Author Topic: Fun with a Racal 9480 with OCXO & 40 10Mhz outputs - (8x 5 chan)  (Read 4453 times)

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Offline bingo600

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Guyzz

I just got a Racal 9480 with OCXO & 40 10Mhz outputs  -  (8x 5 chan) from KJDS

Update: The 9840 has an Opt 04B sticker on the back , so i suppose its a 04B OCXO inside it , also used in some of  the 1991/2 counters.


And decided to connect it to my Phillips PM6680B
My HP 5370 has a fan, and SWMBO hates fannoise  :'(

I'm using my Tbolt GPSDO as input on the PM6680B ext-ref.

Racal ontime is approx 45 hr's , so the OCXO hasn't settled yet. And i haven't adjusted it yet.
Just logging the stability.


Playtime ....


http://www.ebay.de/itm/351323826114


Measuring the :
Racal 9480 with OCXO & 40 10Mhz outputs  -  (8x 5 chan)

I have fumbled around with my PM6680B (ext ref Tbolt GPDSO) , linux-gpib python bindings , and a Beiming USB-GPIB adapter (100% HP Compatible)

I'm measuring on one of the 40 outputs , not the master in front (I want to see it from a clients side)


Code: [Select]
#
#   Line looks like this : 1    2    3       4    5     6     7      8                     9         10          11
#   measline    Collums : Date;Time;DateTime;Temp;F-Max;F-Min;F-Mean;F-SDEV;
#
# 1          2        3                   4       5                   6                   7                   8             
# 2015-03-21;08:47:39;2015-03-21T08:47:39;24.5625;+9.99999886905E+006;+9.99999886353E+006;+9.99999886717E+006;+1.51490921548E-003;
#

Output (.csv)

2015-03-21;08:42:23;2015-03-21T08:42:23;24.5625;+9.99999887083E+006;+9.99999886348E+006;+9.99999886857E+006;+2.14294251018E-003;
2015-03-21;08:42:34;2015-03-21T08:42:34;24.5000;+9.99999887071E+006;+9.99999886380E+006;+9.99999886809E+006;+2.18569307406E-003;
2015-03-21;08:42:46;2015-03-21T08:42:46;24.5625;+9.99999887181E+006;+9.99999886591E+006;+9.99999886918E+006;+1.99033610964E-003;

The counter is saving 10 readings , 1 sec trigger , and doing statistics on the readings.
I'm just reading out the 4 statistics values , and retriggering the counter for 10 more readings.

Seems like there is a 1s overhead , so each measurement is 11 sec apart

But it was a "tough" , but learning experience.
Mostly to figure out the PM6680B commands.
But i actually spent the most time fumbling with detecting the REQ bit on the GPIB-Bus , from inside the linux-gpib python bindings.


The Racal can also take the Tbolt 10Mhz as input , and will automatically detect an ext-ref and switch from OCXO to Ext-ref.
But i'm testing the OCXO now, turnon time approx 45 hours , so the OCXO is prob not stable yet

I guess i'm fit with enough channels for my instruments for now.

Attached some newly created .csv files from my python script


Any suggestions (examples) for fun measurements are welcome.


Edit: Added some more measurements

/Bingo
« Last Edit: March 21, 2015, 01:35:24 pm by bingo600 »
 

Offline KJDS

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Re: Fun with a Racal 9480 with OCXO & 40 10Mhz outputs - (8x 5 chan)
« Reply #1 on: March 21, 2015, 11:36:54 am »
I think these were last adjusted about 10 years ago, so to only be 1.2Hz low is testament to how good they are.

Online Howardlong

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Re: Fun with a Racal 9480 with OCXO & 40 10Mhz outputs - (8x 5 chan)
« Reply #2 on: March 21, 2015, 12:17:26 pm »
Thanks for the heads up, just bought one. Looks like they have an external ref input too, so can be used as a distribution unit for a rubidium or GPS disciplined source also.
 

Offline bingo600

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Re: Fun with a Racal 9480 with OCXO & 40 10Mhz outputs - (8x 5 chan)
« Reply #3 on: March 21, 2015, 01:28:31 pm »
Howard

KJDS have manuals.

But they should also be on ko4bb , thanx to a kind fellow time-nut  :-+

http://www.ko4bb.com/manuals/index.php?dir=Racal

/Bingo
 

Offline Mr Simpleton

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Re: Fun with a Racal 9480 with OCXO & 40 10Mhz outputs - (8x 5 chan)
« Reply #4 on: March 21, 2015, 07:08:49 pm »
@Howard.... so you're the one :D I was trying to make up my mind if I "needed" a box like this... :scared: and poof gone. No need to make room it   :clap: Guess I should thank you  :-+
 

Online Howardlong

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Re: Fun with a Racal 9480 with OCXO & 40 10Mhz outputs - (8x 5 chan)
« Reply #5 on: March 23, 2015, 10:27:58 pm »
@Howard.... so you're the one :D I was trying to make up my mind if I "needed" a box like this... :scared: and poof gone. No need to make room it   :clap: Guess I should thank you  :-+

"Need" and "want" are two different concepts!

I already have a Rb source to which I added my own homebrew distribution amps about ten years ago. It works fine for simple frequency measurement but it suffers from serious jitter/phase noise because I built it on veroboard, not a properly laid out PCB, so it's not so good for some other applications. The only other advantage with my current setup is that I have some older bits of TE that need 2MHz and 5MHz, so I might pull my finger out and do it properly. One other plus I suppose with my current setup is that I routed all the distributed outputs to the front panel.

Sorry you missed out!
 

Offline bingo600

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Re: Fun with a Racal 9480 with OCXO & 40 10Mhz outputs - (8x 5 chan)
« Reply #6 on: April 16, 2015, 06:27:25 pm »
My Racal OCXO seem to have settled now.

Here is logging from yesterday.

My PM6680B is taking 60 readings (one/sec) , calculating Fmax,Fmin,Fmean,StdDev
Then logging the calculated results (one per  minute)

That's not bad at all for a freerunning osc.

/Bingo
 


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