JL
J. L. Trantham
Sun, Sep 16, 2012 8:36 PM
I have been following the discussion about the LM399 heater, noting mention
of the Fluke Wire Wound resistors used often in Fluke precision equipment.
I have a 731A that I have been resuscitating and have found that the R8A R8B
wire wound resistor is failing. Initially, the source was very unstable
then went to about 8 VDC. This led me to an open R8B. I was able to
reconnect the broken ends, loosing about half a turn of wire. Then,
again, unstable and went to about 13 VDC. This led me to an open R8A.
Again, able to reconnect, and, again, loosing about ½ turn.
It appears that the wire is corroded with corrosion leading to failure.
This brings up several questions.
- What are the benefits of these wire wound resistors? Tempco?
Ability to construct precise resistance?
- Is there a source of the resistance wire used in these resistors so
that the resistor can be reconstructed? I think the resistance is in the 30
to 40 ohms per foot range. Something like 36 to 38 gauge Nichrome 60 would
work but it has to be insulated.
- Would it be better to look for a collection of commercial resistors
to replace R8A, R8B? If so, what? The manual states that IC2, the
voltage reference, R6, R7, R9, and R10, are factory selected and all
appear to be OK.
- Would it be better to completely abandon the voltage reference
section of the 731A in favor of a new (perhaps LM399, LTZ1000A, etc.,
based) reference to generate 10 VDC and still use the output divider of the
731A to generate the remaining voltages?
The 731A manual and schematic are here:
http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instruction_
Manual.pdf
R8A is the high side of a voltage divider with R8B, R9, R10 and R11 (a 10
ohm, 20 turn pot) forming the low side, dividing 10 VDC to feed the
voltage reference, IC2, a DH80417B. The op amp, IC1, used to generate the
10 VDC is an LM301AH.
R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9 measures
about 78.02 ohms, and R10 measures about 399.8 ohms.
Thanks in advance for any and all information and suggestions.
Joe
I have been following the discussion about the LM399 heater, noting mention
of the Fluke Wire Wound resistors used often in Fluke precision equipment.
I have a 731A that I have been resuscitating and have found that the R8A R8B
wire wound resistor is failing. Initially, the source was very unstable
then went to about 8 VDC. This led me to an open R8B. I was able to
reconnect the broken ends, loosing about half a turn of wire. Then,
again, unstable and went to about 13 VDC. This led me to an open R8A.
Again, able to reconnect, and, again, loosing about ½ turn.
It appears that the wire is corroded with corrosion leading to failure.
This brings up several questions.
1. What are the benefits of these wire wound resistors? Tempco?
Ability to construct precise resistance?
2. Is there a source of the resistance wire used in these resistors so
that the resistor can be reconstructed? I think the resistance is in the 30
to 40 ohms per foot range. Something like 36 to 38 gauge Nichrome 60 would
work but it has to be insulated.
3. Would it be better to look for a collection of commercial resistors
to replace R8A, R8B? If so, what? The manual states that IC2, the
voltage reference, R6, R7, R9, and R10, are factory selected and all
appear to be OK.
4. Would it be better to completely abandon the voltage reference
section of the 731A in favor of a new (perhaps LM399, LTZ1000A, etc.,
based) reference to generate 10 VDC and still use the output divider of the
731A to generate the remaining voltages?
The 731A manual and schematic are here:
http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instruction_
Manual.pdf
R8A is the high side of a voltage divider with R8B, R9, R10 and R11 (a 10
ohm, 20 turn pot) forming the low side, dividing 10 VDC to feed the
voltage reference, IC2, a DH80417B. The op amp, IC1, used to generate the
10 VDC is an LM301AH.
R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9 measures
about 78.02 ohms, and R10 measures about 399.8 ohms.
Thanks in advance for any and all information and suggestions.
Joe
PL
Pete Lancashire
Sun, Sep 16, 2012 9:02 PM
There is a good chance the wire is Manganin or an allow that is similar.
If what you use to connect to the resistance wire is not the same you run
into things like EMF (think thermocouple) being created at the repair.
-pete
On Sun, Sep 16, 2012 at 1:36 PM, J. L. Trantham jltran@att.net wrote:
I have been following the discussion about the LM399 heater, noting mention
of the Fluke Wire Wound resistors used often in Fluke precision equipment.
I have a 731A that I have been resuscitating and have found that the R8A R8B
wire wound resistor is failing. Initially, the source was very unstable
then went to about 8 VDC. This led me to an open R8B. I was able to
‘reconnect’ the broken ends, loosing about half a turn of wire. Then,
again, unstable and went to about 13 VDC. This led me to an open R8A.
Again, able to reconnect, and, again, loosing about ½ turn.
It appears that the wire is corroded with corrosion leading to failure.
This brings up several questions.
-
What are the benefits of these wire wound resistors? Tempco?
Ability to construct precise resistance?
2. Is there a source of the resistance wire used in these resistors so
that the resistor can be reconstructed? I think the resistance is in the 30
to 40 ohms per foot range. Something like 36 to 38 gauge Nichrome 60 would
work but it has to be insulated.
3. Would it be better to look for a collection of commercial resistors
to ‘replace’ R8A, R8B? If so, what? The manual states that IC2, the
voltage reference, R6, R7, R9, and R10, are ‘factory selected’ and all
appear to be OK.
4. Would it be better to completely abandon the voltage reference
section of the 731A in favor of a ‘new’ (perhaps LM399, LTZ1000A, etc.,
based) reference to generate 10 VDC and still use the output divider of the
731A to generate the remaining voltages?
The 731A manual and schematic are here:
http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instruction_
Manual.pdf
R8A is the ‘high’ side of a voltage divider with R8B, R9, R10 and R11 (a 10
ohm, 20 turn pot) forming the ‘low’ side, dividing 10 VDC to feed the
voltage reference, IC2, a DH80417B. The op amp, IC1, used to generate the
10 VDC is an LM301AH.
R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9 measures
about 78.02 ohms, and R10 measures about 399.8 ohms.
Thanks in advance for any and all information and suggestions.
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
There is a good chance the wire is Manganin or an allow that is similar.
If what you use to connect to the resistance wire is not the same you run
into things like EMF (think thermocouple) being created at the repair.
-pete
On Sun, Sep 16, 2012 at 1:36 PM, J. L. Trantham <jltran@att.net> wrote:
> I have been following the discussion about the LM399 heater, noting mention
> of the Fluke Wire Wound resistors used often in Fluke precision equipment.
>
>
>
> I have a 731A that I have been resuscitating and have found that the R8A R8B
> wire wound resistor is failing. Initially, the source was very unstable
> then went to about 8 VDC. This led me to an open R8B. I was able to
> ‘reconnect’ the broken ends, loosing about half a turn of wire. Then,
> again, unstable and went to about 13 VDC. This led me to an open R8A.
> Again, able to reconnect, and, again, loosing about ½ turn.
>
>
>
> It appears that the wire is corroded with corrosion leading to failure.
> This brings up several questions.
>
>
>
> 1. What are the benefits of these wire wound resistors? Tempco?
> Ability to construct precise resistance?
> 2. Is there a source of the resistance wire used in these resistors so
> that the resistor can be reconstructed? I think the resistance is in the 30
> to 40 ohms per foot range. Something like 36 to 38 gauge Nichrome 60 would
> work but it has to be insulated.
> 3. Would it be better to look for a collection of commercial resistors
> to ‘replace’ R8A, R8B? If so, what? The manual states that IC2, the
> voltage reference, R6, R7, R9, and R10, are ‘factory selected’ and all
> appear to be OK.
> 4. Would it be better to completely abandon the voltage reference
> section of the 731A in favor of a ‘new’ (perhaps LM399, LTZ1000A, etc.,
> based) reference to generate 10 VDC and still use the output divider of the
> 731A to generate the remaining voltages?
>
>
>
> The 731A manual and schematic are here:
>
>
>
> http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instruction_
> Manual.pdf
>
>
>
> R8A is the ‘high’ side of a voltage divider with R8B, R9, R10 and R11 (a 10
> ohm, 20 turn pot) forming the ‘low’ side, dividing 10 VDC to feed the
> voltage reference, IC2, a DH80417B. The op amp, IC1, used to generate the
> 10 VDC is an LM301AH.
>
>
>
> R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9 measures
> about 78.02 ohms, and R10 measures about 399.8 ohms.
>
>
>
> Thanks in advance for any and all information and suggestions.
>
>
>
> Joe
>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
JL
J. L. Trantham
Sun, Sep 16, 2012 9:54 PM
Pete,
Thanks for the reply.
I was just looking at the properties of the wire. I guess I don't
understand the 'resistivity' of 43-48 uOhmcm for the wire that is about the
same size as what the resistor is made of. Also, it is quite expensive,
about $300 per 100 feet.
It lists a tempco of .00001 per K.
As best I can tell, the 5903 ohm resistor is about 15.5 mm long, on a 1 inch
flat form about 1 mm thick (about 2 inches per turn) and about 14 turns per
mm as best I can tell. I measured the wire at .05 mm thickness. That would
put it at about 217 turns, 434 inches, and about 13.6 ohms per inch. My
original calculation appears to be wrong.
So, how to proceed?
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Pete Lancashire
Sent: Sunday, September 16, 2012 4:03 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 731A Transfer Standard and Fluke Wire
WoundResistors
There is a good chance the wire is Manganin or an allow that is similar.
If what you use to connect to the resistance wire is not the same you run
into things like EMF (think thermocouple) being created at the repair.
-pete
On Sun, Sep 16, 2012 at 1:36 PM, J. L. Trantham jltran@att.net wrote:
I have been following the discussion about the LM399 heater, noting
of the Fluke Wire Wound resistors used often in Fluke precision equipment.
I have a 731A that I have been resuscitating and have found that the R8A
wire wound resistor is failing. Initially, the source was very unstable
then went to about 8 VDC. This led me to an open R8B. I was able to
reconnect the broken ends, loosing about half a turn of wire. Then,
again, unstable and went to about 13 VDC. This led me to an open R8A.
Again, able to reconnect, and, again, loosing about ½ turn.
It appears that the wire is corroded with corrosion leading to failure.
This brings up several questions.
-
What are the benefits of these wire wound resistors? Tempco?
Ability to construct precise resistance?
2. Is there a source of the resistance wire used in these resistors
that the resistor can be reconstructed? I think the resistance is in the
to 40 ohms per foot range. Something like 36 to 38 gauge Nichrome 60
work but it has to be insulated.
3. Would it be better to look for a collection of commercial
to replace R8A, R8B? If so, what? The manual states that IC2, the
voltage reference, R6, R7, R9, and R10, are factory selected and all
appear to be OK.
4. Would it be better to completely abandon the voltage reference
section of the 731A in favor of a new (perhaps LM399, LTZ1000A, etc.,
based) reference to generate 10 VDC and still use the output divider of
731A to generate the remaining voltages?
The 731A manual and schematic are here:
Manual.pdf
R8A is the high side of a voltage divider with R8B, R9, R10 and R11 (a
ohm, 20 turn pot) forming the low side, dividing 10 VDC to feed the
voltage reference, IC2, a DH80417B. The op amp, IC1, used to generate the
10 VDC is an LM301AH.
R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9 measures
about 78.02 ohms, and R10 measures about 399.8 ohms.
Thanks in advance for any and all information and suggestions.
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
Pete,
Thanks for the reply.
I was just looking at the properties of the wire. I guess I don't
understand the 'resistivity' of 43-48 uOhmcm for the wire that is about the
same size as what the resistor is made of. Also, it is quite expensive,
about $300 per 100 feet.
It lists a tempco of .00001 per K.
As best I can tell, the 5903 ohm resistor is about 15.5 mm long, on a 1 inch
flat form about 1 mm thick (about 2 inches per turn) and about 14 turns per
mm as best I can tell. I measured the wire at .05 mm thickness. That would
put it at about 217 turns, 434 inches, and about 13.6 ohms per inch. My
original calculation appears to be wrong.
So, how to proceed?
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Pete Lancashire
Sent: Sunday, September 16, 2012 4:03 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 731A Transfer Standard and Fluke Wire
WoundResistors
There is a good chance the wire is Manganin or an allow that is similar.
If what you use to connect to the resistance wire is not the same you run
into things like EMF (think thermocouple) being created at the repair.
-pete
On Sun, Sep 16, 2012 at 1:36 PM, J. L. Trantham <jltran@att.net> wrote:
> I have been following the discussion about the LM399 heater, noting
mention
> of the Fluke Wire Wound resistors used often in Fluke precision equipment.
>
>
>
> I have a 731A that I have been resuscitating and have found that the R8A
R8B
> wire wound resistor is failing. Initially, the source was very unstable
> then went to about 8 VDC. This led me to an open R8B. I was able to
> reconnect the broken ends, loosing about half a turn of wire. Then,
> again, unstable and went to about 13 VDC. This led me to an open R8A.
> Again, able to reconnect, and, again, loosing about ½ turn.
>
>
>
> It appears that the wire is corroded with corrosion leading to failure.
> This brings up several questions.
>
>
>
> 1. What are the benefits of these wire wound resistors? Tempco?
> Ability to construct precise resistance?
> 2. Is there a source of the resistance wire used in these resistors
so
> that the resistor can be reconstructed? I think the resistance is in the
30
> to 40 ohms per foot range. Something like 36 to 38 gauge Nichrome 60
would
> work but it has to be insulated.
> 3. Would it be better to look for a collection of commercial
resistors
> to replace R8A, R8B? If so, what? The manual states that IC2, the
> voltage reference, R6, R7, R9, and R10, are factory selected and all
> appear to be OK.
> 4. Would it be better to completely abandon the voltage reference
> section of the 731A in favor of a new (perhaps LM399, LTZ1000A, etc.,
> based) reference to generate 10 VDC and still use the output divider of
the
> 731A to generate the remaining voltages?
>
>
>
> The 731A manual and schematic are here:
>
>
>
>
http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instruction_
> Manual.pdf
>
>
>
> R8A is the high side of a voltage divider with R8B, R9, R10 and R11 (a
10
> ohm, 20 turn pot) forming the low side, dividing 10 VDC to feed the
> voltage reference, IC2, a DH80417B. The op amp, IC1, used to generate the
> 10 VDC is an LM301AH.
>
>
>
> R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9 measures
> about 78.02 ohms, and R10 measures about 399.8 ohms.
>
>
>
> Thanks in advance for any and all information and suggestions.
>
>
>
> Joe
>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
_______________________________________________
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
JL
J. L. Trantham
Mon, Sep 17, 2012 12:38 PM
Pete,
As far as the connection goes, the current resistor wire appears to be
'soldered' to what appear to be gold plated steel wires (very stiff yet
bendable). If the temperature is relatively stable, it should not be too
bad a problem as far as the repair goes. However, it seems to drift all
over the place.
I changed the Op Amp to no benefit.
I am leaning to switching to a different voltage reference. I have a
'spare' reference board from an HP 3458A and it would make a good project to
install this, change the wiring to the Op Amp to adjust the 'other side' of
the Op Amp input to adjust to 10.000000 VDC and still be able to use the
output divider in the 731A to get the rest of the voltages offered by the
731A.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Pete Lancashire
Sent: Sunday, September 16, 2012 4:03 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 731A Transfer Standard and Fluke Wire
WoundResistors
There is a good chance the wire is Manganin or an allow that is similar.
If what you use to connect to the resistance wire is not the same you run
into things like EMF (think thermocouple) being created at the repair.
-pete
On Sun, Sep 16, 2012 at 1:36 PM, J. L. Trantham jltran@att.net wrote:
I have been following the discussion about the LM399 heater, noting
mention of the Fluke Wire Wound resistors used often in Fluke
precision equipment.
I have a 731A that I have been resuscitating and have found that the
R8A R8B wire wound resistor is failing. Initially, the source was
very unstable then went to about 8 VDC. This led me to an open R8B.
I was able to reconnect the broken ends, loosing about half a turn
of wire. Then, again, unstable and went to about 13 VDC. This led me
to an open R8A. Again, able to reconnect, and, again, loosing about ½
turn.
It appears that the wire is corroded with corrosion leading to
failure. This brings up several questions.
-
What are the benefits of these wire wound resistors? Tempco?
Ability to construct precise resistance?
2. Is there a source of the resistance wire used in these resistors
that the resistor can be reconstructed? I think the resistance is in
the 30 to 40 ohms per foot range. Something like 36 to 38 gauge
Nichrome 60 would work but it has to be insulated.
3. Would it be better to look for a collection of commercial
to replace R8A, R8B? If so, what? The manual states that IC2, the
voltage reference, R6, R7, R9, and R10, are factory selected and all
appear to be OK.
4. Would it be better to completely abandon the voltage reference
section of the 731A in favor of a new (perhaps LM399, LTZ1000A,
etc.,
based) reference to generate 10 VDC and still use the output divider of
731A to generate the remaining voltages?
The 731A manual and schematic are here:
http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instru
ction_
Manual.pdf
R8A is the high side of a voltage divider with R8B, R9, R10 and R11
(a 10 ohm, 20 turn pot) forming the low side, dividing 10 VDC to
feed the voltage reference, IC2, a DH80417B. The op amp, IC1, used to
generate the 10 VDC is an LM301AH.
R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9
measures about 78.02 ohms, and R10 measures about 399.8 ohms.
Thanks in advance for any and all information and suggestions.
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
Pete,
As far as the connection goes, the current resistor wire appears to be
'soldered' to what appear to be gold plated steel wires (very stiff yet
bendable). If the temperature is relatively stable, it should not be too
bad a problem as far as the repair goes. However, it seems to drift all
over the place.
I changed the Op Amp to no benefit.
I am leaning to switching to a different voltage reference. I have a
'spare' reference board from an HP 3458A and it would make a good project to
install this, change the wiring to the Op Amp to adjust the 'other side' of
the Op Amp input to adjust to 10.000000 VDC and still be able to use the
output divider in the 731A to get the rest of the voltages offered by the
731A.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Pete Lancashire
Sent: Sunday, September 16, 2012 4:03 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 731A Transfer Standard and Fluke Wire
WoundResistors
There is a good chance the wire is Manganin or an allow that is similar.
If what you use to connect to the resistance wire is not the same you run
into things like EMF (think thermocouple) being created at the repair.
-pete
On Sun, Sep 16, 2012 at 1:36 PM, J. L. Trantham <jltran@att.net> wrote:
> I have been following the discussion about the LM399 heater, noting
> mention of the Fluke Wire Wound resistors used often in Fluke
> precision equipment.
>
>
>
> I have a 731A that I have been resuscitating and have found that the
> R8A R8B wire wound resistor is failing. Initially, the source was
> very unstable then went to about 8 VDC. This led me to an open R8B.
> I was able to reconnect the broken ends, loosing about half a turn
> of wire. Then, again, unstable and went to about 13 VDC. This led me
> to an open R8A. Again, able to reconnect, and, again, loosing about ½
> turn.
>
>
>
> It appears that the wire is corroded with corrosion leading to
> failure. This brings up several questions.
>
>
>
> 1. What are the benefits of these wire wound resistors? Tempco?
> Ability to construct precise resistance?
> 2. Is there a source of the resistance wire used in these resistors
so
> that the resistor can be reconstructed? I think the resistance is in
> the 30 to 40 ohms per foot range. Something like 36 to 38 gauge
> Nichrome 60 would work but it has to be insulated.
> 3. Would it be better to look for a collection of commercial
resistors
> to replace R8A, R8B? If so, what? The manual states that IC2, the
> voltage reference, R6, R7, R9, and R10, are factory selected and all
> appear to be OK.
> 4. Would it be better to completely abandon the voltage reference
> section of the 731A in favor of a new (perhaps LM399, LTZ1000A,
> etc.,
> based) reference to generate 10 VDC and still use the output divider of
the
> 731A to generate the remaining voltages?
>
>
>
> The 731A manual and schematic are here:
>
>
>
> http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instru
> ction_
> Manual.pdf
>
>
>
> R8A is the high side of a voltage divider with R8B, R9, R10 and R11
> (a 10 ohm, 20 turn pot) forming the low side, dividing 10 VDC to
> feed the voltage reference, IC2, a DH80417B. The op amp, IC1, used to
> generate the 10 VDC is an LM301AH.
>
>
>
> R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9
> measures about 78.02 ohms, and R10 measures about 399.8 ohms.
>
>
>
> Thanks in advance for any and all information and suggestions.
>
>
>
> Joe
>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
_______________________________________________
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
FS
Fred Schneider
Mon, Sep 17, 2012 2:29 PM
My 731A also drifts all over the place. The LM399 I am making was first ment to become a replacement for use in the 731A, and like you, use the diverder. But not any more, I have a LT1027B reference that is on 24/7 for about a year and nice behaving. The 1027 behaves better as my 731A and delivers 10V . Weak point is the resitors i used to adjust it to 10V. ( I was young and.... ;-) ) I plan to change that using better ones and a better construction and after that, use that to feed the divider of the 731A. Also replaced the opamp of the 731A for a better one but that improved only a little.
Then use a chopper opamp with LM10 as buffer on the output of the 731A so its output impedance will be lower and it will be able to be used direct without a null detector, or before a KV devider without collapsing.
Fred PA4TIM
Op 17 sep. 2012 om 14:38 heeft "J. L. Trantham" jltran@att.net het volgende geschreven:
Pete,
As far as the connection goes, the current resistor wire appears to be
'soldered' to what appear to be gold plated steel wires (very stiff yet
bendable). If the temperature is relatively stable, it should not be too
bad a problem as far as the repair goes. However, it seems to drift all
over the place.
I changed the Op Amp to no benefit.
I am leaning to switching to a different voltage reference. I have a
'spare' reference board from an HP 3458A and it would make a good project to
install this, change the wiring to the Op Amp to adjust the 'other side' of
the Op Amp input to adjust to 10.000000 VDC and still be able to use the
output divider in the 731A to get the rest of the voltages offered by the
731A.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Pete Lancashire
Sent: Sunday, September 16, 2012 4:03 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 731A Transfer Standard and Fluke Wire
WoundResistors
There is a good chance the wire is Manganin or an allow that is similar.
If what you use to connect to the resistance wire is not the same you run
into things like EMF (think thermocouple) being created at the repair.
-pete
On Sun, Sep 16, 2012 at 1:36 PM, J. L. Trantham jltran@att.net wrote:
I have been following the discussion about the LM399 heater, noting
mention of the Fluke Wire Wound resistors used often in Fluke
precision equipment.
I have a 731A that I have been resuscitating and have found that the
R8A R8B wire wound resistor is failing. Initially, the source was
very unstable then went to about 8 VDC. This led me to an open R8B.
I was able to ‘reconnect’ the broken ends, loosing about half a turn
of wire. Then, again, unstable and went to about 13 VDC. This led me
to an open R8A. Again, able to reconnect, and, again, loosing about ½
turn.
It appears that the wire is corroded with corrosion leading to
failure. This brings up several questions.
-
What are the benefits of these wire wound resistors? Tempco?
Ability to construct precise resistance?
2. Is there a source of the resistance wire used in these resistors
that the resistor can be reconstructed? I think the resistance is in
the 30 to 40 ohms per foot range. Something like 36 to 38 gauge
Nichrome 60 would work but it has to be insulated.
3. Would it be better to look for a collection of commercial
to ‘replace’ R8A, R8B? If so, what? The manual states that IC2, the
voltage reference, R6, R7, R9, and R10, are ‘factory selected’ and all
appear to be OK.
4. Would it be better to completely abandon the voltage reference
section of the 731A in favor of a ‘new’ (perhaps LM399, LTZ1000A,
etc.,
based) reference to generate 10 VDC and still use the output divider of
731A to generate the remaining voltages?
The 731A manual and schematic are here:
http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instru
ction_
Manual.pdf
R8A is the ‘high’ side of a voltage divider with R8B, R9, R10 and R11
(a 10 ohm, 20 turn pot) forming the ‘low’ side, dividing 10 VDC to
feed the voltage reference, IC2, a DH80417B. The op amp, IC1, used to
generate the 10 VDC is an LM301AH.
R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9
measures about 78.02 ohms, and R10 measures about 399.8 ohms.
Thanks in advance for any and all information and suggestions.
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
My 731A also drifts all over the place. The LM399 I am making was first ment to become a replacement for use in the 731A, and like you, use the diverder. But not any more, I have a LT1027B reference that is on 24/7 for about a year and nice behaving. The 1027 behaves better as my 731A and delivers 10V . Weak point is the resitors i used to adjust it to 10V. ( I was young and.... ;-) ) I plan to change that using better ones and a better construction and after that, use that to feed the divider of the 731A. Also replaced the opamp of the 731A for a better one but that improved only a little.
Then use a chopper opamp with LM10 as buffer on the output of the 731A so its output impedance will be lower and it will be able to be used direct without a null detector, or before a KV devider without collapsing.
Fred PA4TIM
Op 17 sep. 2012 om 14:38 heeft "J. L. Trantham" <jltran@att.net> het volgende geschreven:
> Pete,
>
> As far as the connection goes, the current resistor wire appears to be
> 'soldered' to what appear to be gold plated steel wires (very stiff yet
> bendable). If the temperature is relatively stable, it should not be too
> bad a problem as far as the repair goes. However, it seems to drift all
> over the place.
>
> I changed the Op Amp to no benefit.
>
> I am leaning to switching to a different voltage reference. I have a
> 'spare' reference board from an HP 3458A and it would make a good project to
> install this, change the wiring to the Op Amp to adjust the 'other side' of
> the Op Amp input to adjust to 10.000000 VDC and still be able to use the
> output divider in the 731A to get the rest of the voltages offered by the
> 731A.
>
> Joe
>
> -----Original Message-----
> From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
> Behalf Of Pete Lancashire
> Sent: Sunday, September 16, 2012 4:03 PM
> To: Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] Fluke 731A Transfer Standard and Fluke Wire
> WoundResistors
>
>
> There is a good chance the wire is Manganin or an allow that is similar.
>
> If what you use to connect to the resistance wire is not the same you run
> into things like EMF (think thermocouple) being created at the repair.
>
> -pete
>
> On Sun, Sep 16, 2012 at 1:36 PM, J. L. Trantham <jltran@att.net> wrote:
>> I have been following the discussion about the LM399 heater, noting
>> mention of the Fluke Wire Wound resistors used often in Fluke
>> precision equipment.
>>
>>
>>
>> I have a 731A that I have been resuscitating and have found that the
>> R8A R8B wire wound resistor is failing. Initially, the source was
>> very unstable then went to about 8 VDC. This led me to an open R8B.
>> I was able to ‘reconnect’ the broken ends, loosing about half a turn
>> of wire. Then, again, unstable and went to about 13 VDC. This led me
>> to an open R8A. Again, able to reconnect, and, again, loosing about ½
>> turn.
>>
>>
>>
>> It appears that the wire is corroded with corrosion leading to
>> failure. This brings up several questions.
>>
>>
>>
>> 1. What are the benefits of these wire wound resistors? Tempco?
>> Ability to construct precise resistance?
>> 2. Is there a source of the resistance wire used in these resistors
> so
>> that the resistor can be reconstructed? I think the resistance is in
>> the 30 to 40 ohms per foot range. Something like 36 to 38 gauge
>> Nichrome 60 would work but it has to be insulated.
>> 3. Would it be better to look for a collection of commercial
> resistors
>> to ‘replace’ R8A, R8B? If so, what? The manual states that IC2, the
>> voltage reference, R6, R7, R9, and R10, are ‘factory selected’ and all
>> appear to be OK.
>> 4. Would it be better to completely abandon the voltage reference
>> section of the 731A in favor of a ‘new’ (perhaps LM399, LTZ1000A,
>> etc.,
>> based) reference to generate 10 VDC and still use the output divider of
> the
>> 731A to generate the remaining voltages?
>>
>>
>>
>> The 731A manual and schematic are here:
>>
>>
>>
>> http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instru
>> ction_
>> Manual.pdf
>>
>>
>>
>> R8A is the ‘high’ side of a voltage divider with R8B, R9, R10 and R11
>> (a 10 ohm, 20 turn pot) forming the ‘low’ side, dividing 10 VDC to
>> feed the voltage reference, IC2, a DH80417B. The op amp, IC1, used to
>> generate the 10 VDC is an LM301AH.
>>
>>
>>
>> R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9
>> measures about 78.02 ohms, and R10 measures about 399.8 ohms.
>>
>>
>>
>> Thanks in advance for any and all information and suggestions.
>>
>>
>>
>> Joe
>>
>> _______________________________________________
>> volt-nuts mailing list -- volt-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>> and follow the instructions there.
>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
>
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> and follow the instructions there.
BS
Bob Smither
Mon, Sep 17, 2012 8:53 PM
On 09/16/2012 04:54 PM, J. L. Trantham wrote:
Pete,
Thanks for the reply.
I was just looking at the properties of the wire. I guess I don't
understand the 'resistivity' of 43-48 uOhmcm for the wire that is about the
same size as what the resistor is made of.
Example:
45 uOhmCm * L / A = Ohms
L = length of wire in Cm
A = Area of wire in Cm^2
It lists a tempco of .00001 per K.
Hmmm - 10 ppm / C? Not great. I assume that the resistors are empirically
matched in pairs during manufacturing.
As best I can tell, the 5903 ohm resistor is about 15.5 mm long, on a 1 inch
flat form about 1 mm thick (about 2 inches per turn) and about 14 turns per
mm as best I can tell. I measured the wire at .05 mm thickness. That would
put it at about 217 turns, 434 inches, and about 13.6 ohms per inch. My
original calculation appears to be wrong.
Using 45 uOhmCm:
45E-6 * 434 in * (2.54 Cm / in) / (pi * (.005 cm / 2)^2) = 2.52 KOhm
At the risk of stating the obvious, have you considered Vishay resistors for the
rebuild?
Best regards,
--
Bob Smither, Ph.D. Smither@c-c-i.com
---========
"I'm sorry I ever invented the Electoral College." - Al Gore 11/08/00
---========
On 09/16/2012 04:54 PM, J. L. Trantham wrote:
> Pete,
>
> Thanks for the reply.
>
> I was just looking at the properties of the wire. I guess I don't
> understand the 'resistivity' of 43-48 uOhmcm for the wire that is about the
> same size as what the resistor is made of.
Example:
45 uOhmCm * L / A = Ohms
L = length of wire in Cm
A = Area of wire in Cm^2
> It lists a tempco of .00001 per K.
Hmmm - 10 ppm / C? Not great. I assume that the resistors are empirically
matched in pairs during manufacturing.
> As best I can tell, the 5903 ohm resistor is about 15.5 mm long, on a 1 inch
> flat form about 1 mm thick (about 2 inches per turn) and about 14 turns per
> mm as best I can tell. I measured the wire at .05 mm thickness. That would
> put it at about 217 turns, 434 inches, and about 13.6 ohms per inch. My
> original calculation appears to be wrong.
Using 45 uOhmCm:
45E-6 * 434 in * (2.54 Cm / in) / (pi * (.005 cm / 2)^2) = 2.52 KOhm
At the risk of stating the obvious, have you considered Vishay resistors for the
rebuild?
Best regards,
--
Bob Smither, Ph.D. Smither@c-c-i.com
==========================================================================
"I'm sorry I ever invented the Electoral College." - Al Gore 11/08/00
==========================================================================
RP
Roy Phillips
Tue, Sep 18, 2012 8:56 AM
Joe
I guess that there are many of us with a reference board from the HP3458A
who would be pleased to have a good design making use of this item. For
those of you who have been around a long time, I recently obtained a
Weston - Rotex DC Absolute Voltage/Current Standard which came from a
Standards Lab. Much to my surprise it still performs very well, and its
interesting to note that each standard output is delivered to a separate
pair of terminals, unlike the Fluke 731B, but more in keeping with the
latter models. So it would seem that the old-timers knew a thing or two
about 'high standards', but at a price of course. It required a mass of
components to produce the result - it would appear to be 1960's
design/manufacture. Are there many of these out there ? - I would be
interested to see its specification as I cannot find any reference to this
item.
Roy
-----Original Message-----
From: Fred Schneider
Sent: Monday, September 17, 2012 3:29 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 731A Transfer Standard and Fluke
WireWoundResistors
My 731A also drifts all over the place. The LM399 I am making was first
ment to become a replacement for use in the 731A, and like you, use the
diverder. But not any more, I have a LT1027B reference that is on 24/7 for
about a year and nice behaving. The 1027 behaves better as my 731A and
delivers 10V . Weak point is the resitors i used to adjust it to 10V. ( I
was young and.... ;-) ) I plan to change that using better ones and a better
construction and after that, use that to feed the divider of the 731A. Also
replaced the opamp of the 731A for a better one but that improved only a
little.
Then use a chopper opamp with LM10 as buffer on the output of the 731A so
its output impedance will be lower and it will be able to be used direct
without a null detector, or before a KV devider without collapsing.
Fred PA4TIM
Op 17 sep. 2012 om 14:38 heeft "J. L. Trantham" jltran@att.net het
volgende geschreven:
Pete,
As far as the connection goes, the current resistor wire appears to be
'soldered' to what appear to be gold plated steel wires (very stiff yet
bendable). If the temperature is relatively stable, it should not be too
bad a problem as far as the repair goes. However, it seems to drift all
over the place.
I changed the Op Amp to no benefit.
I am leaning to switching to a different voltage reference. I have a
'spare' reference board from an HP 3458A and it would make a good project
to
install this, change the wiring to the Op Amp to adjust the 'other side'
of
the Op Amp input to adjust to 10.000000 VDC and still be able to use the
output divider in the 731A to get the rest of the voltages offered by the
731A.
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Pete Lancashire
Sent: Sunday, September 16, 2012 4:03 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 731A Transfer Standard and Fluke Wire
WoundResistors
There is a good chance the wire is Manganin or an allow that is similar.
If what you use to connect to the resistance wire is not the same you run
into things like EMF (think thermocouple) being created at the repair.
-pete
On Sun, Sep 16, 2012 at 1:36 PM, J. L. Trantham jltran@att.net wrote:
I have been following the discussion about the LM399 heater, noting
mention of the Fluke Wire Wound resistors used often in Fluke
precision equipment.
I have a 731A that I have been resuscitating and have found that the
R8A R8B wire wound resistor is failing. Initially, the source was
very unstable then went to about 8 VDC. This led me to an open R8B.
I was able to ‘reconnect’ the broken ends, loosing about half a turn
of wire. Then, again, unstable and went to about 13 VDC. This led me
to an open R8A. Again, able to reconnect, and, again, loosing about ½
turn.
It appears that the wire is corroded with corrosion leading to
failure. This brings up several questions.
-
What are the benefits of these wire wound resistors? Tempco?
Ability to construct precise resistance?
2. Is there a source of the resistance wire used in these resistors
that the resistor can be reconstructed? I think the resistance is in
the 30 to 40 ohms per foot range. Something like 36 to 38 gauge
Nichrome 60 would work but it has to be insulated.
3. Would it be better to look for a collection of commercial
to ‘replace’ R8A, R8B? If so, what? The manual states that IC2, the
voltage reference, R6, R7, R9, and R10, are ‘factory selected’ and all
appear to be OK.
4. Would it be better to completely abandon the voltage reference
section of the 731A in favor of a ‘new’ (perhaps LM399, LTZ1000A,
etc.,
based) reference to generate 10 VDC and still use the output divider of
731A to generate the remaining voltages?
The 731A manual and schematic are here:
http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instru
ction_
Manual.pdf
R8A is the ‘high’ side of a voltage divider with R8B, R9, R10 and R11
(a 10 ohm, 20 turn pot) forming the ‘low’ side, dividing 10 VDC to
feed the voltage reference, IC2, a DH80417B. The op amp, IC1, used to
generate the 10 VDC is an LM301AH.
R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9
measures about 78.02 ohms, and R10 measures about 399.8 ohms.
Thanks in advance for any and all information and suggestions.
Joe
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
Joe
I guess that there are many of us with a reference board from the HP3458A
who would be pleased to have a good design making use of this item. For
those of you who have been around a long time, I recently obtained a
Weston - Rotex DC Absolute Voltage/Current Standard which came from a
Standards Lab. Much to my surprise it still performs very well, and its
interesting to note that each standard output is delivered to a separate
pair of terminals, unlike the Fluke 731B, but more in keeping with the
latter models. So it would seem that the old-timers knew a thing or two
about 'high standards', but at a price of course. It required a mass of
components to produce the result - it would appear to be 1960's
design/manufacture. Are there many of these out there ? - I would be
interested to see its specification as I cannot find any reference to this
item.
Roy
-----Original Message-----
From: Fred Schneider
Sent: Monday, September 17, 2012 3:29 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 731A Transfer Standard and Fluke
WireWoundResistors
My 731A also drifts all over the place. The LM399 I am making was first
ment to become a replacement for use in the 731A, and like you, use the
diverder. But not any more, I have a LT1027B reference that is on 24/7 for
about a year and nice behaving. The 1027 behaves better as my 731A and
delivers 10V . Weak point is the resitors i used to adjust it to 10V. ( I
was young and.... ;-) ) I plan to change that using better ones and a better
construction and after that, use that to feed the divider of the 731A. Also
replaced the opamp of the 731A for a better one but that improved only a
little.
Then use a chopper opamp with LM10 as buffer on the output of the 731A so
its output impedance will be lower and it will be able to be used direct
without a null detector, or before a KV devider without collapsing.
Fred PA4TIM
Op 17 sep. 2012 om 14:38 heeft "J. L. Trantham" <jltran@att.net> het
volgende geschreven:
> Pete,
>
> As far as the connection goes, the current resistor wire appears to be
> 'soldered' to what appear to be gold plated steel wires (very stiff yet
> bendable). If the temperature is relatively stable, it should not be too
> bad a problem as far as the repair goes. However, it seems to drift all
> over the place.
>
> I changed the Op Amp to no benefit.
>
> I am leaning to switching to a different voltage reference. I have a
> 'spare' reference board from an HP 3458A and it would make a good project
> to
> install this, change the wiring to the Op Amp to adjust the 'other side'
> of
> the Op Amp input to adjust to 10.000000 VDC and still be able to use the
> output divider in the 731A to get the rest of the voltages offered by the
> 731A.
>
> Joe
>
> -----Original Message-----
> From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
> Behalf Of Pete Lancashire
> Sent: Sunday, September 16, 2012 4:03 PM
> To: Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] Fluke 731A Transfer Standard and Fluke Wire
> WoundResistors
>
>
> There is a good chance the wire is Manganin or an allow that is similar.
>
> If what you use to connect to the resistance wire is not the same you run
> into things like EMF (think thermocouple) being created at the repair.
>
> -pete
>
> On Sun, Sep 16, 2012 at 1:36 PM, J. L. Trantham <jltran@att.net> wrote:
>> I have been following the discussion about the LM399 heater, noting
>> mention of the Fluke Wire Wound resistors used often in Fluke
>> precision equipment.
>>
>>
>>
>> I have a 731A that I have been resuscitating and have found that the
>> R8A R8B wire wound resistor is failing. Initially, the source was
>> very unstable then went to about 8 VDC. This led me to an open R8B.
>> I was able to ‘reconnect’ the broken ends, loosing about half a turn
>> of wire. Then, again, unstable and went to about 13 VDC. This led me
>> to an open R8A. Again, able to reconnect, and, again, loosing about ½
>> turn.
>>
>>
>>
>> It appears that the wire is corroded with corrosion leading to
>> failure. This brings up several questions.
>>
>>
>>
>> 1. What are the benefits of these wire wound resistors? Tempco?
>> Ability to construct precise resistance?
>> 2. Is there a source of the resistance wire used in these resistors
> so
>> that the resistor can be reconstructed? I think the resistance is in
>> the 30 to 40 ohms per foot range. Something like 36 to 38 gauge
>> Nichrome 60 would work but it has to be insulated.
>> 3. Would it be better to look for a collection of commercial
> resistors
>> to ‘replace’ R8A, R8B? If so, what? The manual states that IC2, the
>> voltage reference, R6, R7, R9, and R10, are ‘factory selected’ and all
>> appear to be OK.
>> 4. Would it be better to completely abandon the voltage reference
>> section of the 731A in favor of a ‘new’ (perhaps LM399, LTZ1000A,
>> etc.,
>> based) reference to generate 10 VDC and still use the output divider of
> the
>> 731A to generate the remaining voltages?
>>
>>
>>
>> The 731A manual and schematic are here:
>>
>>
>>
>> http://www.ko4bb.com/Manuals/Fluke/Fluke_731A_Transfer_Standard_Instru
>> ction_
>> Manual.pdf
>>
>>
>>
>> R8A is the ‘high’ side of a voltage divider with R8B, R9, R10 and R11
>> (a 10 ohm, 20 turn pot) forming the ‘low’ side, dividing 10 VDC to
>> feed the voltage reference, IC2, a DH80417B. The op amp, IC1, used to
>> generate the 10 VDC is an LM301AH.
>>
>>
>>
>> R8A measures about 5903 ohms, R8B measures about 11558 ohms, R9
>> measures about 78.02 ohms, and R10 measures about 399.8 ohms.
>>
>>
>>
>> Thanks in advance for any and all information and suggestions.
>>
>>
>>
>> Joe
>>
>> _______________________________________________
>> volt-nuts mailing list -- volt-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>> and follow the instructions there.
>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
>
> _______________________________________________
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
_______________________________________________
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