GPSDO externe

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KD0RC

Steve VanWambeck

Martin AA6E

The only way your external GPSDO can work with your Flex is by supplying a high stability 10 MHz reference to the Flex external reference input. The Flex SSDR will not know about your GPS details, but you will get the high accuracy you want. 73 Martin AA6E

Brian Denley KB1VBF

He won’t need any calibration station.  The program will just use the external 10 MHz GPSDO signal to calibrate.  But he will need to press START.

KD0RC

Hi Brian, I believe that it works the same way whether it is the TCXO, internal GPSDO or external GPSDO. It locks in on whichever oscillator source it has, then uses whatever calibration sig is specified (e.g. 10 MHz WWV). In my case, WWV at 2.5 MHZ gives me an adjustment of -3 ppb when using the GPSDO. Using the TCXO, it gives an adjustment of somewhere around -1200 ppb. If you were to manually set the adjustment to zero with a GPSDO, you would likely be within a fraction of a Hz anyway, so I recognize that it is not critical to do the cal in that case. 73, Len, KD0RC

Brian Denley KB1VBF

Exactly.  I was just pointing out the he didn’t need to hear any cal station.  Just press start.

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Larry _ NY8T

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Logan KE7AZ

The 6300, 6500, and 6700 only check for an external reference on power up. I’d suggest you turn your radio off, make sure the external GPSDO is on and locked, then turn your 6700 on. It should lock to the GPSDO during power up. Logan, KE7AZ

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KD0RC

Start only works with an off the air cal station. Without a cal stn, you can just enter ppb to manually adjust (typically 0 if you use a gpsdo). Here is an experiment that shows how it works. With the gpsdo running, type 1000 into the ppb adjustment box and hit enter. Now go to WWV and see that you are off freq. Press start, and see that WWV comes up in AM mode, and the ppb moves to some small number. If no cal stn was involved, you would just enter an adj of zero in ppb. Make sense? Len

Brian Denley KB1VBF

I connected my gpsdo, pressed start and it came back with 0 one time, 3 another.  I checked against WWV and it was perfect.  I just assumed that was the way to do it since it worked so well.

KD0RC

Yep, it worked because there is a WWV freq listed in the Cal Frequency box.  If it finds a sig there, it calibrates that last few PPB out.  If not, I think it just goes with whatever it finds (noise?) and gives a bogus adjustment.  Given that we are talking about a fraction of a Hz, setting the adjustment to zero and don't hit the Start (if you have a GPSDO) will work fine if you don't have a good cal sig to work with.  I am only an hour's drive south of Ft. Collins, so I get WWV really well...

73,
Len