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DS

David Scott Coburn

Sun, Feb 19, 2017 10:41 PM

I have an HP5065A Rubidium Frequency Standard which is not working.

All of the oven temperatures look OK.
The power supply voltages look OK.
The ~60 MHz going into the RVFS package looks OK.
The 5.000 MHz and the ~5.315 MHz signals are within a few Hz. (The unit is running open loop only.)
The A7 AC amp looks to be working OK.
The A8 137/234 Hz signals look OK.
There is 20 VDC feeding the RVFS lamp oscillator.

But, there is no current coming from the photodiode. (Maybe a few picoamps of dark current, certainly not the expected ~50 microamps of DC, and no 137/234 Hz signals).

It seems the most likely problem is that the Rb lamp is not coming on. Maybe possible that the photodiode is faulty, or a broken wire, etc.

Any other possibilities I should check before setting off into the innards of the RVFS package?

Thanks in advance!

Cheers,

Scott

I have an HP5065A Rubidium Frequency Standard which is not working. All of the oven temperatures look OK. The power supply voltages look OK. The ~60 MHz going into the RVFS package looks OK. The 5.000 MHz and the ~5.315 MHz signals are within a few Hz. (The unit is running open loop only.) The A7 AC amp looks to be working OK. The A8 137/234 Hz signals look OK. There is 20 VDC feeding the RVFS lamp oscillator. But, there is no current coming from the photodiode. (Maybe a few picoamps of dark current, certainly not the expected ~50 microamps of DC, and no 137/234 Hz signals). It seems the most likely problem is that the Rb lamp is not coming on. Maybe possible that the photodiode is faulty, or a broken wire, etc. Any other possibilities I should check before setting off into the innards of the RVFS package? Thanks in advance! Cheers, Scott

BH

Bill Hawkins

Mon, Feb 20, 2017 3:51 AM

Well, if it was not working when you acquired it, the physics package
had probably reached the end of its life.

If it had been working recently and is not now, it might be repairable.

Others on this list know more about repairing than I.

Bill Hawkins

-----Original Message-----
From: David Scott Coburn
Sent: Sunday, February 19, 2017 4:42 PM

I have an HP5065A Rubidium Frequency Standard which is not working.

All of the oven temperatures look OK.
The power supply voltages look OK.
The ~60 MHz going into the RVFS package looks OK.
The 5.000 MHz and the ~5.315 MHz signals are within a few Hz. (The unit
is running open loop only.) The A7 AC amp looks to be working OK.
The A8 137/234 Hz signals look OK.
There is 20 VDC feeding the RVFS lamp oscillator.

But, there is no current coming from the photodiode. (Maybe a few
picoamps of dark current, certainly not the expected ~50 microamps of
DC, and no 137/234 Hz signals).

It seems the most likely problem is that the Rb lamp is not coming on.
Maybe possible that the photodiode is faulty, or a broken wire, etc.

Any other possibilities I should check before setting off into the
innards of the RVFS package?

Thanks in advance!

Cheers,

Scott

Well, if it was not working when you acquired it, the physics package had probably reached the end of its life. If it had been working recently and is not now, it might be repairable. Others on this list know more about repairing than I. Bill Hawkins -----Original Message----- From: David Scott Coburn Sent: Sunday, February 19, 2017 4:42 PM I have an HP5065A Rubidium Frequency Standard which is not working. All of the oven temperatures look OK. The power supply voltages look OK. The ~60 MHz going into the RVFS package looks OK. The 5.000 MHz and the ~5.315 MHz signals are within a few Hz. (The unit is running open loop only.) The A7 AC amp looks to be working OK. The A8 137/234 Hz signals look OK. There is 20 VDC feeding the RVFS lamp oscillator. But, there is no current coming from the photodiode. (Maybe a few picoamps of dark current, certainly not the expected ~50 microamps of DC, and no 137/234 Hz signals). It seems the most likely problem is that the Rb lamp is not coming on. Maybe possible that the photodiode is faulty, or a broken wire, etc. Any other possibilities I should check before setting off into the innards of the RVFS package? Thanks in advance! Cheers, Scott

T

timeok

Mon, Feb 20, 2017 6:47 AM

Hi Scott,
I have never find a photodiode faulty. When applied 20 volts to the lamp it should come on within about 10 seconds, and the PHOTO I meter on the panel will be between 20 and 50. If this does not happen the most probable failure is the resistance R1 on the lamp board (1330ohm 2W). In this case, I suggest you replace it with two 2700-ohm 1W resistors in parallel.

Other faults that I found were: the broken transistor Q1 and the exciter coil detached from one side, but these failure are very rare.
let me know,
regards,
Luciano

There is 20 VDC feeding the RVFS lamp oscillator.

But, there is no current coming from the photodiode. (Maybe a few picoamps of dark current, certainly not the expected ~50 microamps of DC, and no 137/234 Hz signals).

It seems the most likely problem is that the Rb lamp is not coming on. Maybe possible that the photodiode is faulty, or a broken wire, etc.

Hi Scott, I have never find a photodiode faulty. When applied 20 volts to the lamp it should come on within about 10 seconds, and the PHOTO I meter on the panel will be between 20 and 50. If this does not happen the most probable failure is the resistance R1 on the lamp board (1330ohm 2W). In this case, I suggest you replace it with two 2700-ohm 1W resistors in parallel. Other faults that I found were: the broken transistor Q1 and the exciter coil detached from one side, but these failure are very rare. let me know, regards, Luciano There is 20 VDC feeding the RVFS lamp oscillator. But, there is no current coming from the photodiode. (Maybe a few picoamps of dark current, certainly not the expected ~50 microamps of DC, and no 137/234 Hz signals). It seems the most likely problem is that the Rb lamp is not coming on. Maybe possible that the photodiode is faulty, or a broken wire, etc.

PS

paul swed

Mon, Feb 20, 2017 2:14 PM

Scott do not know if anyone responded to you. Looks like a lot is working.
But the devil is in the details. On the lamp measure the current feeding
the lamp oscillator.
That may give you a hint thats its running. If its 15 ma then most likely
its not oscillating.
Would be good to know what tools you have available also.
Regards
Paul
WB8TSL

On Sun, Feb 19, 2017 at 5:41 PM, David Scott Coburn scotttt@optonline.net
wrote:

I have an HP5065A Rubidium Frequency Standard which is not working.

All of the oven temperatures look OK.
The power supply voltages look OK.
The ~60 MHz going into the RVFS package looks OK.
The 5.000 MHz and the ~5.315 MHz signals are within a few Hz. (The unit
is running open loop only.)
The A7 AC amp looks to be working OK.
The A8 137/234 Hz signals look OK.
There is 20 VDC feeding the RVFS lamp oscillator.

But, there is no current coming from the photodiode. (Maybe a few
picoamps of dark current, certainly not the expected ~50 microamps of DC,
and no 137/234 Hz signals).

It seems the most likely problem is that the Rb lamp is not coming on.
Maybe possible that the photodiode is faulty, or a broken wire, etc.

Any other possibilities I should check before setting off into the innards
of the RVFS package?

Thanks in advance!

Cheers,

Scott

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.

Scott do not know if anyone responded to you. Looks like a lot is working. But the devil is in the details. On the lamp measure the current feeding the lamp oscillator. That may give you a hint thats its running. If its 15 ma then most likely its not oscillating. Would be good to know what tools you have available also. Regards Paul WB8TSL On Sun, Feb 19, 2017 at 5:41 PM, David Scott Coburn <scotttt@optonline.net> wrote: > I have an HP5065A Rubidium Frequency Standard which is not working. > > All of the oven temperatures look OK. > The power supply voltages look OK. > The ~60 MHz going into the RVFS package looks OK. > The 5.000 MHz and the ~5.315 MHz signals are within a few Hz. (The unit > is running open loop only.) > The A7 AC amp looks to be working OK. > The A8 137/234 Hz signals look OK. > There is 20 VDC feeding the RVFS lamp oscillator. > > But, there is no current coming from the photodiode. (Maybe a few > picoamps of dark current, certainly not the expected ~50 microamps of DC, > and no 137/234 Hz signals). > > It seems the most likely problem is that the Rb lamp is not coming on. > Maybe possible that the photodiode is faulty, or a broken wire, etc. > > Any other possibilities I should check before setting off into the innards > of the RVFS package? > > Thanks in advance! > > Cheers, > > Scott > _______________________________________________ > 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. >

SM

Scott McGrath

Mon, Feb 20, 2017 4:11 PM

Get the manual because if it's been off a long time the RB migrates out of the reservoir and coats the bulb so light does not escape

There is a built in 'cold trap' which is used to return the Rb to the reservoir

Using this is version specific and you need a good power supply as you can damage the Rb assembly if done incorrectly

Luciano's recommended steps should be checked first though

On Feb 20, 2017, at 1:47 AM, timeok timeok@timeok.it wrote:

Hi Scott,
I have never find a photodiode faulty. When applied 20 volts to the lamp it should come on within about 10 seconds, and the PHOTO I meter on the panel will be between 20 and 50. If this does not happen the most probable failure is the resistance R1 on the lamp board (1330ohm 2W). In this case, I suggest you replace it with two 2700-ohm 1W resistors in parallel.

Other faults that I found were: the broken transistor Q1 and the exciter coil detached from one side, but these failure are very rare.
let me know,
regards,
Luciano

There is 20 VDC feeding the RVFS lamp oscillator.

But, there is no current coming from the photodiode. (Maybe a few picoamps of dark current, certainly not the expected ~50 microamps of DC, and no 137/234 Hz signals).

It seems the most likely problem is that the Rb lamp is not coming on. Maybe possible that the photodiode is faulty, or a broken wire, etc.

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.

Get the manual because if it's been off a long time the RB migrates out of the reservoir and coats the bulb so light does not escape There is a built in 'cold trap' which is used to return the Rb to the reservoir Using this is version specific and you need a good power supply as you can damage the Rb assembly if done incorrectly Luciano's recommended steps should be checked first though > On Feb 20, 2017, at 1:47 AM, timeok <timeok@timeok.it> wrote: > > > Hi Scott, > I have never find a photodiode faulty. When applied 20 volts to the lamp it should come on within about 10 seconds, and the PHOTO I meter on the panel will be between 20 and 50. If this does not happen the most probable failure is the resistance R1 on the lamp board (1330ohm 2W). In this case, I suggest you replace it with two 2700-ohm 1W resistors in parallel. > > Other faults that I found were: the broken transistor Q1 and the exciter coil detached from one side, but these failure are very rare. > let me know, > regards, > Luciano > > There is 20 VDC feeding the RVFS lamp oscillator. > > But, there is no current coming from the photodiode. (Maybe a few picoamps of dark current, certainly not the expected ~50 microamps of DC, and no 137/234 Hz signals). > > It seems the most likely problem is that the Rb lamp is not coming on. Maybe possible that the photodiode is faulty, or a broken wire, etc. > _______________________________________________ > 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 Rubidium question