[time-nuts] TS2100 OCXO Conversion: Command exploration

[Esa Heikkinen]

Hi!

I have TS2100 which I modified from TCXO to OCXO. I have the 'offical' 
MTI OCXO, which I bought from someone on this board. I have also 
replaced the GPS unit to the HEOL Design model, which was required to 
get correct time at all. It's also much more accurate than the original 
Trimble.

> 	Now, with all this said: I'm still waiting for a 'Lock' indicator on
> the front. It's tracking, and the D/A value certainly has changed from
> what I had it at last night, but I'm still not getting a lock. Here are
> my current numbers:

If I turn off the unit and the OCXO is totally cooled down then it might 
need even 2-3 hours before getting the LOCK indicator on again! So 
please be patient.

According to my measurements the LOCK indicator will turn on when the 
PPS has gone within 1  microsecond of UTC. But it's not fully locked 
even at this point! With HEOL Design GPS unit it will end up within 50 
nanoseconds of UTC, but that requires even more time.

If you have trouble with locking you should compare the PPS with 
oscilloscope with some other receiver (for example Thunderbolt) or maybe 
you could 'steal' the PPS from the internal GPS and compare it with 
output. You should see it trying to reach the correct PPS and if it 
passes it at startup, it should change the direction and finally settle 
near the PPS input. In case of trouble you could also try with different 
A/D values manually and see what they do.

> root timing utils tfp 0 -- returned 0x00f2

That cannot be correct: Value is too low, near zero volts perhaps and it 
might be clipped. Looks like it has drived itself to the lower limit 
without getting correct feedback. This is a clear sign that clock 
steering is not working at all.

 From my unit:
1 ? tim
2 ? utils
3 ? tfp 0
0xb676

> root timing utils tfp 6 -- returned KM = 0.9994965

4 ? tfp 6
KM = 0.9994965

> root timing utils tfp 7 -- returned KO = 0.9994965

5 ? tfp 7
KO = 0.9994965

> root timing utils gain -- returned gain now:20 (There seems to be a

6 ? gain
gain now:-20

> root eng eeprom info -- returned 00000024

Same here. Please note that to enable any eeprom writes you must close 
JP4 temporary.

By the way: you don't need to start every command with 'root'. It just 
resets the menu structure back start every time, which sounds 
impractical. You gan enter the menus, type '?' to see the available 
commands and go back to previous menu level with 'pop' command.

> 	Any thoughts on why I don't have a lock as yet?

According to A/D value it looks like clock steering is not working at 
all. You should use oscilloscope to find out if A/D values have any 
effect at all.

If you have rubidium or other kind of 10 MHz source put it to one trace 
of oscilloscope and TS2100 10 MHz output to another. Then try with 
different A/D values manually and see if it's even possible to get waves 
syncronized. If it's not possible with any A/D value then it will never 
lock, perhaps your OCXO is not compatible.

-- 
73s!
Esa
OH4KJU