[time-nuts] Some Lucent RFTG-m-RB data

[James R. Gorr]

I have a '97 box and the disassembly is as you
described for the '96 box, except I only have 9 screws
on the bottom.

--- Bill Hawkins <bill at iaxs.net> wrote:

> Received two of the subject units, one built in 96
> and one in 97.
> The dates are the first two numbers in the serial
> number.
> 
> Took the 96 apart and learned that the LPRO-101 is
> not physically
> connected to the main board, except through a pin
> connector. When
> the unit is turned upside down, you can see a
> pattern of 6 screws
> in two rows of three. These secure the LPRO. The
> rest of the screws
> hold the main board. Do not turn the unit upside
> down but stand it
> on its rear fins as you remove the screws. This
> keeps the LPRO from
> dropping away and bending the pins.
> 
> The LPRO has a thermal plate that provides good
> conductivity to the
> case, so it can dissipate about 15 watts. There is
> no thermal goo
> between the plate and the box, but the plate may be
> stuck to the box.
> Put a screw in a hole and push on it to release the
> LPRO. Then, if
> you have removed the 10 screws that hold the panel
> to the box, it
> should all lift out easily, with the LPRO hanging by
> its connector.
> I'd recommend laying the box down in its normal
> position and sliding
> the innards out horizontally.
> 
> Imagine my surprise when what I'd learned didn't
> work on the 97 box.
> That assembly has a clamp that holds the LPRO in
> place, so pushing on
> a screw doesn't work. There are four screws on the
> back, between the
> fins. Loosen them to loosen the clamp, but don't
> remove them.
> 
> Reassembled both - you don't want to run the LPRO
> without a heat sink.
> The 97 unit drew 1.4 amps at 24 VDC at startup. The
> NO GPS and Fault
> lights were lit. The current dropped to .7 amp but
> the Fault light was
> still lit. Got 10 MHz at the J1 test point but
> nothing at the 10 MHz
> output. Went away for an hour, came back to find the
> ON light, got 10
> MHz at J2, didn't check 15 MHz. The 96 unit had the
> same behavior, but
> the 10 MHz was more accurate. The box got quite
> warm, but you could
> keep your hand on it. (How's that for quantitative?)
> 
> I have two Z3801s and two Racal-Dana model 1992
> counters set to Phase
> A-B.
> One counter has been measuring a 4040 cesium box
> against one of the GPS
> receivers. The other counter measures the phase
> difference between the
> Z3801s. With the 96 unit in place of the 4040, phase
> rotation was 220
> degrees in 20 minutes. The GPS comparison doesn't
> rotate, but varies
> between 50 and 70 degrees. I consider that an
> indication that the
> receivers
> are OK. The holdover accuracy varies between 0.5 and
> 5 microseconds,
> depending on when the crystal last cracked.
> 
> If I did the math right, a 360 rotation will take
> 2000 seconds. This
> means
> the LPRO is about 5x10E-11 off from GPS, no?
> 
> Two other questions:
> 
> What is the BITE pin on the LPRO? Some Built-In
> Test?
> 
> What is the protocol for the data at J6? Can it be
> the same as the
> Z3801?
> 
> Bill Hawkins
> 
> 
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Fedora Core 4 Linux

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