Empathy List Archives

JM

John Moran, Scawby Design

Mon, Feb 28, 2022 1:26 PM

With all this interesting talk about -

a) How hard it was to build a GPSDO from scratch and
b) How, to measure a signal accurately, you need a reference circa 10x better

I started to get worried since I want to do both. To help with the latter I have acquired an HP5370A that just needs picking up from Scotland, where I was hoping to maybe pick up some surplus oscillators as well. But the 10x specs in the discussions got me worried enough to look around for a known good GPSDO rather than buying a bag-full from China and trying to sort out a good one.

I found this -

https://www.rfx.co.uk/pdfs/GPS_OCXO_1300_10_module.pdf

and have been quoted £500 as a special deal (they normally have a £1,000 minimum one-off charge).

Can anyone please pass some sort of judgement on whether its specs are good enough to stand in as my master reference until I can find a Rubidium device on this side of the pond.

John

With all this interesting talk about - a) How hard it was to build a GPSDO from scratch and b) How, to measure a signal accurately, you need a reference circa 10x better I started to get worried since I want to do both. To help with the latter I have acquired an HP5370A that just needs picking up from Scotland, where I was hoping to maybe pick up some surplus oscillators as well. But the 10x specs in the discussions got me worried enough to look around for a known good GPSDO rather than buying a bag-full from China and trying to sort out a good one. I found this - https://www.rfx.co.uk/pdfs/GPS_OCXO_1300_10_module.pdf and have been quoted £500 as a special deal (they normally have a £1,000 minimum one-off charge). Can anyone please pass some sort of judgement on whether its specs are good enough to stand in as my master reference until I can find a Rubidium device on this side of the pond. John

DC

David C. Partridge

Mon, Feb 28, 2022 1:55 PM

Maybe take a look at:
http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a9
2055b16c36edbdc83f4ac8fb8abc

-----Original Message-----
From: John Moran, Scawby Design john@scawbydesign.co.uk
Sent: 28 February 2022 13:26
To: time-nuts@lists.febo.com
Subject: [time-nuts] GPSDO - GPS1300-10-1000 by RFX Ltd. UK

With all this interesting talk about -

a) How hard it was to build a GPSDO from scratch and
b) How, to measure a signal accurately, you need a reference circa 10x
better

I started to get worried since I want to do both. To help with the latter I
have acquired an HP5370A that just needs picking up from Scotland, where I
was hoping to maybe pick up some surplus oscillators as well. But the 10x
specs in the discussions got me worried enough to look around for a known
good GPSDO rather than buying a bag-full from China and trying to sort out a
good one.

I found this -

https://www.rfx.co.uk/pdfs/GPS_OCXO_1300_10_module.pdf

and have been quoted £500 as a special deal (they normally have a £1,000
minimum one-off charge).

Can anyone please pass some sort of judgement on whether its specs are good
enough to stand in as my master reference until I can find a Rubidium device
on this side of the pond.

John

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.

Maybe take a look at: http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a9 2055b16c36edbdc83f4ac8fb8abc -----Original Message----- From: John Moran, Scawby Design <john@scawbydesign.co.uk> Sent: 28 February 2022 13:26 To: time-nuts@lists.febo.com Subject: [time-nuts] GPSDO - GPS1300-10-1000 by RFX Ltd. UK With all this interesting talk about - a) How hard it was to build a GPSDO from scratch and b) How, to measure a signal accurately, you need a reference circa 10x better I started to get worried since I want to do both. To help with the latter I have acquired an HP5370A that just needs picking up from Scotland, where I was hoping to maybe pick up some surplus oscillators as well. But the 10x specs in the discussions got me worried enough to look around for a known good GPSDO rather than buying a bag-full from China and trying to sort out a good one. I found this - https://www.rfx.co.uk/pdfs/GPS_OCXO_1300_10_module.pdf and have been quoted £500 as a special deal (they normally have a £1,000 minimum one-off charge). Can anyone please pass some sort of judgement on whether its specs are good enough to stand in as my master reference until I can find a Rubidium device on this side of the pond. John _______________________________________________ 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.

DC

David C. Partridge

Mon, Feb 28, 2022 9:48 PM

<http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a
92055b16c36edbdc83f4ac8fb8abc>

D.
-----Original Message-----
From: David C. Partridge david.partridge@perdrix.co.uk
Sent: 28 February 2022 13:56
To: 'Discussion of precise time and frequency measurement'
time-nuts@lists.febo.com
Subject: [time-nuts] Re: GPSDO - GPS1300-10-1000 by RFX Ltd. UK

Maybe take a look at:
http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a9
2055b16c36edbdc83f4ac8fb8abc

-----Original Message-----
From: John Moran, Scawby Design john@scawbydesign.co.uk
Sent: 28 February 2022 13:26
To: time-nuts@lists.febo.com
Subject: [time-nuts] GPSDO - GPS1300-10-1000 by RFX Ltd. UK

With all this interesting talk about -

a) How hard it was to build a GPSDO from scratch and
b) How, to measure a signal accurately, you need a reference circa 10x
better

I started to get worried since I want to do both. To help with the latter I
have acquired an HP5370A that just needs picking up from Scotland, where I
was hoping to maybe pick up some surplus oscillators as well. But the 10x
specs in the discussions got me worried enough to look around for a known
good GPSDO rather than buying a bag-full from China and trying to sort out a
good one.

I found this -

https://www.rfx.co.uk/pdfs/GPS_OCXO_1300_10_module.pdf

and have been quoted £500 as a special deal (they normally have a £1,000
minimum one-off charge).

Can anyone please pass some sort of judgement on whether its specs are good
enough to stand in as my master reference until I can find a Rubidium device
on this side of the pond.

John

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.

<http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a 92055b16c36edbdc83f4ac8fb8abc> D. -----Original Message----- From: David C. Partridge <david.partridge@perdrix.co.uk> Sent: 28 February 2022 13:56 To: 'Discussion of precise time and frequency measurement' <time-nuts@lists.febo.com> Subject: [time-nuts] Re: GPSDO - GPS1300-10-1000 by RFX Ltd. UK Maybe take a look at: http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a9 2055b16c36edbdc83f4ac8fb8abc -----Original Message----- From: John Moran, Scawby Design <john@scawbydesign.co.uk> Sent: 28 February 2022 13:26 To: time-nuts@lists.febo.com Subject: [time-nuts] GPSDO - GPS1300-10-1000 by RFX Ltd. UK With all this interesting talk about - a) How hard it was to build a GPSDO from scratch and b) How, to measure a signal accurately, you need a reference circa 10x better I started to get worried since I want to do both. To help with the latter I have acquired an HP5370A that just needs picking up from Scotland, where I was hoping to maybe pick up some surplus oscillators as well. But the 10x specs in the discussions got me worried enough to look around for a known good GPSDO rather than buying a bag-full from China and trying to sort out a good one. I found this - https://www.rfx.co.uk/pdfs/GPS_OCXO_1300_10_module.pdf and have been quoted £500 as a special deal (they normally have a £1,000 minimum one-off charge). Can anyone please pass some sort of judgement on whether its specs are good enough to stand in as my master reference until I can find a Rubidium device on this side of the pond. John _______________________________________________ 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

Mon, Feb 28, 2022 11:08 PM

John
GPSDOs fun stuff. But following your logic and I do not disagree with it.
Some other GPSDO most likely will not be 10 X better unless the test one
perhaps is quite poor. I am assuming better means lower noise and smaller
frequency deviation. No matter its pretty hard to say if both GPSDOs are
functioning pretty well.
So about that Cesium or maybe Maser your looking for now. Ebay? Humor
intended.
My next project will be a Lars GPSDO using an arduino and such. Its totally
for fun and I have all of the stuff needed. Whats nice the codes clear.
Though plenty of it.
Then I can see how it does against the hp 3801, TBolt, KS series, Rb and Cs
references.
Good luck.
Paul
WB8TSL

On Mon, Feb 28, 2022 at 5:35 PM David C. Partridge <
david.partridge@perdrix.co.uk> wrote:

<
http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a
92055b16c36edbdc83f4ac8fb8abc
http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a92055b16c36edbdc83f4ac8fb8abc

D.
-----Original Message-----
From: David C. Partridge david.partridge@perdrix.co.uk
Sent: 28 February 2022 13:56
To: 'Discussion of precise time and frequency measurement'
time-nuts@lists.febo.com
Subject: [time-nuts] Re: GPSDO - GPS1300-10-1000 by RFX Ltd. UK

Maybe take a look at:

http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a9
2055b16c36edbdc83f4ac8fb8abc
http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a92055b16c36edbdc83f4ac8fb8abc

-----Original Message-----
From: John Moran, Scawby Design john@scawbydesign.co.uk
Sent: 28 February 2022 13:26
To: time-nuts@lists.febo.com
Subject: [time-nuts] GPSDO - GPS1300-10-1000 by RFX Ltd. UK

With all this interesting talk about -

a) How hard it was to build a GPSDO from scratch and
b) How, to measure a signal accurately, you need a reference circa 10x
better

I started to get worried since I want to do both. To help with the latter I
have acquired an HP5370A that just needs picking up from Scotland, where I
was hoping to maybe pick up some surplus oscillators as well. But the 10x
specs in the discussions got me worried enough to look around for a known
good GPSDO rather than buying a bag-full from China and trying to sort out
a
good one.

I found this -

https://www.rfx.co.uk/pdfs/GPS_OCXO_1300_10_module.pdf

and have been quoted £500 as a special deal (they normally have a £1,000
minimum one-off charge).

Can anyone please pass some sort of judgement on whether its specs are good
enough to stand in as my master reference until I can find a Rubidium
device
on this side of the pond.

John

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.

John GPSDOs fun stuff. But following your logic and I do not disagree with it. Some other GPSDO most likely will not be 10 X better unless the test one perhaps is quite poor. I am assuming better means lower noise and smaller frequency deviation. No matter its pretty hard to say if both GPSDOs are functioning pretty well. So about that Cesium or maybe Maser your looking for now. Ebay? Humor intended. My next project will be a Lars GPSDO using an arduino and such. Its totally for fun and I have all of the stuff needed. Whats nice the codes clear. Though plenty of it. Then I can see how it does against the hp 3801, TBolt, KS series, Rb and Cs references. Good luck. Paul WB8TSL On Mon, Feb 28, 2022 at 5:35 PM David C. Partridge < david.partridge@perdrix.co.uk> wrote: > < > http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a > 92055b16c36edbdc83f4ac8fb8abc > <http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a92055b16c36edbdc83f4ac8fb8abc> > > > > D. > -----Original Message----- > From: David C. Partridge <david.partridge@perdrix.co.uk> > Sent: 28 February 2022 13:56 > To: 'Discussion of precise time and frequency measurement' > <time-nuts@lists.febo.com> > Subject: [time-nuts] Re: GPSDO - GPS1300-10-1000 by RFX Ltd. UK > > Maybe take a look at: > > http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a9 > 2055b16c36edbdc83f4ac8fb8abc > <http://www.leobodnar.com/shop/index.php?main_page=index&cPath=107&zenid=15a92055b16c36edbdc83f4ac8fb8abc> > > -----Original Message----- > From: John Moran, Scawby Design <john@scawbydesign.co.uk> > Sent: 28 February 2022 13:26 > To: time-nuts@lists.febo.com > Subject: [time-nuts] GPSDO - GPS1300-10-1000 by RFX Ltd. UK > > With all this interesting talk about - > > a) How hard it was to build a GPSDO from scratch and > b) How, to measure a signal accurately, you need a reference circa 10x > better > > I started to get worried since I want to do both. To help with the latter I > have acquired an HP5370A that just needs picking up from Scotland, where I > was hoping to maybe pick up some surplus oscillators as well. But the 10x > specs in the discussions got me worried enough to look around for a known > good GPSDO rather than buying a bag-full from China and trying to sort out > a > good one. > > I found this - > > https://www.rfx.co.uk/pdfs/GPS_OCXO_1300_10_module.pdf > > and have been quoted £500 as a special deal (they normally have a £1,000 > minimum one-off charge). > > Can anyone please pass some sort of judgement on whether its specs are good > enough to stand in as my master reference until I can find a Rubidium > device > on this side of the pond. > > John > _______________________________________________ > 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. >