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

[k1jos at att.net]

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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