a bit flummoxed and I used two tries to get them right; it’s the blades. The the PP’s lock up nicely. That said, my short #10 cable works good, almost no voltage drop as measured inside of the radio. I should have a min/max standing order with parts express and mouser.
  • edited July 2018
    Agree......it’s the blades..... the 40Amp Blades are better than the lower
    Amperage Blades ( Cause Issues ) on Power Poles  

    73 Mike
  • WayneWayne Member
    edited July 2018
    I had my power cord come unplugged ... I hate anderson power poles such a pita Maybe your cord came unplugged like mine.
  • Bill -VA3WTBBill -VA3WTB Member ✭✭✭
    edited December 2019
     Tim - W4TME, Customer Experience Manage 
    • The reason we did this is that since the shift to using the Anderson PowerPole power connector, the feedback we received was that customers did not primarily direct connect the power supply to the radio.  The use fused power distribution block to power other peripherals and adding in-line fuses would result in redundancy and creates additional resistance that lowers the supply voltage to the radio causing it not to put out full RF power.
    And if need to change an internal fuse, you just pull the cover off.  The fuse is very prominent (it's tall and boldly colored) and easy to locate.
  • Bill -VA3WTBBill -VA3WTB Member ✭✭✭
    edited July 2018
    And to further explain why inline fuses are not a good idea,or not needed

    Mark Thomas

    • I don't agree that fusing negative wires on ham shack equipment is generally a good idea.
    In an automotive environment, fusing both the positive and negative lead of devices, especially those that may be wired directly to the vehicle battery terminals, is extremely important. If the vehicle battery chassis ground return strap fails or develops resistance, that equipment negative wire could become a current-passing path to ground for the rest of the vehicle's electrical system, causing wires to overheat, or other dangerous failure. That negative-wire fuse protects you from high DC current from sources other than the fused radio power taking the path of the chassis via antenna coax braid or metal mounting bolts back to the battery.

    A non-vehicular ham shack (assuming you don't live in a metal house which you are using as your antenna ground plane) is a different situation. There may be other shack DC-powered devices that don't have fuses in their thinner DC return wires, such as external antenna tuners or powered antenna switches. If that Flex radio ground fuse opened up but not the positive fuse, the next time you transmit you could end up with high DC current taking paths such as antenna braid to these other devices with the thinner DC wires to your power supply return. Fuses introduce low but non-zero resistance, and sometimes open up unexpectedly due to poor connections or internal failure. I suggest giving careful consideration to how your specific shack equipment is powered and grounded. There is a reason why even fused AC appliances do not have fuses in their safety-ground or neutral (in the US and similar) wire, and I believe this is a comparable situation.

    I'm not saying it is never a good idea to fuse both positive and negative in non-vehicular setups, but often there may be unexpected consequences. Also, if your power distribution is already fused at reasonable per-circuit values, adding additional fuses in positive power wires doesn't buy further safety but does introduce more voltage drop and possible points of failure.

    -Mark KC3DRE
  • DougDoug Member ✭✭
    edited August 2019
    These replies here should show that there is a lot of dislike in this choice. And to ''just pull off the cover'' to change a fuse means removing several screws which is not a well thought out design. Let's be honest it was a cheap and dirty way along with engineering not bringing the mic connector and headset connector to the front of the radio. Can we once "all you fan boys of Flex " accept the truth. I only am being critical here in hopes that the powers to be will see I still love my Flex and won't have anything but a Flex. However there is always room for improvement.
  • Bill -VA3WTBBill -VA3WTB Member ✭✭✭
    edited July 2018
    No problem Doug your opinions are welcome.
  • Steve K9ZWSteve K9ZW Member ✭✭✭
    edited July 2018

    I don't think there is a chorus of dislike fervent for all the years of Flex-6000 series production.

    If a user wants to change their unit's fusing arrangement to depend on an in-line fuse in their power cord, the modifications are trivial. 

    If you search the discussions on connector locations you will find lots of discussion, both pro and con, concerning the present and what was then proposed connector locations, types and sizes.  There may have even bee informal surveys done at some points.

    Connectors and things like fuses were all well discussed within the community, so nothing cheap and dirty, nor unexpected.

    I share with you a preference for power connectors that are physically more secure than PowerPoles, and prefer font-face access for usual connectors.  But then on my 6700's I found myself using the rear panel balanced connector in the end despite front panel connectors. 

    Reserving front panel space for connectors was a community discussion, with FRS making the economic decision to put them where they are.

    Again a fix is using short patch cables.


    Steve K9ZW

  • WayneWayne Member
    edited July 2018
    So this thread has a lot of noise in it now, getting back to the topic Don did you ever get this fixed and was it the fuse you suspected to be the problem or was there another issue in addition or instead of the fuse which was the cause of your operation to be terminated early?
  • Mark GottliebMark Gottlieb Member
    edited August 2019
    I have had the same experience but it was the fuse in the power cable that went.  I wish they opted for the automobile type fuses instead of these buss fuses in the power cable.
  • Mike-VA3MWMike-VA3MW FlexRadio Employee, Community Manager admin
    edited August 2019

    The cables that are sent with the radios do not have fuses in the cable.  The fuse is actually in the radio and it is a 30A fuse.

    Are you sure you are using the correct cable?

    You can see a picture of the cable here.  http://cart.flexradio.com/Power-Cable-for-FLEX-6000_p_979.html


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