GPSDO On 6700 Erratic

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  • Problem
  • Updated 2 years ago
Just recently my 6700 started having occasional problems with the GPSDO not locking up. It would stay in "holdover" mode. The number of satellites visible seemed to vary rapidly, jumping from 15 to 6 and back in just seconds. Satellites tracked stuck at 99 which is obviously not a good sign.

Running SSDR v2.3.9.

Tonight, it appears to be a permanent situation.  Repeated power downs, removal of power and restarts and executing the "uninstall" then "reinstall" commands for the GPSDO have not changed the holdover status.

Searching the community site indicates this could be a bad antenna (has always been indoors), a bad GPSDO board, or an issue with the GPSDO board connections.

I intend to open up the radio tomorrow and try removing and reinstalling the GPSDO. Just wondering if there are any other suggestions?

Maybe it is time for trouble ticket and trip back to Texas?

Thanks for any suggestions.

73, Tom
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Posted 2 years ago

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Photo of George Molnar, KF2T

George Molnar, KF2T, Elmer

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Have you done a complete “factory” reset? That will usually nail any weird software states. If you can pick up a replacement antenna (they’re pretty generic), I would try that before comsidering shipping it to the mothership.

Opening a ticket is probably a good idea, too.
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Bill -VA3WTB

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Don't gett too far ahead talking about sending the radio in. When they contact you to trouble shoot this, they may ask you to re seat the board. And try another antenna, yes even if it's been in doors.

There will be a number of test they will do with you to determin what is going on. And if they do find the problem is the GPSO board then they can send you one and you can install it yourself,,I think.
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Richard Thompson

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Get a new antenna for the gps. I had the same problem the that fixed it for me. Never had a problem again.
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Jay / NO5J

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I've got the GPSDO option in my 6500, I have had several instances of what seemed to be permanent holdover status. 

They have all, so far, been "not" so permanent.

I'm using both the stock indoor antenna, and another "outdoor" rated stock antenna. One mounted on the inside of a shack window with about half the sky visible.. The other mounted outdoors attached to the roof facia board outside, and just above the window.  The outdoor antenna has a better 360 degree view of the sky, but both seem to work well enough. Sometimes just switching to the other antenna solves the holdover problem, it's in effect doing the same thing I'll describe below.

Try this crazy technique, next time. It doesn't always fix it. but each time I've successfully fixed the permanent holdover problem, it's been one of the steps in the fix.

Disconnect the GPSDO antenna, for about 30 secs then reconnect it.

The antenna is powered and has an internal preamp, disconnecting it will power cycle the preamp.

I'm not sure why power cycling the antenna preamp helps, but it seems to.

The GPSDO is always powered right? So it's always powering the antenna preamp, right? Perhaps the preamp glitches and stops amplifying the GPS signals correctly, and gets stuck. Then power cycling it, get's it unstuck. I don't think just resetting/rebooting the radio, ever resets the GPSDO board or power cycles the antenna preamp, they are always running whenever the radio is powered.

 Quite often I've seen that this caused the GPSDO to begin to acquire, and track, the satellites again, and then lock.

At times, that this hasn't helped, removing power from the radio, or doing a factory reset, afterwards finishes the job.

Sounds kind of crazy doesn't it.    

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         73, Jay - NO5J

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Steve K9ZW, Elmer

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In troubleshooting I'm always looking for what might have changed. 

I also experienced GPS lock-up becoming variable - twice.

In my particular case the solution that worked was repositioning the GPS antenna.  I cannot say with any absoluteness what the detailed issue(s) were - whether foliage growth, some other blanking, a change in the GPS constellation configuration, or the antenna just wanted to feel appreciated. 

Nonetheless simple relocation  sorted it out. 

(I'm thinking it was attenuation due to tree growth.)

Now for confession time - the first time I had GPS lock changes, very early with my radio, I found the antenna was upside-down.  No idea if it worked upside-down until it just didn't, or if it got flipped by someone else.  

There are also plenty of enhanced performance antenna options to try.

GL & 73

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Thanks to all for the helpful replies! 

As suggested, the GPSDO holdover condition was not permanent. In the process of troubleshooting, I moved a lot of cabling behind the radio. Got a lock.  I <think> the culprit is the GPS cable or connector. Wiggling the cable seems to affect whether the unit will lock or immediately go into a holdover state following powering up the radio.

So, off to find a replacement antenna.

Thanks again to the group. The community is a super resource.

73, Tom
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Bill -VA3WTB

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I was fairly sure that was the problem,,good to hear Tom...
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All great suggestions! Another variable is a software problem found its way into the mix at 2.3.7. Try backing up to 2.1.33 and see if symptoms change. Typically what I’ve seen is the color of the power button does not indicate the true GPSDO status, yet it’s working correctly.