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Flex 6400 - Remote Power On ???


I have a remote Flex 6400 & SmartSDR (2.6.2) and all is working fine.

I need to be able to remotely "power-off" (remove DC) the radio when it's not in use and I understand that this cannot be safely done by just cycling the DC input.

So I configured the REMOTE POWER ON and have a SPST relay toggle the RCA input.

Via the SPST relay, I would remotely open the line, the Flex would turn off (green and blue LEDs turn off). Then I would remotely turn OFF the DC supply. So far so good.

To turn it back on, I remotely turn on the DC supply, wait a few seconds, then toggle the relay connected to the REMOTE POWER ON RCA jack. Here is the problem I am seeing:

  • Green power LED comes ON but keeps flashing.
  • The blue LED is steady ON
  • The green LED keeps on flashing ... does not come ON, so the radio is inaccessible <-- How long does it take to turn on??
  • After several tries with the same result and at one point, the power LED started flashing RED
  • At this stage, I had to do a factory reset to recover as I assume that the file got corrupted in the Flex after all of these tries.

OK ... so this is what is happening so I am now looking for suggestions on the proper way to be able to remotely remove power to the Flex 6400 using the REMOTE POWER ON function. What am I missing?


  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Bruno, you have it right. It takes a minute or so for my 6400 to boot up to a solid green light. I would say that if you wait for 2 minutes and the flashing green has not gone to solid green, it is time to put in a support ticket.


    Len, KD0RC

  • W4AFK Bruno
    W4AFK Bruno Member ✭✭

    Thanks ... We will try again tomorrow (I am in California and my remote is in Florida at a ham-host' s garage. We share the Flex 6400 + 1.3K amp and antennas). See my QRZ page for our setup

  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator

    What is the red LED flashing pattern?

    single flash pattern is fan failure. If radio detects fan RPM issue it will not boot.

    three red flashes - probable corrupted SD card.

    In either case, it is best to open a Help Desk ticket.

    What I do for remote is use a DLI Web Switch Pro. 8 independently switchable outlets. I have one outlet each for cable modem, router, DC supply, rotor, local PC, DLI AC relay for remote power on of radio, and another DLI AC relay for remote PTT (to perform local PTT for SmartLink registration).

    The local PC bios is set to power on when AC is supplied.

    I also use a Raspberry Pi running Node Red for integration the amp, rotor, and radio to be able to monitor and control the equipment remote via a web browser.


    Dave wo2x

  • George KF2T
    George KF2T Member ✭✭✭

    Give the radio some time once power is applied before using the remote on relay. A minute ought to be plenty.

  • W4AFK Bruno
    W4AFK Bruno Member ✭✭

    David (WO2X) - Single Flashing RED (fan), but the fan is working fine. I assume that this occurred as we probably didn't respect timing between tries and corrupted something. Didn't see any notes in the manuals on how you need to use the REMOTE POWER ON connection, more specifically with regards to sequencing and timing. It's called "live and learn" :-).

    Remote setup - I use the same DLI WPS (check my QRZ page). I also have a script that "pings" the modem and if it doesn't respond after 5 tries, I assume that it's locked-up so the WPS powers-off the modem and the router, waits a couple of minutes, then powers-up the modem, waits another couple of minutes, then powers-up the router. As for the cable modem's dynamic IP address, I use DynDNS. Been using this for years and it's been working just fine even after many power losses (the remote is in Florida ... lightning capital, with tropical storms and hurricanes LOL). That WPS is #2 ... the first one got damaged by a nearby lightning strike. Per the electrician who had to fix other items, the surge came up the GROUND line. Contrary to all we learned, he said that we should avoid connecting the ground. Another electrician told us the same (go figure). Note that when we don't use the system the antennas are remotely disconnected ... center and shield. Doesn't protect against a direct hit but is does against EMP surges.

    I have a Raspberry Pi3 to "extend" a USB connection to a SPE 1.3K amplifier (using VirtualHere) so I can manage the amp. I then have a Win10 based NUC to manage the Flex. I needed the NUC as you can't reset or make updates to the Flex from the WAN (a shame). The NUC lets me connect to the Flex on the LAN side.

    Both are set to auto-start upon power cycle and run the background apps (VNC, VH, RPC, etc.)


    George (K2FT) - Noted for the timing. I am certain that what I am seeing is just timing of how we are sequencing things.

  • W4AFK Bruno
    W4AFK Bruno Member ✭✭

    Follow-up - My remote-host just told me that he placed the FLEX' front panel switch to OFF to be able to use the REMOTE POWER ON function. Is that what needs to be done?

    He also said that he waited more than 10 minutes and the green LED never came on steady.

  • WX7Y
    WX7Y Member ✭✭✭✭

    If you turn off the front display Power button that turns off the radio.

    Remote power ON/OFF is a RCA jack on the back of the radio that needs to be, first enabled in the Settings windows then connect a contact closer remote power switch that opens and closes the RCA jack on the radio.

    No mater what the Front display needs to be on!

  • W4AFK Bruno
    W4AFK Bruno Member ✭✭
    edited December 2020

    Bret - Thanks ... that's what I thought. He was turning off the radio via the front panel ;-)

  • W4AFK Bruno
    W4AFK Bruno Member ✭✭

    Follow-up "my education question" - As I cannot find a bloc diagram of the Flex 6400 and the radio and SmartSDR manuals seem to be silent on this, can someone please explain what happens when you toggle the REMOTE POWER ON ("RPO") line and the relationship to the radio's status?

    My understanding:

    Radio up and running:

    • DC is provided to the radio
    • Radio is turned ON (front panel)
    • RPO function in SmartSDR is turned ON
    • RPO relay to RCA jack is powered (closed contacts)
    • Radio works normally.

    Shutting down and removing power - sequence:

    • RPO Relay is deactivated (open the contacts to the RCA jack)
    • Radio starts the graceful shutdown by saving and closing any open files
    • Radio then goes into a "standby mode" (powered but ready for full shutdown)
    • After waiting for a minute or so (anything more precise?), remove DC power from the radio
    • Radio turns off (don't touch the power button as it stays in the same position as when the radio was ON)

    Remotely turning the radio back ON - sequence:

    • Remotely turn ON the DC power supply for the radio
    • Radio starts the reboot and sees that the RPO line is OPEN so it stays in standby mode
    • After a minute (exact time?), activate the RPO line (close the relay contact)
    • The radio sees this and does a full startup
    • After "?" time (what should this be?) the radio completes the boot-up and is ready to work

    Is the above how it's supposed to work?

    I ask as if the RPO function is not activated in SmartSDR radio and DC power is lost, when the power comes back the radio does not turn on. You need to activate the front panel button. This is BAD when your radio is remote as you are "dead in the water", hence the use of the RPO line.

    Lastly, if there exists a block diagram (or better yet, a schematic diagram) of the Flex 6400, please point me to it. And yes, after I post this message, I will do a Google search.

    Just trying to understand the process as I can't seem to find this info in neither of the manuals

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    An interesting feature of the Remote On is that if you power up the radio using the front panel button, then turn on (i.e. close) the remote switch, nothing happens. If you subsequently turn off the remote switch, the rig will power off normally. So if you power up with the front panel, then go on a trip and want to remotely shut it down, you have to turn the switch on then back off again. If you powered the rig up with the remote, then power down with the front panel, the rig will power down normally, even though the remote switch is closed.

    If power is lost, then restored, the rig will power up if the remote is already on. In my case, my remote switch is powered from the same supply as the rig, so if power is temporarily lost, I have to use the remote (or front panel switch) to turn the rig back on.

    In answer to your question, yes, you have the sequences correct. In your final set of points, I do not think the radio boots when power is supplied. It only provides power so that the boot sequence can be initiated using the power button or Remote On jack.


    Len, KD0RC

  • Greg N8GD
    Greg N8GD Member ✭✭

    I own a Flex-6300, purchased back in 2014 just when they first came out (@ Hamvention), so I can't speak as to the 6400/6600 action that I am about to describe.

    When the original Signature Series radios (including my 6300) first came out, Flex recommended installing a shorted RCA plug into the RPO jack on the rear of the radio if you wanted it to power up whenever the DC was applied. This original, and simpler method persisted for several years, and worked well. As for my 6300, it is automatically powered up via a Data Loggers Web Power Switch every day (it's programmed to do so) by switching my DC supply feeding it to ON at 7:00 AM (the AC to the supply is activated). The radio comes on without any intervention from me. at 10 PM the Web Power Switch is programmed to switch off the AC to the radio's DC supply, and the 6300 shuts down. I also have control over the Web Power Switch via a cell phone app, so I can power cycle the radio remotely. The automatic power on and off has been occuring daily for the past five years since 2015 with absolutely no problems. A few years ago, Flex started recommending that the DC be applied first, then the RPO jack be shorted, and finally the radio is powered up. I have NEVER done this!. I believe that Flex was concerned that the power on occurring with the RPO jack simultaneously shorted was somehow causing problems with the multiple processors starting in the radio. I have never seen any problem with my method. I also like just power cycling the power supply only and not having to perform a two step process. It works! And, it allows for easy cycling of the radio should something happen, like a lockup or other anomaly. I would suggest trying to eliminate the switching of the RPO jack and leave it permanently shorted. See how it works. My guess is that things will work more reliably. It's worth experimenting with it at least.

    By the way, my radio is fed with a 40 Amp DIamond GZV4000 switching DC supply, and always has been. I don't know if there is a difference in how quickly my switching supply comes up to 13.8 VDC vs a linear supply, but I have quite a few radios connected to that supply as well as several others connected to another, identical supply. None of the radios present any trouble with powering then up with the switching supply via applied AC - I NEVER use the ON/OFF switches on the radios.

  • Ken Hansen
    Ken Hansen Member ✭✭


    If I understand correctly, based on your very comprehensive post (above) and what I've read elsewhere here, the following should work:


    Wall power into a "smart switch" into the 12V power adapter into the radio. (In other words, just a "smart" internet-controlled outlet switch that turns 12 volt power adapter on/off.)

    If I want to power-up the Flex, if I have the remote RCA jack on the radio shorted, once power is supplied, the radio will boot up (as your 6300 has for years)

    But where I'm lost is power-down. If I cut the 12 volt power adapter, the radio will just shut down hard - that seems bad - as I read your post that is what you've done "for years" without issue.

    Is that correct, does your radio just crash down when power is removed?

    I can put a relay on the RCA jack, but honestly I'd prefer to keep this as simple as possible, and shorting the RCA jack seems simplest.

    Right now my remote shack is minimalist - 6400, PS, and internet connection, with a 40 meter dipole (NVIS) and a cobweb antenna - easy-peasy, nothing complex.

    I'm seeking an answer, as this week for the first time my remote 6400 got "wedged" and wouldn't respond to SmartSDR software, so I had to wait for the opportunity to visit the radio and power-cycle it in-person. I now have the radio on a dedicated Astron linear PS and the Astron is on a "smart outlet", so I can turn power off, but without a shorted RCA jack the radio will just sit in standby untill I press the power button in-person.

    Thanks in advance,

    Ken, N2VIP

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