HP 10811 update
Ed Palmer wrote:
Hi Paul,
Did you see this page that talks about tweaking the 10811 oven controller?
http://www.realhamradio.com/z3801a-turning-point.htm
Ed
Although this article anecdotally claims success, it overlooks
a number of important issues. First of all, a large proportion
of 10811 crystals DO NOT HAVE A TURNOVER. They merely have a
very low TC around 82 degrees. It is ALWAYS 82 degrees for these
crystals. The crystals that do, technically, have a turnover,
still have very low TC even if the oven is slightly off the turnover.
Secondly, the tempco of the electronics, specifically
the selected 2N5179 oscillator transistor, is a significant player.
The thermal gain, if properly adjusted, is around 1000 at the
crystal, but is much less at the oscillator transistor. It may
very well be the dominant factor in overall oscillator tempco.
Possibly, if you have a crystal with a turnover, you should
deliberately operate off the turnover at a point where the crystal
drift cancels the drift of the electronics.
If you want to tweak a 10811, you should also tweak the thermal
gain by custom adjustment of the heat balancing resistors for
the heater transistors. This has to be done by converting the
oscillator to mode B and then converting it back to mode C
afterwards.
Rick Karlquist N6RK
Yes thanks ran across it. Skimmed it. Did not think I would be doing it. :-)
On Fri, Jul 26, 2013 at 1:15 PM, Ed Palmer ed_palmer@sasktel.net wrote:
Hi Paul,
Did you see this page that talks about tweaking the 10811 oven controller?
http://www.realhamradio.com/**z3801a-turning-point.htmhttp://www.realhamradio.com/z3801a-turning-point.htm
Ed
On 7/26/2013 10:47 AM, paul swed wrote:
sounds like time to add a R across the temp set R. That will lower the R
and raise the temp. Its also easy to actually do.
Thanks
On Fri, Jul 26, 2013 at 12:08 PM, Bob Camp lists@rtty.us wrote:
Hi
HP spec'd the crystals to be at a < 1x10^-8 / C slope at the marked
temperature on the crystal. The center of the curve should be in the
vicinity of 90C.
You are ~ -4.5 x 10^-6 low, so that would be > 10 C away from that point
going cold and a bit further going hot. Since the oven is at ~80C, it's
not
to hot…
Bob
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Rick
Thanks. But I am far simpler than that. I am trying to get the 10811 back
to 10 Mhz its -45Hz. In the long thread above I go into the troubleshooting
details so far. Because a crystal simply can't go this bad. :-) I hope not
at least.
Regards
Paul.
On Fri, Jul 26, 2013 at 1:38 PM, Rick Karlquist richard@karlquist.comwrote:
Ed Palmer wrote:
Hi Paul,
Did you see this page that talks about tweaking the 10811 oven
controller?
Although this article anecdotally claims success, it overlooks
a number of important issues. First of all, a large proportion
of 10811 crystals DO NOT HAVE A TURNOVER. They merely have a
very low TC around 82 degrees. It is ALWAYS 82 degrees for these
crystals. The crystals that do, technically, have a turnover,
still have very low TC even if the oven is slightly off the turnover.
Secondly, the tempco of the electronics, specifically
the selected 2N5179 oscillator transistor, is a significant player.
The thermal gain, if properly adjusted, is around 1000 at the
crystal, but is much less at the oscillator transistor. It may
very well be the dominant factor in overall oscillator tempco.
Possibly, if you have a crystal with a turnover, you should
deliberately operate off the turnover at a point where the crystal
drift cancels the drift of the electronics.
If you want to tweak a 10811, you should also tweak the thermal
gain by custom adjustment of the heat balancing resistors for
the heater transistors. This has to be done by converting the
oscillator to mode B and then converting it back to mode C
afterwards.
Rick Karlquist N6RK
time-nuts mailing list -- time-nuts@febo.com
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Hi
Doing any real adjustment on these OCXO's pretty much requires you have a temperature chamber and a pretty good standard. A GPSDO will do for the standard, the chamber is a bit harder to come by.
Bob
On Jul 26, 2013, at 1:38 PM, Rick Karlquist richard@karlquist.com wrote:
Ed Palmer wrote:
Hi Paul,
Did you see this page that talks about tweaking the 10811 oven controller?
http://www.realhamradio.com/z3801a-turning-point.htm
Ed
Although this article anecdotally claims success, it overlooks
a number of important issues. First of all, a large proportion
of 10811 crystals DO NOT HAVE A TURNOVER. They merely have a
very low TC around 82 degrees. It is ALWAYS 82 degrees for these
crystals. The crystals that do, technically, have a turnover,
still have very low TC even if the oven is slightly off the turnover.
Secondly, the tempco of the electronics, specifically
the selected 2N5179 oscillator transistor, is a significant player.
The thermal gain, if properly adjusted, is around 1000 at the
crystal, but is much less at the oscillator transistor. It may
very well be the dominant factor in overall oscillator tempco.
Possibly, if you have a crystal with a turnover, you should
deliberately operate off the turnover at a point where the crystal
drift cancels the drift of the electronics.
If you want to tweak a 10811, you should also tweak the thermal
gain by custom adjustment of the heat balancing resistors for
the heater transistors. This has to be done by converting the
oscillator to mode B and then converting it back to mode C
afterwards.
Rick Karlquist N6RK
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and follow the instructions there.
So laying a sock over the insulated oven can doesn't count? Its a thick
sock.
Still not at the stage of needing a chamber I am 45 Hz off.
On Fri, Jul 26, 2013 at 2:36 PM, Bob Camp lists@rtty.us wrote:
Hi
Doing any real adjustment on these OCXO's pretty much requires you have a
temperature chamber and a pretty good standard. A GPSDO will do for the
standard, the chamber is a bit harder to come by.
Bob
On Jul 26, 2013, at 1:38 PM, Rick Karlquist richard@karlquist.com wrote:
Ed Palmer wrote:
Hi Paul,
Did you see this page that talks about tweaking the 10811 oven
controller?
Although this article anecdotally claims success, it overlooks
a number of important issues. First of all, a large proportion
of 10811 crystals DO NOT HAVE A TURNOVER. They merely have a
very low TC around 82 degrees. It is ALWAYS 82 degrees for these
crystals. The crystals that do, technically, have a turnover,
still have very low TC even if the oven is slightly off the turnover.
Secondly, the tempco of the electronics, specifically
the selected 2N5179 oscillator transistor, is a significant player.
The thermal gain, if properly adjusted, is around 1000 at the
crystal, but is much less at the oscillator transistor. It may
very well be the dominant factor in overall oscillator tempco.
Possibly, if you have a crystal with a turnover, you should
deliberately operate off the turnover at a point where the crystal
drift cancels the drift of the electronics.
If you want to tweak a 10811, you should also tweak the thermal
gain by custom adjustment of the heat balancing resistors for
the heater transistors. This has to be done by converting the
oscillator to mode B and then converting it back to mode C
afterwards.
Rick Karlquist N6RK
time-nuts mailing list -- time-nuts@febo.com
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Hi
Tossing a nice fluffy towel over it works pretty well. Just the thing if you are doing a bench turn hunt on an AT based OCXO. It's also a quick way to answer the age old question "is it broke or is it just all the people walking by while I'm trying to test it".
You need something that will let you go say 25C 5C 25C 45C 25C. Each time you make a change and re-test, you want to run the same temperatures. You need enough air circulation (and proper ducting) so that the device OCXO stabilizes quickly. 300 to 600 CFM is the range most chambers run in. Dead air = hard to know what temperature you are at / large delta T within the chamber. A dwell of maybe an hour at each one is about right. A Tenny Jr is a pretty good chamber for home use (no CO2). Keeping the refrigeration repaired can be a chore though…
Bob
On Jul 26, 2013, at 3:33 PM, paul swed paulswedb@gmail.com wrote:
So laying a sock over the insulated oven can doesn't count? Its a thick
sock.
Still not at the stage of needing a chamber I am 45 Hz off.
On Fri, Jul 26, 2013 at 2:36 PM, Bob Camp lists@rtty.us wrote:
Hi
Doing any real adjustment on these OCXO's pretty much requires you have a
temperature chamber and a pretty good standard. A GPSDO will do for the
standard, the chamber is a bit harder to come by.
Bob
On Jul 26, 2013, at 1:38 PM, Rick Karlquist richard@karlquist.com wrote:
Ed Palmer wrote:
Hi Paul,
Did you see this page that talks about tweaking the 10811 oven
controller?
Although this article anecdotally claims success, it overlooks
a number of important issues. First of all, a large proportion
of 10811 crystals DO NOT HAVE A TURNOVER. They merely have a
very low TC around 82 degrees. It is ALWAYS 82 degrees for these
crystals. The crystals that do, technically, have a turnover,
still have very low TC even if the oven is slightly off the turnover.
Secondly, the tempco of the electronics, specifically
the selected 2N5179 oscillator transistor, is a significant player.
The thermal gain, if properly adjusted, is around 1000 at the
crystal, but is much less at the oscillator transistor. It may
very well be the dominant factor in overall oscillator tempco.
Possibly, if you have a crystal with a turnover, you should
deliberately operate off the turnover at a point where the crystal
drift cancels the drift of the electronics.
If you want to tweak a 10811, you should also tweak the thermal
gain by custom adjustment of the heat balancing resistors for
the heater transistors. This has to be done by converting the
oscillator to mode B and then converting it back to mode C
afterwards.
Rick Karlquist N6RK
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Bob
I think the power bill exceeds the cost of a 10811. The chamber and CO2.
Going to pass.Though I am sure I can run down to work and throw a unit in
the various walk in units we have. Suspect they will not appreciate me
adjusting the temps though.
Back to work as they say.
Regards
Paul
WB8TSL
On Fri, Jul 26, 2013 at 3:53 PM, Bob Camp lists@rtty.us wrote:
Hi
Tossing a nice fluffy towel over it works pretty well. Just the thing if
you are doing a bench turn hunt on an AT based OCXO. It's also a quick way
to answer the age old question "is it broke or is it just all the people
walking by while I'm trying to test it".
You need something that will let you go say 25C 5C 25C 45C 25C. Each time
you make a change and re-test, you want to run the same temperatures. You
need enough air circulation (and proper ducting) so that the device OCXO
stabilizes quickly. 300 to 600 CFM is the range most chambers run in. Dead
air = hard to know what temperature you are at / large delta T within the
chamber. A dwell of maybe an hour at each one is about right. A Tenny Jr is
a pretty good chamber for home use (no CO2). Keeping the refrigeration
repaired can be a chore though…
Bob
On Jul 26, 2013, at 3:33 PM, paul swed paulswedb@gmail.com wrote:
So laying a sock over the insulated oven can doesn't count? Its a thick
sock.
Still not at the stage of needing a chamber I am 45 Hz off.
On Fri, Jul 26, 2013 at 2:36 PM, Bob Camp lists@rtty.us wrote:
Hi
Doing any real adjustment on these OCXO's pretty much requires you have
a
temperature chamber and a pretty good standard. A GPSDO will do for the
standard, the chamber is a bit harder to come by.
Bob
On Jul 26, 2013, at 1:38 PM, Rick Karlquist richard@karlquist.com
wrote:
Ed Palmer wrote:
Hi Paul,
Did you see this page that talks about tweaking the 10811 oven
controller?
Although this article anecdotally claims success, it overlooks
a number of important issues. First of all, a large proportion
of 10811 crystals DO NOT HAVE A TURNOVER. They merely have a
very low TC around 82 degrees. It is ALWAYS 82 degrees for these
crystals. The crystals that do, technically, have a turnover,
still have very low TC even if the oven is slightly off the turnover.
Secondly, the tempco of the electronics, specifically
the selected 2N5179 oscillator transistor, is a significant player.
The thermal gain, if properly adjusted, is around 1000 at the
crystal, but is much less at the oscillator transistor. It may
very well be the dominant factor in overall oscillator tempco.
Possibly, if you have a crystal with a turnover, you should
deliberately operate off the turnover at a point where the crystal
drift cancels the drift of the electronics.
If you want to tweak a 10811, you should also tweak the thermal
gain by custom adjustment of the heat balancing resistors for
the heater transistors. This has to be done by converting the
oscillator to mode B and then converting it back to mode C
afterwards.
Rick Karlquist N6RK
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
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Hi
Well if you get desperate to try it, I have CO2 and a chamber sitting in the garage. The biggest issue is that if we use too much CO2 for the chamber, the beer may go flat…
Bob
On Jul 26, 2013, at 4:09 PM, paul swed paulswedb@gmail.com wrote:
Bob
I think the power bill exceeds the cost of a 10811. The chamber and CO2.
Going to pass.Though I am sure I can run down to work and throw a unit in
the various walk in units we have. Suspect they will not appreciate me
adjusting the temps though.
Back to work as they say.
Regards
Paul
WB8TSL
On Fri, Jul 26, 2013 at 3:53 PM, Bob Camp lists@rtty.us wrote:
Hi
Tossing a nice fluffy towel over it works pretty well. Just the thing if
you are doing a bench turn hunt on an AT based OCXO. It's also a quick way
to answer the age old question "is it broke or is it just all the people
walking by while I'm trying to test it".
You need something that will let you go say 25C 5C 25C 45C 25C. Each time
you make a change and re-test, you want to run the same temperatures. You
need enough air circulation (and proper ducting) so that the device OCXO
stabilizes quickly. 300 to 600 CFM is the range most chambers run in. Dead
air = hard to know what temperature you are at / large delta T within the
chamber. A dwell of maybe an hour at each one is about right. A Tenny Jr is
a pretty good chamber for home use (no CO2). Keeping the refrigeration
repaired can be a chore though…
Bob
On Jul 26, 2013, at 3:33 PM, paul swed paulswedb@gmail.com wrote:
So laying a sock over the insulated oven can doesn't count? Its a thick
sock.
Still not at the stage of needing a chamber I am 45 Hz off.
On Fri, Jul 26, 2013 at 2:36 PM, Bob Camp lists@rtty.us wrote:
Hi
Doing any real adjustment on these OCXO's pretty much requires you have
a
temperature chamber and a pretty good standard. A GPSDO will do for the
standard, the chamber is a bit harder to come by.
Bob
On Jul 26, 2013, at 1:38 PM, Rick Karlquist richard@karlquist.com
wrote:
Ed Palmer wrote:
Hi Paul,
Did you see this page that talks about tweaking the 10811 oven
controller?
Although this article anecdotally claims success, it overlooks
a number of important issues. First of all, a large proportion
of 10811 crystals DO NOT HAVE A TURNOVER. They merely have a
very low TC around 82 degrees. It is ALWAYS 82 degrees for these
crystals. The crystals that do, technically, have a turnover,
still have very low TC even if the oven is slightly off the turnover.
Secondly, the tempco of the electronics, specifically
the selected 2N5179 oscillator transistor, is a significant player.
The thermal gain, if properly adjusted, is around 1000 at the
crystal, but is much less at the oscillator transistor. It may
very well be the dominant factor in overall oscillator tempco.
Possibly, if you have a crystal with a turnover, you should
deliberately operate off the turnover at a point where the crystal
drift cancels the drift of the electronics.
If you want to tweak a 10811, you should also tweak the thermal
gain by custom adjustment of the heat balancing resistors for
the heater transistors. This has to be done by converting the
oscillator to mode B and then converting it back to mode C
afterwards.
Rick Karlquist N6RK
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
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On 26/07/13 22:16, Bob Camp wrote:
Hi
Well if you get desperate to try it, I have CO2 and a chamber sitting in the garage. The biggest issue is that if we use too much CO2 for the chamber, the beer may go flat…
Can't have that in the name of science, we need good beer after the
experiments, and you know that. :)
What would be good ovens for hobby usage / semi-pro BTW?
Cheers,
Magnus
Hi
On Jul 31, 2013, at 5:23 AM, Magnus Danielson magnus@rubidium.dyndns.org wrote:
On 26/07/13 22:16, Bob Camp wrote:
Hi
Well if you get desperate to try it, I have CO2 and a chamber sitting in the garage. The biggest issue is that if we use too much CO2 for the chamber, the beer may go flat…
Can't have that in the name of science, we need good beer after the experiments, and you know that. :)
What would be good ovens for hobby usage / semi-pro BTW?
It's just like at work - go with a refrigeration setup and get to know the service guy real well, or go with a CO2 chamber and become a regular at the gas store. The Delta chambers are pretty good for CO2. They show up at auction from time to time. Most of what's in them is pretty common stuff, so keeping them running isn't all that hard. You can convert them to a non-Delta controller without a lot of work if you have to.
Bob
Cheers,
Magnus
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