[time-nuts] Lucent RFG-RB

John Ackermann N8UR jra at febo.com
Thu Dec 28 13:46:20 UTC 2006


Thanks, Rex.

Does anyone know how these two units work together?  I assume it must be
for redundancy, but it's hard to figure out just how it all works
together.  I assume the Rb is intended to provide long-term holdover if
the GPS or XO fails.  It'd sure be nice to find at least some
system-level documentation.

John
----

Rex said the following on 12/28/2006 03:22 AM:
> I just received a Lucent RFG-RB (no -m- in this one) rubidium unit eBay
> buy from the lady in Atlanta. Thought I'd share a few notes on what it
> is. Maybe some of this has already been covered -- I lost track of all
> the emails.
> 
> Like John, I immediately opened it up, haven't tried it yet, and won't
> for a while.
> 
> No GPS, as has been noted in the other messages, that seems to be in the
> crystal unit. This one was made in 2000. Inside mine, the main component
> is a Datum LPRO 102500. Seems to be functionally identical to the one in
> the manual here:
> http://www.symmetricom.com/media/pdf/manuals/man-lpro.pdf
> 
> Box front panel:
> 3 sma's - TP (J1), 10 MHz RF Out (J2), 15 MHz Out (J4)
> 3 db9's - +24V (P1), Alarm (J3), Interface (J5)
> 3 led's - Fault, Stby, On
> 
> Seems the +24V connector only uses two pins: 1 = +24, 2 = return/gnd
> I assume those two are all that's needed to make it run.
> 
> Main board is made by Efratom.
> 
> I don't see any connection to the rubidium C-field pin so I don't think
> there is any adjustment through the main board, just the adjustment thru
> the case of the LPRO.
> 
> With some tracing, I can't figure where the 10 MHz output (sma) comes
> from. I assume it is functional, but haven't applied power yet. 
> 
> The 15 MHz generation looks very similar to the other boad I described
> in another message on an FRS-C unit. The active source again seems to
> come from an Altera PLD. Maybe it divides 10 MHz by two, and (guess)
> narrows the pulse for better 3rd harmonic? Anyway, then it seems to go
> through a series resonant LC, with a trimmer on the C. Then thru the 15
> MHz filter, two stages of amplification, and a MCL low-pass filter to
> the sma.
> 
> BITE signal from the LPRO goes somewhere so I assume it is at least part
> of the alarm connector output.
> 
> If anyone finds or works out the pins on the alarm and interface
> connectors, I'd eb interested to hear about it.
> 
> So there we are for now. Quick first look without even trying it yet.
> Assuming it works, the LPRO was probably worth my $130 investment. Hope
> some of my comments helps someone.
> 
> -Rex
> 
> 
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