Empathy List Archives

JC

Jared Cabot

Thu, Nov 18, 2021 2:47 PM

Hi all,

I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd harmonic.
My voltages are all ok, the physics package hasn't overheated and I have replaced the usual resistors on the lamp assembly (and it was running fine afterward for a while), the lamp illuminates, and I've done the procedure to remove cell flooding.
All readings on the 'circuit check' switch are nominal, apart from the 2nd harmonic position. No matter what I do, I can no longer get it to raise above 0.
However, when I first turn the unit on, the needle drops to 0 and flicks a little before settling on 0 and staying there.

Can someone help me get this unit up and running again?

Thanks!
Jared

Hi all, I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd harmonic. My voltages are all ok, the physics package hasn't overheated and I have replaced the usual resistors on the lamp assembly (and it was running fine afterward for a while), the lamp illuminates, and I've done the procedure to remove cell flooding. All readings on the 'circuit check' switch are nominal, apart from the 2nd harmonic position. No matter what I do, I can no longer get it to raise above 0. However, when I first turn the unit on, the needle drops to 0 and flicks a little before settling on 0 and staying there. Can someone help me get this unit up and running again? Thanks! Jared

PS

paul swed

Thu, Nov 18, 2021 11:25 PM

Jared I would be happy to see if I can help remotely. We may want to take
this offline or not. Others may find it interesting.
Regards
Paul
WB8TSL

On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts <
time-nuts@lists.febo.com> wrote:

Hi all,

I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd
harmonic.
My voltages are all ok, the physics package hasn't overheated and I have
replaced the usual resistors on the lamp assembly (and it was running fine
afterward for a while), the lamp illuminates, and I've done the procedure
to remove cell flooding.
All readings on the 'circuit check' switch are nominal, apart from the 2nd
harmonic position. No matter what I do, I can no longer get it to raise
above 0.
However, when I first turn the unit on, the needle drops to 0 and flicks a
little before settling on 0 and staying there.

Can someone help me get this unit up and running again?

Thanks!
Jared_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.

Jared I would be happy to see if I can help remotely. We may want to take this offline or not. Others may find it interesting. Regards Paul WB8TSL On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts < time-nuts@lists.febo.com> wrote: > Hi all, > > I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd > harmonic. > My voltages are all ok, the physics package hasn't overheated and I have > replaced the usual resistors on the lamp assembly (and it was running fine > afterward for a while), the lamp illuminates, and I've done the procedure > to remove cell flooding. > All readings on the 'circuit check' switch are nominal, apart from the 2nd > harmonic position. No matter what I do, I can no longer get it to raise > above 0. > However, when I first turn the unit on, the needle drops to 0 and flicks a > little before settling on 0 and staying there. > > Can someone help me get this unit up and running again? > > Thanks! > Jared_______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-leave@lists.febo.com > To unsubscribe, go to and follow the instructions there.

JC

Jared Cabot

Fri, Nov 19, 2021 12:48 AM

Hi,
Your help is appreciated. We can keep this on-list for now I guess, on the chance it helps someone in the future.

Jared.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Friday, November 19th, 2021 at 08:25, paul swed paulswedb@gmail.com wrote:

Jared I would be happy to see if I can help remotely. We may want to take this offline or not. Others may find it interesting.
Regards
Paul
WB8TSL

On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts time-nuts@lists.febo.com wrote:

Hi all,

I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd harmonic.
My voltages are all ok, the physics package hasn't overheated and I have replaced the usual resistors on the lamp assembly (and it was running fine afterward for a while), the lamp illuminates, and I've done the procedure to remove cell flooding.
All readings on the 'circuit check' switch are nominal, apart from the 2nd harmonic position. No matter what I do, I can no longer get it to raise above 0.
However, when I first turn the unit on, the needle drops to 0 and flicks a little before settling on 0 and staying there.

Can someone help me get this unit up and running again?

Thanks!
Jared_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.

Hi, Your help is appreciated. We can keep this on-list for now I guess, on the chance it helps someone in the future. Jared. ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Friday, November 19th, 2021 at 08:25, paul swed <paulswedb@gmail.com> wrote: > Jared I would be happy to see if I can help remotely. We may want to take this offline or not. Others may find it interesting. > Regards > Paul > WB8TSL > > On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts <time-nuts@lists.febo.com> wrote: > > > Hi all, > > > > I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd harmonic. > > My voltages are all ok, the physics package hasn't overheated and I have replaced the usual resistors on the lamp assembly (and it was running fine afterward for a while), the lamp illuminates, and I've done the procedure to remove cell flooding. > > All readings on the 'circuit check' switch are nominal, apart from the 2nd harmonic position. No matter what I do, I can no longer get it to raise above 0. > > However, when I first turn the unit on, the needle drops to 0 and flicks a little before settling on 0 and staying there. > > > > Can someone help me get this unit up and running again? > > > > Thanks! > > Jared_______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com > > To unsubscribe, go to and follow the instructions there.

DW

Dana Whitlow

Fri, Nov 19, 2021 9:48 AM

TVB, I'm interested in the nitty-gritty of this problem and would appreciate
it if you OK this thread's being kept on the group.

Dana

On Thu, Nov 18, 2021 at 6:58 PM Jared Cabot via time-nuts <
time-nuts@lists.febo.com> wrote:

Hi,
Your help is appreciated. We can keep this on-list for now I guess, on the
chance it helps someone in the future.

Jared.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Friday, November 19th, 2021 at 08:25, paul swed paulswedb@gmail.com
wrote:

Jared I would be happy to see if I can help remotely. We may want to

take this offline or not. Others may find it interesting.

Regards
Paul
WB8TSL

On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts <

time-nuts@lists.febo.com> wrote:

Hi all,

I have a 5065A Rubidium Standard that was working ok, but has lost the

2nd harmonic.

My voltages are all ok, the physics package hasn't overheated and I

have replaced the usual resistors on the lamp assembly (and it was running
fine afterward for a while), the lamp illuminates, and I've done the
procedure to remove cell flooding.

All readings on the 'circuit check' switch are nominal, apart from the

2nd harmonic position. No matter what I do, I can no longer get it to raise
above 0.

However, when I first turn the unit on, the needle drops to 0 and

flicks a little before settling on 0 and staying there.

Can someone help me get this unit up and running again?

Thanks!
Jared_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe

send an email to time-nuts-leave@lists.febo.com

To unsubscribe, go to and follow the instructions

there._______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.

TVB, I'm interested in the nitty-gritty of this problem and would appreciate it if you OK this thread's being kept on the group. Dana On Thu, Nov 18, 2021 at 6:58 PM Jared Cabot via time-nuts < time-nuts@lists.febo.com> wrote: > Hi, > Your help is appreciated. We can keep this on-list for now I guess, on the > chance it helps someone in the future. > > Jared. > > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > On Friday, November 19th, 2021 at 08:25, paul swed <paulswedb@gmail.com> > wrote: > > > Jared I would be happy to see if I can help remotely. We may want to > take this offline or not. Others may find it interesting. > > Regards > > Paul > > WB8TSL > > > > > On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts < > time-nuts@lists.febo.com> wrote: > > > > > > Hi all, > > > > > > > I have a 5065A Rubidium Standard that was working ok, but has lost the > 2nd harmonic. > > > My voltages are all ok, the physics package hasn't overheated and I > have replaced the usual resistors on the lamp assembly (and it was running > fine afterward for a while), the lamp illuminates, and I've done the > procedure to remove cell flooding. > > > All readings on the 'circuit check' switch are nominal, apart from the > 2nd harmonic position. No matter what I do, I can no longer get it to raise > above 0. > > > However, when I first turn the unit on, the needle drops to 0 and > flicks a little before settling on 0 and staying there. > > > > > > > Can someone help me get this unit up and running again? > > > > > > > Thanks! > > > Jared_______________________________________________ > > > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe > send an email to time-nuts-leave@lists.febo.com > > > To unsubscribe, go to and follow the instructions > there._______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-leave@lists.febo.com > To unsubscribe, go to and follow the instructions there.

TV

Tom Van Baak

Fri, Nov 19, 2021 10:39 AM

List -- I've contacted Dana, Paul, and Jared to find out how this thread
degenerated. There is no reason I can think of for a discussion about hp
5065A, one of the most prized frequency standards in the time nuts
repertoire, to be hijacked or suppressed by anyone on this mailing list.

A reminder, the email address for on-topic time nuts postings is:
time-nuts@lists.febo.com
And anything else, from email problems to admin questions to rants, goes
to: time-nuts-owner@lists.febo.com

Thanks,
/tvb
http://leapsecond.com/time-nuts.htm

On 11/19/2021 1:48 AM, Dana Whitlow wrote:

TVB, I'm interested in the nitty-gritty of this problem and would
appreciate it if you OK this thread's being kept on the group.
Dana

On Thu, Nov 18, 2021 at 6:58 PM Jared Cabot wrote:

Hi, Your help is appreciated. We can keep this on-list for now I
guess, on the chance it helps someone in the future.
Jared.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Friday, November 19th, 2021 at
08:25, paul swed paulswedb@gmail.com wrote:

Jared I would be happy to see if I can help remotely. We may want
to take this offline or not. Others may find it interesting.
Regards Paul WB8TSL

List -- I've contacted Dana, Paul, and Jared to find out how this thread degenerated. There is no reason I can think of for a discussion about hp 5065A, one of the most prized frequency standards in the time nuts repertoire, to be hijacked or suppressed by anyone on this mailing list. A reminder, the email address for on-topic time nuts postings is: time-nuts@lists.febo.com And anything else, from email problems to admin questions to rants, goes to: time-nuts-owner@lists.febo.com Thanks, /tvb http://leapsecond.com/time-nuts.htm On 11/19/2021 1:48 AM, Dana Whitlow wrote: > TVB, I'm interested in the nitty-gritty of this problem and would > appreciate it if you OK this thread's being kept on the group. > Dana > > On Thu, Nov 18, 2021 at 6:58 PM Jared Cabot wrote: >> Hi, Your help is appreciated. We can keep this on-list for now I >> guess, on the chance it helps someone in the future. >> Jared. >> >> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Friday, November 19th, 2021 at >> 08:25, paul swed <paulswedb@gmail.com> wrote: >>> Jared I would be happy to see if I can help remotely. We may want >>> to take this offline or not. Others may find it interesting. >>> Regards Paul WB8TSL

BK

Bob kb8tq

Fri, Nov 19, 2021 1:47 PM

Hi

Well backing up a bit, why does a 5065 have a second harmonic?

Very quickly:

The stuff in the physics package creates an absorption notch. You
interrogate this notch with a phase modulated locally generated microwave
signal. When the signal is at the right frequency it dumps photons and
you get a signal in the photo diode. That signal has the (audio) second
harmonic in it when you are doing everything just right.

Yes, there’s a lot of hand waving in there, but that’s the really fast version.

Since a lot of “stuff” is involved, there are a number of ways to loose the
second harmonic.

Bob

On Nov 18, 2021, at 7:48 PM, Jared Cabot via time-nuts time-nuts@lists.febo.com wrote:

Hi,
Your help is appreciated. We can keep this on-list for now I guess, on the chance it helps someone in the future.

Jared.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Friday, November 19th, 2021 at 08:25, paul swed paulswedb@gmail.com wrote:

Jared I would be happy to see if I can help remotely. We may want to take this offline or not. Others may find it interesting.
Regards
Paul
WB8TSL

On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts time-nuts@lists.febo.com wrote:

Hi all,

I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd harmonic.
My voltages are all ok, the physics package hasn't overheated and I have replaced the usual resistors on the lamp assembly (and it was running fine afterward for a while), the lamp illuminates, and I've done the procedure to remove cell flooding.
All readings on the 'circuit check' switch are nominal, apart from the 2nd harmonic position. No matter what I do, I can no longer get it to raise above 0.
However, when I first turn the unit on, the needle drops to 0 and flicks a little before settling on 0 and staying there.

Can someone help me get this unit up and running again?

Thanks!
Jared_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.

time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.

Hi Well backing up a bit, why does a 5065 have a second harmonic? Very quickly: The stuff in the physics package creates an absorption notch. You interrogate this notch with a phase modulated locally generated microwave signal. When the signal is at the right frequency it dumps photons and you get a signal in the photo diode. That signal has the (audio) second harmonic in it when you are doing everything just right. Yes, there’s a lot of hand waving in there, but that’s the really fast version. Since a lot of “stuff” is involved, there are a number of ways to loose the second harmonic. Bob > On Nov 18, 2021, at 7:48 PM, Jared Cabot via time-nuts <time-nuts@lists.febo.com> wrote: > > Hi, > Your help is appreciated. We can keep this on-list for now I guess, on the chance it helps someone in the future. > > Jared. > > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > On Friday, November 19th, 2021 at 08:25, paul swed <paulswedb@gmail.com> wrote: > >> Jared I would be happy to see if I can help remotely. We may want to take this offline or not. Others may find it interesting. >> Regards >> Paul >> WB8TSL >> > >> On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts <time-nuts@lists.febo.com> wrote: >> > >>> Hi all, >>> > >>> I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd harmonic. >>> My voltages are all ok, the physics package hasn't overheated and I have replaced the usual resistors on the lamp assembly (and it was running fine afterward for a while), the lamp illuminates, and I've done the procedure to remove cell flooding. >>> All readings on the 'circuit check' switch are nominal, apart from the 2nd harmonic position. No matter what I do, I can no longer get it to raise above 0. >>> However, when I first turn the unit on, the needle drops to 0 and flicks a little before settling on 0 and staying there. >>> > >>> Can someone help me get this unit up and running again? >>> > >>> Thanks! >>> Jared_______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com >>> To unsubscribe, go to and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com > To unsubscribe, go to and follow the instructions there.

GH

Germán Herrera

Fri, Nov 19, 2021 2:11 PM

Hi there

I don't have much experience with the HP5065A, but one I did this very
same issue on my Efratom FRK-L. Turns out the thermistor controlling the
resonator cavity temperature was broken and the cavity temperature was
off. This caused loss of resonance lock, and by definition, loss of the
2nd harmonic.

Reaffirming what Bob says, there a number of other factors that might
cause the issue.

Cheers,
German

Germán Herrera
Responsable IT
Ingeniería
SES Sistemas Electrónicos S.A.| Espinosa 1045 (C1405AMM) | Buenos Aires
| Argentina
W: +54 11 54538426 | Email: g.herrera@ses.com.ar

On 2021-11-19 10:47, Bob kb8tq wrote:

Hi

Well backing up a bit, why does a 5065 have a second harmonic?

Very quickly:

The stuff in the physics package creates an absorption notch. You
interrogate this notch with a phase modulated locally generated
microwave
signal. When the signal is at the right frequency it dumps photons and
you get a signal in the photo diode. That signal has the (audio) second
harmonic in it when you are doing everything just right.

Yes, there’s a lot of hand waving in there, but that’s the really fast
version.

Since a lot of “stuff” is involved, there are a number of ways to loose
the
second harmonic.

Bob

On Nov 18, 2021, at 7:48 PM, Jared Cabot via time-nuts
time-nuts@lists.febo.com wrote:

Hi,
Your help is appreciated. We can keep this on-list for now I guess, on
the chance it helps someone in the future.

Jared.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Friday, November 19th, 2021 at 08:25, paul swed
paulswedb@gmail.com wrote:

Jared I would be happy to see if I can help remotely. We may want to
take this offline or not. Others may find it interesting.
Regards
Paul
WB8TSL

On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts
time-nuts@lists.febo.com wrote:

Hi all,

I have a 5065A Rubidium Standard that was working ok, but has lost
the 2nd harmonic.
My voltages are all ok, the physics package hasn't overheated and I
have replaced the usual resistors on the lamp assembly (and it was
running fine afterward for a while), the lamp illuminates, and I've
done the procedure to remove cell flooding.
All readings on the 'circuit check' switch are nominal, apart from
the 2nd harmonic position. No matter what I do, I can no longer get
it to raise above 0.
However, when I first turn the unit on, the needle drops to 0 and
flicks a little before settling on 0 and staying there.

Can someone help me get this unit up and running again?

Thanks!
Jared_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.

time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.

time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.

Hi there I don't have much experience with the HP5065A, but one I did this very same issue on my Efratom FRK-L. Turns out the thermistor controlling the resonator cavity temperature was broken and the cavity temperature was off. This caused loss of resonance lock, and by definition, loss of the 2nd harmonic. Reaffirming what Bob says, there a number of other factors that might cause the issue. Cheers, German --- Germán Herrera Responsable IT Ingeniería SES Sistemas Electrónicos S.A.| Espinosa 1045 (C1405AMM) | Buenos Aires | Argentina W: +54 11 54538426 | Email: g.herrera@ses.com.ar On 2021-11-19 10:47, Bob kb8tq wrote: > Hi > > Well backing up a bit, why does a 5065 have a second harmonic? > > Very quickly: > > The stuff in the physics package creates an absorption notch. You > interrogate this notch with a phase modulated locally generated > microwave > signal. When the signal is at the right frequency it dumps photons and > you get a signal in the photo diode. That signal has the (audio) second > harmonic in it when you are doing everything just right. > > Yes, there’s a lot of hand waving in there, but that’s the really fast > version. > > Since a lot of “stuff” is involved, there are a number of ways to loose > the > second harmonic. > > Bob > >> On Nov 18, 2021, at 7:48 PM, Jared Cabot via time-nuts >> <time-nuts@lists.febo.com> wrote: >> >> Hi, >> Your help is appreciated. We can keep this on-list for now I guess, on >> the chance it helps someone in the future. >> >> Jared. >> >> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ >> On Friday, November 19th, 2021 at 08:25, paul swed >> <paulswedb@gmail.com> wrote: >> >>> Jared I would be happy to see if I can help remotely. We may want to >>> take this offline or not. Others may find it interesting. >>> Regards >>> Paul >>> WB8TSL >>> >> >>> On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts >>> <time-nuts@lists.febo.com> wrote: >>> >> >>>> Hi all, >>>> >> >>>> I have a 5065A Rubidium Standard that was working ok, but has lost >>>> the 2nd harmonic. >>>> My voltages are all ok, the physics package hasn't overheated and I >>>> have replaced the usual resistors on the lamp assembly (and it was >>>> running fine afterward for a while), the lamp illuminates, and I've >>>> done the procedure to remove cell flooding. >>>> All readings on the 'circuit check' switch are nominal, apart from >>>> the 2nd harmonic position. No matter what I do, I can no longer get >>>> it to raise above 0. >>>> However, when I first turn the unit on, the needle drops to 0 and >>>> flicks a little before settling on 0 and staying there. >>>> >> >>>> Can someone help me get this unit up and running again? >>>> >> >>>> Thanks! >>>> Jared_______________________________________________ >>>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >>>> send an email to time-nuts-leave@lists.febo.com >>>> To unsubscribe, go to and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe >> send an email to time-nuts-leave@lists.febo.com >> To unsubscribe, go to and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe > send an email to time-nuts-leave@lists.febo.com > To unsubscribe, go to and follow the instructions there.

PS

paul swed

Fri, Nov 19, 2021 8:38 PM

Jared
OK lets start.
Can you share a bit with us please.
Whats types of test equipment do you have.
Believe we will need a scope, DVM (Reasonable grade), audio sig gen,
perhaps a fairly good reference GPSDO. I am coming at this with the
possibility the issue could be anyplace.
The suggestion that the oven temps could be off is a good one. Though I
have not so far run into that on CS or Rb references. I need to pull the
5065 manual and take a look but injecting small amounts of first and second
signals should make the meter tick upscale. I believe that is 137 and 274
hz. Its possible and I have seen this issues simply on the metering board.
But want to approach it logically by eliminating the detector chain.
Regards
Paul

On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts <
time-nuts@lists.febo.com> wrote:

Hi all,

I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd
harmonic.
My voltages are all ok, the physics package hasn't overheated and I have
replaced the usual resistors on the lamp assembly (and it was running fine
afterward for a while), the lamp illuminates, and I've done the procedure
to remove cell flooding.
All readings on the 'circuit check' switch are nominal, apart from the 2nd
harmonic position. No matter what I do, I can no longer get it to raise
above 0.
However, when I first turn the unit on, the needle drops to 0 and flicks a
little before settling on 0 and staying there.

Can someone help me get this unit up and running again?

Thanks!
Jared_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.

Jared OK lets start. Can you share a bit with us please. Whats types of test equipment do you have. Believe we will need a scope, DVM (Reasonable grade), audio sig gen, perhaps a fairly good reference GPSDO. I am coming at this with the possibility the issue could be anyplace. The suggestion that the oven temps could be off is a good one. Though I have not so far run into that on CS or Rb references. I need to pull the 5065 manual and take a look but injecting small amounts of first and second signals should make the meter tick upscale. I believe that is 137 and 274 hz. Its possible and I have seen this issues simply on the metering board. But want to approach it logically by eliminating the detector chain. Regards Paul On Thu, Nov 18, 2021 at 12:56 PM Jared Cabot via time-nuts < time-nuts@lists.febo.com> wrote: > Hi all, > > I have a 5065A Rubidium Standard that was working ok, but has lost the 2nd > harmonic. > My voltages are all ok, the physics package hasn't overheated and I have > replaced the usual resistors on the lamp assembly (and it was running fine > afterward for a while), the lamp illuminates, and I've done the procedure > to remove cell flooding. > All readings on the 'circuit check' switch are nominal, apart from the 2nd > harmonic position. No matter what I do, I can no longer get it to raise > above 0. > However, when I first turn the unit on, the needle drops to 0 and flicks a > little before settling on 0 and staying there. > > Can someone help me get this unit up and running again? > > Thanks! > Jared_______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-leave@lists.febo.com > To unsubscribe, go to and follow the instructions there.

time-nuts@lists.febo.com

HP 5065A, no 2nd harmonic.