Empathy List Archives

C

cdelect@juno.com

Fri, Nov 17, 2017 8:37 PM

Luciano,

The TX and choke and filter caps were removed as I had envisioned I would
have to re-mount the A1 and A7 in their location.
However with some judicious movement of the mounting holes I was able to
squeeze them in close
to their original spots.

The 5065 chassis was removed and inserted into a chassis from an HP
8405A. (just used the side panels
and the rear panel.)

I'll post a schematic of the new C-field supply next week. It consists of
two LM299AH in series feeding
a string consisting of a 2.4K, 1k, 1K and a 1K low TC pot. A switch
allows you to short out one or both of the 1K resistors as a coarse
adjustment. All resistor are 1PPM.

Fixing the 20Volt and the C-field temperature contributions allowed me to
isolate the optical units changes
due to temp.

The resistor thermistor combo I mentioned would be taped to the optical
unit and compensate it only.
It would be in series with the C-field coil.
Not needed in my unit but thought that others might want to try it rather
than getting as complex as I have.

Yes the active baro and temp circuit would be an alternative for a unit
without my mods.

attached are PIX of the enclosed optical unit and the front panel.

Cheers,

Corby

Luciano, The TX and choke and filter caps were removed as I had envisioned I would have to re-mount the A1 and A7 in their location. However with some judicious movement of the mounting holes I was able to squeeze them in close to their original spots. The 5065 chassis was removed and inserted into a chassis from an HP 8405A. (just used the side panels and the rear panel.) I'll post a schematic of the new C-field supply next week. It consists of two LM299AH in series feeding a string consisting of a 2.4K, 1k, 1K and a 1K low TC pot. A switch allows you to short out one or both of the 1K resistors as a coarse adjustment. All resistor are 1PPM. Fixing the 20Volt and the C-field temperature contributions allowed me to isolate the optical units changes due to temp. The resistor thermistor combo I mentioned would be taped to the optical unit and compensate it only. It would be in series with the C-field coil. Not needed in my unit but thought that others might want to try it rather than getting as complex as I have. Yes the active baro and temp circuit would be an alternative for a unit without my mods. attached are PIX of the enclosed optical unit and the front panel. Cheers, Corby

T

timeok@timeok.it

Tue, Nov 21, 2017 10:18 AM

Hi Corby,
about the C field ten turn pot you write is a low TC pot. Normally a good Vishay pot is 20 PPM/C, This is in conflict with the 1PPM resistors ad voltage reference.
What kind of pot do you have used?
http://www.mouser.com/ds/2/427/533534-768216.pdf
Luciano
timeok

Da "time-nuts" time-nuts-bounces@febo.com
A time-nuts@febo.com
Cc
Data Fri, 17 Nov 2017 12:37:57 -0800
Oggetto [time-nuts] HP5065A C-field mods and optical unit mods
Luciano,

The TX and choke and filter caps were removed as I had envisioned I would
have to re-mount the A1 and A7 in their location.
However with some judicious movement of the mounting holes I was able to
squeeze them in close
to their original spots.

The 5065 chassis was removed and inserted into a chassis from an HP
8405A. (just used the side panels
and the rear panel.)

I'll post a schematic of the new C-field supply next week. It consists of
two LM299AH in series feeding
a string consisting of a 2.4K, 1k, 1K and a 1K low TC pot. A switch
allows you to short out one or both of the 1K resistors as a coarse
adjustment. All resistor are 1PPM.

Fixing the 20Volt and the C-field temperature contributions allowed me to
isolate the optical units changes
due to temp.

The resistor thermistor combo I mentioned would be taped to the optical
unit and compensate it only.
It would be in series with the C-field coil.
Not needed in my unit but thought that others might want to try it rather
than getting as complex as I have.

Yes the active baro and temp circuit would be an alternative for a unit
without my mods.

attached are PIX of the enclosed optical unit and the front panel.

Cheers,

Corby

Hi Corby, about the C field ten turn pot you write is a low TC pot. Normally a good Vishay pot is 20 PPM/C, This is in conflict with the 1PPM resistors ad voltage reference. What kind of pot do you have used? http://www.mouser.com/ds/2/427/533534-768216.pdf Luciano timeok Da "time-nuts" time-nuts-bounces@febo.com A time-nuts@febo.com Cc Data Fri, 17 Nov 2017 12:37:57 -0800 Oggetto [time-nuts] HP5065A C-field mods and optical unit mods Luciano, The TX and choke and filter caps were removed as I had envisioned I would have to re-mount the A1 and A7 in their location. However with some judicious movement of the mounting holes I was able to squeeze them in close to their original spots. The 5065 chassis was removed and inserted into a chassis from an HP 8405A. (just used the side panels and the rear panel.) I'll post a schematic of the new C-field supply next week. It consists of two LM299AH in series feeding a string consisting of a 2.4K, 1k, 1K and a 1K low TC pot. A switch allows you to short out one or both of the 1K resistors as a coarse adjustment. All resistor are 1PPM. Fixing the 20Volt and the C-field temperature contributions allowed me to isolate the optical units changes due to temp. The resistor thermistor combo I mentioned would be taped to the optical unit and compensate it only. It would be in series with the C-field coil. Not needed in my unit but thought that others might want to try it rather than getting as complex as I have. Yes the active baro and temp circuit would be an alternative for a unit without my mods. attached are PIX of the enclosed optical unit and the front panel. Cheers, Corby

CS

Charles Steinmetz

Tue, Nov 21, 2017 11:31 AM

Luciano wrote:

about the C field ten turn pot you write is a low TC pot. Normally a good Vishay pot is 20 PPM/C, This is in conflict with the 1PPM resistors ad voltage reference.

In the schematic Corby posted, the potentiometer (used as a variable
resistor) makes up a very small part of the total resistance of the
series string, so the overall tempco is dominated by the tempcos of the
fixed resistors (2.4k to 4.4k 1ppm/ C, depending on trim). The pot will
increase the overall tempco a little bit, but not anywhere near 20ppm.

Best regards,

Charles

Luciano wrote: > about the C field ten turn pot you write is a low TC pot. Normally a good Vishay pot is 20 PPM/C, This is in conflict with the 1PPM resistors ad voltage reference. In the schematic Corby posted, the potentiometer (used as a variable resistor) makes up a very small part of the total resistance of the series string, so the overall tempco is dominated by the tempcos of the fixed resistors (2.4k to 4.4k 1ppm/ C, depending on trim). The pot will increase the overall tempco a little bit, but not anywhere near 20ppm. Best regards, Charles

T

timeok@timeok.it

Tue, Nov 21, 2017 12:41 PM

Hi Charles,
what you refer is the resistance relation referred to the LM299 source around 14VDc but you have to consider
the tuning range of the pot, in the original HP5065A is 2E10-9.
Of course, it depends on the setting value of the variable resistance, but you have to consider a possible variation of 20PPM/c on 2E10-9.
Regards
Luciano
timeok

Da "time-nuts" time-nuts-bounces@febo.com
A time-nuts@febo.com
Cc
Data Tue, 21 Nov 2017 06:31:25 -0500
Oggetto Re: [time-nuts] HP5065A C-field mods and optical unit mods
Luciano wrote:

about the C field ten turn pot you write is a low TC pot. Normally a good Vishay pot is 20 PPM/C, This is in conflict with the 1PPM resistors ad voltage reference.

In the schematic Corby posted, the potentiometer (used as a variable
resistor) makes up a very small part of the total resistance of the
series string, so the overall tempco is dominated by the tempcos of the
fixed resistors (2.4k to 4.4k 1ppm/ C, depending on trim). The pot will
increase the overall tempco a little bit, but not anywhere near 20ppm.

Best regards,

Charles

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.

Hi Charles, what you refer is the resistance relation referred to the LM299 source around 14VDc but you have to consider the tuning range of the pot, in the original HP5065A is 2E10-9. Of course, it depends on the setting value of the variable resistance, but you have to consider a possible variation of 20PPM/c on 2E10-9. Regards Luciano timeok Da "time-nuts" time-nuts-bounces@febo.com A time-nuts@febo.com Cc Data Tue, 21 Nov 2017 06:31:25 -0500 Oggetto Re: [time-nuts] HP5065A C-field mods and optical unit mods Luciano wrote: > about the C field ten turn pot you write is a low TC pot. Normally a good Vishay pot is 20 PPM/C, This is in conflict with the 1PPM resistors ad voltage reference. In the schematic Corby posted, the potentiometer (used as a variable resistor) makes up a very small part of the total resistance of the series string, so the overall tempco is dominated by the tempcos of the fixed resistors (2.4k to 4.4k 1ppm/ C, depending on trim). The pot will increase the overall tempco a little bit, but not anywhere near 20ppm. Best regards, Charles _______________________________________________ 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.

CS

Charles Steinmetz

Tue, Nov 21, 2017 8:16 PM

Luciano wrote:

 what you refer is the resistance relation referred to the LM299 source around 14VDc but you have to consider
 the tuning range of the pot, in the original HP5065A is 2E10-9.
 Of course, it depends on the setting value of the variable resistance, but you have to consider a possible variation of 20PPM/c on 2E10-9.

No, you don't. The tempco that matters is the aggregate tempco of the
series string. Only a very small portion of the string voltage appears
across the pot, so a 20ppm tempco of that small part will cause a much
smaller change in overall tempco of the series string.

Perhaps Corby will tell us what value the pot is, and then you can
calculate the aggregate tempco of the string at various pot settings and
see for yourself.

Charles

Luciano wrote: > what you refer is the resistance relation referred to the LM299 source around 14VDc but you have to consider > the tuning range of the pot, in the original HP5065A is 2E10-9. > Of course, it depends on the setting value of the variable resistance, but you have to consider a possible variation of 20PPM/c on 2E10-9. No, you don't. The tempco that matters is the aggregate tempco of the series string. Only a very small portion of the string voltage appears across the pot, so a 20ppm tempco of that small part will cause a much smaller change in overall tempco of the series string. Perhaps Corby will tell us what value the pot is, and then you can calculate the aggregate tempco of the string at various pot settings and see for yourself. Charles

BG

Bruce Griffiths

Tue, Nov 21, 2017 8:40 PM

What is the effect of the C-field coil dimension tempco?

At some point this will surely dominate overthe coil current tempco.

Bruce

 On 22 November 2017 at 09:16 Charles Steinmetz <csteinmetz@yandex.com> wrote:

 Luciano wrote:

     what you refer is the resistance relation referred to the LM299 source around 14VDc but you have to consider
     the tuning range of the pot, in the original HP5065A is 2E10-9.
     Of course, it depends on the setting value of the variable resistance, but you have to consider a possible variation of 20PPM/c on 2E10-9.

 No, you don't. The tempco that matters is the aggregate tempco of the
 series string. Only a very small portion of the string voltage appears
 across the pot, so a 20ppm tempco of that small part will cause a much
 smaller change in overall tempco of the series string.

 Perhaps Corby will tell us what value the pot is, and then you can
 calculate the aggregate tempco of the string at various pot settings and
 see for yourself.

 Charles

 _______________________________________________
 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.

What is the effect of the C-field coil dimension tempco? At some point this will surely dominate overthe coil current tempco. Bruce > > On 22 November 2017 at 09:16 Charles Steinmetz <csteinmetz@yandex.com> wrote: > > Luciano wrote: > > > > > > what you refer is the resistance relation referred to the LM299 source around 14VDc but you have to consider > > the tuning range of the pot, in the original HP5065A is 2E10-9. > > Of course, it depends on the setting value of the variable resistance, but you have to consider a possible variation of 20PPM/c on 2E10-9. > > > > > > No, you don't. The tempco that matters is the aggregate tempco of the > series string. Only a very small portion of the string voltage appears > across the pot, so a 20ppm tempco of that small part will cause a much > smaller change in overall tempco of the series string. > > Perhaps Corby will tell us what value the pot is, and then you can > calculate the aggregate tempco of the string at various pot settings and > see for yourself. > > Charles > > _______________________________________________ > 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. >

PK

Poul-Henning Kamp

Tue, Nov 21, 2017 10:06 PM

In message 1159987519.5777361.1511296831768@webmail.xtra.co.nz, Bruce Griffit
hs writes:

What is the effect of the C-field coil dimension tempco?

I have not been able to measure it.

The C-coil is located thermally close to the temperature controlled
parts of the physics package.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

-------- In message <1159987519.5777361.1511296831768@webmail.xtra.co.nz>, Bruce Griffit hs writes: >What is the effect of the C-field coil dimension tempco? I have not been able to measure it. The C-coil is located thermally close to the temperature controlled parts of the physics package. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.

T

timeok@timeok.it

Wed, Nov 22, 2017 8:58 AM

Charles,
Imagine having a source and fixed resistors with TC equal to zero.
The current variation of the coil varies between 2.5 and 6 mA.
In addition, the relationship between current and frequency variation of the HP5065A is not linear.
If the pot is short-circuit, the current is 6 mA and the overall TC is that of the imaginary generator ie zero, in our real case 1ppm / C (source+fixed resistors).
So the pot TC is completely irrelevant.
When the pot is fully inserted the current will be 2.5mA, so the total current variation is 3.5mA.
The whole thefull range of pot resistance generates a 3.5mA current variation. This variation generates a frequency fine adjustment of 2E-9.
As a result, the influence of the pot TC is directly correlated to the current stability with a nonlinear frequency variation between zero and X in the range of 6- 2.5mA.
Or not?

best regards,
Luciano
timeok

Da "time-nuts" time-nuts-bounces@febo.com
A "Discussion of precise time and frequency measurement" time-nuts@febo.com
Cc
Data Tue, 21 Nov 2017 15:16:36 -0500
Oggetto Re: [time-nuts] HP5065A C-field mods and optical unit mods
Luciano wrote:

what you refer is the resistance relation referred to the LM299 source around 14VDc but you have to consider
the tuning range of the pot, in the original HP5065A is 2E10-9.
Of course, it depends on the setting value of the variable resistance, but you have to consider a possible variation of 20PPM/c on 2E10-9.

No, you don't. The tempco that matters is the aggregate tempco of the
series string. Only a very small portion of the string voltage appears
across the pot, so a 20ppm tempco of that small part will cause a much
smaller change in overall tempco of the series string.

Perhaps Corby will tell us what value the pot is, and then you can
calculate the aggregate tempco of the string at various pot settings and
see for yourself.

Charles

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.

Charles, Imagine having a source and fixed resistors with TC equal to zero. The current variation of the coil varies between 2.5 and 6 mA. In addition, the relationship between current and frequency variation of the HP5065A is not linear. If the pot is short-circuit, the current is 6 mA and the overall TC is that of the imaginary generator ie zero, in our real case 1ppm / C (source+fixed resistors). So the pot TC is completely irrelevant. When the pot is fully inserted the current will be 2.5mA, so the total current variation is 3.5mA. The whole thefull range of pot resistance generates a 3.5mA current variation. This variation generates a frequency fine adjustment of 2E-9. As a result, the influence of the pot TC is directly correlated to the current stability with a nonlinear frequency variation between zero and X in the range of 6- 2.5mA. Or not? best regards, Luciano timeok Da "time-nuts" time-nuts-bounces@febo.com A "Discussion of precise time and frequency measurement" time-nuts@febo.com Cc Data Tue, 21 Nov 2017 15:16:36 -0500 Oggetto Re: [time-nuts] HP5065A C-field mods and optical unit mods Luciano wrote: > what you refer is the resistance relation referred to the LM299 source around 14VDc but you have to consider > the tuning range of the pot, in the original HP5065A is 2E10-9. > Of course, it depends on the setting value of the variable resistance, but you have to consider a possible variation of 20PPM/c on 2E10-9. No, you don't. The tempco that matters is the aggregate tempco of the series string. Only a very small portion of the string voltage appears across the pot, so a 20ppm tempco of that small part will cause a much smaller change in overall tempco of the series string. Perhaps Corby will tell us what value the pot is, and then you can calculate the aggregate tempco of the string at various pot settings and see for yourself. Charles _______________________________________________ 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.

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HP5065A C-field mods and optical unit mods