[time-nuts] LPRO testing

[WarrenS]

Magnus

After you find/fix the working ones, may want to measure their Ageing rate, 
room temperature Tempco, and ADEV.

Two example plots attached, one from LadyHeather using a Tbolt with the LPRO 
as it's ref Osc,
the other is a TimeLab plot using a XOR phase comparator to test an 
undisciplined LPRO.
To get valid ageing rate and tempco data that is good enough to measured a 
correctly working LPRO,
using this Tbolt method, need to log at least three days and preferable a 
week or more of data.
To measure my LPROs' ADEV which is typically ~1e-11 at 1 sec and crosses 
1e-12 at ~ 200 seconds, a couple hours of data will do.

TimeLab's freq plot will give a great plot of the LPRO's locked warm-up 
performance.
For this, depending on the time period and DUT's noise and drift rate,
I find setting the TimeLab's freq display filter from 10 to 1000 seconds 
works best.

ws
************
----- Original Message ----- 
From: "Magnus Danielson" <magnus at rubidium.dyndns.org>
To: "Time-Nuts" <time-nuts at febo.com>
Sent: Saturday, January 19, 2013 5:45 PM
Subject: [time-nuts] LPRO testing


> Fellow time-nuts,
>
> As I received a box of suspect LPROs I now have a largish amount of LPROs 
> to test through.
>
> I got the LPRO manual as well as the repair guide.
>
> Seems like I need to solder up a connector and hook a few things up.
>
> I will have to improvise on the heat-sink side until I find something 
> useful.
>
> I would think that I would sort them into a few different piles depending 
> on the failure modes. By external observing I should see these:
>
> 1) Heater problem (monitoring current would have heating gone or 
> overheating)
> 2) Lamp problem (monitoring the lamp monitor output)
> 3) Lock problem (monitoring the BITE as well as frequency)
> 4) RF problem (monitoring the existence of RF output)
>
> What else did can people think off?
>
> I think the above would work as a systematic check-list.
>
> Now, I'd love to hear about hints and tips from you folks.
>
> Cheers,
> Magnus
>
> 
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