External GPS 10MHz source stops working after a few hours of power up

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  • Updated 1 year ago
I am running a 10MHz GPS source to my equipment here and I am having a problem with my 6700 syncing with the external source. 
When I first turn on the radio it works fine but after several hours it stops syncing, My Flex5000 stays locked that is using the same source and have noticed NO issues with the 10MHz source failing.

Anyone else having this same issue?

Thanks 
73's
Bret WX7Y
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WX7Y

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Posted 1 year ago

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Lee - N2LEE

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Bret, I thought the 6000 series only syncs to the 10mhz source on start up and thats it.

If this is indeed the problem you are having I would like to know if it is possible to have SSDR continue to sync to the external 10mhz source. 

Lee
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WX7Y

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yes that was my understanding as well BUT when I leave the radio on for a while then it looses sync with the 10MHz source and I have to power off the radio and power it back on and it's good for a while, so to test this you go to WWV and check it after its sits overnight with the power on.  

Bret
(Edited)
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Lee - N2LEE

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Unless its a hardware issue I would like to see Flex poll the 10mhz input the same way they do the internal GPSDO. Having external 10mhz frequency standard was one of the reasons I wanted to upgrade to the 6500.
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kk4x

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I too purchased a radio hoping to use the 10mhz external Freq Standard.

it would be nice if the software can detect it and a little icon can light up stating that is is currently locked on the Reference

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k3Tim

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Reading the 6x00 (x = (5 | 7)) Section 7.5 the external source is sampled at startup to detect a signal. If present the radio will lock to this signal. If the external signal is lost, an internal signal is used.  The external is only "Detected" at startup. Therefore if the ext sig drops out the system locks to the internal.
Sounds like the problem is the 6500 is saying it lost the ext sig, for whatever reason.

Spec is 1.0V P-P min, 3.3V P-P maximum. (4dBm min - +15dBm max)

One should check when connected.

Hope you can track this down.

Tim
(Edited)
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WX7Y

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Yes I know all of this as I have read the manual several times and have tested this with my other equipment as I stated before including my FLEX 5000 using the same 10 MHz GPS source and the only device that is having this issue with loosing sync is the 6700.

All I was asking is if others where having the same issues when trying to use the external GPS source for extended radio power up.

If people don't have a way to test this then there is no need to respond to my query.

73's
Bret
WX7Y
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k3Tim

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Hi Bret,

Sorry for the bother,
Happy New year to ya'.

k3Tim
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WX7Y

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No bother Tim, it's just hard to get help on here anymore and gets frustrating weeding through the Email responses if you know what I mean.
Thanks for understanding.

Happy New Year 
Bret
WX7Y
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Frank WA3NHK

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Brett...just curious how you determine that your radio has lost lock with the external source. I'm using a homebrew GPSDO to drive the radio and my test gear. My test gear is definitely seeing the reference but I'm going on faith that my 6500 has locked to the external source. A discrete indication in SSDR would sure be nice.

73.... Frank / WA3NHK
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WX7Y

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1: first thing to do is to turn radio off
2: turn the radio on and go to 10.0000MHz
3:ZOOM in so the pass band fills as far as you can zoom using the magnifying glass icon in the bottom left of the SmartSDR display. 
4: the center carrier on AM should be exactly ZERO beet with 10.0000 MHz on the radio if not then it isn't locked to your 10MHz Source or your source is off frequency, you should see your own 10MHz source if wwv signal is lower then your 10 MHz source. 
5: there should also be 2 smaller peaks on either side of the center 10MHz WWV carrier so you know which one is WWV.
6: stop SmartSDR BUT leave the radio powered on overnight and check it the next morning to see if it stays put. 

Mine does NOT stay locked but reverts back to the internal clock which is off a little bit.

I'll try to enclose a picture of how it looks when it's locked on. 

WWV on 15MHz should also be exact center when it is locked on.

73's 
Bret
WX7Y


(Edited)
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Frank WA3NHK

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That's a reasonable test.  It looks like I'm on freq.  (I'll try to insert the image)  Now I'm wondering why I can't zoom in as much as you.  Your first freq hack with a label is at +/- 100 Hz, but my first labeled hack is at +/- 400 Hz.  And I have the slice zoomed in all the way.

I think it would be reasonable to suggest to Tim that they consider adding a discrete indication to SSDR.  Perhaps in the menu bar or somewhere in the Radio Setup dialog box.  Any thoughts on that?  It could give you an easier indication of where things are going wrong for you.

73.....Frank

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WX7Y

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It would be VERY good to have a indicator of the external GPS being locked some where even in the Setup window but the Bar down at the bottom by the TNF indicator would be wonderful. 

Don't forget to check yours again after the radio has been powered on for a long time and please report back here if you would. 

Could be just your monitor resolution why it won't zoom in as far as mine does, my radio is a 6700.
]
73
Bret
WX7Y
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WX7Y

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Here is my Radio's WWV signal this morning, as you can see it is actually down about 28Hz from my GPS Source compared to the picture I sent right after a power up.

This is after leaving the radio on for about 12 hours. 


if no one elses is doing this then maybe my comercial 10MHz source is reseting in the night. 

Bret
WX7Y
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Lee - N2LEE

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I don't have the internal gpsdo so maybe one of you can answer a question.

When you have the internal or external 10mhz source, what happens when you hit the START button under the RX Freq Offset menu ?

Does the radio compare the frequency against the 10mhz source ?
Or is this menu disabled because of the internal timebase ?
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WX7Y

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It does the same thing if you don't have a 10mhz source your offset should be very very low if it's on
Don't know about the internal gps
Bret
Wx7y
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Jay / NO5J

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Lee

With the internal gpsdo, SSDR detects it's presence when it starts, and disciplines the T/OXCO from then on. The only way to check the frequency calibration on the RX Freq Offset menu is to disable the gpsdo first. Then the options to do that appear.

  SDRgadgets

#FlexRadio IRC chat

  73, Jay - NO5J

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Tom K3TF

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Bret

I run a GPSDO 10Mhz. reference oscillator with my other rigs here. I had to order a BNC to RCA pin adapter to work with my new Flex 6500. I hope to have it running in a couple days. I will get back to you with my results. Hopefully it will stay locked to the GPSDO standard 24/7. My other radios certainly do. 

There should be some sort if indicator to let me that it is staying locked. Having to zoom in on WWV is not a good solution. 

Tom
K3TF...
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Frank WA3NHK

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Slightly OT comment....when I first plumbed my GPSDO to my 6500 I was shocked...SHOCKED!!!!!! to find that Flex chose to use a cheap, 70 year old connector on a $4,000 radio instead of the extremely standard BNC that the rest of the world uses for ext ref inputs on pretty much everything.  This is the same foolishness that Heath used back in the day when they'd use an RCA connector for the antenna connection on several HF and 2m transceivers.
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k3Tim

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I would respectfully disagree. In a So Cal  wireless mfg labs I've seen train loads of test gear and not a BNC in site - all SMA. 

_..--
k3Tim
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Frank WA3NHK

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I guess BNC is an east coast thing.  <G>  Are you talking about benchtop test gear or cards?   But you reinforce my point...what is that ancient phono connector doing on a multi-$k radio? 

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Tom K3TF

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Bret,

Connected my 10Mhz GPSDO Reference to my new Flex 6500. I am feeding a 2.2V P-P 10Mhz. sine wave with no DC offset. Plus 1.1V to minus 1.1V. It locked up fine when I re-booted the 6500 and it is right on WWV frequency.

I run my equipment 24/7 here so will check it tomorrow to see if it is still locked up and will let you know. 

73,
Tom
K3TF........
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WX7Y

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thank you very much and appreciate you checking it for me and letting me know back

Bret
WX7Y
(Edited)
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Frank WA3NHK

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Bret.....I'm still zero beat on WWV since we last chatted.  I'm thinking you have some sort of intermittent output on your GPSDO.  If you have a reasonably accurate and stable sig gen available consider a test in which you use its output to drive your flex's input for a few days and observe your tuning drift. 

73....Frank
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WX7Y

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okay thank you very much for checking for me 


Bret
WX7Y
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Tom K3TF

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Hi Bret,

I been running with my GPSDO for about 24 hours here and it is staying locked up. I zoomed in on WWV and it is staying right on the money. I would suggest checking the signal from your GPSDO on a scope. I have a clean 10Mhz. sine wave 2.2V P-P on my Tektronix 465. 

The Flex manual states 1 to 3.3 Volts peak to peak. 

Good luck, I hope you can figure it out. 

73,
Tom
K3TF........
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WX7Y

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Thank you all very much for checking for me now at least I know where to start looking 
My unit here is a Rack mount Spectracom commercial unit but it may have a issue.

73's
WX7Y
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Tim - W4TME, Customer Experience Manager

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Here is what I suspect is happening.  The radio is losing lock from the external clock source.  When this happens, the radio will not revert to an internal clock source because the radio has no way in real-time to detect a valid external clock signal (type and strength).  When the reference clock signal is lost, the master oscillator will drift, resulting in a frequency difference within the range that you have stated above. The FLEX-6000 needs at a bare minimum a +2 dBm signal for the external clock.  Ideally, a +5 to +10 dBm signals is needed.  If your clock source at the radio is very near +2 dBm, then that can cause the radio to lose lock.  We have seen this before where a single reference clock is used to drive multiple devices and the signal attenuation from splitting the signal falls below the +2 dBm minimum.
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WX7Y

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At this point that is what I expected I will check the levels again on the weekend after running through my Power divider of course to make sure what the level is doing right at the Radio's source and log it on my communications test set to see what is happening.,
It's just weird that the FLEX5000 works flawsley with my 10MHz source.
 
I did make a change to my Spectracom clock source settings but not sure yet if that helps but not sure there.


Thanks again Tim and all those who commented 
73's

Bret
WX7Y