[time-nuts] Lucent RFTG-m-XO GPSDO

Randy D. Hunt randy_hunt960 at yahoo.com
Sun Oct 9 16:25:42 UTC 2011


On 10/9/2011 6:55 AM, EB4APL wrote:
> Peter,
>
> My UT+ works ok with common antennas, I tested it with a Trimble 
> 28367-00 and with a  INPAQ AAF-03B 5V.  Both are quite old garden 
> variety GPS antennas intended for car navigators so your problem can 
> be in the receiver.
> I bought mine from fluke.l and he still have some available on his 
> other shop:
> http://www.ebay.com/itm/130303889204?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 
> <http://www.ebay.com/itm/130303889204?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649> 
>
> They are cheap enough to buy one as a spare just in case.  Also you 
> can try with another antenna anyway, because the receiver checks only 
> that an antenna is connected (that is, the current range is right) but 
> your antenna could became defective.
>
> Regards,
> Ignacio
>
>
>
> On 09/10/2011 7:52, Peter Bell wrote:
>> On Sun, Oct 9, 2011 at 3:31 AM, k4cle at aol.com<k4cle at aol.com>  wrote:
>>> Peter, do you have the software for this unit?  The GPS antenna is 
>>> supposed
>>> to draw apx. 20 mA at 5 volts in order for the NO GPS LED to turn 
>>> off.  AT&T
>>> (Lucent) used the MicroPulse timing antenna (later sold and now 
>>> provided by
>>> PCTE).  You are correct in that Efratom used the Motorola UT+ 8 
>>> channel GPS
>>> receiver on these units.  The rubidium companion box used the data 
>>> from the
>>> same receiver (via an interconnect cable between the two units).  
>>> Let me
>>> know if you have questions on this unit, Regards, Doug....
>>> Connected by DROID on Verizon Wireless
>>>
>>> -----Original message-----
>>> From: Peter Bell<bell.peter at gmail.com>
>>> To: time-nuts at febo.com
>>> Sent: Fri, Oct 7, 2011 14:13:31 GMT+00:00
>>> Subject: [time-nuts] Lucent RFTG-m-XO GPSDO
>>>
>>> I have been playing with one of these units, and noticed that there
>>> has been some discussion on them before on this list, so I wondered if
>>> anyone might have any suggestions.
>>>
>>> Basically, the unit powers up correctly, but the "No GPS" LED never
>>> goes off - this obviously could be because it's broken or doesn't like
>>> my antenna, but with some of these telecom GPSDOs you have to manually
>>> trigger a site survey if you move them to another location. Does
>>> anyone know if this Lucent box is like that?
>>>
>>> Everything else seems to be working - once the "OK" light comes on the
>>> 15MHz output is enbled, the "No GPS" LED goes from solid to blinking
>>> if you disconnect the antenna - it just doesn't want to get GPS lock.
>>>
>>> I suppose I could pull the Oncore board (a UT+ according to the label)
>>> out of it and test that on it's own - but I thiought I would see if
>>> maybe it's a known issue first.
>>>
>> Hi, Doug
>>
>> I don't have any documentation at all - just the actual box.  The
>> antenna is one that originally came with a Furuno marine GPS, but the
>> spec looks plausible (+5V @ 40mA, Internal L1 preamp with 26dB gain -
>> and it has worked with several other GPS units without problems.
>>
>> I just pulled the oncore out, and connected it up outside the box -
>> and it doesn't work.  It passes the self test with a response code of
>> 0000 (or 8000 with the antenna disconnected / 4000 with a short on the
>> antenna socket - so it seems the current consumption is OK) - but no
>> matter how long you leave it it still says it's tracking 0 satellites,
>> although it happiy generates status reports.
>>
>> I wonder if this UT+ version is expecially sensitive to the antenna?
>> I remember that the oncore VP would work with pretty much anything you
>> hooked up to it.  Of course, it's equally possible that the GPS module
>> is defective.
>>
>> I'm tending towards broken - I also got an RTFG-m-RB with this unit,
>> and that has a faulty LPRO-101 in it (it's probably fixable - it looks
>> like the FET that heats up the Rb cell had gone open circuit) - and
>> the two units together only cost me $40 supplied on a "status unkown,
>> but likely defective" basis. I should get at least $40 of
>> entertainment out of trying to fix them :)
>>
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That's the route I had to go to fix my RTFG pair.  I replaced the 
receiver with one of a pair I purchased from *-Bay. They seem to be working.

Randy, KI6WAS


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