Well, to answer "What are they good for?" Really nothing. I have
rubidium and xtals locked to GPS and can easily get to 10e-12. With
some of the work I do, 1x10e-8 translates to "broken."

However, I also play with old radios, so why not have an "old crystal
calibrator" sitting warm on the work bench. I am kind of excited to
homebrew an oven. Temp sensor are easy these days. Or is that cheating?

That's why I posted to this group, not sci.electronics.design.

Just something fun to do while I am waiting for football to start again.

Steve.
--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA

"Steven Swift" wrote in message
...

Well, to answer "What are they good for?" Really nothing. I have
rubidium and xtals locked to GPS and can easily get to 10e-12. With
some of the work I do, 1x10e-8 translates to "broken."

However, I also play with old radios, so why not have an "old crystal
calibrator" sitting warm on the work bench. I am kind of excited to
homebrew an oven. Temp sensor are easy these days. Or is that cheating?

That's why I posted to this group, not sci.electronics.design.

Just something fun to do while I am waiting for football to start again.

Steve.

Well it is not Bliley ... but a 10 MHz crystal should for an oscillator to
mate with my Motorola Oncore GPS receiver .... poor man's standard.

eBay item number: 280199154465

Greg
w9gb

Don Bowey wrote:
On 2/15/08 10:26 AM, in article ,
"Jeffrey D Angus" wrote:

John Byrns ) writes:
I'm still wondering why these are in tube type cases. It almost suggest
they are better than average crystals, and makes me wonder if they actually
have some sort of heater built in.

They're just a bit better than the tall HC/6-U crystal holder. And less
prone to enviromental issues than the FT-243 type holders.

The "tube" versions usually don't have a heater built in.

So the question is, what are these good for, can they be converted into
a useful project of any sort?

With the availability of crystal oscillator assemblies having better
than 10^-12 stability and and accuracy, there's not much you can use
one of these old crystals for.

A crystal oscillator will not achieve 10^-12 on its own. 10^-12 is the
stability of a Stratum II atomic clock.

Short term stability on a 6C4-based crystal oscillator is pretty good...
the phase noise is going to be lower than some PLL bench oscillators.

Long term stability... it's not very good... it's not good enough to pass
current FCC broadcast standards, even, without a really good oven. On
most of them you can see the frequency jump back and forth as the thermostat
opens and closes....
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

(Scott Dorsey) writes:

Short term stability on a 6C4-based crystal oscillator is pretty good...
the phase noise is going to be lower than some PLL bench oscillators.

Long term stability... it's not very good... it's not good enough to pass
current FCC broadcast standards, even, without a really good oven. On
most of them you can see the frequency jump back and forth as the thermostat
opens and closes....
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Proportional control, with modern parts will really help. My lab is
20C+/-3C, so getting 70C+/-1C should be pretty easy. Unfortunately,
that will still be pretty sloppy (about +/-1ppm). Just fine for
boatanchor calibrating and frequency spotting.

Steve.
--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA

Jeffrey D Angus writes:

Steven Swift wrote:
I want to thank all those who helped, especially Dana at the Bliley
corporation who sent me this:

http://novatech-instr.com/Fun/BG9DS.pdf

Now I know I want to find another one of these. I think I've seen one
in my stash upstairs.

A couple of years ago I was working on a crystal oscillator and watched
as the one I had rolled off of the bench and went "Pock!" as it hit the
floor.

Sigh....

Jeff

Interesting point. The BG9D I have is not the same as the BG9DS. The most
obvious is that the crystal is on pins 2-6 not 3-7. An email to Bliley
hasn't yet been answered. Might have been a special version.

So I am not sure of the other specs either.

Steve.

--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA