Work around for FT8 time sync problem with older Flex units

  • 1
  • Idea
  • Updated 1 month ago
Hello if you have operated FT8 mode with your Flex radio and noticed the decoding has decreased or has problems the longer you operate then this might help. If you notice the DT column when this problem occurs the numbers get larger indicating your time sync is not staying in sync anymore. This has been traced to the VAC use and there does not seem to be much in the way of a remedy for this. Some seem to not have problems but many ops do. Here is my solution: use the line out audio on the rear of the Flex radios. There is a DB9 female connector on rear (looks like a serial port but it is not) here pin 9 is line out RX audio this is independent of the volume control but can be adjusted by use of the Flex Wire Out in the mixer screen. Pin 5 is ground and Pin 2 in line in. See attached picture for the DB9 pin out (rear view). I am using this with great success and now no DT problems. Prior to using the rear connector I did use the phone jack on front but this level is affected by the vol control. DT is a function of the time differential between your computer and any received station. And when this gets to be to great the decoding is diminished. Most ops find this increased as time using radio increased restarting PSDR will temporarily fix but using the DB9 is a permanent fix. I did not change my use of the VAC for TX audio I am only using the line out function. I am using a shielded cable with a stereo male 3.5mm (1/8inch) plug to take the RX audio to line in on my radio use sound card. I hope this might help if you experience problems using FT8 with your Flex radio. 
73 Morris WA4MIT
Photo of Morris Wideman

Morris Wideman

  • 4 Posts
  • 0 Reply Likes

Posted 1 month ago

  • 1
Photo of WX7Y

WX7Y

  • 536 Posts
  • 98 Reply Likes
VAC should work fine
is your computer synced using a known good time sync source?

BktTimeSync by IZ2BKT is a nice little time sync program that may fix your issues, IF you sync the computer every day or so.

Not sure this will help or not but I do know that this is the main reason most of us have had the Issue you described above.

Your mileage may vary of course.

Bret
WX7Y

(Edited)
Photo of Greg - N8GD

Greg - N8GD

  • 207 Posts
  • 76 Reply Likes
I agree this a computer time synchronization issue. I would, however, recommend using “Meinberg” which is a time service installed on your PC that continually steers the time to correct it using a known standard time source, e.g. NIST or others. Once daily corrections are usually insufficient.
Photo of Morris Wideman

Morris Wideman

  • 4 Posts
  • 0 Reply Likes
Hi Fellows
Thanks for your reply`s but this is not caused by the lack of computer time sync, as I stated this involves the RX VAC for some reason it causes a delay which increases over time that you are on the air with it running. People using VAC`s for other non ham uses see problems with delays. Not having your computer time sync`d affects everyone not just Flex users. I exchanged emails with Ken KE9NS he advised a very high end processor with 12 or more threads seemed to work OK but I had another flex user say he had a processor like this and he still had problems. My solution does away with the RX VAC. Newer Flex radios do not have this type problem and apparently not all older flex users do either but if you do have this problem this solution will work.
Thanks 73 Morris WA4MIT 
Photo of K4MT

K4MT

  • 26 Posts
  • 9 Reply Likes
I ran a 5000 on FT8 for a long time and never saw that. Might be because I used VB-Cable. I found it worked much better then the others.  VAC caused me some random problems. And VB-Cable is free.
Photo of Morris Wideman

Morris Wideman

  • 4 Posts
  • 0 Reply Likes
I tried those also did not help they are still a VAC type of situation. Do not know why some work some do not?. wa4mit