Reverse engineering and restoring a 1971 Quartz et Electronique OCXO
Hello,
I am reverse engineering and restoring a 1971 OCXO from "Quartz et
Electronique" (a dead french company acquired by Alcatel).
Information about this company is very hard to find.
This is a 5 MHz unit. I was very surprised to find the shield of the
output signal tied to the +24 volts line inside the enclosure.
If I want my output signal referenced to ground, I'll have to power it
with -24V wrt ground. I suspect this detail was a surprise to many
previous users.
I suspect a normal 24v supply was used and the output was isolated
through a transformer?
No one seem to have been inside this thing past the obvious disassembly
of the outer enclosure.
Here is my mastodon thread about this teardown/restoration project, with
lots of pics:
https://chaos.social/@f4grx/113787268446395457
Here is the currently reversed schematic:
https://cloud.f4grx.net/index.php/s/JtSfTx4rmwZfS7W
I have never seen such a complicated oven design.
To my current understanding, the heater is an oscillator, it's basically
an AC signal path from a pair of thermal sensors in a bridge to the
heating coils. A part of the heating signal is limited with diodes and
excites the thermal sensors.
I do not exactly know how this system starts. I have not applied power
to the unit yet, but it should work, all components are in good
condition, electrolytics are all wet tantalum, which should last quite long.
The oscillator itself is a very compact cordwood wired module which I
have not reversed yet, with two metal can transistors, a variable
transformer and a ceramic piston cap connected to the xtal.
The crystal is a very thick unit in a glass envelope. Probably not a SC
cut since this OCXO was made 3 years before SC cut was discovered.
Anyone has ever hear or seen a similar unit?
Any information about history, context, similar designs, etc. would be
very interesting.
I will do a full description on a web page once the project is complete.
Thanks
Sebastien
This company was a few kilometers from my home in France. It is closed
now since 2001 but i think that it still exist under a different name,
at the same place, after a couple owner changes.
They are manufacturing high end quartz, ocxo, tcxo, gpsdo mainly for
space and military systems.
I can have the full story because i know a retired quartz manufacturing
engineer that did probably work in this company a few years before
closing. And perhaps get a datasheet of this OCXO if they still have
some archive about it.
Let me check with my friend the full story.
Bests,
Olivier ADLER.
Le 21/01/2025 à 10:23, Sebastien F4GRX via time-nuts a écrit :
Hello,
I am reverse engineering and restoring a 1971 OCXO from "Quartz et
Electronique" (a dead french company acquired by Alcatel).
Information about this company is very hard to find.
This is a 5 MHz unit. I was very surprised to find the shield of the
output signal tied to the +24 volts line inside the enclosure.
If I want my output signal referenced to ground, I'll have to power it
with -24V wrt ground. I suspect this detail was a surprise to many
previous users.
I suspect a normal 24v supply was used and the output was isolated
through a transformer?
No one seem to have been inside this thing past the obvious
disassembly of the outer enclosure.
Here is my mastodon thread about this teardown/restoration project,
with lots of pics:
https://chaos.social/@f4grx/113787268446395457
Here is the currently reversed schematic:
https://cloud.f4grx.net/index.php/s/JtSfTx4rmwZfS7W
I have never seen such a complicated oven design.
To my current understanding, the heater is an oscillator, it's
basically an AC signal path from a pair of thermal sensors in a bridge
to the heating coils. A part of the heating signal is limited with
diodes and excites the thermal sensors.
I do not exactly know how this system starts. I have not applied power
to the unit yet, but it should work, all components are in good
condition, electrolytics are all wet tantalum, which should last quite
long.
The oscillator itself is a very compact cordwood wired module which I
have not reversed yet, with two metal can transistors, a variable
transformer and a ceramic piston cap connected to the xtal.
The crystal is a very thick unit in a glass envelope. Probably not a
SC cut since this OCXO was made 3 years before SC cut was discovered.
Anyone has ever hear or seen a similar unit?
Any information about history, context, similar designs, etc. would be
very interesting.
I will do a full description on a web page once the project is complete.
Thanks
Sebastien
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I got an answer.
"Quartz et Electronique" is still in activity under a new name after a
couple owners and names changes.
The company name is actually Rakon. It is located in France near TROYES
city.
At the time of this OCXO, 1971, the company was located near Paris. And
came near TROYES a few years later.
According to a friend, a quartz manufacturing engineer that did work
over there during more than 40 years, the OTHP technology of this OCXO
has been abandoned since 35 years.
He will check if he can get some informations, but the chances are low.
Bests,
Olivier ADLER.
Le 21/01/2025 à 10:23, Sebastien F4GRX via time-nuts a écrit :
Hello,
I am reverse engineering and restoring a 1971 OCXO from "Quartz et
Electronique" (a dead french company acquired by Alcatel).
Information about this company is very hard to find.
This is a 5 MHz unit. I was very surprised to find the shield of the
output signal tied to the +24 volts line inside the enclosure.
If I want my output signal referenced to ground, I'll have to power it
with -24V wrt ground. I suspect this detail was a surprise to many
previous users.
I suspect a normal 24v supply was used and the output was isolated
through a transformer?
No one seem to have been inside this thing past the obvious
disassembly of the outer enclosure.
Here is my mastodon thread about this teardown/restoration project,
with lots of pics:
https://chaos.social/@f4grx/113787268446395457
Here is the currently reversed schematic:
https://cloud.f4grx.net/index.php/s/JtSfTx4rmwZfS7W
I have never seen such a complicated oven design.
To my current understanding, the heater is an oscillator, it's
basically an AC signal path from a pair of thermal sensors in a bridge
to the heating coils. A part of the heating signal is limited with
diodes and excites the thermal sensors.
I do not exactly know how this system starts. I have not applied power
to the unit yet, but it should work, all components are in good
condition, electrolytics are all wet tantalum, which should last quite
long.
The oscillator itself is a very compact cordwood wired module which I
have not reversed yet, with two metal can transistors, a variable
transformer and a ceramic piston cap connected to the xtal.
The crystal is a very thick unit in a glass envelope. Probably not a
SC cut since this OCXO was made 3 years before SC cut was discovered.
Anyone has ever hear or seen a similar unit?
Any information about history, context, similar designs, etc. would be
very interesting.
I will do a full description on a web page once the project is complete.
Thanks
Sebastien
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
ontent.
On Tuesday, January 21st, 2025 at 03:23, Sebastien F4GRX via time-nuts time-nuts@lists.febo.com wrote:
Hello,
I am reverse engineering and restoring a 1971 OCXO from "Quartz et
Electronique" (a dead french company acquired by Alcatel).
Information about this company is very hard to find.
This is a 5 MHz unit. I was very surprised to find the shield of the
output signal tied to the +24 volts line inside the enclosure.
If I want my output signal referenced to ground, I'll have to power it
with -24V wrt ground. I suspect this detail was a surprise to many
previous users.
I suspect a normal 24v supply was used and the output was isolated
through a transformer?
Your oscillator was probably designed to operate in a telco office powered from the -48V battery supply. -24V was probably derived from that. In that case the +24 would have been at ground and the -24 would have been at -24V. We have become so used to the convention of negative ground that we forget that telcos are the other way.
--
Brian Lloyd
706 Flightline
Spring Branch, TX 78070
brian@lloyd.aero
+1.210.620.0011
Hello,
that is one good possibility, thanks for the reminder.
I have started to reverse engineer the cordwood oscillator module, and
noticed that the output is going through an isolation transformer, so it
would be straightforward to rewire the internals so the output signal is
referenced to ground.
Sebastien
On 1/21/25 15:17, Brian Lloyd via time-nuts wrote:
On Tuesday, January 21st, 2025 at 03:23, Sebastien F4GRX via time-nuts time-nuts@lists.febo.com wrote:
Hello,
I am reverse engineering and restoring a 1971 OCXO from "Quartz et
Electronique" (a dead french company acquired by Alcatel).Information about this company is very hard to find.
This is a 5 MHz unit. I was very surprised to find the shield of the
output signal tied to the +24 volts line inside the enclosure.If I want my output signal referenced to ground, I'll have to power it
with -24V wrt ground. I suspect this detail was a surprise to many
previous users.I suspect a normal 24v supply was used and the output was isolated
through a transformer?
Your oscillator was probably designed to operate in a telco office powered from the -48V battery supply. -24V was probably derived from that. In that case the +24 would have been at ground and the -24 would have been at -24V. We have become so used to the convention of negative ground that we forget that telcos are the other way.
--
Brian Lloyd
706 Flightline
Spring Branch, TX 78070
brian@lloyd.aero
+1.210.620.0011
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hello Olivier,
Than you, these are very precious pieces of information! So now they are
Rakon! I did not find this info anywhere.
Asnières is also very close from my location.
I am very interested to learn more about this "OTHP" technology. Any
patent, document, information about usage of the ocxo, information about
the glass packaged crystal used in it would be extremely valuable for my
restoration task.
I am also quite happy just to have this beautiful piece of engineering
fully understood and almost ready for operation again. After all that
time it is only slightly corroded on the outside and still fully
serviceable.
Please send my sincere thanks to this engineer for anything he could do.
Can he confirm that:
-the crystal is AT cut?
-the temperature sensors are PT100 platinum RTDs?
-the temperature is regulated to about 70 degrees C?
-that in case of overheating the internal fuse is voluntarily blown?
I also wonder what is the operating frequency of the oven AC signal.
Sebastien
On 1/21/25 14:10, time-nuts--- via time-nuts wrote:
I got an answer.
"Quartz et Electronique" is still in activity under a new name after a
couple owners and names changes.
The company name is actually Rakon. It is located in France near
TROYES city.
At the time of this OCXO, 1971, the company was located near Paris.
And came near TROYES a few years later.
According to a friend, a quartz manufacturing engineer that did work
over there during more than 40 years, the OTHP technology of this OCXO
has been abandoned since 35 years.
He will check if he can get some informations, but the chances are low.
Bests,
Olivier ADLER.
Le 21/01/2025 à 10:23, Sebastien F4GRX via time-nuts a écrit :
Hello,
I am reverse engineering and restoring a 1971 OCXO from "Quartz et
Electronique" (a dead french company acquired by Alcatel).Information about this company is very hard to find.
This is a 5 MHz unit. I was very surprised to find the shield of the
output signal tied to the +24 volts line inside the enclosure.If I want my output signal referenced to ground, I'll have to power
it with -24V wrt ground. I suspect this detail was a surprise to many
previous users.I suspect a normal 24v supply was used and the output was isolated
through a transformer?No one seem to have been inside this thing past the obvious
disassembly of the outer enclosure.Here is my mastodon thread about this teardown/restoration project,
with lots of pics:https://chaos.social/@f4grx/113787268446395457
Here is the currently reversed schematic:
https://cloud.f4grx.net/index.php/s/JtSfTx4rmwZfS7W
I have never seen such a complicated oven design.
To my current understanding, the heater is an oscillator, it's
basically an AC signal path from a pair of thermal sensors in a
bridge to the heating coils. A part of the heating signal is limited
with diodes and excites the thermal sensors.I do not exactly know how this system starts. I have not applied
power to the unit yet, but it should work, all components are in good
condition, electrolytics are all wet tantalum, which should last
quite long.The oscillator itself is a very compact cordwood wired module which I
have not reversed yet, with two metal can transistors, a variable
transformer and a ceramic piston cap connected to the xtal.The crystal is a very thick unit in a glass envelope. Probably not a
SC cut since this OCXO was made 3 years before SC cut was discovered.Anyone has ever hear or seen a similar unit?
Any information about history, context, similar designs, etc. would
be very interesting.I will do a full description on a web page once the project is
complete.Thanks
Sebastien
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
ontent.
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