David,

Besides the Symmetricom SA22c unit which can be found here :

http://www.symmetricom.com/products/frequency-references/rubidium-frequency-standard/SA22c/

There is also the Frequency Electronics Inc. unit FE-5650 which is very much the
same size and can be found here :

http://www.frequencyelectronics.com/rb_oscillators.html

The SA22c is .91" high by 3.0x wide and 4.4x long.  In contrast the FEI unit is
1.4" high by 3.03" square.  So take your pick !

The SA22c has additional options that the FEI does not have like external 1pps
sync input for connection to a GPS and RS232 communication port for enhanced data
between the SA22c and your computer.

I guess it depends upon what you need it for.

Bill....WB6BNQ

"Dr. David Kirkby" wrote:

On 05/23/11 09:31 AM, Rob Kimberley wrote:

Thank you. I don't have know what board area I have available, but I think think
its going to be considerably less than that size. I think the only option will
be to use an TCXO, which to be honest is good enough, but if there were small
rubidiums, I would consider using one. But it seems they are not as small as I
would have liked.

--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

I believe thats because RB and CS have cavities that essentially establish
the operating size, because they work at a given frequency. You have to go
to a different technology method to reduce its size, like the new
Symmetricom CS oscillator. Still overall pretty darned amazing in size and
power consumption. (Still waiting for the time-nuts offer of $100 each.
Limited time offer call before midnight. Shipping and handling included)
So at this time it would not be possible to equal the size or power of a
typical TCXO these days. 1/4 dip stuff.
Though we have given you answers you had not ever really stated what you
needed to accomplish.
Regards
Paul
WB8TSL

On Mon, May 23, 2011 at 9:07 AM, Dr. David Kirkby
david.kirkby@onetel.netwrote:

I couldn't resist commenting about how top posting annoys you.
Interestingly, I have always top posted ever since my first email way, way
back. Everyone else I dealt with in business did it that way. It wasn't
until I got involved with groups like this, that it apparently became a
problem.

It always seemed logical to me to have the answers to a question at the top
i.e. the most recent comment in the chain.

No doubt I'll get a lot of replies both top and bottom about this...
:-)
RK

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Dr. David Kirkby
Sent: 23 May 2011 2:07 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] smallest rubidium

On 05/23/11 09:31 AM, Rob Kimberley wrote:

Thank you. I don't have know what board area I have available, but I think
think its going to be considerably less than that size. I think the only
option will be to use an TCXO, which to be honest is good enough, but if
there were small rubidiums, I would consider using one. But it seems they
are not as small as I would have liked.

--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

On 5/23/11 6:07 AM, Dr. David Kirkby wrote:

Depending on your actual needs/other stuff available in your device, a
non-TCXO and a temperature sensor might do as well. The non-TC means
that the crystal can be higher Q, so better close in phase noise, the
temperature sensor means you can calibrate the variation with
temperature (assuming your downstream application can work with
"knowledge" of the frequency.. if you're trying to generate 10 MHz, then
that doesn't help as much)

On 05/23/11 02:20 PM, paul swed wrote:

That makes sense
You have to go

I've bought an amateur radio transceiver - Kenwood TS-940S. This has a 20 MHz
crystal osciallator (not 10 as I stated before), but it was optionally available
with a 20 MHz TCXO, called SO-1 which sat on a small (how small?) circuit board.
But these TCXO's seem to be like rocking horse dung, so I wondered about putting
my own TCXO on a board. Then the idea of perhaps using a rubidium hit me.

Some enterprising sole is selling on eBay a circuit board which replaces the
SO-1, and has a 10 MHz reference input. But of course that means you need to
rely on having the external reference. Having it built in would be nice, but I
don't think there's enough room.

Perhaps an OCXO might be practical - better than a TCXO, but not as big as a
rubidium.

Dave