DK
David Kirkby
Sun, Sep 10, 2023 4:19 PM
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
I thought that one of the 100 uF 400 V capacitors after the rectifier might
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same for
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know there
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
I thought that one of the 100 uF 400 V capacitors after the rectifier might
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same for
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know there
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT
WB
Wilko Bulte
Sun, Sep 10, 2023 8:57 PM
Wild guess here, this sounds to me like a coil "whistling". Maybe there is an inductor or transformer that lost its potting compound, or has somehow come loose from its fittings?
best,
Wilko
On 10 Sep 2023, at 21:24, David Kirkby via time-nuts time-nuts@lists.febo.com wrote:
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
I thought that one of the 100 uF 400 V capacitors after the rectifier might
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same for
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know there
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Wild guess here, this sounds to me like a coil "whistling". Maybe there is an inductor or transformer that lost its potting compound, or has somehow come loose from its fittings?
best,
Wilko
> On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <time-nuts@lists.febo.com> wrote:
>
> After about 6 months of being powered off, I switched on my GPS receiver
> yesterday. The PSU is buzzing quite loudly. Sound file at
>
> https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
>
> I thought that one of the 100 uF 400 V capacitors after the rectifier might
> be bulging, although I was unsure. The capacitance measures okay, and the
> ESR is below that of anything I can buy that will physically fit. Same for
> the 47 uF 400 V capacitor. These were both measured out of circuit, using
> an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
> have 50 Hz mains here in the UK, as data normally seems to be provided on
> capacitors at 120 Hz.
>
> Has anyone experienced this before? I believe that someone wrote here, or
> might have been elsewhere, that the GPS receiver was pushing one of the
> supplies to the limit, and another one was not loaded enough. I know there
> was some mention of converting it to run from a linear supply, although I
> think that would be physically larger, so not fit in the case.
>
>
> --
> Dr David Kirkby Ph.D
> Kirkby Microwave Ltd
> Email: drkirkby@kirkbymicrowave.co.uk
> Web: https://www.kirkbymicrowave.co.uk/
> Telephone 07910 441670 (UK) or +44 7910 441670 (international)
> Registered in England and Wales, company number 08914892.
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
MH
Matt Huszagh
Mon, Sep 11, 2023 2:01 AM
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
I thought that one of the 100 uF 400 V capacitors after the rectifier might
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same for
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know there
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT
https://www.google.com/maps/search/Burnham+Rd,+Althorne,+Essex,+CM3+6DT?entry=gmail&source=g
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
I experienced a buzzing in a polyester cap in a 6114A. That cap was totally
fine, but the buzzing annoyed me and a replaced it. You can read about it
here:
https://groups.io/g/HP-Agilent-Keysight-equipment/topic/95761333#131192
It sounds like your buzzing is a bit worse though. Good luck tracking it
down.
Matt
On Sun, Sep 10, 2023 at 1:41 PM David Kirkby via time-nuts <
time-nuts@lists.febo.com> wrote:
> After about 6 months of being powered off, I switched on my GPS receiver
> yesterday. The PSU is buzzing quite loudly. Sound file at
>
>
> https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
>
> I thought that one of the 100 uF 400 V capacitors after the rectifier might
> be bulging, although I was unsure. The capacitance measures okay, and the
> ESR is below that of anything I can buy that will physically fit. Same for
> the 47 uF 400 V capacitor. These were both measured out of circuit, using
> an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
> have 50 Hz mains here in the UK, as data normally seems to be provided on
> capacitors at 120 Hz.
>
> Has anyone experienced this before? I believe that someone wrote here, or
> might have been elsewhere, that the GPS receiver was pushing one of the
> supplies to the limit, and another one was not loaded enough. I know there
> was some mention of converting it to run from a linear supply, although I
> think that would be physically larger, so not fit in the case.
>
>
> --
> Dr David Kirkby Ph.D
> Kirkby Microwave Ltd
> Email: drkirkby@kirkbymicrowave.co.uk
> Web: https://www.kirkbymicrowave.co.uk/
> Telephone 07910 441670 (UK) or +44 7910 441670 (international)
> Registered in England and Wales, company number 08914892.
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT
> <https://www.google.com/maps/search/Burnham+Rd,+Althorne,+Essex,+CM3+6DT?entry=gmail&source=g>
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>
EM
Ed Marciniak
Mon, Sep 11, 2023 2:31 AM
I don’t have one of those units, but switching power supplies under certain load conditions can have subharmonic oscillations that happen to fall in the audible frequency range. Absent an overload from a shorter capacitor or similar, I’d take a hard look at whether there are capacitors that no longer meet their ESR specifications and/or have cold solder joints effectively removing them from the circuit.
From: Wilko Bulte via time-nuts time-nuts@lists.febo.com
Sent: Sunday, September 10, 2023 3:57:06 PM
To: Discussion of precise time and frequency measurement time-nuts@lists.febo.com
Cc: Wilko Bulte wkb@xs4all.nl
Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
Wild guess here, this sounds to me like a coil "whistling". Maybe there is an inductor or transformer that lost its potting compound, or has somehow come loose from its fittings?
best,
Wilko
On 10 Sep 2023, at 21:24, David Kirkby via time-nuts time-nuts@lists.febo.com wrote:
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
I thought that one of the 100 uF 400 V capacitors after the rectifier might
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same for
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know there
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
I don’t have one of those units, but switching power supplies under certain load conditions can have subharmonic oscillations that happen to fall in the audible frequency range. Absent an overload from a shorter capacitor or similar, I’d take a hard look at whether there are capacitors that no longer meet their ESR specifications and/or have cold solder joints effectively removing them from the circuit.
________________________________
From: Wilko Bulte via time-nuts <time-nuts@lists.febo.com>
Sent: Sunday, September 10, 2023 3:57:06 PM
To: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com>
Cc: Wilko Bulte <wkb@xs4all.nl>
Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
Wild guess here, this sounds to me like a coil "whistling". Maybe there is an inductor or transformer that lost its potting compound, or has somehow come loose from its fittings?
best,
Wilko
> On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <time-nuts@lists.febo.com> wrote:
>
> After about 6 months of being powered off, I switched on my GPS receiver
> yesterday. The PSU is buzzing quite loudly. Sound file at
>
> https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
>
> I thought that one of the 100 uF 400 V capacitors after the rectifier might
> be bulging, although I was unsure. The capacitance measures okay, and the
> ESR is below that of anything I can buy that will physically fit. Same for
> the 47 uF 400 V capacitor. These were both measured out of circuit, using
> an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
> have 50 Hz mains here in the UK, as data normally seems to be provided on
> capacitors at 120 Hz.
>
> Has anyone experienced this before? I believe that someone wrote here, or
> might have been elsewhere, that the GPS receiver was pushing one of the
> supplies to the limit, and another one was not loaded enough. I know there
> was some mention of converting it to run from a linear supply, although I
> think that would be physically larger, so not fit in the case.
>
>
> --
> Dr David Kirkby Ph.D
> Kirkby Microwave Ltd
> Email: drkirkby@kirkbymicrowave.co.uk
> Web: https://www.kirkbymicrowave.co.uk/
> Telephone 07910 441670 (UK) or +44 7910 441670 (international)
> Registered in England and Wales, company number 08914892.
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
AG
Adrian Godwin
Mon, Sep 11, 2023 8:10 AM
I don't have a 58503A but I do have some RFTG-u which I understand to be
quite similar. I'm not sure if that extends to the power supply
architecture. Do they just have an integral mains power supply before a
Lucent DC-DC converter ?
I had one fail due to a tantalum capacitor downstream of the DC-DC
converter. It didn't shut down the DC-DC but it did cause it to take a
heavy incoming current resulting in the literal melting (and subsequent
mains breaker cutout) of a cheap power brick that was being used to provide
24V.
So, the mains part of the supply might be running at an overcurrent without
shutting down.
Replacing the tant (and the power brick) fixed it without any other damage.
On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
time-nuts@lists.febo.com> wrote:
I don’t have one of those units, but switching power supplies under
certain load conditions can have subharmonic oscillations that happen to
fall in the audible frequency range. Absent an overload from a shorter
capacitor or similar, I’d take a hard look at whether there are capacitors
that no longer meet their ESR specifications and/or have cold solder joints
effectively removing them from the circuit.
From: Wilko Bulte via time-nuts time-nuts@lists.febo.com
Sent: Sunday, September 10, 2023 3:57:06 PM
To: Discussion of precise time and frequency measurement <
time-nuts@lists.febo.com>
Cc: Wilko Bulte wkb@xs4all.nl
Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
Wild guess here, this sounds to me like a coil "whistling". Maybe there is
an inductor or transformer that lost its potting compound, or has somehow
come loose from its fittings?
best,
Wilko
On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
I thought that one of the 100 uF 400 V capacitors after the rectifier
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
I don't have a 58503A but I do have some RFTG-u which I understand to be
quite similar. I'm not sure if that extends to the power supply
architecture. Do they just have an integral mains power supply before a
Lucent DC-DC converter ?
I had one fail due to a tantalum capacitor downstream of the DC-DC
converter. It didn't shut down the DC-DC but it did cause it to take a
heavy incoming current resulting in the literal melting (and subsequent
mains breaker cutout) of a cheap power brick that was being used to provide
24V.
So, the mains part of the supply might be running at an overcurrent without
shutting down.
Replacing the tant (and the power brick) fixed it without any other damage.
On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
time-nuts@lists.febo.com> wrote:
> I don’t have one of those units, but switching power supplies under
> certain load conditions can have subharmonic oscillations that happen to
> fall in the audible frequency range. Absent an overload from a shorter
> capacitor or similar, I’d take a hard look at whether there are capacitors
> that no longer meet their ESR specifications and/or have cold solder joints
> effectively removing them from the circuit.
> ________________________________
> From: Wilko Bulte via time-nuts <time-nuts@lists.febo.com>
> Sent: Sunday, September 10, 2023 3:57:06 PM
> To: Discussion of precise time and frequency measurement <
> time-nuts@lists.febo.com>
> Cc: Wilko Bulte <wkb@xs4all.nl>
> Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
>
> Wild guess here, this sounds to me like a coil "whistling". Maybe there is
> an inductor or transformer that lost its potting compound, or has somehow
> come loose from its fittings?
>
> best,
> Wilko
>
> > On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
> time-nuts@lists.febo.com> wrote:
> >
> > After about 6 months of being powered off, I switched on my GPS receiver
> > yesterday. The PSU is buzzing quite loudly. Sound file at
> >
> >
> https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
> >
> > I thought that one of the 100 uF 400 V capacitors after the rectifier
> might
> > be bulging, although I was unsure. The capacitance measures okay, and the
> > ESR is below that of anything I can buy that will physically fit. Same
> for
> > the 47 uF 400 V capacitor. These were both measured out of circuit, using
> > an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
> > have 50 Hz mains here in the UK, as data normally seems to be provided on
> > capacitors at 120 Hz.
> >
> > Has anyone experienced this before? I believe that someone wrote here, or
> > might have been elsewhere, that the GPS receiver was pushing one of the
> > supplies to the limit, and another one was not loaded enough. I know
> there
> > was some mention of converting it to run from a linear supply, although I
> > think that would be physically larger, so not fit in the case.
> >
> >
> > --
> > Dr David Kirkby Ph.D
> > Kirkby Microwave Ltd
> > Email: drkirkby@kirkbymicrowave.co.uk
> > Web: https://www.kirkbymicrowave.co.uk/
> > Telephone 07910 441670 (UK) or +44 7910 441670 (international)
> > Registered in England and Wales, company number 08914892.
> > Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
> 6DT
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
JL
Jim Lux
Mon, Sep 11, 2023 8:20 PM
Instability in a switching regulator faced with a capacitive load isn't unusual. So if the mains supply is a switcher, it might not be stable into the actual load. So a input capacitor (or the equivalent input capacitance from the input of a downstream switcher) that changes, either up or down, can destabilize the upstream switcher.
I'd point out that this is something that is quite tricky in real life - tools like LT Spice, or the tools provided by the mfrs can help, but ultimately, it's "breadboard it and measure it." Especially since capacitors have significantly wide tolerance bands.
On Mon, 11 Sep 2023 09:10:08 +0100, Adrian Godwin via time-nuts time-nuts@lists.febo.com wrote:
I don't have a 58503A but I do have some RFTG-u which I understand to be
quite similar. I'm not sure if that extends to the power supply
architecture. Do they just have an integral mains power supply before a
Lucent DC-DC converter ?
I had one fail due to a tantalum capacitor downstream of the DC-DC
converter. It didn't shut down the DC-DC but it did cause it to take a
heavy incoming current resulting in the literal melting (and subsequent
mains breaker cutout) of a cheap power brick that was being used to provide
24V.
So, the mains part of the supply might be running at an overcurrent without
shutting down.
Replacing the tant (and the power brick) fixed it without any other damage.
On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
time-nuts@lists.febo.com> wrote:
I don’t have one of those units, but switching power supplies under
certain load conditions can have subharmonic oscillations that happen to
fall in the audible frequency range. Absent an overload from a shorter
capacitor or similar, I’d take a hard look at whether there are capacitors
that no longer meet their ESR specifications and/or have cold solder joints
effectively removing them from the circuit.
From: Wilko Bulte via time-nuts
Sent: Sunday, September 10, 2023 3:57:06 PM
To: Discussion of precise time and frequency measurement <
time-nuts@lists.febo.com>
Cc: Wilko Bulte
Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
Wild guess here, this sounds to me like a coil "whistling". Maybe there is
an inductor or transformer that lost its potting compound, or has somehow
come loose from its fittings?
best,
Wilko
On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
I thought that one of the 100 uF 400 V capacitors after the rectifier
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
Instability in a switching regulator faced with a capacitive load isn't unusual. So if the mains supply is a switcher, it might not be stable into the actual load. So a input capacitor (or the equivalent input capacitance from the input of a downstream switcher) that changes, either up or down, can destabilize the upstream switcher.
I'd point out that this is something that is quite tricky in real life - tools like LT Spice, or the tools provided by the mfrs can help, but ultimately, it's "breadboard it and measure it." Especially since capacitors have significantly wide tolerance bands.
On Mon, 11 Sep 2023 09:10:08 +0100, Adrian Godwin via time-nuts <time-nuts@lists.febo.com> wrote:
I don't have a 58503A but I do have some RFTG-u which I understand to be
quite similar. I'm not sure if that extends to the power supply
architecture. Do they just have an integral mains power supply before a
Lucent DC-DC converter ?
I had one fail due to a tantalum capacitor downstream of the DC-DC
converter. It didn't shut down the DC-DC but it did cause it to take a
heavy incoming current resulting in the literal melting (and subsequent
mains breaker cutout) of a cheap power brick that was being used to provide
24V.
So, the mains part of the supply might be running at an overcurrent without
shutting down.
Replacing the tant (and the power brick) fixed it without any other damage.
On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
time-nuts@lists.febo.com> wrote:
> I don’t have one of those units, but switching power supplies under
> certain load conditions can have subharmonic oscillations that happen to
> fall in the audible frequency range. Absent an overload from a shorter
> capacitor or similar, I’d take a hard look at whether there are capacitors
> that no longer meet their ESR specifications and/or have cold solder joints
> effectively removing them from the circuit.
> ________________________________
> From: Wilko Bulte via time-nuts
> Sent: Sunday, September 10, 2023 3:57:06 PM
> To: Discussion of precise time and frequency measurement <
> time-nuts@lists.febo.com>
> Cc: Wilko Bulte
> Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
>
> Wild guess here, this sounds to me like a coil "whistling". Maybe there is
> an inductor or transformer that lost its potting compound, or has somehow
> come loose from its fittings?
>
> best,
> Wilko
>
> > On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
> time-nuts@lists.febo.com> wrote:
> >
> > After about 6 months of being powered off, I switched on my GPS receiver
> > yesterday. The PSU is buzzing quite loudly. Sound file at
> >
> >
> https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
> >
> > I thought that one of the 100 uF 400 V capacitors after the rectifier
> might
> > be bulging, although I was unsure. The capacitance measures okay, and the
> > ESR is below that of anything I can buy that will physically fit. Same
> for
> > the 47 uF 400 V capacitor. These were both measured out of circuit, using
> > an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
> > have 50 Hz mains here in the UK, as data normally seems to be provided on
> > capacitors at 120 Hz.
> >
> > Has anyone experienced this before? I believe that someone wrote here, or
> > might have been elsewhere, that the GPS receiver was pushing one of the
> > supplies to the limit, and another one was not loaded enough. I know
> there
> > was some mention of converting it to run from a linear supply, although I
> > think that would be physically larger, so not fit in the case.
> >
> >
> > --
> > Dr David Kirkby Ph.D
> > Kirkby Microwave Ltd
> > Email: drkirkby@kirkbymicrowave.co.uk
> > Web: https://www.kirkbymicrowave.co.uk/
> > Telephone 07910 441670 (UK) or +44 7910 441670 (international)
> > Registered in England and Wales, company number 08914892.
> > Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
> 6DT
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
JS
jung.schorndorf@t-online.de
Mon, Sep 11, 2023 9:01 PM
Hello time and frequency standard owners,
a similar problem, tap Power Transformer ...
my power supply MPS in the device MFS (Modular Frequency Systems) from EFRATOM-DATUM_SYMMETRICOM has plagued me with a hum noise
for many months. When it stopped working and I opened it, the power transformer turned out with a turn damage (photo) and totally corroded - in laboratory conditions!
I can also operate the device externally with 24V DC. However, I would like to replace the unavailable original transformer,
but have not seen any transformer data (U, I) because missing documents. Because winding interruption I can not measure it either.
In the data sheets I only find different DC data (20.5V DC, 23-33V DC, 40 W, 55 W ??).
The transformer had 2 AC outputs on the secondary side.
I have only a few inserts and do not need the theoretical 200 VA max. power.
Does anyone in the US still have circuits? The German branch has nothing more.
Thanks for info
Helmut
-----Ursprüngliche Nachricht-----
Von: Adrian Godwin via time-nuts time-nuts@lists.febo.com
Gesendet: Montag, 11. September 2023 10:10
An: Discussion of precise time and frequency measurement time-nuts@lists.febo.com
Cc: Adrian Godwin artgodwin@gmail.com
Betreff: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
I don't have a 58503A but I do have some RFTG-u which I understand to be
quite similar. I'm not sure if that extends to the power supply
architecture. Do they just have an integral mains power supply before a
Lucent DC-DC converter ?
I had one fail due to a tantalum capacitor downstream of the DC-DC
converter. It didn't shut down the DC-DC but it did cause it to take a
heavy incoming current resulting in the literal melting (and subsequent
mains breaker cutout) of a cheap power brick that was being used to provide
24V.
So, the mains part of the supply might be running at an overcurrent without
shutting down.
Replacing the tant (and the power brick) fixed it without any other damage.
On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
time-nuts@lists.febo.com> wrote:
I don’t have one of those units, but switching power supplies under
certain load conditions can have subharmonic oscillations that happen to
fall in the audible frequency range. Absent an overload from a shorter
capacitor or similar, I’d take a hard look at whether there are capacitors
that no longer meet their ESR specifications and/or have cold solder joints
effectively removing them from the circuit.
From: Wilko Bulte via time-nuts time-nuts@lists.febo.com
Sent: Sunday, September 10, 2023 3:57:06 PM
To: Discussion of precise time and frequency measurement <
time-nuts@lists.febo.com>
Cc: Wilko Bulte wkb@xs4all.nl
Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
Wild guess here, this sounds to me like a coil "whistling". Maybe there is
an inductor or transformer that lost its potting compound, or has somehow
come loose from its fittings?
best,
Wilko
On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
I thought that one of the 100 uF 400 V capacitors after the rectifier
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
Hello time and frequency standard owners,
a similar problem, tap Power Transformer ...
my power supply MPS in the device MFS (Modular Frequency Systems) from EFRATOM-DATUM_SYMMETRICOM has plagued me with a hum noise
for many months. When it stopped working and I opened it, the power transformer turned out with a turn damage (photo) and totally corroded - in laboratory conditions!
I can also operate the device externally with 24V DC. However, I would like to replace the unavailable original transformer,
but have not seen any transformer data (U, I) because missing documents. Because winding interruption I can not measure it either.
In the data sheets I only find different DC data (20.5V DC, 23-33V DC, 40 W, 55 W ??).
The transformer had 2 AC outputs on the secondary side.
I have only a few inserts and do not need the theoretical 200 VA max. power.
Does anyone in the US still have circuits? The German branch has nothing more.
Thanks for info
Helmut
-----Ursprüngliche Nachricht-----
Von: Adrian Godwin via time-nuts <time-nuts@lists.febo.com>
Gesendet: Montag, 11. September 2023 10:10
An: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com>
Cc: Adrian Godwin <artgodwin@gmail.com>
Betreff: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
I don't have a 58503A but I do have some RFTG-u which I understand to be
quite similar. I'm not sure if that extends to the power supply
architecture. Do they just have an integral mains power supply before a
Lucent DC-DC converter ?
I had one fail due to a tantalum capacitor downstream of the DC-DC
converter. It didn't shut down the DC-DC but it did cause it to take a
heavy incoming current resulting in the literal melting (and subsequent
mains breaker cutout) of a cheap power brick that was being used to provide
24V.
So, the mains part of the supply might be running at an overcurrent without
shutting down.
Replacing the tant (and the power brick) fixed it without any other damage.
On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
time-nuts@lists.febo.com> wrote:
> I don’t have one of those units, but switching power supplies under
> certain load conditions can have subharmonic oscillations that happen to
> fall in the audible frequency range. Absent an overload from a shorter
> capacitor or similar, I’d take a hard look at whether there are capacitors
> that no longer meet their ESR specifications and/or have cold solder joints
> effectively removing them from the circuit.
> ________________________________
> From: Wilko Bulte via time-nuts <time-nuts@lists.febo.com>
> Sent: Sunday, September 10, 2023 3:57:06 PM
> To: Discussion of precise time and frequency measurement <
> time-nuts@lists.febo.com>
> Cc: Wilko Bulte <wkb@xs4all.nl>
> Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
>
> Wild guess here, this sounds to me like a coil "whistling". Maybe there is
> an inductor or transformer that lost its potting compound, or has somehow
> come loose from its fittings?
>
> best,
> Wilko
>
> > On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
> time-nuts@lists.febo.com> wrote:
> >
> > After about 6 months of being powered off, I switched on my GPS receiver
> > yesterday. The PSU is buzzing quite loudly. Sound file at
> >
> >
> https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
> >
> > I thought that one of the 100 uF 400 V capacitors after the rectifier
> might
> > be bulging, although I was unsure. The capacitance measures okay, and the
> > ESR is below that of anything I can buy that will physically fit. Same
> for
> > the 47 uF 400 V capacitor. These were both measured out of circuit, using
> > an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
> > have 50 Hz mains here in the UK, as data normally seems to be provided on
> > capacitors at 120 Hz.
> >
> > Has anyone experienced this before? I believe that someone wrote here, or
> > might have been elsewhere, that the GPS receiver was pushing one of the
> > supplies to the limit, and another one was not loaded enough. I know
> there
> > was some mention of converting it to run from a linear supply, although I
> > think that would be physically larger, so not fit in the case.
> >
> >
> > --
> > Dr David Kirkby Ph.D
> > Kirkby Microwave Ltd
> > Email: drkirkby@kirkbymicrowave.co.uk
> > Web: https://www.kirkbymicrowave.co.uk/
> > Telephone 07910 441670 (UK) or +44 7910 441670 (international)
> > Registered in England and Wales, company number 08914892.
> > Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
> 6DT
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
TK
Tom Knox
Tue, Sep 12, 2023 12:31 AM
I would bet it is the cap and possibly semiconductor on the front right of the main board, not the main supply.
Hope that helps.
Cheers;
Tom Knox
SR Test and Measurement Engineer
Phoenix Research
4870 Meredith Way Apt 102
Boulder, Co 80303
Formerly of:
357 Fox Lane
Superior Co 80027
303-554-0307
actast@hotmail.com
https://www.thedenverchannel.com/news/marshall-fire/superior-man-moving-forward-after-losing-dream-research-lab-during-marshall-fire
"Peace is not the absence of violence, but the presence of Justice" Both MLK and Albert Einstein
From: Jim Lux via time-nuts time-nuts@lists.febo.com
Sent: Monday, September 11, 2023 2:20 PM
To: time-nuts@lists.febo.com time-nuts@lists.febo.com
Cc: Jim Lux jim@luxfamily.com
Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
Instability in a switching regulator faced with a capacitive load isn't unusual. So if the mains supply is a switcher, it might not be stable into the actual load. So a input capacitor (or the equivalent input capacitance from the input of a downstream switcher) that changes, either up or down, can destabilize the upstream switcher.
I'd point out that this is something that is quite tricky in real life - tools like LT Spice, or the tools provided by the mfrs can help, but ultimately, it's "breadboard it and measure it." Especially since capacitors have significantly wide tolerance bands.
On Mon, 11 Sep 2023 09:10:08 +0100, Adrian Godwin via time-nuts time-nuts@lists.febo.com wrote:
I don't have a 58503A but I do have some RFTG-u which I understand to be
quite similar. I'm not sure if that extends to the power supply
architecture. Do they just have an integral mains power supply before a
Lucent DC-DC converter ?
I had one fail due to a tantalum capacitor downstream of the DC-DC
converter. It didn't shut down the DC-DC but it did cause it to take a
heavy incoming current resulting in the literal melting (and subsequent
mains breaker cutout) of a cheap power brick that was being used to provide
24V.
So, the mains part of the supply might be running at an overcurrent without
shutting down.
Replacing the tant (and the power brick) fixed it without any other damage.
On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
time-nuts@lists.febo.com> wrote:
I don’t have one of those units, but switching power supplies under
certain load conditions can have subharmonic oscillations that happen to
fall in the audible frequency range. Absent an overload from a shorter
capacitor or similar, I’d take a hard look at whether there are capacitors
that no longer meet their ESR specifications and/or have cold solder joints
effectively removing them from the circuit.
From: Wilko Bulte via time-nuts
Sent: Sunday, September 10, 2023 3:57:06 PM
To: Discussion of precise time and frequency measurement <
time-nuts@lists.febo.com>
Cc: Wilko Bulte
Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
Wild guess here, this sounds to me like a coil "whistling". Maybe there is
an inductor or transformer that lost its potting compound, or has somehow
come loose from its fittings?
best,
Wilko
On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
I thought that one of the 100 uF 400 V capacitors after the rectifier
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
I would bet it is the cap and possibly semiconductor on the front right of the main board, not the main supply.
Hope that helps.
Cheers;
Tom Knox
SR Test and Measurement Engineer
Phoenix Research
4870 Meredith Way Apt 102
Boulder, Co 80303
Formerly of:
357 Fox Lane
Superior Co 80027
303-554-0307
actast@hotmail.com
https://www.thedenverchannel.com/news/marshall-fire/superior-man-moving-forward-after-losing-dream-research-lab-during-marshall-fire
"Peace is not the absence of violence, but the presence of Justice" Both MLK and Albert Einstein
________________________________
From: Jim Lux via time-nuts <time-nuts@lists.febo.com>
Sent: Monday, September 11, 2023 2:20 PM
To: time-nuts@lists.febo.com <time-nuts@lists.febo.com>
Cc: Jim Lux <jim@luxfamily.com>
Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
Instability in a switching regulator faced with a capacitive load isn't unusual. So if the mains supply is a switcher, it might not be stable into the actual load. So a input capacitor (or the equivalent input capacitance from the input of a downstream switcher) that changes, either up or down, can destabilize the upstream switcher.
I'd point out that this is something that is quite tricky in real life - tools like LT Spice, or the tools provided by the mfrs can help, but ultimately, it's "breadboard it and measure it." Especially since capacitors have significantly wide tolerance bands.
On Mon, 11 Sep 2023 09:10:08 +0100, Adrian Godwin via time-nuts <time-nuts@lists.febo.com> wrote:
I don't have a 58503A but I do have some RFTG-u which I understand to be
quite similar. I'm not sure if that extends to the power supply
architecture. Do they just have an integral mains power supply before a
Lucent DC-DC converter ?
I had one fail due to a tantalum capacitor downstream of the DC-DC
converter. It didn't shut down the DC-DC but it did cause it to take a
heavy incoming current resulting in the literal melting (and subsequent
mains breaker cutout) of a cheap power brick that was being used to provide
24V.
So, the mains part of the supply might be running at an overcurrent without
shutting down.
Replacing the tant (and the power brick) fixed it without any other damage.
On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
time-nuts@lists.febo.com> wrote:
> I don’t have one of those units, but switching power supplies under
> certain load conditions can have subharmonic oscillations that happen to
> fall in the audible frequency range. Absent an overload from a shorter
> capacitor or similar, I’d take a hard look at whether there are capacitors
> that no longer meet their ESR specifications and/or have cold solder joints
> effectively removing them from the circuit.
> ________________________________
> From: Wilko Bulte via time-nuts
> Sent: Sunday, September 10, 2023 3:57:06 PM
> To: Discussion of precise time and frequency measurement <
> time-nuts@lists.febo.com>
> Cc: Wilko Bulte
> Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
>
> Wild guess here, this sounds to me like a coil "whistling". Maybe there is
> an inductor or transformer that lost its potting compound, or has somehow
> come loose from its fittings?
>
> best,
> Wilko
>
> > On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
> time-nuts@lists.febo.com> wrote:
> >
> > After about 6 months of being powered off, I switched on my GPS receiver
> > yesterday. The PSU is buzzing quite loudly. Sound file at
> >
> >
> https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
> >
> > I thought that one of the 100 uF 400 V capacitors after the rectifier
> might
> > be bulging, although I was unsure. The capacitance measures okay, and the
> > ESR is below that of anything I can buy that will physically fit. Same
> for
> > the 47 uF 400 V capacitor. These were both measured out of circuit, using
> > an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
> > have 50 Hz mains here in the UK, as data normally seems to be provided on
> > capacitors at 120 Hz.
> >
> > Has anyone experienced this before? I believe that someone wrote here, or
> > might have been elsewhere, that the GPS receiver was pushing one of the
> > supplies to the limit, and another one was not loaded enough. I know
> there
> > was some mention of converting it to run from a linear supply, although I
> > think that would be physically larger, so not fit in the case.
> >
> >
> > --
> > Dr David Kirkby Ph.D
> > Kirkby Microwave Ltd
> > Email: drkirkby@kirkbymicrowave.co.uk
> > Web: https://www.kirkbymicrowave.co.uk/
> > Telephone 07910 441670 (UK) or +44 7910 441670 (international)
> > Registered in England and Wales, company number 08914892.
> > Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
> 6DT
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
_______________________________________________
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
WB
Wilko Bulte
Tue, Sep 12, 2023 8:23 PM
hello Helmut,
Are you 100% sure the transformer is indeed dead? And, in other words, it is not a problem in the DC part 'behind' the transformer like a dead bridge rectifier, bulk cap or pass transistor? Are you certain you have open or short windings on the transformer?
The MPS transformer in my MFS system does not look better than yours, also some corrosion etc. That is not a reason perse for worry, mine works just fine.
Just my €0,02..
MfG,
Willo
On 12 Sep 2023, at 21:29, jung.schorndorf--- via time-nuts time-nuts@lists.febo.com wrote:
Hello time and frequency standard owners,
a similar problem, tap Power Transformer ...
my power supply MPS in the device MFS (Modular Frequency Systems) from EFRATOM-DATUM_SYMMETRICOM has plagued me with a hum noise
for many months. When it stopped working and I opened it, the power transformer turned out with a turn damage (photo) and totally corroded - in laboratory conditions!
I can also operate the device externally with 24V DC. However, I would like to replace the unavailable original transformer,
but have not seen any transformer data (U, I) because missing documents. Because winding interruption I can not measure it either.
In the data sheets I only find different DC data (20.5V DC, 23-33V DC, 40 W, 55 W ??).
The transformer had 2 AC outputs on the secondary side.
I have only a few inserts and do not need the theoretical 200 VA max. power.
Does anyone in the US still have circuits? The German branch has nothing more.
Thanks for info
Helmut
-----Ursprüngliche Nachricht-----
Von: Adrian Godwin via time-nuts time-nuts@lists.febo.com
Gesendet: Montag, 11. September 2023 10:10
An: Discussion of precise time and frequency measurement time-nuts@lists.febo.com
Cc: Adrian Godwin artgodwin@gmail.com
Betreff: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
I don't have a 58503A but I do have some RFTG-u which I understand to be
quite similar. I'm not sure if that extends to the power supply
architecture. Do they just have an integral mains power supply before a
Lucent DC-DC converter ?
I had one fail due to a tantalum capacitor downstream of the DC-DC
converter. It didn't shut down the DC-DC but it did cause it to take a
heavy incoming current resulting in the literal melting (and subsequent
mains breaker cutout) of a cheap power brick that was being used to provide
24V.
So, the mains part of the supply might be running at an overcurrent without
shutting down.
Replacing the tant (and the power brick) fixed it without any other damage.
On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
time-nuts@lists.febo.com> wrote:
I don’t have one of those units, but switching power supplies under
certain load conditions can have subharmonic oscillations that happen to
fall in the audible frequency range. Absent an overload from a shorter
capacitor or similar, I’d take a hard look at whether there are capacitors
that no longer meet their ESR specifications and/or have cold solder joints
effectively removing them from the circuit.
From: Wilko Bulte via time-nuts time-nuts@lists.febo.com
Sent: Sunday, September 10, 2023 3:57:06 PM
To: Discussion of precise time and frequency measurement <
time-nuts@lists.febo.com>
Cc: Wilko Bulte wkb@xs4all.nl
Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
Wild guess here, this sounds to me like a coil "whistling". Maybe there is
an inductor or transformer that lost its potting compound, or has somehow
come loose from its fittings?
best,
Wilko
On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
I thought that one of the 100 uF 400 V capacitors after the rectifier
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
hello Helmut,
Are you 100% sure the transformer is indeed dead? And, in other words, it is not a problem in the DC part 'behind' the transformer like a dead bridge rectifier, bulk cap or pass transistor? Are you certain you have open or short windings on the transformer?
The MPS transformer in my MFS system does not look better than yours, also some corrosion etc. That is not a reason perse for worry, mine works just fine.
Just my €0,02..
MfG,
Willo
> On 12 Sep 2023, at 21:29, jung.schorndorf--- via time-nuts <time-nuts@lists.febo.com> wrote:
>
> Hello time and frequency standard owners,
>
> a similar problem, tap Power Transformer ...
>
> my power supply MPS in the device MFS (Modular Frequency Systems) from EFRATOM-DATUM_SYMMETRICOM has plagued me with a hum noise
> for many months. When it stopped working and I opened it, the power transformer turned out with a turn damage (photo) and totally corroded - in laboratory conditions!
> I can also operate the device externally with 24V DC. However, I would like to replace the unavailable original transformer,
> but have not seen any transformer data (U, I) because missing documents. Because winding interruption I can not measure it either.
> In the data sheets I only find different DC data (20.5V DC, 23-33V DC, 40 W, 55 W ??).
> The transformer had 2 AC outputs on the secondary side.
> I have only a few inserts and do not need the theoretical 200 VA max. power.
> Does anyone in the US still have circuits? The German branch has nothing more.
>
> Thanks for info
> Helmut
>
>
>
>
> -----Ursprüngliche Nachricht-----
> Von: Adrian Godwin via time-nuts <time-nuts@lists.febo.com>
> Gesendet: Montag, 11. September 2023 10:10
> An: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com>
> Cc: Adrian Godwin <artgodwin@gmail.com>
> Betreff: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
>
> I don't have a 58503A but I do have some RFTG-u which I understand to be
> quite similar. I'm not sure if that extends to the power supply
> architecture. Do they just have an integral mains power supply before a
> Lucent DC-DC converter ?
>
> I had one fail due to a tantalum capacitor downstream of the DC-DC
> converter. It didn't shut down the DC-DC but it did cause it to take a
> heavy incoming current resulting in the literal melting (and subsequent
> mains breaker cutout) of a cheap power brick that was being used to provide
> 24V.
>
> So, the mains part of the supply might be running at an overcurrent without
> shutting down.
>
> Replacing the tant (and the power brick) fixed it without any other damage.
>
>
>> On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
>> time-nuts@lists.febo.com> wrote:
>>
>> I don’t have one of those units, but switching power supplies under
>> certain load conditions can have subharmonic oscillations that happen to
>> fall in the audible frequency range. Absent an overload from a shorter
>> capacitor or similar, I’d take a hard look at whether there are capacitors
>> that no longer meet their ESR specifications and/or have cold solder joints
>> effectively removing them from the circuit.
>> ________________________________
>> From: Wilko Bulte via time-nuts <time-nuts@lists.febo.com>
>> Sent: Sunday, September 10, 2023 3:57:06 PM
>> To: Discussion of precise time and frequency measurement <
>> time-nuts@lists.febo.com>
>> Cc: Wilko Bulte <wkb@xs4all.nl>
>> Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
>>
>> Wild guess here, this sounds to me like a coil "whistling". Maybe there is
>> an inductor or transformer that lost its potting compound, or has somehow
>> come loose from its fittings?
>>
>> best,
>> Wilko
>>
>>> On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
>> time-nuts@lists.febo.com> wrote:
>>>
>>> After about 6 months of being powered off, I switched on my GPS receiver
>>> yesterday. The PSU is buzzing quite loudly. Sound file at
>>>
>>>
>> https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
>>>
>>> I thought that one of the 100 uF 400 V capacitors after the rectifier
>> might
>>> be bulging, although I was unsure. The capacitance measures okay, and the
>>> ESR is below that of anything I can buy that will physically fit. Same
>> for
>>> the 47 uF 400 V capacitor. These were both measured out of circuit, using
>>> an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
>>> have 50 Hz mains here in the UK, as data normally seems to be provided on
>>> capacitors at 120 Hz.
>>>
>>> Has anyone experienced this before? I believe that someone wrote here, or
>>> might have been elsewhere, that the GPS receiver was pushing one of the
>>> supplies to the limit, and another one was not loaded enough. I know
>> there
>>> was some mention of converting it to run from a linear supply, although I
>>> think that would be physically larger, so not fit in the case.
>>>
>>>
>>> --
>>> Dr David Kirkby Ph.D
>>> Kirkby Microwave Ltd
>>> Email: drkirkby@kirkbymicrowave.co.uk
>>> Web: https://www.kirkbymicrowave.co.uk/
>>> Telephone 07910 441670 (UK) or +44 7910 441670 (international)
>>> Registered in England and Wales, company number 08914892.
>>> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
>> 6DT
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
> <MPS_8.jpg>
> <MPS_1.jpg>
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
JS
jung.schorndorf@t-online.de
Wed, Sep 13, 2023 8:54 AM
I am also a lover of hp measurement technology, but I do not have the described frequency and time standard 58503A/B of hp or Symmetricom.
My frequency standards (also rubidium) come from DATUM-Symmetricom, Meinberg and other manufacturers.
To the problem described here in the forum I can give from my experience the tip on the power transformer.
I think the time-nuts fans also have many devices and may be able to give me information on my DATUM-Symmetricom device.
Hello Willo,
yes, my transformer has 230V winding interruption on primary side. Secondary side pin 6-7 has 1.6 ohms, pin 8-9 has 0.3 ohms.
To find the right transformer, I need the low-voltage AC voltages and currents. If your power supply is open again, I ask for measurements or schematic information.
Thanks
MfG
Helmut
-----Ursprüngliche Nachricht-----
Von: Wilko Bulte via time-nuts mailto:time-nuts@lists.febo.com
Gesendet: Dienstag, 12. September 2023 22:23
An: Discussion of precise time and frequency measurement mailto:time-nuts@lists.febo.com
Cc: Wilko Bulte mailto:wkb@xs4all.nl
Betreff: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
hello Helmut,
Are you 100% sure the transformer is indeed dead? And, in other words, it is not a problem in the DC part 'behind' the transformer like a dead bridge rectifier, bulk cap or pass transistor? Are you certain you have open or short windings on the transformer?
The MPS transformer in my MFS system does not look better than yours, also some corrosion etc. That is not a reason perse for worry, mine works just fine.
Just my €0,02..
MfG,
Willo
On 12 Sep 2023, at 21:29, jung.schorndorf--- via time-nuts mailto:time-nuts@lists.febo.com wrote:
Hello time and frequency standard owners,
a similar problem, tap Power Transformer ...
my power supply MPS in the device MFS (Modular Frequency Systems) from EFRATOM-DATUM_SYMMETRICOM has plagued me with a hum noise
for many months. When it stopped working and I opened it, the power transformer turned out with a turn damage (photo) and totally corroded - in laboratory conditions!
I can also operate the device externally with 24V DC. However, I would like to replace the unavailable original transformer,
but have not seen any transformer data (U, I) because missing documents. Because winding interruption I can not measure it either.
In the data sheets I only find different DC data (20.5V DC, 23-33V DC, 40 W, 55 W ??).
The transformer had 2 AC outputs on the secondary side.
I have only a few inserts and do not need the theoretical 200 VA max. power.
Does anyone in the US still have circuits? The German branch has nothing more.
Thanks for info
Helmut
-----Ursprüngliche Nachricht-----
Von: Adrian Godwin via time-nuts mailto:time-nuts@lists.febo.com
Gesendet: Montag, 11. September 2023 10:10
An: Discussion of precise time and frequency measurement mailto:time-nuts@lists.febo.com
Cc: Adrian Godwin mailto:artgodwin@gmail.com
Betreff: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
I don't have a 58503A but I do have some RFTG-u which I understand to be
quite similar. I'm not sure if that extends to the power supply
architecture. Do they just have an integral mains power supply before a
Lucent DC-DC converter ?
I had one fail due to a tantalum capacitor downstream of the DC-DC
converter. It didn't shut down the DC-DC but it did cause it to take a
heavy incoming current resulting in the literal melting (and subsequent
mains breaker cutout) of a cheap power brick that was being used to provide
24V.
So, the mains part of the supply might be running at an overcurrent without
shutting down.
Replacing the tant (and the power brick) fixed it without any other damage.
On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
mailto:time-nuts@lists.febo.com> wrote:
I don’t have one of those units, but switching power supplies under
certain load conditions can have subharmonic oscillations that happen to
fall in the audible frequency range. Absent an overload from a shorter
capacitor or similar, I’d take a hard look at whether there are capacitors
that no longer meet their ESR specifications and/or have cold solder joints
effectively removing them from the circuit.
From: Wilko Bulte via time-nuts mailto:time-nuts@lists.febo.com
Sent: Sunday, September 10, 2023 3:57:06 PM
To: Discussion of precise time and frequency measurement <
mailto:time-nuts@lists.febo.com>
Cc: Wilko Bulte mailto:wkb@xs4all.nl
Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
Wild guess here, this sounds to me like a coil "whistling". Maybe there is
an inductor or transformer that lost its potting compound, or has somehow
come loose from its fittings?
best,
Wilko
On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
After about 6 months of being powered off, I switched on my GPS receiver
yesterday. The PSU is buzzing quite loudly. Sound file at
I thought that one of the 100 uF 400 V capacitors after the rectifier
be bulging, although I was unsure. The capacitance measures okay, and the
ESR is below that of anything I can buy that will physically fit. Same
the 47 uF 400 V capacitor. These were both measured out of circuit, using
an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
have 50 Hz mains here in the UK, as data normally seems to be provided on
capacitors at 120 Hz.
Has anyone experienced this before? I believe that someone wrote here, or
might have been elsewhere, that the GPS receiver was pushing one of the
supplies to the limit, and another one was not loaded enough. I know
was some mention of converting it to run from a linear supply, although I
think that would be physically larger, so not fit in the case.
--
Dr David Kirkby Ph.D
Kirkby Microwave Ltd
Email: mailto:drkirkby@kirkbymicrowave.co.uk
Web: https://www.kirkbymicrowave.co.uk/
Telephone 07910 441670 (UK) or +44 7910 441670 (international)
Registered in England and Wales, company number 08914892.
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
I am also a lover of hp measurement technology, but I do not have the described frequency and time standard 58503A/B of hp or Symmetricom.
My frequency standards (also rubidium) come from DATUM-Symmetricom, Meinberg and other manufacturers.
To the problem described here in the forum I can give from my experience the tip on the power transformer.
I think the time-nuts fans also have many devices and may be able to give me information on my DATUM-Symmetricom device.
Hello Willo,
yes, my transformer has 230V winding interruption on primary side. Secondary side pin 6-7 has 1.6 ohms, pin 8-9 has 0.3 ohms.
To find the right transformer, I need the low-voltage AC voltages and currents. If your power supply is open again, I ask for measurements or schematic information.
Thanks
MfG
Helmut
-----Ursprüngliche Nachricht-----
Von: Wilko Bulte via time-nuts <mailto:time-nuts@lists.febo.com>
Gesendet: Dienstag, 12. September 2023 22:23
An: Discussion of precise time and frequency measurement <mailto:time-nuts@lists.febo.com>
Cc: Wilko Bulte <mailto:wkb@xs4all.nl>
Betreff: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
hello Helmut,
Are you 100% sure the transformer is indeed dead? And, in other words, it is not a problem in the DC part 'behind' the transformer like a dead bridge rectifier, bulk cap or pass transistor? Are you certain you have open or short windings on the transformer?
The MPS transformer in my MFS system does not look better than yours, also some corrosion etc. That is not a reason perse for worry, mine works just fine.
Just my €0,02..
MfG,
Willo
> On 12 Sep 2023, at 21:29, jung.schorndorf--- via time-nuts <mailto:time-nuts@lists.febo.com> wrote:
>
> Hello time and frequency standard owners,
>
> a similar problem, tap Power Transformer ...
>
> my power supply MPS in the device MFS (Modular Frequency Systems) from EFRATOM-DATUM_SYMMETRICOM has plagued me with a hum noise
> for many months. When it stopped working and I opened it, the power transformer turned out with a turn damage (photo) and totally corroded - in laboratory conditions!
> I can also operate the device externally with 24V DC. However, I would like to replace the unavailable original transformer,
> but have not seen any transformer data (U, I) because missing documents. Because winding interruption I can not measure it either.
> In the data sheets I only find different DC data (20.5V DC, 23-33V DC, 40 W, 55 W ??).
> The transformer had 2 AC outputs on the secondary side.
> I have only a few inserts and do not need the theoretical 200 VA max. power.
> Does anyone in the US still have circuits? The German branch has nothing more.
>
> Thanks for info
> Helmut
>
>
>
>
> -----Ursprüngliche Nachricht-----
> Von: Adrian Godwin via time-nuts <mailto:time-nuts@lists.febo.com>
> Gesendet: Montag, 11. September 2023 10:10
> An: Discussion of precise time and frequency measurement <mailto:time-nuts@lists.febo.com>
> Cc: Adrian Godwin <mailto:artgodwin@gmail.com>
> Betreff: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
>
> I don't have a 58503A but I do have some RFTG-u which I understand to be
> quite similar. I'm not sure if that extends to the power supply
> architecture. Do they just have an integral mains power supply before a
> Lucent DC-DC converter ?
>
> I had one fail due to a tantalum capacitor downstream of the DC-DC
> converter. It didn't shut down the DC-DC but it did cause it to take a
> heavy incoming current resulting in the literal melting (and subsequent
> mains breaker cutout) of a cheap power brick that was being used to provide
> 24V.
>
> So, the mains part of the supply might be running at an overcurrent without
> shutting down.
>
> Replacing the tant (and the power brick) fixed it without any other damage.
>
>
>> On Mon, Sep 11, 2023 at 5:31 AM Ed Marciniak via time-nuts <
>> mailto:time-nuts@lists.febo.com> wrote:
>>
>> I don’t have one of those units, but switching power supplies under
>> certain load conditions can have subharmonic oscillations that happen to
>> fall in the audible frequency range. Absent an overload from a shorter
>> capacitor or similar, I’d take a hard look at whether there are capacitors
>> that no longer meet their ESR specifications and/or have cold solder joints
>> effectively removing them from the circuit.
>> ________________________________
>> From: Wilko Bulte via time-nuts <mailto:time-nuts@lists.febo.com>
>> Sent: Sunday, September 10, 2023 3:57:06 PM
>> To: Discussion of precise time and frequency measurement <
>> mailto:time-nuts@lists.febo.com>
>> Cc: Wilko Bulte <mailto:wkb@xs4all.nl>
>> Subject: [time-nuts] Re: Power supply buzzing in HP 58503A GPS receiver.
>>
>> Wild guess here, this sounds to me like a coil "whistling". Maybe there is
>> an inductor or transformer that lost its potting compound, or has somehow
>> come loose from its fittings?
>>
>> best,
>> Wilko
>>
>>> On 10 Sep 2023, at 21:24, David Kirkby via time-nuts <
>> mailto:time-nuts@lists.febo.com> wrote:
>>>
>>> After about 6 months of being powered off, I switched on my GPS receiver
>>> yesterday. The PSU is buzzing quite loudly. Sound file at
>>>
>>>
>> https://www.kirkbymicrowave.co.uk/noisy-PSU-in-HP-58503A-GPS-time-and-frequency-standard-recorded-10th-Sempember-2023.m4a
>>>
>>> I thought that one of the 100 uF 400 V capacitors after the rectifier
>> might
>>> be bulging, although I was unsure. The capacitance measures okay, and the
>>> ESR is below that of anything I can buy that will physically fit. Same
>> for
>>> the 47 uF 400 V capacitor. These were both measured out of circuit, using
>>> an HP 4284A LCR meter at 120 Hz. I chose that, despite the fact that we
>>> have 50 Hz mains here in the UK, as data normally seems to be provided on
>>> capacitors at 120 Hz.
>>>
>>> Has anyone experienced this before? I believe that someone wrote here, or
>>> might have been elsewhere, that the GPS receiver was pushing one of the
>>> supplies to the limit, and another one was not loaded enough. I know
>> there
>>> was some mention of converting it to run from a linear supply, although I
>>> think that would be physically larger, so not fit in the case.
>>>
>>>
>>> --
>>> Dr David Kirkby Ph.D
>>> Kirkby Microwave Ltd
>>> Email: mailto:drkirkby@kirkbymicrowave.co.uk
>>> Web: https://www.kirkbymicrowave.co.uk/
>>> Telephone 07910 441670 (UK) or +44 7910 441670 (international)
>>> Registered in England and Wales, company number 08914892.
>>> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
>> 6DT
>>> _______________________________________________
>>> time-nuts mailing list -- mailto:time-nuts@lists.febo.com
>>> To unsubscribe send an email to mailto:time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- mailto:time-nuts@lists.febo.com
>> To unsubscribe send an email to mailto:time-nuts-leave@lists.febo.com
>> _______________________________________________
>> time-nuts mailing list -- mailto:time-nuts@lists.febo.com
>> To unsubscribe send an email to mailto:time-nuts-leave@lists.febo.com
> _______________________________________________
> time-nuts mailing list -- mailto:time-nuts@lists.febo.com
> To unsubscribe send an email to mailto:time-nuts-leave@lists.febo.com
> <MPS_8.jpg>
> <MPS_1.jpg>
> _______________________________________________
> time-nuts mailing list -- mailto:time-nuts@lists.febo.com
> To unsubscribe send an email to mailto:time-nuts-leave@lists.febo.com
_______________________________________________
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To unsubscribe send an email to mailto:time-nuts-leave@lists.febo.com
