[time-nuts] Racal-Dana 1992 Startup -- GPIB!

Robert Atkinson robert8rpi at yahoo.co.uk
Wed Nov 16 14:56:42 EST 2011


These counters used Racal's own 94xx series OCXO's. The 04A normally had a 9442, the 04E had the 9420. Easy way to tell which is which is the size. They are both 51mm (2") square with the 9442 being 51mm tall and the 9420 is 96mm (3.75") tall. The 9442 is also classed as fast warm-up, 6 minutes to 3x10^7. 

These OCXO's were also used in Racal's frequency standards such as the 9478. They are very good OCXO's. All of them are 5MHz. Unfortunatly Racal considered them propriatry and never released any circuits or service information.
All my information comes from Racal manuals and the 1984/85 catalogue.

Robert G8RPI.



________________________________
From: Larry McDavid <lmcdavid at lmceng.com>
To: Robert Atkinson <robert8rpi at yahoo.co.uk>; Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Wednesday, 16 November 2011, 18:25
Subject: Re: [time-nuts] Racal-Dana 1992 Startup -- GPIB!

There are other Racal timebase options as well.

I have a Racal 1999 counter that originally had a 04C timebase option that was not ovened and had a single adjustment screw. I replaced it with a 04A ovened ocxo that has a single adjustment screw. I will shortly install a 04E ocxo as Robert describes below. There is also a 04B ocxo option with two adjustment screws (coarse and fine). All the specs are slightly different. My manuals do not show a 04T option.

There is also a Rb oscillator option, 04R. I've never seen one of these.

None of these is necessarily on frequency! You must have something like a GPSDO that outputs 10 MHz to set any of the timebase options accurately. Accuracy is relative, of course!

I use a HP Z3801A GPSDO and a TAPR distribution amplifier to distribute the GPS-steered 10 MHz to numerous devices that accept an external timebase, such as the Racal counter.

It's a very nice counter.

Larry W6FUB


On 11/16/2011 10:02 AM, Robert Atkinson wrote:
> Hi Chuck,
> You need to look at the option sticker on the back of the unit. The 04* is the oscillator option.
> 
> 04T is a TCXO 3x10^7 per month&  temp1x10^6 0-40 deg C
> 
> 04A Ovened oscillator 3x10^9 per Day&  temp3x10^9 0-45 deg
> 
> 04E High stability ovened oscillator 5x10^10 per day&  temp7x10^9 0-50 deg C
> No 04* is basic crystal oscillator. If yours has a mechanical and electrical trim it will be a 04A or 04E.
...
> 
> ________________________________
> From: Chuck Forsberg WA7KGX N2469R<caf at omen.com>
> To: time-nuts<time-nuts at febo.com>
> Sent: Wednesday, 16 November 2011, 16:47
> Subject: [time-nuts] Racal-Dana 1992 Startup -- GPIB!
> 
> I found a use for the GPIB interface on my counter - record
> the frequency drift of its internal timebase during warm up.
> It looks like an oven warming up.  I don't know exactly which
> timebase my 1992 has, but I did notice the 5 to 10 MHz doubler
> on the back of the oscillator,  The back has separate coarse
> and fine frequency adjustments.  Can someone identify which
> timebase is fitted to this counter?
> 
> The link below has the story and plot.
> 
> http://www.omen.com/ham/racal.html
...
-- Best wishes,

Larry McDavid W6FUB
Anaheim, CA  (20 miles southeast of Los Angeles, near Disneyland)


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