[time-nuts] Is Timelab with a Prologix-Eth and a PM6680 - working ?

cfo xnews3 at luna.dyndns.dk
Tue Jul 3 15:46:12 UTC 2012


On Tue, 03 Jul 2012 14:34:08 +0000, cfo wrote:

> I just got a PM6680/016 - Std. Osc + GPIB + 1.3Ghz -Chan.C The best my
> budget could afford :-)
> 
> I would like to try out John's Timelab. But only have a
> Prologix-Ethernet GPIB adapter , no USB version.
> 
> I was wondering if anyone can confirm that Timelab would work on a
> PM6680 , using a Prologix-Eth ?
> 
Well (blush)

I can ansver my own question here.
Timelab autodetects the Prologix-Eth (with mac & ip) , and lists it below 
all the COMM-Ports. Nice work John ...

So all i had to do was to select the detected Prologix , and set the 
PM6680 GPIB address.

I'm acquiring data now , although not very impressive.

I run my Tbolt signal through a Video Dist-Amp (400Mhz bw) , to get 
6-channels. So i know the 75ohm imp there , but it's not been an issue so 
far.

I feed the PM6680 Ext-Ref and Chan-A via a Dist-Amp output on a BNC-T.
And have put a BNC-T on Chan-A with a 50ohm terminator on it. 
I have Chan-A set to 1Mohm , as i terminate the input via the BNC-T on 
Chan-A.

But i wonder if the PM6680 Ext-Ref input already terminates with 50-ohm , 
and that could be the issue ??

The counter flickers occasionally in the last digit between 0 , 1 and 9

And Timelab says ADEV is 9.442-E-6 on T=1000 Secs.

I would have expected something better .... 

LH says the ADEV is Osc ADEV is 5.442-E-13 on 10000 Secs

I wonder where i have FSCK'ed up , or is a Tbolt on Ext-Ref & the same 
signal on Chan-A supposed to show that ?


CFO - (Feeling very T-Nut Beginner now)






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