Work around for FT8 time sync problem with older Flex units

Morris Wideman

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

WX7Y

Greg N8GD

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.

Morris Wideman

K4MT

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.

Morris Wideman

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

Morris Wideman

WX7Y

Dudley WA5QPZ

Michel VE2XK

Morris Wideman

Hello thanks for your reply's I personally see no reason to go back to using the VAC method as what I have done has corrected the DT and sound problems. I do use a time sync program D4 and did not have any problems with other radios I own and operate on FT8 mode. All these problems were caused by the use of VAC's so why go back now. Thanks and 73 Morris WA4MIT

Bruno Beckers

Michel VE2XK

Bruno Beckers

Michel VE2XK

Bob G W1GLV

Bruno Beckers

Michel VE2XK

Thank you very much Bruno but for some reason i was not able to select the virtual cable 1 and 2 after i have select the driver «Windows WDM-KS» . They simply don't appear by clicking the arrow . I suspect that this driver is not present on the computer even with VAC 4.6.
But i find another way with the very great help of Darrin KE9NS to be able to eliminating almost completely the DT problem . Note that i use Meinberg since a while and that this problem not coming from PC sync time at all . The other trick consist to use the VOX capability insteat the CAT PTT command were bring that cumulated TX delai timing issue. If some are interesting let me know . My english is not so gud but i think would be able with a few screenshot and explanation to have that done. I'm a happy Flex 5000A RX2 ATU user since 7 years now. Michel VE2XK