Thunderbolts
There is a lot of misinformation out there. It is not the OCXO that changes, Bruce did extensive testing and I did some too. The Vectron is super, would like to know what is in it but do not want to open one. Once warmed up the stable OCXO temperature is a main contributor to the board temperature. Using a Dual Oven may give you a warm feeling but only adds 1 more Watt of stable heat to the board making the temperature change smaller. The OCXO is important during Hold Over and that is why it is there. The changes are the DAC which is updated once a second. Very temperature sensitive. Cheap. We have done the tests 10811, OSA 8600, FRK and M100. For fun did use a cheap small OCXO, no performance change. Was done in Juerg's temperature stable basement. See attached picture. Bert Kehren
My experiences with the T'Bolt have not been entirely satisfactory. If I
set the loop
lime constant long enough to get a satisfying smoothing of the GPS noise (a
few hundred
seconds), then the thermal sensitivity of the VCXO on the T'Bolt rears its
ugly head and
I see a lot of my HVAC system cycling instead. The T'Bolt E supposedly has
a double-
oven XO, so I'd like to give that a try. But my wallet says "whoa"!
According to Bodnar, his units do have some choices in the time constant
setting.
I've been considering ordering a Bodnar just for frequency agility, but
have been
holding off out of concern for the complications of dealing with a foreign
supplier.
Dana
I've been considering ordering a Bodnar just for frequency agility, but
have been
holding off out of concern for the complications of dealing with a foreign
supplier.
Dana
Bert, remember that I need a very long locking loop time constant setting in
order to smooth out GPS noise, so in a sense the GPSDo is almost in a
holdover state anyway, all the time.
Probably the smartest thing for me to do is to buy a spanking new PRS-10,
with the PPS locking feature present. Then I could just leave it locked to
GPS most all the time, but disconnect the PPS and let it go into holdover
on the rare occasions when I need a few hours of even better stability.
Dana
On Tue, Jul 20, 2021 at 6:56 PM ew via time-nuts time-nuts@lists.febo.com
wrote:
There is a lot of misinformation out there. It is not the OCXO that
changes, Bruce did extensive testing and I did some too. The Vectron is
super, would like to know what is in it but do not want to open one. Once
warmed up the stable OCXO temperature is a main contributor to the board
temperature. Using a Dual Oven may give you a warm feeling but only adds 1
more Watt of stable heat to the board making the temperature change
smaller. The OCXO is important during Hold Over and that is why it is
there. The changes are the DAC which is updated once a second. Very
temperature sensitive. Cheap. We have done the tests 10811, OSA 8600, FRK
and M100. For fun did use a cheap small OCXO, no performance change. Was
done in Juerg's temperature stable basement. See attached picture.
Bert Kehren
My experiences with the T'Bolt have not been entirely satisfactory. If I
set the loop
lime constant long enough to get a satisfying smoothing of the GPS noise (a
few hundred
seconds), then the thermal sensitivity of the VCXO on the T'Bolt rears its
ugly head and
I see a lot of my HVAC system cycling instead. The T'Bolt E supposedly has
a double-
oven XO, so I'd like to give that a try. But my wallet says "whoa"!
According to Bodnar, his units do have some choices in the time constant
setting.
I've been considering ordering a Bodnar just for frequency agility, but
have been
holding off out of concern for the complications of dealing with a foreign
supplier.
Dana
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To unsubscribe, go to and follow the instructions there.
I'll second the PRS-10, I have a used unit that I am very happy with. My
only complaint is that a few times an hour it fails to produce a PPS. On
my unit I expect that the problem is that it is going out of lock
(used!!!).
--mike
On Wed, Jul 21, 2021 at 4:04 AM Dana Whitlow k8yumdoober@gmail.com wrote:
Bert, remember that I need a very long locking loop time constant setting
in
order to smooth out GPS noise, so in a sense the GPSDo is almost in a
holdover state anyway, all the time.
Probably the smartest thing for me to do is to buy a spanking new PRS-10,
with the PPS locking feature present. Then I could just leave it locked to
GPS most all the time, but disconnect the PPS and let it go into holdover
on the rare occasions when I need a few hours of even better stability.
Dana
On Tue, Jul 20, 2021 at 6:56 PM ew via time-nuts <time-nuts@lists.febo.com
wrote:
There is a lot of misinformation out there. It is not the OCXO that
changes, Bruce did extensive testing and I did some too. The Vectron is
super, would like to know what is in it but do not want to open one. Once
warmed up the stable OCXO temperature is a main contributor to the board
temperature. Using a Dual Oven may give you a warm feeling but only adds
1
more Watt of stable heat to the board making the temperature change
smaller. The OCXO is important during Hold Over and that is why it is
there. The changes are the DAC which is updated once a second. Very
temperature sensitive. Cheap. We have done the tests 10811, OSA 8600,
FRK
and M100. For fun did use a cheap small OCXO, no performance change. Was
done in Juerg's temperature stable basement. See attached picture.
Bert Kehren
My experiences with the T'Bolt have not been entirely satisfactory. If I
set the loop
lime constant long enough to get a satisfying smoothing of the GPS noise
(a
few hundred
seconds), then the thermal sensitivity of the VCXO on the T'Bolt rears
its
ugly head and
I see a lot of my HVAC system cycling instead. The T'Bolt E supposedly
has
a double-
oven XO, so I'd like to give that a try. But my wallet says "whoa"!
According to Bodnar, his units do have some choices in the time constant
setting.
I've been considering ordering a Bodnar just for frequency agility, but
have been
holding off out of concern for the complications of dealing with a
foreign
send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Hi
With the PRS-10 you get that hump in the ADEV. I’m not saying that it’s the
end of the world, but it really does bug me that it’s there ….
Bob
On Jul 20, 2021, at 10:03 PM, Dana Whitlow k8yumdoober@gmail.com wrote:
Bert, remember that I need a very long locking loop time constant setting in
order to smooth out GPS noise, so in a sense the GPSDo is almost in a
holdover state anyway, all the time.
Probably the smartest thing for me to do is to buy a spanking new PRS-10,
with the PPS locking feature present. Then I could just leave it locked to
GPS most all the time, but disconnect the PPS and let it go into holdover
on the rare occasions when I need a few hours of even better stability.
Dana
On Tue, Jul 20, 2021 at 6:56 PM ew via time-nuts time-nuts@lists.febo.com
wrote:
There is a lot of misinformation out there. It is not the OCXO that
changes, Bruce did extensive testing and I did some too. The Vectron is
super, would like to know what is in it but do not want to open one. Once
warmed up the stable OCXO temperature is a main contributor to the board
temperature. Using a Dual Oven may give you a warm feeling but only adds 1
more Watt of stable heat to the board making the temperature change
smaller. The OCXO is important during Hold Over and that is why it is
there. The changes are the DAC which is updated once a second. Very
temperature sensitive. Cheap. We have done the tests 10811, OSA 8600, FRK
and M100. For fun did use a cheap small OCXO, no performance change. Was
done in Juerg's temperature stable basement. See attached picture.
Bert Kehren
My experiences with the T'Bolt have not been entirely satisfactory. If I
set the loop
lime constant long enough to get a satisfying smoothing of the GPS noise (a
few hundred
seconds), then the thermal sensitivity of the VCXO on the T'Bolt rears its
ugly head and
I see a lot of my HVAC system cycling instead. The T'Bolt E supposedly has
a double-
oven XO, so I'd like to give that a try. But my wallet says "whoa"!
According to Bodnar, his units do have some choices in the time constant
setting.
I've been considering ordering a Bodnar just for frequency agility, but
have been
holding off out of concern for the complications of dealing with a foreign
supplier.
Dana
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Hi
All of the Thunderbolt E’s that I have seen have single oven OCXO’s.
I don’t know of any “current production” GPSDO’s that come stock
with double ovens. There are a few with some interesting options.
I have not dug into just what all those odd options actually are.
Bob
On Jul 20, 2021, at 7:55 PM, ew via time-nuts time-nuts@lists.febo.com wrote:
There is a lot of misinformation out there. It is not the OCXO that changes, Bruce did extensive testing and I did some too. The Vectron is super, would like to know what is in it but do not want to open one. Once warmed up the stable OCXO temperature is a main contributor to the board temperature. Using a Dual Oven may give you a warm feeling but only adds 1 more Watt of stable heat to the board making the temperature change smaller. The OCXO is important during Hold Over and that is why it is there. The changes are the DAC which is updated once a second. Very temperature sensitive. Cheap. We have done the tests 10811, OSA 8600, FRK and M100. For fun did use a cheap small OCXO, no performance change. Was done in Juerg's temperature stable basement. See attached picture. Bert Kehren
My experiences with the T'Bolt have not been entirely satisfactory. If I
set the loop
lime constant long enough to get a satisfying smoothing of the GPS noise (a
few hundred
seconds), then the thermal sensitivity of the VCXO on the T'Bolt rears its
ugly head and
I see a lot of my HVAC system cycling instead. The T'Bolt E supposedly has
a double-
oven XO, so I'd like to give that a try. But my wallet says "whoa"!
According to Bodnar, his units do have some choices in the time constant
setting.
I've been considering ordering a Bodnar just for frequency agility, but
have been
holding off out of concern for the complications of dealing with a foreign
supplier.
Dana
<Tbolt_spez.jpg>_______________________________________________
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To unsubscribe, go to and follow the instructions there.
Bob, I'm aware of the hump, but it's so much smaller than what I see from
GPSDO that
I don't mind it too much.
My current usage scenario is that I use one or more GPSDOs as a reference
for
tweaking one of my Rb stds to reasonable conformance with GPS. Frequency
noise on either gets in the way of doing this most accurately, and greatly
extends
the observation time required to do a good tweak job. I "observe" with the
aid of
a home-built quadrature demodulator and a duan-channel DSO running in very
slow "roll mode", with its two channels driven by I & Q outputs of the
demod.
Thus I can learn a lot just by an occasional glance at the display as I
happen
to pass near the 'scope in the course of other activities.
I currently own a new CNS Clock II and three older T'Bolts. The CNS unit
has a very fast
tracking loop, with an estimated time constant of only a very few seconds
(not user-
adjustable). It's 10 MHz output is incredibly noisy, with
frequent frequency excursions
of several PPB either way. But at least it does not have much trouble with
ambient
temperature sensitivity. The T'Bolts have user-adjustable time constant,
and I've
spent a lot of time playing with those. For very short TC settings the GPS
noise dominates
the picture, and for very long settings ambient temperature fluctuations on
the GPSDO's
VCXO dominate. I keep going back to the CNS clock because although its
frequency
fluctuations are more severe, I find it's easier to visually estimate tweak
amounts.
My desire is to maintain an Rb within 10 PPT most or all of the time with
little or no
manual attention.
In response to your latest, I'm sure I saw mention of a double-oven in
connection with the
T'Bolt E, on the Trimble site. But perhaps this is an extra cost option.
Thanks for mentioning
this.
As an amusing side note I occasionally rely on a local taxi service, and
one of the regular
drivers' last names is Trimble. Perhaps I should inquire if there is any
connection :-)
Dana
On Wed, Jul 21, 2021 at 8:20 AM Bob kb8tq kb8tq@n1k.org wrote:
Hi
With the PRS-10 you get that hump in the ADEV. I’m not saying that it’s
the
end of the world, but it really does bug me that it’s there ….
Bob
On Jul 20, 2021, at 10:03 PM, Dana Whitlow k8yumdoober@gmail.com
wrote:
Bert, remember that I need a very long locking loop time constant
setting in
order to smooth out GPS noise, so in a sense the GPSDo is almost in a
holdover state anyway, all the time.
Probably the smartest thing for me to do is to buy a spanking new PRS-10,
with the PPS locking feature present. Then I could just leave it locked
to
GPS most all the time, but disconnect the PPS and let it go into holdover
on the rare occasions when I need a few hours of even better stability.
Dana
On Tue, Jul 20, 2021 at 6:56 PM ew via time-nuts <
wrote:
There is a lot of misinformation out there. It is not the OCXO that
changes, Bruce did extensive testing and I did some too. The Vectron is
super, would like to know what is in it but do not want to open one.
Once
warmed up the stable OCXO temperature is a main contributor to the board
temperature. Using a Dual Oven may give you a warm feeling but only
adds 1
more Watt of stable heat to the board making the temperature change
smaller. The OCXO is important during Hold Over and that is why it is
there. The changes are the DAC which is updated once a second. Very
temperature sensitive. Cheap. We have done the tests 10811, OSA 8600,
FRK
and M100. For fun did use a cheap small OCXO, no performance change. Was
done in Juerg's temperature stable basement. See attached picture.
Bert Kehren
My experiences with the T'Bolt have not been entirely satisfactory. If
I
set the loop
lime constant long enough to get a satisfying smoothing of the GPS
noise (a
few hundred
seconds), then the thermal sensitivity of the VCXO on the T'Bolt rears
its
ugly head and
I see a lot of my HVAC system cycling instead. The T'Bolt E supposedly
has
a double-
oven XO, so I'd like to give that a try. But my wallet says "whoa"!
According to Bodnar, his units do have some choices in the time constant
setting.
I've been considering ordering a Bodnar just for frequency agility, but
have been
holding off out of concern for the complications of dealing with a
foreign
send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
send an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
an email to time-nuts-leave@lists.febo.com
To unsubscribe, go to and follow the instructions there.
Hi
Trimble mentions the E oscillator in a couple of places. They also seem to only
talk about holdover in very vague terms. They never tie down anything that
would track back to the stability of the OCXO. If it is a high(er) performance
OCXO, I find that all a bit weird.
The ADEV plot they show looks a lot like the fine old TBolt we all know and love ….
Bob
On Jul 21, 2021, at 9:48 AM, Dana Whitlow k8yumdoober@gmail.com wrote:
Bob, I'm aware of the hump, but it's so much smaller than what I see from
GPSDO that
I don't mind it too much.
My current usage scenario is that I use one or more GPSDOs as a reference
for
tweaking one of my Rb stds to reasonable conformance with GPS. Frequency
noise on either gets in the way of doing this most accurately, and greatly
extends
the observation time required to do a good tweak job. I "observe" with the
aid of
a home-built quadrature demodulator and a duan-channel DSO running in very
slow "roll mode", with its two channels driven by I & Q outputs of the
demod.
Thus I can learn a lot just by an occasional glance at the display as I
happen
to pass near the 'scope in the course of other activities.
I currently own a new CNS Clock II and three older T'Bolts. The CNS unit
has a very fast
tracking loop, with an estimated time constant of only a very few seconds
(not user-
adjustable). It's 10 MHz output is incredibly noisy, with
frequent frequency excursions
of several PPB either way. But at least it does not have much trouble with
ambient
temperature sensitivity. The T'Bolts have user-adjustable time constant,
and I've
spent a lot of time playing with those. For very short TC settings the GPS
noise dominates
the picture, and for very long settings ambient temperature fluctuations on
the GPSDO's
VCXO dominate. I keep going back to the CNS clock because although its
frequency
fluctuations are more severe, I find it's easier to visually estimate tweak
amounts.
My desire is to maintain an Rb within 10 PPT most or all of the time with
little or no
manual attention.
In response to your latest, I'm sure I saw mention of a double-oven in
connection with the
T'Bolt E, on the Trimble site. But perhaps this is an extra cost option.
Thanks for mentioning
this.
As an amusing side note I occasionally rely on a local taxi service, and
one of the regular
drivers' last names is Trimble. Perhaps I should inquire if there is any
connection :-)
Dana
On Wed, Jul 21, 2021 at 8:20 AM Bob kb8tq kb8tq@n1k.org wrote:
Hi
With the PRS-10 you get that hump in the ADEV. I’m not saying that it’s
the
end of the world, but it really does bug me that it’s there ….
Bob
On Jul 20, 2021, at 10:03 PM, Dana Whitlow k8yumdoober@gmail.com
wrote:
Bert, remember that I need a very long locking loop time constant
setting in
order to smooth out GPS noise, so in a sense the GPSDo is almost in a
holdover state anyway, all the time.
Probably the smartest thing for me to do is to buy a spanking new PRS-10,
with the PPS locking feature present. Then I could just leave it locked
to
GPS most all the time, but disconnect the PPS and let it go into holdover
on the rare occasions when I need a few hours of even better stability.
Dana
On Tue, Jul 20, 2021 at 6:56 PM ew via time-nuts <
wrote:
There is a lot of misinformation out there. It is not the OCXO that
changes, Bruce did extensive testing and I did some too. The Vectron is
super, would like to know what is in it but do not want to open one.
Once
warmed up the stable OCXO temperature is a main contributor to the board
temperature. Using a Dual Oven may give you a warm feeling but only
adds 1
more Watt of stable heat to the board making the temperature change
smaller. The OCXO is important during Hold Over and that is why it is
there. The changes are the DAC which is updated once a second. Very
temperature sensitive. Cheap. We have done the tests 10811, OSA 8600,
FRK
and M100. For fun did use a cheap small OCXO, no performance change. Was
done in Juerg's temperature stable basement. See attached picture.
Bert Kehren
My experiences with the T'Bolt have not been entirely satisfactory. If
I
set the loop
lime constant long enough to get a satisfying smoothing of the GPS
noise (a
few hundred
seconds), then the thermal sensitivity of the VCXO on the T'Bolt rears
its
ugly head and
I see a lot of my HVAC system cycling instead. The T'Bolt E supposedly
has
a double-
oven XO, so I'd like to give that a try. But my wallet says "whoa"!
According to Bodnar, his units do have some choices in the time constant
setting.
I've been considering ordering a Bodnar just for frequency agility, but
have been
holding off out of concern for the complications of dealing with a
foreign
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.
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.