[time-nuts] Racal 1992

Alan Melia alan.melia at btinternet.com
Thu Aug 27 18:52:22 UTC 2009


Hi Ed I dont know whther it would be of interest but i have a page from a
cat with the comparative specs for those OXCOs

Alan G3NYK

----- Original Message -----
From: "Ed Palmer" <ed_palmer at sasktel.net>
To: "Time Nuts Mailing List" <time-nuts at febo.com>
Sent: Thursday, August 27, 2009 6:52 PM
Subject: Re: [time-nuts] Racal 1992


> John Green wrote:
> > Ed Palmer wrote:Which timebase does yours have?  I've got option 4E
(similar
> > to 4B).
> > Although the timebase appears to be stable, I've noticed that the
> > counter drifts about 5e-9 during warmup, even when the oscillator has
> > been on standby for many days.  It takes a couple of hours to settle
> > down.  Does yours do anything similar?
> >
> >
> >
> > Ed, Exactly which reference I have seems to be something of a mystery.
The
> > part number on it is 454879. The part number listed in my manual is
404386.
> > My manual makes no reference to optional timebases. The manual I
downloaded
> > does but doesn't list the part number I have as a choice. Though it is
> > ovenized, I don't believe it is the best high stability type. It does
look
> > pretty good in general terms. Retrace is important to me and it seems
pretty
> > good in this respect. I did try to
> > get it in sync with the GPSDO and after several minor adjustments and
> > several hours of observation, I still saw movement. This isn't that
> > important as I can always use the GPSDO as a standard.
> > I did find out why it doesn't output a sine wave. There is a nice sine
wave
> > out of the oscillator itself but that goes through a conditioning
amplifier
> > and into IC39 which is some kind of 40 pin device. IC39 actually feeds
the
> > back panel BNC. Why they do this is beyond me but it answers the
question.
> > I haven't looked at how it behaves coming out of standby yet. I'll let
you
> > know when I have done that.
> >
>
> Yes, they seem to have made a few oscillator substitutions along the
> way. I'm guessing that they outsourced the oscillators and changed
> suppliers a few times during the life of the 1991/1992 product. I have
> two units, one labelled as having 04A and the other having 04E. Pulling
> info from various manuals, data sheets, and my units, I think the info
> is as follows:
>
> Option Osc. Part # Physical Description - based on my oscillators only
> 04A 9444* or 11-1710 Approx. cube 5 cm., only one adjustment
> 04B 9423 Don't know - haven't seen one of these
> 04E 9462* or 404386 or 454879* Approx 5x5x10cm., two adjustments
>
> * these are the markings on my oscillators. The 04E oscillator is
> actually labelled "9462 454879, Rev. A ERC 87-34". Both of my
> oscillators are 5 MHz with freq. doubler boards attached to the bottom.
>
> IC39 is one of the "Magic happens here" chips in these units. One of my
> units died shortly after I got it. IC39 didn't let the magic smoke out,
> but it was running at a temperature of ~90C! IC39 in the other unit was
> running at ~60C. I decided to put a heat sink on it just in case.
>
> Ed
>
>
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