[time-nuts] Re: Thunderbolts ...

[Dana Whitlow]

Dave,

The usual source for old used Thunderbolts is either on eBay, or private
sales by
individuals.

I've twice now requested a quote for a new model from Trimble, and they did
not
even bother to respond.  Perhaps there are distributors, but if so I
haven't been
able to identify any.

Dana


On Sat, Jul 17, 2021 at 2:18 PM Dave  wrote:

> I'm a bit of a newbie at this, but is it possible to buy thunderbolts ??
>
> If so, where ?
>
> Regards,
> Dave
>
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[time-nuts] Re: Thunderbolts ...

[Bob kb8tq]

Hi

Current version of the Thunderbolt is a Thunderbolt E. The device we call a
Thunderbolt has been out of production for a *long* time. 

These guys:

https://novotech.com/products/timing-modules.html 


At least have a listing suggesting you can buy a Thunderbolt E.

Bob


> On Jul 17, 2021, at 3:28 PM, Dana Whitlow  wrote:
> 
> Dave,
> 
> The usual source for old used Thunderbolts is either on eBay, or private
> sales by
> individuals.
> 
> I've twice now requested a quote for a new model from Trimble, and they did
> not
> even bother to respond.  Perhaps there are distributors, but if so I
> haven't been
> able to identify any.
> 
> Dana
> 
> 
> On Sat, Jul 17, 2021 at 2:18 PM Dave  wrote:
> 
>> I'm a bit of a newbie at this, but is it possible to buy thunderbolts ??
>> 
>> If so, where ?
>> 
>> Regards,
>> Dave
>> 
>> ___
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[time-nuts] Re: Thunderbolts ...

[Tom Van Baak]

I still have a large box of TBolt's left over from the TAPR group buy 
that we organized years ago. We held dozens in reserve in order to give 
free replacements to anyone with a problem. As it turns out there have 
been almost no failures so the reserve pile is still here. It's time to 
let them go. About 20 people have inquired about these in the past year 
but I haven't gotten around to announcing the offer yet.


If you or anyone else is interested in one of these contact me off-list. 
I'm t...@leapsecond.com


Like the first group buy these are all original USA OEM surplus units in 
mint condition, not the beat up boxes you find on eBay from overseas 
sellers. They will be fully tested, with the same no-questions-asked 
exchange policy.


/tvb


On 7/16/2021 4:06 PM, Dave wrote:

I'm a bit of a newbie at this, but is it possible to buy thunderbolts ??

If so, where ?

Regards,
Dave


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[time-nuts] Re: Thunderbolts ...

[Dana Whitlow]

Thanks, Bob, for the clue about Novotech- it looks somewhat promising.

Dana


On Sat, Jul 17, 2021 at 2:52 PM Bob kb8tq  wrote:

> Hi
>
> Current version of the Thunderbolt is a Thunderbolt E. The device we call a
> Thunderbolt has been out of production for a *long* time.
>
> These guys:
>
> https://novotech.com/products/timing-modules.html <
> https://novotech.com/products/timing-modules.html>
>
> At least have a listing suggesting you can buy a Thunderbolt E.
>
> Bob
>
>
> > On Jul 17, 2021, at 3:28 PM, Dana Whitlow  wrote:
> >
> > Dave,
> >
> > The usual source for old used Thunderbolts is either on eBay, or private
> > sales by
> > individuals.
> >
> > I've twice now requested a quote for a new model from Trimble, and they
> did
> > not
> > even bother to respond.  Perhaps there are distributors, but if so I
> > haven't been
> > able to identify any.
> >
> > Dana
> >
> >
> > On Sat, Jul 17, 2021 at 2:18 PM Dave  wrote:
> >
> >> I'm a bit of a newbie at this, but is it possible to buy thunderbolts ??
> >>
> >> If so, where ?
> >>
> >> Regards,
> >> Dave
> >>
> >> ___
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> send
> >> an email to time-nuts-le...@lists.febo.com
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> >>
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[time-nuts] Re: Thunderbolts ...

[Gary E. Miller]

Yo Dave!

On Sat, 17 Jul 2021 00:06:42 +0100
Dave  wrote:

> I'm a bit of a newbie at this, but is it possible to buy thunderbolts

WHy?  They newer Trimble GNSS timing modules work beter.  Like the ICM SMT 360:

https://timing.trimble.com/products/gnss-receivers/icm-smt-360-multi-gnss-timing-module/

> If so, where ?

Hobbyist GNSS receivers are in short supply.  You gotta look harder than
before COVID.

An ICM SMT 360 on a carrier board is $125:

https://novotech.com/icm-smt-360-337.html

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588

Veritas liberabit vos. -- Quid est veritas?
"If you can't measure it, you can't improve it." - Lord Kelvin


pgp0narUIUY8R.pgp
Description: OpenPGP digital signature
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[time-nuts] Re: Thunderbolts ...

[djl]

Newer module:  $650.00   meh

On 2021-07-17 19:45, Gary E. Miller wrote:

Yo Dave!

On Sat, 17 Jul 2021 00:06:42 +0100
Dave  wrote:


I'm a bit of a newbie at this, but is it possible to buy thunderbolts


WHy?  They newer Trimble GNSS timing modules work beter.  Like the ICM 
SMT 360:


https://timing.trimble.com/products/gnss-receivers/icm-smt-360-multi-gnss-timing-module/


If so, where ?


Hobbyist GNSS receivers are in short supply.  You gotta look harder 
than

before COVID.

An ICM SMT 360 on a carrier board is $125:

https://novotech.com/icm-smt-360-337.html

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588

Veritas liberabit vos. -- Quid est veritas?
"If you can't measure it, you can't improve it." - Lord Kelvin

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--

The whole world is a straight man.
--
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304
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[time-nuts] Re: Thunderbolts ...

[Ziggy]

$650 for the _starter_ kit - $124 for the carrier board with module. So 
I'd say that's affordable. But the ±7us over a 5-minute period and 
100ppb over 24 hours holdover spec seems a bit inferior.


On 7/18/2021 9:40 PM, djl wrote:

Newer module:  $650.00   meh

On 2021-07-17 19:45, Gary E. Miller wrote:

Yo Dave!

On Sat, 17 Jul 2021 00:06:42 +0100
Dave  wrote:


I'm a bit of a newbie at this, but is it possible to buy thunderbolts


WHy?  They newer Trimble GNSS timing modules work beter.  Like the 
ICM SMT 360:


https://timing.trimble.com/products/gnss-receivers/icm-smt-360-multi-gnss-timing-module/ 




If so, where ?


Hobbyist GNSS receivers are in short supply.  You gotta look harder than
before COVID.

An ICM SMT 360 on a carrier board is $125:

https://novotech.com/icm-smt-360-337.html

RGDS
GARY
--- 


Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588

    Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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[time-nuts] Re: Thunderbolts ...

[Dana Whitlow]

Agreed, Ziggy.

I'm actually thinking (a little bit) about getting a Thunderbolt E.  But
the price does
kind of hurt.

Dana


On Mon, Jul 19, 2021 at 1:08 PM Ziggy 
wrote:

> $650 for the _starter_ kit - $124 for the carrier board with module. So
> I'd say that's affordable. But the ±7us over a 5-minute period and
> 100ppb over 24 hours holdover spec seems a bit inferior.
>
> On 7/18/2021 9:40 PM, djl wrote:
> > Newer module:  $650.00   meh
> >
> > On 2021-07-17 19:45, Gary E. Miller wrote:
> >> Yo Dave!
> >>
> >> On Sat, 17 Jul 2021 00:06:42 +0100
> >> Dave  wrote:
> >>
> >>> I'm a bit of a newbie at this, but is it possible to buy thunderbolts
> >>
> >> WHy?  They newer Trimble GNSS timing modules work beter.  Like the
> >> ICM SMT 360:
> >>
> >>
> https://timing.trimble.com/products/gnss-receivers/icm-smt-360-multi-gnss-timing-module/
> >>
> >>
> >>> If so, where ?
> >>
> >> Hobbyist GNSS receivers are in short supply.  You gotta look harder than
> >> before COVID.
> >>
> >> An ICM SMT 360 on a carrier board is $125:
> >>
> >> https://novotech.com/icm-smt-360-337.html
> >>
> >> RGDS
> >> GARY
> >>
> ---
> >>
> >> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
> >> g...@rellim.com  Tel:+1 541 382 8588
> >>
> >> Veritas liberabit vos. -- Quid est veritas?
> >> "If you can't measure it, you can't improve it." - Lord Kelvin
> >>
> >> ___
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> >
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[time-nuts] Re: Thunderbolts ...

[Robert DiRosario]

I found this on ebay from Chine:

Trimble 10MHz ThunderBolt GPS Disciplined Clock GPSDO Module Frequency 
Standard

https://www.ebay.com/itm/332390729098?
US $197.00 or make offer.  He does take lower offers.

He also lists:
Power Supply & Antenna FOR Trimble 10MHz ThunderBolt GPS Disciplined 
Clock GPSDO

https://www.ebay.com/itm/332786802886?
US $55.00

Both have free shipping.

I purchased both, they just arrived.  It looks good, I need to test it, 
once I find another outlet strip for my

time-nuts setup.

Other sells have it for more.  No US sellers.

Robert

On 07/16/2021 07:06 PM, Dave wrote:

I'm a bit of a newbie at this, but is it possible to buy thunderbolts ??

If so, where ?

Regards,
Dave

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[time-nuts] Re: Thunderbolts ...

[John Miles]

If you're looking for a low cost surplus GPSDO, the ones Tom mentioned in
his post on Saturday are the ones you want.  Not a Thunderbolt-E, and not
something from the China surplus/e-waste market.

-- john, KE5FX

> -Original Message-
> From: Robert DiRosario [mailto:ka3...@comcast.net]
> Sent: Monday, July 19, 2021 4:08 PM
> To: time-nuts@lists.febo.com
> Subject: [time-nuts] Re: Thunderbolts ...
> 
> I found this on ebay from Chine:
> ...
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[time-nuts] Re: Thunderbolts ...

[Wes]

I wrote Tom, at the address he gave, on Saturday with a query.  So far, no 
reply.

Wes  N7WS

 On 7/19/2021 4:59 PM, John Miles wrote:

If you're looking for a low cost surplus GPSDO, the ones Tom mentioned in
his post on Saturday are the ones you want.  Not a Thunderbolt-E, and not
something from the China surplus/e-waste market.

-- john, KE5FX


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[time-nuts] Re: Thunderbolts ...

[Bob Darlington]

Same.  He probably got 250+ requests in short order.  I'm curious how the
Leo Bodnar GPSDOs compare.   I'm considering one of these over a
thunderbolt for field use for ham radio EME work.

-Bob N3XKB

On Tue, Jul 20, 2021 at 10:59 AM Wes  wrote:

> I wrote Tom, at the address he gave, on Saturday with a query.  So far, no
> reply.
>
> Wes  N7WS
>
>   On 7/19/2021 4:59 PM, John Miles wrote:
> > If you're looking for a low cost surplus GPSDO, the ones Tom mentioned in
> > his post on Saturday are the ones you want.  Not a Thunderbolt-E, and not
> > something from the China surplus/e-waste market.
> >
> > -- john, KE5FX
> >
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[time-nuts] Re: Thunderbolts ...

[John Ackermann]

The Bodnar GPSDO is great for what it is, and has the great advantages of small 
size, low power consumption, low cost, and frequency agility.  But it doesn't 
have an OCXO so its short term and holdover performance isn't in the same 
league as the T'bolt or Z38whatever boxes.

John

On Jul 20, 2021, 1:11 PM, at 1:11 PM, Bob Darlington  
wrote:
>Same.  He probably got 250+ requests in short order.  I'm curious how
>the
>Leo Bodnar GPSDOs compare.   I'm considering one of these over a
>thunderbolt for field use for ham radio EME work.
>
>-Bob N3XKB
>
>On Tue, Jul 20, 2021 at 10:59 AM Wes  wrote:
>
>> I wrote Tom, at the address he gave, on Saturday with a query.  So
>far, no
>> reply.
>>
>> Wes  N7WS
>>
>>   On 7/19/2021 4:59 PM, John Miles wrote:
>> > If you're looking for a low cost surplus GPSDO, the ones Tom
>mentioned in
>> > his post on Saturday are the ones you want.  Not a Thunderbolt-E,
>and not
>> > something from the China surplus/e-waste market.
>> >
>> > -- john, KE5FX
>> >
>> ___
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[time-nuts] Re: Thunderbolts ...

[Andy Talbot]

If you're interested in the Short Term Stability of the LB GPSDO.

http://g4jnt.com/ShortTermStabilityLeoBodnarGPSDO.pdf

Andy
www.g4jnt.com



On Tue, 20 Jul 2021 at 18:12, Bob Darlington  wrote:

> Same.  He probably got 250+ requests in short order.  I'm curious how the
> Leo Bodnar GPSDOs compare.   I'm considering one of these over a
> thunderbolt for field use for ham radio EME work.
>
> -Bob N3XKB
>
>
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[time-nuts] Re: Thunderbolts ...

[Dana Whitlow]

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




On Tue, Jul 20, 2021 at 12:42 PM John Ackermann  wrote:

> The Bodnar GPSDO is great for what it is, and has the great advantages of
> small size, low power consumption, low cost, and frequency agility.  But it
> doesn't have an OCXO so its short term and holdover performance isn't in
> the same league as the T'bolt or Z38whatever boxes.
>
> John
>
> On Jul 20, 2021, 1:11 PM, at 1:11 PM, Bob Darlington <
> rdarling...@gmail.com> wrote:
> >Same.  He probably got 250+ requests in short order.  I'm curious how
> >the
> >Leo Bodnar GPSDOs compare.   I'm considering one of these over a
> >thunderbolt for field use for ham radio EME work.
> >
> >-Bob N3XKB
> >
> >On Tue, Jul 20, 2021 at 10:59 AM Wes  wrote:
> >
> >> I wrote Tom, at the address he gave, on Saturday with a query.  So
> >far, no
> >> reply.
> >>
> >> Wes  N7WS
> >>
> >>   On 7/19/2021 4:59 PM, John Miles wrote:
> >> > If you're looking for a low cost surplus GPSDO, the ones Tom
> >mentioned in
> >> > his post on Saturday are the ones you want.  Not a Thunderbolt-E,
> >and not
> >> > something from the China surplus/e-waste market.
> >> >
> >> > -- john, KE5FX
> >> >
> >> ___
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[time-nuts] Re: Thunderbolts ...

[N1BUG]

Good question on the Leo Bodnar comparison. That's what I am using now 
and I am sure it is good enough for my purposes but I really want 
something I can use with LH and maybe the KO4BB Thunderbolt Monitor. I 
also inquired about the Thunderbolts and hope there's enough supply that 
I can grab one. I've been looking for a while but am hesitant on eBay units.


Paul N1BUG



On 7/20/21 1:11 PM, Bob Darlington wrote:

Same.  He probably got 250+ requests in short order.  I'm curious how the
Leo Bodnar GPSDOs compare.   I'm considering one of these over a
thunderbolt for field use for ham radio EME work.

-Bob N3XKB

On Tue, Jul 20, 2021 at 10:59 AM Wes  wrote:


I wrote Tom, at the address he gave, on Saturday with a query.  So far, no
reply.

Wes  N7WS

   On 7/19/2021 4:59 PM, John Miles wrote:

If you're looking for a low cost surplus GPSDO, the ones Tom mentioned in
his post on Saturday are the ones you want.  Not a Thunderbolt-E, and not
something from the China surplus/e-waste market.

-- john, KE5FX


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[time-nuts] Re: Thunderbolts ...

[David G. McGaw]

I have been using several versions of the UCCM units (Trimble, 
Symmetricom and Samsung) with mostly good results, both bare and 
packaged, as well as having several Thunderbolts.  The one thing that 
the Bodinar unit has which is nice is the synthesizer built in.  The 
Thunderbolts and UCCMs do not have this.  On the other hand, as has been 
said, the Bodinar unit has poor hold-over performance if you lose GPS 
lock, which here in NH amongst the trees and hills can happen fairly 
frequently.  As a result, I use OXCO GPSDOs with an external synthesizer.


David N1HAC

On 7/20/21 1:32 PM, N1BUG wrote:
Good question on the Leo Bodnar comparison. That's what I am using now 
and I am sure it is good enough for my purposes but I really want 
something I can use with LH and maybe the KO4BB Thunderbolt Monitor. I 
also inquired about the Thunderbolts and hope there's enough supply 
that I can grab one. I've been looking for a while but am hesitant on 
eBay units.


Paul N1BUG



On 7/20/21 1:11 PM, Bob Darlington wrote:
Same.  He probably got 250+ requests in short order.  I'm curious how 
the

Leo Bodnar GPSDOs compare.   I'm considering one of these over a
thunderbolt for field use for ham radio EME work.

-Bob N3XKB

On Tue, Jul 20, 2021 at 10:59 AM Wes  wrote:

I wrote Tom, at the address he gave, on Saturday with a query.  So 
far, no

reply.

Wes  N7WS

   On 7/19/2021 4:59 PM, John Miles wrote:
If you're looking for a low cost surplus GPSDO, the ones Tom 
mentioned in
his post on Saturday are the ones you want.  Not a Thunderbolt-E, 
and not

something from the China surplus/e-waste market.

-- john, KE5FX


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[time-nuts] Re: Thunderbolts ...

[Andy Talbot]

The LB uses a modern, third generation GPS module , Ublox 7 or 8 that has
the weak signal performance of its generation. Streets ahead of the old
Trimbles , Motorola and Garmins we used to love.
Here I use a passive patch antenna on mine in the shack and it stays
locked.


On Tue, 20 Jul 2021 at 20:34, David G. McGaw 
wrote:

> I have been using several versions of the UCCM units (Trimble,
> Symmetricom and Samsung) with mostly good results, both bare and
> packaged, as well as having several Thunderbolts.  The one thing that
> the Bodinar unit has which is nice is the synthesizer built in.  The
> Thunderbolts and UCCMs do not have this.  On the other hand, as has been
> said, the Bodinar unit has poor hold-over performance if you lose GPS
> lock, which here in NH amongst the trees and hills can happen fairly
> frequently.  As a result, I use OXCO GPSDOs with an external synthesizer.
>
> David N1HAC
>
> On 7/20/21 1:32 PM, N1BUG wrote:
> > Good question on the Leo Bodnar comparison. That's what I am using now
> > and I am sure it is good enough for my purposes but I really want
> > something I can use with LH and maybe the KO4BB Thunderbolt Monitor. I
> > also inquired about the Thunderbolts and hope there's enough supply
> > that I can grab one. I've been looking for a while but am hesitant on
> > eBay units.
> >
> > Paul N1BUG
> >
> >
> >
> > On 7/20/21 1:11 PM, Bob Darlington wrote:
> >> Same.  He probably got 250+ requests in short order.  I'm curious how
> >> the
> >> Leo Bodnar GPSDOs compare.   I'm considering one of these over a
> >> thunderbolt for field use for ham radio EME work.
> >>
> >> -Bob N3XKB
> >>
> >> On Tue, Jul 20, 2021 at 10:59 AM Wes  wrote:
> >>
> >>> I wrote Tom, at the address he gave, on Saturday with a query.  So
> >>> far, no
> >>> reply.
> >>>
> >>> Wes  N7WS
> >>>
> >>>On 7/19/2021 4:59 PM, John Miles wrote:
>  If you're looking for a low cost surplus GPSDO, the ones Tom
>  mentioned in
>  his post on Saturday are the ones you want.  Not a Thunderbolt-E,
>  and not
>  something from the China surplus/e-waste market.
> 
>  -- john, KE5FX
> 
> >>> ___
> >>> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> >>> send
> >>> an email to time-nuts-le...@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-le...@lists.febo.com
> >> To unsubscribe, go to and follow the instructions there.
> >>
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-- 
Andy (out keeping fit)
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[time-nuts] Re: Thunderbolts ...

[Tom Holmes]

Dana...

That temperature sensitivity to HVAC systems exists to some degree on most 
examples of this type of box, and really suggests
that more attention needs to be paid to keeping drafts at bay, as well as 
providing a reasonably stable temperature and
humidity environment for the T'bolt. I wouldn't be so fast to blame the box.

Tom Holmes, N8ZM

-Original Message-
From: Dana Whitlow  
Sent: Tuesday, July 20, 2021 2:23 PM
To: Discussion of precise time and frequency measurement 

Subject: [time-nuts] Re: Thunderbolts ...

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




On Tue, Jul 20, 2021 at 12:42 PM John Ackermann  wrote:

> The Bodnar GPSDO is great for what it is, and has the great advantages of
> small size, low power consumption, low cost, and frequency agility.  But it
> doesn't have an OCXO so its short term and holdover performance isn't in
> the same league as the T'bolt or Z38whatever boxes.
>
> John
>
> On Jul 20, 2021, 1:11 PM, at 1:11 PM, Bob Darlington <
> rdarling...@gmail.com> wrote:
> >Same.  He probably got 250+ requests in short order.  I'm curious how
> >the
> >Leo Bodnar GPSDOs compare.   I'm considering one of these over a
> >thunderbolt for field use for ham radio EME work.
> >
> >-Bob N3XKB
> >
> >On Tue, Jul 20, 2021 at 10:59 AM Wes  wrote:
> >
> >> I wrote Tom, at the address he gave, on Saturday with a query.  So
> >far, no
> >> reply.
> >>
> >> Wes  N7WS
> >>
> >>   On 7/19/2021 4:59 PM, John Miles wrote:
> >> > If you're looking for a low cost surplus GPSDO, the ones Tom
> >mentioned in
> >> > his post on Saturday are the ones you want.  Not a Thunderbolt-E,
> >and not
> >> > something from the China surplus/e-waste market.
> >> >
> >> > -- john, KE5FX
> >> >
> >> ___
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> >send
> >> an email to time-nuts-le...@lists.febo.com
> >> To unsubscribe, go to and follow the instructions there.
> >___
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[time-nuts] Re: Thunderbolts ...

[Tom Van Baak]

Hi Wes (and many others),

Yes, I have been getting large interest in this project. I'll get back 
to everyone by email by the end of the week. I'll also post details 
about pricing, testing, and delivery schedule at that time.


Please continue to email me directly ( t...@leapsecond.com ) for 
questions, or to be put on the buyers list.


/tvb


On 7/20/2021 9:58 AM, Wes wrote:
I wrote Tom, at the address he gave, on Saturday with a query.  So 
far, no reply.


Wes  N7WS

 On 7/19/2021 4:59 PM, John Miles wrote:
If you're looking for a low cost surplus GPSDO, the ones Tom 
mentioned in
his post on Saturday are the ones you want.  Not a Thunderbolt-E, and 
not

something from the China surplus/e-waste market.

-- john, KE5FX


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[time-nuts] Re: Thunderbolts ...

[Charles Steinmetz]

Dana wrote:


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.

Sounds like you have a not very good Tbolt.  First, understand that the 
original Tbolt was supplied by Trimble with several different VCXOs. 
ONLY the ones with Trimble 37265 oscillators have low tempcos.  Tbolts 
with other factory-installed oscillators are 100x or more worse.


However, *NOT ALL* 37265 VCXOs give proper tempco performance.  In the 
few samples I've tested, and by reviewing posted data for other 37265 
Tbolts, I identified two groups.  One group had what I expect for 37265 
Tbolt tempcos, while the others (maybe 50%+ of units?) all had tempcos 
grouped around 100x worse.  Generally, these also had tempcos of the 
opposite sign from the "properly working" units.


I reported this finding on the list in 2012.  There is a thread in the 
archive -- begin here: 





According to Bodnar, his units do have some choices in the time constant
setting.


Yeah, but that still doesn't fix the fact that their short-term 
stability is greatly inferior to any GPSDO with an OCXO, even one that 
has not been optimized.  Exactly what one doesn't want for most time-nut 
purposes.



Best regards,

Charles

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[time-nuts] Re: Thunderbolts ...

[Wes]

I guess I was thinking about being a man with three watches.  I have a Leo 
Bodnar (dual frequency model) and a BG7TBL GPSDO, 2019 model, already.  Leo 
makes (or made) two models, neither to my knowledge have ovenized oscillators.  
The programming software is not friendly on my model.


The Chinese unit has an OCXO.  I had it apart once and noted what parts were 
used, but I've misplaced those notes.  I have no good method(s), equipment wise, 
to compare these.


Wes  N7WS


On 7/20/2021 10:42 AM, John Ackermann wrote:

The Bodnar GPSDO is great for what it is, and has the great advantages of small 
size, low power consumption, low cost, and frequency agility.  But it doesn't 
have an OCXO so its short term and holdover performance isn't in the same 
league as the T'bolt or Z38whatever boxes.

John


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[time-nuts] Re: Thunderbolts

[Wes]

https://v3.airspy.us/product/lb-gpsdo-mini/



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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[time-nuts] Re: Thunderbolts

[Dana Whitlow]

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
> supplier.
>
> Dana
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[time-nuts] Re: Thunderbolts

[Mike Ingle]

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  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
> > supplier.
> >
> > Dana
> > ___
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> send
> > an email to time-nuts-le...@lists.febo.com
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[time-nuts] Re: Thunderbolts

[Bob kb8tq]

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  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
>> supplier.
>> 
>> Dana
>> ___
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>> an email to time-nuts-le...@lists.febo.com
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[time-nuts] Re: Thunderbolts

[Bob kb8tq]

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  
> 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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[time-nuts] Re: Thunderbolts

[Dana Whitlow]

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  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 
> 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
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[time-nuts] Re: Thunderbolts

[Bob kb8tq]

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  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  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 
>> 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 ju

[time-nuts] Re: Thunderbolts ...

[Stewart Cobb]

A few days ago, Charles Steinmetz mentioned that even the "good"
Thunderbolts with the 37265 OCXOs fall into two groups, one 100x worse than
the other. Perhaps that difference is not due to the OCXOs themselves but
to other parts on the board.

We know that, during the production run, the high-resolution board
temperature sensor was replaced by a software incompatible chip which
resulted in much coarser temperature resolution. We don't know how that
measurement was used in the control loop.

I gave a writeup of the OCXO control DAC here:



I forgot to mention in that writeup that the 74AC174 flip flop that
implements the PWM output gets its power from a precision voltage reference
chip. This stabilizes the DAC voltage over temperature. That reference, or
the precision opamp that serves as a level shifter for the DAC, might have
been substituted for parts with worse tempco at some point in the
production run. Either of those could cause an apparent increase in
observed tempco for the system as a whole.

It's even possible that the "good" units had offsetting temperature
coefficients between the OCXO and the DAC, and that insignificant parts
changes destroyed that favorable offset, even though all the parts remained
within spec.

The only good way to find out would be to examine all the date codes and
part numbers on the relevant parts, and to compare a group of "good" units
with a group of "bad" units and look for correlations.

Still if someone wants a project ...

Cheers!
--Stu
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[time-nuts] Re: Thunderbolts ...

[Bob kb8tq]

Hi

The OCXO “as shipped” on units after about 2021 or 2022 is in the low parts 
in 10^-9 over -20 to +70. Is yours 1 x 10^-9 or 2 x 10^-9? there’s no easy way
to tell. 

If you assume the TC is linear ( it may not be …) that gets you into the 10 to
20 ppt / C range. With a room that swings a couple of degrees, that’s going to
be tough to measure ….. Even if the TC is a bit non-linear, it’s unlikely you 
are
over 40 ppt / C. 

Bob

> On Jul 24, 2021, at 2:30 PM, Stewart Cobb  wrote:
> 
> A few days ago, Charles Steinmetz mentioned that even the "good"
> Thunderbolts with the 37265 OCXOs fall into two groups, one 100x worse than
> the other. Perhaps that difference is not due to the OCXOs themselves but
> to other parts on the board.
> 
> We know that, during the production run, the high-resolution board
> temperature sensor was replaced by a software incompatible chip which
> resulted in much coarser temperature resolution. We don't know how that
> measurement was used in the control loop.
> 
> I gave a writeup of the OCXO control DAC here:
> 
> 
> 
> I forgot to mention in that writeup that the 74AC174 flip flop that
> implements the PWM output gets its power from a precision voltage reference
> chip. This stabilizes the DAC voltage over temperature. That reference, or
> the precision opamp that serves as a level shifter for the DAC, might have
> been substituted for parts with worse tempco at some point in the
> production run. Either of those could cause an apparent increase in
> observed tempco for the system as a whole.
> 
> It's even possible that the "good" units had offsetting temperature
> coefficients between the OCXO and the DAC, and that insignificant parts
> changes destroyed that favorable offset, even though all the parts remained
> within spec.
> 
> The only good way to find out would be to examine all the date codes and
> part numbers on the relevant parts, and to compare a group of "good" units
> with a group of "bad" units and look for correlations.
> 
> Still if someone wants a project ...
> 
> Cheers!
> --Stu
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[time-nuts] Re: Thunderbolts ...

[Charles Steinmetz]

Stewart wrote:


A few days ago, Charles Steinmetz mentioned that even the "good"
Thunderbolts with the 37265 OCXOs fall into two groups, one 100x worse than
the other. Perhaps that difference is not due to the OCXOs themselves but
to other parts on the board.


If that were true, it would mean that the actual EFC voltage in those 
units was varying with respect to the DAC voltage as reported over the 
Tbolt's serial port.  While not impossible (after all, we know almost 
nothing about the internal architecture of the Tbolt), for a number of 
reasons I think that is unlikely.



We know that, during the production run, the high-resolution board
temperature sensor was replaced by a software incompatible chip which
resulted in much coarser temperature resolution. We don't know how that
measurement was used in the control loop.


We do know that the temperature as reported by the DS1620 chip is used 
only to trim the OCXO frequency during holdover.  It plays *no* part in 
controlling the frequency during normal (GPS-controlled)  operation, nor 
during free-running operation (control loop off).


There is some discussion of this in the archive.

Best regards,

Charles

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[time-nuts] Re: Thunderbolts ...

[Hal Murray]

csteinm...@yandex.com said:
> If that were true, it would mean that the actual EFC voltage in those  units
> was varying with respect to the DAC voltage as reported over the  Tbolt's
> serial port.  While not impossible (after all, we know almost  nothing about
> the internal architecture of the Tbolt), for a number of  reasons I think
> that is unlikely. 

The only thing that the TBolt can report is the number that it feeds to the 
DAC.

I expect the actual voltage out would vary with temperature, supply voltage, 
age, and whatever.  Add in the reference voltage if that's not included in the 
DAC.

I haven't looked at DAC data sheets recently.  How many of the modern ones 
have a set of small graphs showing parameters like that?


-- 
These are my opinions.  I hate spam.


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[time-nuts] Re: Thunderbolts ...

[Bob kb8tq]

Hi

Most good DAC’s show you information on temperature / supply / and reference
stability (along with a bunch of other stuff like noise …). You are paying for 
those
parameters when you buy a “good” DAC. 

The TBolt has a “home brew” DAC and (maybe) feedback setup. For whatever reason
(one would guess cost) they did it all themselves in a FPGA rather than running
a “stock” chip. You can trace out portions of the setup. Once it goes back into 
the FPGA …. who knows. Some sort of Sigma Delta Something Somewhere is 
probably a good guess. 

Bottom line is, you can’t just go to the label on this or that chip and grab 
the 
data sheet for “the DAC”.  I don’t even recall anybody finding “the reference
IC” for “the DAC”. They may well have and I’ve simply forgotten over the last 10
or 15 years ...

What you *could* do is to rig up a Volt Nuts grade bench, set the DAC to various
voltages and run the beast over temperature. Somehow that sounds like a lot
of work. Unless you have a “group” it would only tell you part of the story ….

Bob

> On Jul 25, 2021, at 5:03 AM, Hal Murray  wrote:
> 
> 
> csteinm...@yandex.com said:
>> If that were true, it would mean that the actual EFC voltage in those  units
>> was varying with respect to the DAC voltage as reported over the  Tbolt's
>> serial port.  While not impossible (after all, we know almost  nothing about
>> the internal architecture of the Tbolt), for a number of  reasons I think
>> that is unlikely. 
> 
> The only thing that the TBolt can report is the number that it feeds to the 
> DAC.
> 
> I expect the actual voltage out would vary with temperature, supply voltage, 
> age, and whatever.  Add in the reference voltage if that's not included in 
> the 
> DAC.
> 
> I haven't looked at DAC data sheets recently.  How many of the modern ones 
> have a set of small graphs showing parameters like that?
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
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