HP5065A S/N 0048-00131 - Worth repairing (and how to do it)?
HP 5065A S/N 0048-00131
Repairing the heater...
I was able to get my hand on a faulty 5065A
that was left for dead.
The date codes on the semiconductors says 1968
so this unit is 50 years old... This instrument
has some provenance as it was
used in the European end during the very first
trans-atlantic VLBI (Radio Astronomy)
experiments between Sweden and the USA.
The unit has the known problem with one of the
rubidium unit (s/n 05065-6001)
heater wires shorted to GND.
This failure was the cause of the decomissioning.
I managed to salvage:The transmitter lamp (fires up within seconds when connecting it to a 20V DC source),The Rubidium glass cavity, The photo-cell at the receiving end.
Having downloaded the "First-aid" documents
from KO4BB, I read a quote from Corby Dowson
regarding this problem and what to do about it.
I have been able to separate the TX/Rb/Rx assembly from
the magnetic shields but after this, I hesitate
about how to proceed. (why did not HP put more energy
in trying to isolate the magnetic winding from the shield?
Any scratch on the enameled copper wire and a short
circuit will be the result here as well?)
As far as I can see, the magnetic
winding has to come off. The rest of the
polyurethane (?) structure has to be removed
after which that structure has to be rebuilt
using some other material (PTFE?).
One other reason why I hesitate is that this unit is
v e r y old. It uses regenerative dividers
instead of binary (etc) and a lot of other
obsolete components.
I could use some suggestions about what to do next.
One other question is of course if it is worth
putting a lot of energy trying to repair
a 5065 as old as this. Perhaps easier to go
look for a working modern 5065A on the open market?
Comments invited.
Ulf Kylenfall
SM6GXV
Hi
……. You have just discovered why we all depend on hard working Corby so much. Repairing these
old beasts is not as easy as it first seems !!
The traditional theory about mag wire on a metal tube was that they both have very similar
temperature coefficients (maybe) and that there is no motion between them (maybe). With
zero motion, the insulation (maybe) goes nowhere even if it degrades. For heater windings
the theory was that the direct contact gave you better heat transfer. That works for round
cavities (like the 5065). All of this falls apart a bit for square cavities (think OCXO’s). There
the wire hits on the corners and floats as it goes over the broad sides of the part.
Lots of fun !!
Bob
On May 6, 2017, at 5:49 AM, Ulf Kylenfall via time-nuts time-nuts@febo.com wrote:
HP 5065A S/N 0048-00131
Repairing the heater...
I was able to get my hand on a faulty 5065A
that was left for dead.
The date codes on the semiconductors says 1968
so this unit is 50 years old... This instrument
has some provenance as it was
used in the European end during the very first
trans-atlantic VLBI (Radio Astronomy)
experiments between Sweden and the USA.
The unit has the known problem with one of the
rubidium unit (s/n 05065-6001)
heater wires shorted to GND.
This failure was the cause of the decomissioning.
I managed to salvage:The transmitter lamp (fires up within seconds when connecting it to a 20V DC source),The Rubidium glass cavity, The photo-cell at the receiving end.
Having downloaded the "First-aid" documents
from KO4BB, I read a quote from Corby Dowson
regarding this problem and what to do about it.
I have been able to separate the TX/Rb/Rx assembly from
the magnetic shields but after this, I hesitate
about how to proceed. (why did not HP put more energy
in trying to isolate the magnetic winding from the shield?
Any scratch on the enameled copper wire and a short
circuit will be the result here as well?)
As far as I can see, the magnetic
winding has to come off. The rest of the
polyurethane (?) structure has to be removed
after which that structure has to be rebuilt
using some other material (PTFE?).
One other reason why I hesitate is that this unit is
v e r y old. It uses regenerative dividers
instead of binary (etc) and a lot of other
obsolete components.
I could use some suggestions about what to do next.
One other question is of course if it is worth
putting a lot of energy trying to repair
a 5065 as old as this. Perhaps easier to go
look for a working modern 5065A on the open market?
Comments invited.
Ulf Kylenfall
SM6GXV
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.
On phone
Absolutely repair you can do numbers of things to isolate the short by
floating it
Far to much for a phone
On Saturday, May 6, 2017, Ulf Kylenfall via time-nuts time-nuts@febo.com
wrote:
HP 5065A S/N 0048-00131
Repairing the heater...
I was able to get my hand on a faulty 5065A
that was left for dead.
The date codes on the semiconductors says 1968
so this unit is 50 years old... This instrument
has some provenance as it was
used in the European end during the very first
trans-atlantic VLBI (Radio Astronomy)
experiments between Sweden and the USA.
The unit has the known problem with one of the
rubidium unit (s/n 05065-6001)
heater wires shorted to GND.
This failure was the cause of the decomissioning.
I managed to salvage:The transmitter lamp (fires up within seconds when
connecting it to a 20V DC source),The Rubidium glass cavity, The photo-cell
at the receiving end.
Having downloaded the "First-aid" documents
from KO4BB, I read a quote from Corby Dowson
regarding this problem and what to do about it.
I have been able to separate the TX/Rb/Rx assembly from
the magnetic shields but after this, I hesitate
about how to proceed. (why did not HP put more energy
in trying to isolate the magnetic winding from the shield?
Any scratch on the enameled copper wire and a short
circuit will be the result here as well?)
As far as I can see, the magnetic
winding has to come off. The rest of the
polyurethane (?) structure has to be removed
after which that structure has to be rebuilt
using some other material (PTFE?).
One other reason why I hesitate is that this unit is
v e r y old. It uses regenerative dividers
instead of binary (etc) and a lot of other
obsolete components.
I could use some suggestions about what to do next.
One other question is of course if it is worth
putting a lot of energy trying to repair
a 5065 as old as this. Perhaps easier to go
look for a working modern 5065A on the open market?
Comments invited.
Ulf Kylenfall
SM6GXV
time-nuts mailing list -- time-nuts@febo.com javascript:;
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
and follow the instructions there.
Ulf
On a larger keyboard. The reason not to go digging is that the 5065s are
quite good and the fact that the lamp came up with power applied is a good
sign. So the risk is digging in and perhaps destroying it or finding a way
to use the winding as is.
I have done this on several unusual things like CRTs with shorted grids and
such and recently on an old crystal oven and it works.
So taking a look to see how you might be able to float that heater for me
at least is far more likely to succeed and nothing to loose.
If you for some reason through this effort you discover you can't float it
or its shorted etc then you still have the option of doing what you are
currently considering.
Best of luck to you.
Regards
Paul
WB8TSL
On Sat, May 6, 2017 at 10:08 AM, Bob kb8tq kb8tq@n1k.org wrote:
Hi
……. You have just discovered why we all depend on hard working Corby so
much. Repairing these
old beasts is not as easy as it first seems !!
The traditional theory about mag wire on a metal tube was that they both
have very similar
temperature coefficients (maybe) and that there is no motion between them
(maybe). With
zero motion, the insulation (maybe) goes nowhere even if it degrades. For
heater windings
the theory was that the direct contact gave you better heat transfer. That
works for round
cavities (like the 5065). All of this falls apart a bit for square
cavities (think OCXO’s). There
the wire hits on the corners and floats as it goes over the broad sides of
the part.
Lots of fun !!
Bob
On May 6, 2017, at 5:49 AM, Ulf Kylenfall via time-nuts <
time-nuts@febo.com> wrote:
HP 5065A S/N 0048-00131
Repairing the heater...
I was able to get my hand on a faulty 5065A
that was left for dead.
The date codes on the semiconductors says 1968
so this unit is 50 years old... This instrument
has some provenance as it was
used in the European end during the very first
trans-atlantic VLBI (Radio Astronomy)
experiments between Sweden and the USA.
The unit has the known problem with one of the
rubidium unit (s/n 05065-6001)
heater wires shorted to GND.
This failure was the cause of the decomissioning.
I managed to salvage:The transmitter lamp (fires up within seconds when
connecting it to a 20V DC source),The Rubidium glass cavity, The photo-cell
at the receiving end.
Having downloaded the "First-aid" documents
from KO4BB, I read a quote from Corby Dowson
regarding this problem and what to do about it.
I have been able to separate the TX/Rb/Rx assembly from
the magnetic shields but after this, I hesitate
about how to proceed. (why did not HP put more energy
in trying to isolate the magnetic winding from the shield?
Any scratch on the enameled copper wire and a short
circuit will be the result here as well?)
As far as I can see, the magnetic
winding has to come off. The rest of the
polyurethane (?) structure has to be removed
after which that structure has to be rebuilt
using some other material (PTFE?).
One other reason why I hesitate is that this unit is
v e r y old. It uses regenerative dividers
instead of binary (etc) and a lot of other
obsolete components.
I could use some suggestions about what to do next.
One other question is of course if it is worth
putting a lot of energy trying to repair
a 5065 as old as this. Perhaps easier to go
look for a working modern 5065A on the open market?
Comments invited.
Ulf Kylenfall
SM6GXV
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.
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.
Hej Ulf,
Having repaired and trimmed a few HP5065As, I'd say it is worth the
trouble. I have not encountered this specific fault thought.
MVH
Magnus SA0MAD
On 05/06/2017 11:49 AM, Ulf Kylenfall via time-nuts wrote:
HP 5065A S/N 0048-00131
Repairing the heater...
I was able to get my hand on a faulty 5065A
that was left for dead.
The date codes on the semiconductors says 1968
so this unit is 50 years old... This instrument
has some provenance as it was
used in the European end during the very first
trans-atlantic VLBI (Radio Astronomy)
experiments between Sweden and the USA.
The unit has the known problem with one of the
rubidium unit (s/n 05065-6001)
heater wires shorted to GND.
This failure was the cause of the decomissioning.
I managed to salvage:The transmitter lamp (fires up within seconds when connecting it to a 20V DC source),The Rubidium glass cavity, The photo-cell at the receiving end.
Having downloaded the "First-aid" documents
from KO4BB, I read a quote from Corby Dowson
regarding this problem and what to do about it.
I have been able to separate the TX/Rb/Rx assembly from
the magnetic shields but after this, I hesitate
about how to proceed. (why did not HP put more energy
in trying to isolate the magnetic winding from the shield?
Any scratch on the enameled copper wire and a short
circuit will be the result here as well?)
As far as I can see, the magnetic
winding has to come off. The rest of the
polyurethane (?) structure has to be removed
after which that structure has to be rebuilt
using some other material (PTFE?).
One other reason why I hesitate is that this unit is
v e r y old. It uses regenerative dividers
instead of binary (etc) and a lot of other
obsolete components.
I could use some suggestions about what to do next.
One other question is of course if it is worth
putting a lot of energy trying to repair
a 5065 as old as this. Perhaps easier to go
look for a working modern 5065A on the open market?
Comments invited.
Ulf Kylenfall
SM6GXV
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.