[time-nuts] Re: RFTGm-II (KS-24019) XO Fault but GPS to Rb is OK

[k1jos at att.net]

If the XO is failing due to GPS or Antenna problem, then why does the NO GPS led go out on both the XO and Rb and the Rb unit thinks it has a GPS lock?

Jerry

 
-----Original Message-----
From: k1jos at att.net <k1jos at att.net> 
Sent: Sunday, October 31, 2021 10:36 PM
To: 'Discussion of precise time and frequency measurement' <time-nuts at lists.febo.com>
Subject: [time-nuts] Re: RFTGm-II (KS-24019) XO Fault but GPS to Rb is OK

Thanks Bob,

I swapped with a known good antenna from my TBolt and still no tracking.  The XO is putting out 5vdc on the antenna jack.  I think I have a spare Motorola UT+ to try and will report back.  

Jerry

-----Original Message-----
From: Bob kb8tq <kb8tq at n1k.org>
Sent: Sunday, October 31, 2021 9:47 PM
To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com>
Subject: [time-nuts] Re: RFTGm-II (KS-24019) XO Fault but GPS to Rb is OK

Hi

I think you will find that the list of “visible” sats is coming from the stored almanac and your position (from the hold mode). 
You may have an antenna problem.

Bob

> On Oct 31, 2021, at 7:21 PM, k1jos at att.net wrote:
> 
> Here's a follow-up.. 
> 
> I took out the XO pcb's and powered it up stand-alone.  In the RFTGM 
> software, it shows as Active, Warmup, No Fail code and it is 
> outputting a clean 15MHz sine wave. In GPS - It's showing 8 visible 
> Sats but Zero Tracking SATs and is "Acquiring SATS/Position Hold" .
> The SAT IDs are listed but Signal Strength and Channel Status are all 
> zero.  Its been powered up for about an hour so far.  Checking XO 
> Voltages, all seems good Control=14.574V, Temp 36.49, Ant Feed 16mA.  The ADC = 0v as I think it
> would be in warm-up mode.   Now hopefully it will acquire and run for a
> while.   
> 
> Jerry
> 
> 
> 
> From: k1jos at att.net <k1jos at att.net>
> Sent: Sunday, October 31, 2021 10:20 AM
> To: 'time-nuts at lists.febo.com' <time-nuts at lists.febo.com>
> Subject: RFTGm-II (KS-24019) XO Fault but GPS to Rb is OK
> 
> I have had a KS-24019 (L108-L109) pair running continuously for 
> several years.  Now have a red LED Fault on the XO unit and the RB unit shows green
> LED On-Line status.   The NO-GPS LEDs are off on both the -XO and -RB units
> but if I disconnect the antenna - they do show Yellow NO_GPS status.   Got
> out my old XP laptop and ran the Lucent software.  The Rb (REF 0) is 
> active and locked to GPS and working fine.  The XO says Unit Failed 
> but the message code for the first 4 hex nibbles which should show 
> alarm status are all zero bits so no failure code is evident.  The 
> last 2 alarm nibbles are 53 representing the # of hours since failure.
> The GPS time is correct on the Rb but is fixed on the XO at 80-01-06 00:00:00.  The XO checksum shows PASS.
> Based on this the XO GPS is working, locked and sending correct GPS messages
> to Rb.   The XO CPU seems to be working as well so am I correct this seems
> to be a Osc failure?  Besides checking voltages (which I'm not sure 
> what they should be) - any advice how to go about further testing sand repair?
> 
> Thanks in advance
> 
> Jerry NY2KW
> 
> 
> 
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