Volker,
I have also a Trimble Nortel NTG550AA and fortunately it works very well
from the beginning. I have a downloaded manual and some other info that
I can send you if interested.
And one word of caution: if you observe the cable that goes from the
main board to the small interface board, you will see that one of the
connectors is reversed so be careful if you make a custom one for your
cabinet, do it in the same fashion. Using a normal cable produces
bizarre results that can actually drive you nuts, don't ask how I know.
The coax connector, J5 is a 9.8304 MHz output, an odd frequency used by
the cell tower equipment, J4 carries 1/2 PPS (even seconds), the next
one (J1) is the for the antenna and J4 is the 10 MHz output. You already
know that but I want to note that the 9.8304 frequency has mislead some
users to think that it was the 10 MHz output, not your case.
The seller (Bob Mokia , fluke.l) is well known to the Time Nuts, he has
a technical background and normally known quite well what he sells and
is very positive about solving the problems that may arise, his only
problem is that his English is worse than mine . I think that he
regularly monitors this list.
I have observed a strange thing on this offering, at the end of the page
he says:
"power on it ...
after 30 minutes/it will locked/10mhz come on the SMB connector
1pps on the back d sub connector "
I never heard of a 1PPS signal on these units, only 1/2 PPS on the J4
coax and I had asked on this list if anybody had found how to extract 1
PPS from the unit. I have to put a scope on the DSR pin because it is
the only connected to the main board other than TxD and RxD. Could you
verify this on your unit when you change the OCXO and get it running?
Best regards,
Ignacio EB4APL
On 24/01/2014 16:23, Volker Esper wrote:
...thanks, Bob, it seems to be the oscillator, that is at it's limit, it
cannot tune to 10 MHz at full EFC voltage, see new thread (started by Mark).
Volker
Am 24.01.2014 01:09, schrieb Bob Camp:
Hi
That’s a cell phone base station board. It’s got a bunch of outputs, some of
which are related to the cell network it was built for rather than 10MHz. I’d
bet your 9.8 MHz output is one of those. They are DDS based so there likely is
some range of possible outputs.
The age alarm is not unusual on a newly powered up board. It’s moving faster
than it should. It may settle down.
The DAC at limit is not a real good sign ….
Bob
On Jan 23, 2014, at 6:43 PM, Volker Esper <ail...@t-online.de> wrote:
Hi!
I bought a Trimble/Nortel GPSDO
http://www.ebay.de/itm/300933951405?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648
and Lady Heather's now tells me that everything is alright - except
- DAC 6.000004V
- OSC BAD
- osc age alarm
The rectangle "10MHz" output signal (J5) shows a signal at about 9.8MHz
(a deviation of about 200kHz), wobbling 4Hz up and down. Oddly enough,
the direct oscillator output (J4) shows a sine wave at a stable
10.0000004MHz (a deviation of 0.4Hz).
It seems to me it's not the oscillator that is bad but the servo loop -
what can I do?
Thank you
Volker
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