[time-nuts] Question and help with LPRO-101

Neville Michie namichie at gmail.com
Mon Oct 20 20:19:23 UTC 2008


Hi,
a word of caution about opening the LPRO,
the manual says that the case is made of Mu metal.
This alloy has an enormously hi permeability and shields
low level magnetic fields from the rubidium cell.
Back in the 60s when I worked on instrument maintenance
and oscilloscopes had Mu metal shields they warned that the
metal was annealed and lost its properties if it was bent (work hardened
I assume). So just be careful to gently spring the case just enough  
for the pips to
clear the locating holes.
The frequency of operation depends precisely on the magnetic field,
cheers, Neville MIchie



On 21/10/2008, at 6:31 AM, Ian Sheffield wrote:

> Many thanks Don,
>
> The only thing I want to look at (and tweek) is the C Field  
> adjustment. For
> some reason I can't seem to be able to turn the pot properly  
> through the
> small hole in the case, so I will have a look to see if anything is
> mechanically mis-aligned.
>
> I promise I won't tweek anything else!
>
> Cheers,
>
> Ian.
>
> ----- Original Message -----
> From: "Don @ True-Cal" <true-cal at swbell.net>
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Sent: Monday, October 20, 2008 7:57 PM
> Subject: Re: [time-nuts] Question and help with LPRO-101
>
>
> Ian,
>
> No problem, more discussion - the better.
>
> Unscrew the two hex standoffs on either side on the connector, pull  
> the
> 10-pin feed-through out of the internal connector. Note the  
> position of the
> grounded pins vs. the capacitive bypass feedthrough pins. This will  
> free up
> the metal cover to "snap" off of the base plate. A very small  
> screwdriver
> can be used in the small slots at each of the four coners to pry  
> the box
> cover free from the base plate.
>
> Caution, here is where a little will-power is needed to resist  
> tuning the
> several adjustments for "better performance".
>
> Have fun,
> Don
>
>
> ----- Original Message ----
> From: Ian Sheffield <ian.sheffield1 at tesco.net>
> To: Discussion of precise time and frequency measurement
> <time-nuts at febo.com>
> Sent: Monday, October 20, 2008 1:34:01 PM
> Subject: Re: [time-nuts] Question and help with LPRO-101
>
> Hello Don,
>
> Sorry to hijack your question, but how do you get inside an  
> LPRO-101? Does
> the case just spring off?
>
> Thanks,
>
> Ian.
>
>
> ----- Original Message -----
> From: "Don @ True-Cal" <true-cal at swbell.net>
> To: <time-nuts at febo.com>
> Sent: Monday, October 20, 2008 7:05 PM
> Subject: [time-nuts] Question and help with LPRO-101
>
>
> Hello,
>
> Can anyone guide me or give me a link to internal settings on the  
> Efratom
> LPRO-101 Rb oscillator. I have the User's and Integration Guide but  
> I am
> looking for more detailed information on any optional settings that  
> may be
> available from the many inside jumpers and/or hidden connectors.
> Specifically, all of the units I have provide a 10MHz sine wave  
> output and I
> am wanting a 1PPS output on one of the units. I believe there are  
> LPROs that
> provide a 1PPS output but not sure if they are a different part  
> number unit
> with different electronics or just different jumper options inside.  
> I scoped
> the hidden connector J6 but no 1PPS signal.
>
> There is a 9-pair J8 jumper block with 2 jumpers and a 7-pair J8  
> with one
> jumper and a 2-pair J1 with no jumper. There is also a connector  
> block J9
> and a 3-pair J10 but they are back by the Rb lamp/cavity with  
> analog signals
> on some probably for initial test/calibration.
>
> My units are Cage Code 55761, Part Number 102500-001
>
> Thanks...
> Don
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