GPSDO Installation Issue

Justin W4JTD

I recently ordered a GPSDO upgrade kit for my Flex-6700. I'm running windows 10 and SSDR 1.10.16.

I installed the GPSDO as per the instructions from Flex, and installed it in the software Radio Setup Window. After watching it for hours this afternoon, it will not lock a GPS signal from the satellites. It generally shows 99 sats tracked and 0 visible, but occasionally will see 8-12 sats visible and track 4-5. It will give a valid location and altitude briefly, but the Status never changes and the UTC time never updates properly. Then it flicks to 99/0 again, back to valid position for about a second, then starts the cycle over. The status light on the radio remains yellow and never changes. It did manage to grab my correct grid at some point.

I have tried repositioning the antenna several times, and have confirmed with my iPhone that  in its current location the antenna can see enough satellites to get a lock (GPS status app). I tried a factory reset (holding OK) on the radio, uninstalling and reinstalling the GPS in the software radio setup, and several rounds of power off and disconnect from power supply. 

Am I missing something? Below are screenshots of the GPS status tab in the radio setup window. It shows what usually occurs (bottom pic) with no position, and the occasional flash of GPS almost-lock with the correct position and altitude. 

I submitted a helpdesk ticket too, but figured I'd throw this out to the community over the weekend. :-) 

Thanks!

Justin

KL2D

Norm - W7CK

I don't know anything about them really but I'd guess it just isn't seeing any satellites.  This could be due to disconnected antenna on the GPSDO?  Does it have a separate antenna?  Does your house have a metal roof?  I'd guess it needs to have some sort of clear exposure to the sky in order to pick them up?

Rick W7YP

I had the same problem until I switched to an active GPS antenna.  This is what I bought and it works like a champ:

http://www.ebay.com/itm/GlobalSat-AT-65-SMA-GPS-Active-Antenna-/371354852439?_trksid=p2385738.m2548....

73,

Rick, W7YP

George KF2T

My best guess is one of the very small internal RF connectors is either not fully seated or experienced a bent pin during installation.

Justin W4JTD

Thanks Rick. I saw on the forum that several people are using those, I ordered one from Amazon this afternoon.  

I am currently just using the Pulse brand antenna that came from Flex. I feel like it is an antenna issue, as all my other GPS devices can see the satellites just fine from where the GPSDO antenna is located at a large window inside my house. 

Justin W4JTD

Well I hope It's not that... But I guess I could try to disassemble and re-assemble it. 

Also - really appreciate the suggestions!

Rick W7YP

I'm confident the AT-65 will resolve your issue.

Rick

KY6LA_Howard

Try Flipping the Pulse Antenna OVER

The side with the Pulse label on it should be DOWN

I ended up putting a label "BOTTOM" on the antenna to prevent mix ups.

Justin W4JTD

Hi Howard - I actually found your previous post that indicated the "Pulse" should go down, that's the current orientation.

k3Tim

That labelling of the antenna seems backwards, realizing the label goes down but that sure is counter intuitive.

I installed the GPSDO myself and was advised by a Co. Rep (@Yuma) to wiggle the PCB left and right (gently of course) as there is a slight play in the connector to the main board,  Make sure the PCB is centered before tightening it down.  This worked out.

It's great having rock-solid dead-on freq signals, acing the FMT and watching the effects of propagation on WWV with this module.

73'
k3Tim

Patrick

Make sure that the antenna has an unrestricted view of the sky. After using the supplied antenna I bought a High quality antenna and low loss coax and mounted it on the roof with an unrestricktrped view of the sky, horizon to horizon . I get on average lock on 10 to 12 gps sats with the receiver seeing up to 19 stats. The GPS receiver has 12 channels . My 6500 powers the antenna and the antenna feeds 2 GPS receivers. The other receiver is gps/ntp server for time reference, allowing me independence from the internet for ntp services.

Mark Erbaugh

Where is the GPS antenna placed? I taped mine to the inside of a window and have no problems picking up several satellites, energy though the window has a limited view of the sky due to an overhanging porch roof.

Justin W4JTD

I have the antenna currently taped to a very large window that faces southeast. I've tried several other GPS devices in this area and they lock up just fine. It's odd to see the occasional strong but brief and incomplete lock, which made me think it was the antenna itself. I also wanted to praise Flex, Dudley responded to my help desk ticket at about 2230 Texas time last night (Saturday). Boy was I impressed! He also thinks it may just be a bad antenna, but suggested I test the center pin to make sure it's showing 3V. So I will try that today.

Frank WA3NHK

If your window has any sort of UV or low-E transmissivity coating, as most windows do, you're looking thru a thin piece of metal.  (The coating can be there and you won't even notice it.)  Can you take it outside temporarily as a test and give it a clear view of the sky?  I even have trouble receiving XM radio thru my windows because of this.

Justin W4JTD

Well, even though I have several other devices that work just fine inside the shack... 

I took Frank's advice and tried taping it to the OUTSIDE of the window. Instant lock, 16 visible and tracking 10. 

So, issue resolved! 

I have to wonder if the provided Pulse brand antenna lacks sensitivity since the other devices worked fine, but since I have already ordered the GlobalSat AT-65 from eBay I will try that inside the shack and post the results here.

As a point of interest, bringing the antenna back inside, the radio maintains a "locked" status but the position, speed, altitude, and frequency error drift quite a bit so I assume the windows are creating a substantial amount of signal blockage. 

Thank you to everyone who responded!!

Justin
KL2D