I wish to make a master oscillator for the shack, and am considering
cutting my own crystals in order to reduce ageing. Is there a source
of raw material?

Also, for temperature compensation, I am considering the use of bi-metals.
(I've never seen one, but what is the mechanism used in Oxley's
Tempatrimmer?)

On Fri, 10 Oct 2003 09:47:26 +0100, "Airy R. Bean"
wrote:

I wish to make a master oscillator for the shack, and am considering
cutting my own crystals in order to reduce ageing. Is there a source
of raw material?

Also, for temperature compensation, I am considering the use of bi-metals.
(I've never seen one, but what is the mechanism used in Oxley's
Tempatrimmer?)

My dear Airy, I am so pleased to hear of your proposed project. The
'Raw Material' is readily available here in Cornwall, its called
Quartz, and is free for those willing to collect it. However if you
send me a large SAE I'll send you a few tons. HI

I'll assume the question is a genuine one about the Oxley trimmers
so...
AFIR it was two variables in one encapsulation, one with a positive
temp coeficient and the other negative. when you varied the trimmer it
added one coeficient and reduced the other, without changing the
capacitance.. At least thats the way it was explained to me many years
ago. I hav'nt seen one for years except in my junk box, and come to
think of it I hav'nt seen those for a while.

hth Mike W

In article ,
says...
| I wish to make a master oscillator for the shack, and am considering
| cutting my own crystals in order to reduce ageing. Is there a source
| of raw material?

Yes, open up an old crystal if you really must consider cutting your
own crystals. It is a very tricky task, so practise on scrap ones
first. Any crystal cut, will then take lots of time to settle and age.
Far better to use an old crystal which has already achieved stability
'as is', rather than start the aging process off again.

|
| Also, for temperature compensation, I am considering the use of bi-metals.
| (I've never seen one, but what is the mechanism used in Oxley's
| Tempatrimmer?)
|
|

A good quality crystal in an oven which provides proportional
temperature control, rather than on/off switching is difficult to beat
once it has had an hour to settle. Even better is a double ovened
crystal. Old lab grade equipment is a good source for these.

If you really must have the ultimate stand-alone standard then rubidium
standards are coming onto the second-hand market at quite affordable
prices.

Another solution is to build a little gadget which derives a frequency
standard off-the-air, phase locked using a PLL. Suitable sources are
198Khz LW and slightly less accurate, the line timebase of a TV tuned
and synched to a BBC channel (15,625 hertz). This is what I have used
to check the calibration of my own instruments for the past 20 years.

You would probably need that latter item anyway, otherwise what would
you calibrate your own standard against?


--
Regards,
Harry (M1BYT)...

Remove the 'NOSPAM' in my email address to reply.

Free Amateur Radio Courses:-
http://www.ukradioamateur.org

On Fri, 10 Oct 2003 09:47:26 +0100, "Airy R. Bean"
wrote:

I wish to make a master oscillator for the shack, and am considering
cutting my own crystals in order to reduce ageing. Is there a source
of raw material?

Also, for temperature compensation, I am considering the use of bi-metals.
(I've never seen one, but what is the mechanism used in Oxley's
Tempatrimmer?)

My dear Airy, I am so pleased to hear of your proposed project. The
'Raw Material' is readily available here in Cornwall, its called
Quartz, and is free for those willing to collect it. However if you
send me a large SAE I'll send you a few tons. HI

I'll assume the question is a genuine one about the Oxley trimmers
so...
AFIR it was two variables in one encapsulation, one with a positive
temp coeficient and the other negative. when you varied the trimmer it
added one coeficient and reduced the other, without changing the
capacitance.. At least thats the way it was explained to me many years
ago. I hav'nt seen one for years except in my junk box, and come to
think of it I hav'nt seen those for a while.

hth Mike W

In article ,
says...
| I wish to make a master oscillator for the shack, and am considering
| cutting my own crystals in order to reduce ageing. Is there a source
| of raw material?

Yes, open up an old crystal if you really must consider cutting your
own crystals. It is a very tricky task, so practise on scrap ones
first. Any crystal cut, will then take lots of time to settle and age.
Far better to use an old crystal which has already achieved stability
'as is', rather than start the aging process off again.

|
| Also, for temperature compensation, I am considering the use of bi-metals.
| (I've never seen one, but what is the mechanism used in Oxley's
| Tempatrimmer?)
|
|

A good quality crystal in an oven which provides proportional
temperature control, rather than on/off switching is difficult to beat
once it has had an hour to settle. Even better is a double ovened
crystal. Old lab grade equipment is a good source for these.

If you really must have the ultimate stand-alone standard then rubidium
standards are coming onto the second-hand market at quite affordable
prices.

Another solution is to build a little gadget which derives a frequency
standard off-the-air, phase locked using a PLL. Suitable sources are
198Khz LW and slightly less accurate, the line timebase of a TV tuned
and synched to a BBC channel (15,625 hertz). This is what I have used
to check the calibration of my own instruments for the past 20 years.

You would probably need that latter item anyway, otherwise what would
you calibrate your own standard against?


--
Regards,
Harry (M1BYT)...

Remove the 'NOSPAM' in my email address to reply.

Free Amateur Radio Courses:-
http://www.ukradioamateur.org

Try http://www.realhamradio.com/GPS_Frequency_Standard.htm
Far more stable than cutting your own crystal, can't imagine why you think making one yourself would
be more stable than a good surplus xtal and oven.

Steve H

"Airy R. Bean" wrote in message
...
I wish to make a master oscillator for the shack, and am considering
cutting my own crystals in order to reduce ageing. Is there a source
of raw material?

Also, for temperature compensation, I am considering the use of bi-metals.
(I've never seen one, but what is the mechanism used in Oxley's
Tempatrimmer?)





---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
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In article ,
says...

Try http://www.realhamradio.com/GPS_Frequency_Standard.htm
Far more stable than cutting your own crystal, can't imagine why you think making one yourself would
be more stable than a good surplus xtal and oven.

...And it's disciplined to GPS as well. Can't get much more stable
than that. 'Bout the same as a cesium standard, if I recall correctly.


--
Dr. Anton Squeegee, Director, Dutch Surrealist Plumbing Institute
(Known to some as Bruce Lane, KC7GR)
kyrrin a/t bluefeathertech d-o=t c&o&m
"Quando Omni Flunkus Moritati" (Red Green)

In article ,
says...

Try http://www.realhamradio.com/GPS_Frequency_Standard.htm
Far more stable than cutting your own crystal, can't imagine why you think making one yourself would
be more stable than a good surplus xtal and oven.

...And it's disciplined to GPS as well. Can't get much more stable
than that. 'Bout the same as a cesium standard, if I recall correctly.


--
Dr. Anton Squeegee, Director, Dutch Surrealist Plumbing Institute
(Known to some as Bruce Lane, KC7GR)
kyrrin a/t bluefeathertech d-o=t c&o&m
"Quando Omni Flunkus Moritati" (Red Green)

In article ,
says...
|Try http://www.realhamradio.com/GPS_Frequency_Standard.htm
|Far more stable than cutting your own crystal, can't imagine why you think making one yourself would
|be more stable than a good surplus xtal and oven.

A real radio amateur would build and set up their own network of GPS
satellites ;-)

--
Regards,
Harry (M1BYT)
http://www.ukradioamateur.org

In article ,
says...
|Try http://www.realhamradio.com/GPS_Frequency_Standard.htm
|Far more stable than cutting your own crystal, can't imagine why you think making one yourself would
|be more stable than a good surplus xtal and oven.

A real radio amateur would build and set up their own network of GPS
satellites ;-)

--
Regards,
Harry (M1BYT)
http://www.ukradioamateur.org