Flex-6700 External GPSDO Questions

KD0RC

How high do you have the output level on the GPSDO?  Check to see what the 6700 expects, then use GPSClockConfig to set the output close to that.  Kind of shooting in the dark at this point, but maybe this will do it...

73,
Len, KD0RC

Ed, K0KC

Len,

For my previous tests, I set the GPSDO drive at 16 mA which should give me +9.0 dBm output according to the GPSDO documentation. I use a 3 dB splitter, so the input to the 6700 should be +6.0 dBm. I understand that the 6700 specs are for +4.0 dBm minimum, so it should be ok.

I just changed the GPSDO drive to 32 mA which is supposed to give +10.3 dBm out minus the 3 dB loss from the splitter for an input of +7.3 dBm to the 6700. This is less than the 6700 spec of +15 dBm max.

I will let this setup run overnight to see if the increased output from the GPSDO solves the problem.

Thanks for your suggestion!

Ed, K0KC

Dwayne_AB6A

The Leo Bodnar 9700 injection board requires 49.152Mhz and not 10Mhz. The Leo Bodnar GPS clock sources can be set to output any frequency including 49.152Mhz.

If you are using a Flex and a 9700 and using the Leo Bodnar injection board, you will need two clock sources - 10Mhz for the Flex and Transverters, and 49.152Mhz for the 9700. 

I have transverters and have synced the Flex and Transverters to a 10Mhz GPSDO Clock.

http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=352

The original Icom input was 10Mhz which may be part of the confusion.

Note that Leo Bodnar's own twin GPS unit cannot support both 49.152Mhz and 10Mhz...

Troubleshooting - if IC-9700 does not lock

• Make sure external reference is switched on, has correct 49.152MHz frequency and 10-20dBm power level
• Verify that REF Adjust is set correctly. Coarse scale should be roughly in 40-50% range. Follow fine adjustment procedure above.
• Lock range for proper set up is wider than 100Hz (2m band), 300Hz (70cm band), 800Hz (1200MHz band) in both direction. This is about two times wider than extreme excursion during continuous transmit and receive periods.

Please note the dual output GPS Clock is very limited when choosing 49152000Hz on an output. For example 10MHz cannot be output at the same time

Ed, K0KC

Dwayne,

Thanks for your comments.

I am not using the Leo Bodnar injection board. I am using the Leo Bodnar mini GPSDO and a 3 dB splitter to run the 10 MHz output to the IC-9700 reference input and to the Flex-6700.

I am seeing a big improvement in lock with the increase to 7.3 dBm on the Flex. It did not lose lock overnight and is still locked this afternoon. I will let it run overnight again before celebrating.

I realize that I am using the reference input on the IC-9700 and that this rig is not truly locked to a GPSDO as it would be with the injection board. I am not having any problems with the IC-9700 with my setup.

Ed, K0KC

Dwayne_AB6A

The reason for the 3rd party injection board is that the 9700 frequency will drift when the fan comes on. Its a hardware issue with this radio. Using the 10Mhz reference input and synchronization will not hold frequency with use. 

Flex and transverters use the 10Mhz source for continuous reference. The 9700 does not. In my humble opinion, the 9700 10Mhz eternal injection is next to useless given the lack of continuous reference.

KD0RC

Great news, Ed! If it stays locked for a second day, I would say you have it solved. Len

Ed, K0KC

Dwayne,

I agree on the IC-9700 but the point of my posts on this Community was to seek help with a Flex-6700 problem and not address the shortcomings of the IC-9700.

Ed, K0KC

Ed, K0KC

Ok, it is probably time to wrap-up this thread. Here are my conclusions:

• My Flex-6700 apparently does lock to an external 10 MHz GPSDO signal of amplitude +7.3 dBm as evidenced by approximately 48 hours of continuous testing against CHU and WWV. The Flex spec of a minimum amplitude of +4 dBm is apparently not applicable to my 6700.
  
  
• Injection of an external 10 MHz GPSDO signal apparently solves the problem of the significant 2 meter transmit and receive calibration errors.
  
  
• In my situation, RFI from a 6 meter transmitter with an antenna relatively close to the shack and my HF antenna can cause the Flex-6700 to lose lock. My interim solution is to power-down the Flex, including shutting down the 13.8 volt power supply whenever I operate 6 meters. I may experiment with ferrites and grounding of the GPSDO enclosure in an attempt to address this problem in the future.

Thanks to everyone who contributed to this discussion!

Ed, K0KC

Tim - W4TME

#3 may be RF overload, not RFI since the GPS antenna is an active antenna.  You may need additional physical separation to solve this issue.

Ed, K0KC

Final comment (really):

I solved the RFI problem today!!! It turns out that for some reason the 6 meter transmitter that caused the problem (IC-7700) was not connected to my single-point ground. I must have missed this connection when I rearranged the equipment some time ago. In any case, everything seems fine now.

Thanks again for all of the suggestions!

Ed, K0KC

KD0RC

YES!!  Glad you got that all figured out.  It is so frustrating when you carefully set everything up and still have problems.  Just shows that it can be the smallest thing that messes things up.

Len

Larry _ NY8T

 Resurecting this this thread to compare notes with 6700 owners that couldn't keep the external GPSDO's locked with the radio. After the v3.2.31 update I decided to hook my GPSDO back up and see if there was any improvement and so far its been a week and it has stayed locked. Previously it wouldn't go a full 24 hours without the 6700 loosing lock with the external GPSDO. I am interested to see if this is true for anyone else.

Ed, K0KC

As indicated in one of my old posts, my 6700 has stayed locked...no issues anymore.

Ed, K0KC

WX7Y

My 10MHz external GPS clock has also stayed locked on the 6700

Larry _ NY8T

Bret, since this last update or before the update has your external gpsdo stayed locked on your 6700?

Mike-VA3MW

@Ed, K0KC

I took a quick scan of this, but can you describe your Sky view and is the Flex GPS antenna near your other GPS antenna?

I know that sounds weird, but in years for using GPS's in commercial drones, I have seen 1 GPS cause another one to go out of lock due, what we think, is local oscillator interference.

Please describe the physical setup.

73

WX7Y

It would only stay locked on for 2 or at the most 3 days on the 6700, I have not powered down the radio to restart the 10MHz clock sink sense I installed version 3.2.31 when it first came out (KNOCK ON WOOD).

My FLEX 6600 always stayed locked at the exact same station just the 6700 would unlock even with the two radio's sitting side by side.

I do not use the built in FLEX GPS's in my radios.

Ed, K0KC

As indicated in one of my old posts, my 6700 has stayed locked...no issues anymore.

Ed, K0KC