Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bob Camp]

Hi

Indeed, driving the device with a low noise (as in -175 dbc/Hz) OCXO does 
produce the expected -172 dbc/Hz
output. Checking either with a power splitter ahead of the sine to square 
conversion or splitting with logic gates
after the conversion yields a similar floor number. Close in noise is indeed 
higher than -175, but it’s still better 
than any source you can buy to drive the device.

Bob



> On Dec 22, 2015, at 2:07 PM, Bruce Griffiths  
> wrote:
> 
> Thanks, driving the input with a low PN OCXO is probably the difference, John 
> Miles used an HP8642 - not quite as low PN.
> The PN test set is supposed to reject the source PN as it drives both inputs 
> of the PN test set. However this rejection isn't perfect.
> I'll try driving a 74AC04 input directly (I have sufficient signal level for 
> this at the output of various low PN amplifiers). I'll also see if I can just 
> measure the output of a single gate using a pair of low PN amps to drive the 
> Timepod Channel0 and Channel2 inputs separately..
> 
> Deuterating the chip apparently reduces flicker noise more effectively than 
> simply using Hydrogen to terminate dangling Si bonds at the oxide interface.
> However I guess there's no easy way to determine if the chip was soaked in 
> hydrogen or deuterium?? Perhaps baking the packaged chip in deuterium might 
> help if the passivation and package are sufficiently permeable.
> 
> Bruce
> 
> On Tuesday, December 22, 2015 07:49:42 AM Bob Camp wrote:
>> Hi
>> 
>> To be very specific about the floor on the gates (as measured with a
>> TimePod):
>> 
>> 1) Clean 5.5V supply (max the part can rationally take).
>> 2) Input signal L network transformed to just below the protection diode
>> threshold (roughly 6V p-p) 3) Input signal to the power splitter is from an
>> OCXO so it’s pretty clean and does not have a lot of “junk” on it. 4)
>> Output is Tee network matched off of a pair of gates in parallel 5) Power
>> supply is clean, but nothing special (LT1764).
>> 
>> I believe there are plots in the archives.
>> 
>> Bob
>> 
>>> On Dec 21, 2015, at 10:20 PM, Bruce Griffiths 
>>> wrote:
>>> 
>>> Do those modern CMOS gates use deuterated wafers?I've not found any
>>> measurements of the PN of modern CMOS gates.The measurements of devices
>>> like the venerable 74AC04 indicate a PN floor around 10dBc/Hz worse than
>>> that. Bruce
>>> 
>>>   On Tuesday, 22 December 2015 3:00 PM, Bob Camp  wrote:
>>> Hi
>>> 
>>> To go through the whole deal a step at a time *assuming* that broadband
>>> noise is the only issue:
>>> 
>>> -147 dbm noise per Hz
>>> +10 dbm signal
>>> 
>>> => -157 dbc / Hz
>>> 
>>> half to AM, half to PM
>>> 
>>> => -160 dbc / Hz
>>> 
>>> ssb is already taken care of (noise on both sides if it’s broadband)
>>> 
>>> => -160 dbc / Hz
>>> 
>>> Now, assuming you have a modulation on the edge due to low frequency
>>> noise:
>>> 
>>> -147 dbm noise per Hz
>>> +10 dbm signal
>>> +0 conversion gain (might be less, rarely is more)
>>> 
>>> => -157 dbc / Hz
>>> 
>>> It all may go to PM so
>>> 
>>> => -157 dbc / Hz
>>> 
>>> It’s DSB (sidebands are coherent) modulation so
>>> 
>>> => -151 dbc / Hz
>>> 
>>> You could easily say that all of the stuff after the conversion gain
>>> number is just messing around. That would indeed be correct. All that has
>>> been done is to calculate a conversion gain for low frequency noise to PM
>>> as read by a phase noise test set. The main point is to illustrate that
>>> you may be *more* sensitive to low frequency noise than you might think.
>>> 
>>> =
>>> 
>>> Biased CMOS gates are looking better and better … -175 dbc / Hz floor with
>>> a 7 dbm input …. :)
>>> 
>>> Bob
>>> 
 On Dec 21, 2015, at 3:05 PM, Anders Wallin  
> wrote:
>> AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
>> input-referred voltage noise PSD (if I calculated correctly..)
> 
> With +10dBm input the corresponding SSB PN floor should be  around
> -163dBc/Hz.
 
 HI,
 How is that calculated? I only get this far:
 9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz
 
 what then? split half-and-half into AM and PN, and how to relate that to
 the carrier power +10dBm?
 
 thanks,
 Anders
 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the
 instructions there.
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
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>>> instructions there.
>>> 
>>> 
>>> 
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>>> To unsubscribe, go to
>>> 

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bruce Griffiths]

Thanks, driving the input with a low PN OCXO is probably the difference, John 
Miles used an HP8642 - not quite as low PN.
The PN test set is supposed to reject the source PN as it drives both inputs 
of the PN test set. However this rejection isn't perfect.
I'll try driving a 74AC04 input directly (I have sufficient signal level for 
this at the output of various low PN amplifiers). I'll also see if I can just 
measure the output of a single gate using a pair of low PN amps to drive the 
Timepod Channel0 and Channel2 inputs separately..

Deuterating the chip apparently reduces flicker noise more effectively than 
simply using Hydrogen to terminate dangling Si bonds at the oxide interface.
However I guess there's no easy way to determine if the chip was soaked in 
hydrogen or deuterium?? Perhaps baking the packaged chip in deuterium might 
help if the passivation and package are sufficiently permeable.

Bruce

On Tuesday, December 22, 2015 07:49:42 AM Bob Camp wrote:
> Hi
> 
> To be very specific about the floor on the gates (as measured with a
> TimePod):
> 
> 1) Clean 5.5V supply (max the part can rationally take).
> 2) Input signal L network transformed to just below the protection diode
> threshold (roughly 6V p-p) 3) Input signal to the power splitter is from an
> OCXO so it’s pretty clean and does not have a lot of “junk” on it. 4)
> Output is Tee network matched off of a pair of gates in parallel 5) Power
> supply is clean, but nothing special (LT1764).
> 
> I believe there are plots in the archives.
> 
> Bob
> 
> > On Dec 21, 2015, at 10:20 PM, Bruce Griffiths 
> > wrote:
> > 
> > Do those modern CMOS gates use deuterated wafers?I've not found any
> > measurements of the PN of modern CMOS gates.The measurements of devices
> > like the venerable 74AC04 indicate a PN floor around 10dBc/Hz worse than
> > that. Bruce
> > 
> >On Tuesday, 22 December 2015 3:00 PM, Bob Camp  wrote:
> > Hi
> > 
> > To go through the whole deal a step at a time *assuming* that broadband
> > noise is the only issue:
> > 
> > -147 dbm noise per Hz
> > +10 dbm signal
> > 
> > => -157 dbc / Hz
> > 
> > half to AM, half to PM
> > 
> > => -160 dbc / Hz
> > 
> > ssb is already taken care of (noise on both sides if it’s broadband)
> > 
> > => -160 dbc / Hz
> > 
> > Now, assuming you have a modulation on the edge due to low frequency
> > noise:
> > 
> > -147 dbm noise per Hz
> > +10 dbm signal
> > +0 conversion gain (might be less, rarely is more)
> > 
> > => -157 dbc / Hz
> > 
> > It all may go to PM so
> > 
> > => -157 dbc / Hz
> > 
> > It’s DSB (sidebands are coherent) modulation so
> > 
> > => -151 dbc / Hz
> > 
> > You could easily say that all of the stuff after the conversion gain
> > number is just messing around. That would indeed be correct. All that has
> > been done is to calculate a conversion gain for low frequency noise to PM
> > as read by a phase noise test set. The main point is to illustrate that
> > you may be *more* sensitive to low frequency noise than you might think.
> > 
> > =
> > 
> > Biased CMOS gates are looking better and better … -175 dbc / Hz floor with
> > a 7 dbm input …. :)
> > 
> > Bob
> > 
> >> On Dec 21, 2015, at 3:05 PM, Anders Wallin  
wrote:
>  AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
>  input-referred voltage noise PSD (if I calculated correctly..)
> >>> 
> >>> With +10dBm input the corresponding SSB PN floor should be  around
> >>> -163dBc/Hz.
> >> 
> >> HI,
> >> How is that calculated? I only get this far:
> >> 9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz
> >> 
> >> what then? split half-and-half into AM and PN, and how to relate that to
> >> the carrier power +10dBm?
> >> 
> >> thanks,
> >> Anders
> >> ___
> >> time-nuts mailing list -- time-nuts@febo.com
> >> To unsubscribe, go to
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the
> >> instructions there.
> > 
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
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> > instructions there.
> > 
> > 
> > 
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bob Camp]

Hi

To be very specific about the floor on the gates (as measured with a TimePod):

1) Clean 5.5V supply (max the part can rationally take).
2) Input signal L network transformed to just below the protection diode 
threshold (roughly 6V p-p)
3) Input signal to the power splitter is from an OCXO so it’s pretty clean and 
does not have a lot of “junk” on it.
4) Output is Tee network matched off of a pair of gates in parallel 
5) Power supply is clean, but nothing special (LT1764). 

I believe there are plots in the archives. 

Bob


> On Dec 21, 2015, at 10:20 PM, Bruce Griffiths  
> wrote:
> 
> Do those modern CMOS gates use deuterated wafers?I've not found any 
> measurements of the PN of modern CMOS gates.The measurements of devices like 
> the venerable 74AC04 indicate a PN floor around 10dBc/Hz worse than that.
> Bruce
> 
> 
>On Tuesday, 22 December 2015 3:00 PM, Bob Camp  wrote:
> 
> 
> Hi
> 
> To go through the whole deal a step at a time *assuming* that broadband noise 
> is the only issue:
> 
> -147 dbm noise per Hz
> +10 dbm signal
> 
> => -157 dbc / Hz
> 
> half to AM, half to PM
> 
> => -160 dbc / Hz
> 
> ssb is already taken care of (noise on both sides if it’s broadband)
> 
> => -160 dbc / Hz 
> 
> Now, assuming you have a modulation on the edge due to low frequency noise:
> 
> -147 dbm noise per Hz
> +10 dbm signal 
> +0 conversion gain (might be less, rarely is more)
> 
> => -157 dbc / Hz
> 
> It all may go to PM so
> 
> => -157 dbc / Hz
> 
> It’s DSB (sidebands are coherent) modulation so 
> 
> => -151 dbc / Hz
> 
> You could easily say that all of the stuff after the conversion gain number 
> is just messing around. 
> That would indeed be correct. All that has been done is to calculate a 
> conversion gain for low 
> frequency noise to PM as read by a phase noise test set. The main point is to 
> illustrate that you 
> may be *more* sensitive to low frequency noise than you might think. 
> 
> =
> 
> Biased CMOS gates are looking better and better … -175 dbc / Hz floor with a 
> 7 dbm input …. :)
> 
> Bob
> 
> 
> 
> 
>> On Dec 21, 2015, at 3:05 PM, Anders Wallin  
>> wrote:
>> 
 AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
 input-referred voltage noise PSD (if I calculated correctly..)
>>> 
>>> With +10dBm input the corresponding SSB PN floor should be  around
>>> -163dBc/Hz.
>>> 
>> 
>> HI,
>> How is that calculated? I only get this far:
>> 9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz
>> 
>> what then? split half-and-half into AM and PN, and how to relate that to
>> the carrier power +10dBm?
>> 
>> thanks,
>> Anders
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> ___
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> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 
> 
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Anders Wallin]

> > AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
> > input-referred voltage noise PSD (if I calculated correctly..)
>
> With +10dBm input the corresponding SSB PN floor should be  around
> -163dBc/Hz.
>

HI,
How is that calculated? I only get this far:
9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz

what then? split half-and-half into AM and PN, and how to relate that to
the carrier power +10dBm?

thanks,
Anders
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bob Camp]

Hi

To go through the whole deal a step at a time *assuming* that broadband noise 
is the only issue:

-147 dbm noise per Hz
+10 dbm signal

=> -157 dbc / Hz

half to AM, half to PM

=> -160 dbc / Hz

ssb is already taken care of (noise on both sides if it’s broadband)

=> -160 dbc / Hz 

Now, assuming you have a modulation on the edge due to low frequency noise:

-147 dbm noise per Hz
+10 dbm signal 
+0 conversion gain (might be less, rarely is more)

=> -157 dbc / Hz
 
It all may go to PM so

=> -157 dbc / Hz

It’s DSB (sidebands are coherent) modulation so 

=> -151 dbc / Hz

You could easily say that all of the stuff after the conversion gain number is 
just messing around. 
That would indeed be correct. All that has been done is to calculate a 
conversion gain for low 
frequency noise to PM as read by a phase noise test set. The main point is to 
illustrate that you 
may be *more* sensitive to low frequency noise than you might think. 

=

Biased CMOS gates are looking better and better … -175 dbc / Hz floor with a 7 
dbm input …. :)

Bob




> On Dec 21, 2015, at 3:05 PM, Anders Wallin  
> wrote:
> 
>>> AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
>>> input-referred voltage noise PSD (if I calculated correctly..)
>> 
>> With +10dBm input the corresponding SSB PN floor should be  around
>> -163dBc/Hz.
>> 
> 
> HI,
> How is that calculated? I only get this far:
> 9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz
> 
> what then? split half-and-half into AM and PN, and how to relate that to
> the carrier power +10dBm?
> 
> thanks,
> Anders
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bruce Griffiths]

Do those modern CMOS gates use deuterated wafers?I've not found any 
measurements of the PN of modern CMOS gates.The measurements of devices like 
the venerable 74AC04 indicate a PN floor around 10dBc/Hz worse than that.
Bruce
 

On Tuesday, 22 December 2015 3:00 PM, Bob Camp  wrote:
 

 Hi

To go through the whole deal a step at a time *assuming* that broadband noise 
is the only issue:

-147 dbm noise per Hz
+10 dbm signal

=> -157 dbc / Hz

half to AM, half to PM

=> -160 dbc / Hz

ssb is already taken care of (noise on both sides if it’s broadband)

=> -160 dbc / Hz 

Now, assuming you have a modulation on the edge due to low frequency noise:

-147 dbm noise per Hz
+10 dbm signal 
+0 conversion gain (might be less, rarely is more)

=> -157 dbc / Hz
 
It all may go to PM so

=> -157 dbc / Hz

It’s DSB (sidebands are coherent) modulation so 

=> -151 dbc / Hz

You could easily say that all of the stuff after the conversion gain number is 
just messing around. 
That would indeed be correct. All that has been done is to calculate a 
conversion gain for low 
frequency noise to PM as read by a phase noise test set. The main point is to 
illustrate that you 
may be *more* sensitive to low frequency noise than you might think. 

=

Biased CMOS gates are looking better and better … -175 dbc / Hz floor with a 7 
dbm input …. :)

Bob




> On Dec 21, 2015, at 3:05 PM, Anders Wallin  
> wrote:
> 
>>> AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
>>> input-referred voltage noise PSD (if I calculated correctly..)
>> 
>> With +10dBm input the corresponding SSB PN floor should be  around
>> -163dBc/Hz.
>> 
> 
> HI,
> How is that calculated? I only get this far:
> 9.6nV/sqrt(Hz) into a 50R load is 1.8e-18 W/Hz or -147.3 dBm/Hz
> 
> what then? split half-and-half into AM and PN, and how to relate that to
> the carrier power +10dBm?
> 
> thanks,
> Anders
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bruce Griffiths]

Reverting somewhat closer to the original topic:Attached 2 BJT circuit has 
unity gain with a PN floor well below -180dBc/Hz (10MHz +13dBm input) with a 
reverse isolation better than 60dB. 2nd Harmonic output is about -70dBc or so.4 
of these could be driven from the outputs of a 4 way splitter to achieve a 
channel to channel isolation of 80dB or greater.All that is needed for a 4 
output distribution amp is a low noise low distortion preamp with a gain of at 
least 6dB and an output of 19dBm or so to drive the splitter input.This should 
be easily achieved using 3 (or perhaps less) BJTs.  

Bruce 

On Monday, 21 December 2015 1:01 AM, Clint Jay  wrote:
 

 I once spent a very miserable but profitable weekend remaking a thin
ethernet network where the "installation expert" had stripped back 10B2
coax four inches and neatly separated core and shield,  heatshrinked them
into pigtails and then soldered them into panel mount BNC sockets.

He was outraged when I suggested his cabling skills weren't up to much,
insisting he had done many other installs like that and that it worked just
fine because his multimeter measured the correct termination resistance
from one end to the other.

The TDR and vastly improved network speed of course showed exactly how
wrong he was.
On 19 Dec 2015 22:00, "Poul-Henning Kamp"  wrote:

> 
> In message <56757344.2020...@rubidium.se>, Magnus Danielson writes:
>
> >The isolation strategy says that the various equipments should only be
> >power grounded, as required for personal safety, and then have all other
> >grounding paths "galvanically separated" (thus, DC and power frequencies
> >separated in common mode).
> >
> >The mesh strategy says that you extend the grounding of the power ground
> >with additional grounding with every cable and additional grounding
> >cables.
>
> Please bear in mind that there is a *huge* difference between
> single-ended (as in: RF-Coax-BNC) and balanced (as in: Audio-Twinax-XLR)
> for both of these scenarios.
>
> While you can get away with the isolation strategy with balanced,
> because you have high CMRR inputs, there is nothing to "take care
> of" the ground potentials in the single-ended mode.
>
> >As a reference, Ethernet is designed to work in an isolation BN setup,
> >[...]
>
> That is actually a new thing, the original Ethernet was 1/2" coax
> and ground-loops and lightning damage was the order of the day.
>
> The main reason Ethernet went balanced was actually for fault
> isolation (star-topology vs. bus) and signal quality (IT people
> were horrible at "sharking" and crimping coax.)
>
> --
> Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
> p...@freebsd.org        | TCP/IP since RFC 956
> FreeBSD committer      | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
> ___
> time-nuts mailing list -- time-nuts@febo.com
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>
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Poul-Henning Kamp]

In message <20151220042724.0f3d8406...@ip-64-139-1-69.sjc.megapath.net>, Hal 
Murray writes:
>
>p...@phk.freebsd.dk said:
>> The main reason Ethernet went balanced was actually for fault isolation
>> (star-topology vs. bus) and signal quality (IT people were horrible at
>> "sharking" and crimping coax.) 
>
>The reason Ethernet switched to a star topology was to take advantage of the 
>wires that were already installed in most buildings.

That came later.

The first twisted-pair stuff only allowed 30m of wire and was meant for
connecting workstations in an office to a hub, so that only the hub
had to attach to the "backbone" coax.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Clint Jay]

I once spent a very miserable but profitable weekend remaking a thin
ethernet network where the "installation expert" had stripped back 10B2
coax four inches and neatly separated core and shield,  heatshrinked them
into pigtails and then soldered them into panel mount BNC sockets.

He was outraged when I suggested his cabling skills weren't up to much,
insisting he had done many other installs like that and that it worked just
fine because his multimeter measured the correct termination resistance
from one end to the other.

The TDR and vastly improved network speed of course showed exactly how
wrong he was.
On 19 Dec 2015 22:00, "Poul-Henning Kamp"  wrote:

> 
> In message <56757344.2020...@rubidium.se>, Magnus Danielson writes:
>
> >The isolation strategy says that the various equipments should only be
> >power grounded, as required for personal safety, and then have all other
> >grounding paths "galvanically separated" (thus, DC and power frequencies
> >separated in common mode).
> >
> >The mesh strategy says that you extend the grounding of the power ground
> >with additional grounding with every cable and additional grounding
> >cables.
>
> Please bear in mind that there is a *huge* difference between
> single-ended (as in: RF-Coax-BNC) and balanced (as in: Audio-Twinax-XLR)
> for both of these scenarios.
>
> While you can get away with the isolation strategy with balanced,
> because you have high CMRR inputs, there is nothing to "take care
> of" the ground potentials in the single-ended mode.
>
> >As a reference, Ethernet is designed to work in an isolation BN setup,
> >[...]
>
> That is actually a new thing, the original Ethernet was 1/2" coax
> and ground-loops and lightning damage was the order of the day.
>
> The main reason Ethernet went balanced was actually for fault
> isolation (star-topology vs. bus) and signal quality (IT people
> were horrible at "sharking" and crimping coax.)
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Magnus Danielson]

Tim,

There is two major strategies as you build a system and needs to figure 
out how your ground bonding network (often just referred to bonding 
network or grounding) should operate.


The isolation strategy says that the various equipments should only be 
power grounded, as required for personal safety, and then have all other 
grounding paths "galvanically separated" (thus, DC and power frequencies 
separated in common mode).


The mesh strategy says that you extend the grounding of the power ground 
with additional grounding with every cable and additional grounding 
cables. This strategy strengthen with every cable you pull, as the 
conductance increases. Any potential difference produce a current that 
is current shared by the shunted conductors. It is common to explicitly 
add main grounding conductors to take the main current and reduce the 
current on other cables.


The difficulty with the isolation strategy is that if you happens to 
make contact with ground, you can now be the source of a large current 
to average out the potential, and that may not be what you want to see 
on your coax cable for instance. We have pointed out that it may not be 
so nice that we have sparks jumping the connectors on broadcast 
equipment, as we saw once.


Another difficulty with the isolation strategy is that it makes the EMC 
aspect harder to do, as you want the shield of your cable to extend the 
shield of your box, and not become a source of energy emitting out on 
the cable and thus be a conducted source of RF emission (and reception).
The RF choke with associated capacitance (or conductance, the important 
being low-impedance path) on both sides is the way to go to achieve good 
common mode RF rejection.


In the mesh strategy, you can skip transformers most of the time and 
only use RF chokes, and then mostly to decouple the chassi and PCB 
RF-wise on common mode.


Measurement instruments is most of the times built for the mesh 
strategy, with BNC/SMA/N connectors hard-tied to the chassi. There is 
the braindead idea to cut the chassi to ground connection, which do make 
some measurements easier, but kills the safety. If you follow the mesh 
strategy, you have the star-ground of the power-system complemented with 
additional grounding wires of the racks etc.
So, you wire your instruments together, and then provide multiple ground 
connections to your DUT. You need to figure out how to avoid common mode 
to differential mode conversions, but that is not unique to the mesh BN 
strategy, it's even more important in the isolation BN strategy as you 
have higher potentials to isolate.


Even when having the majority of the rig being mesh BN style, for some 
measurement connections it can be beneficial to do DC separation of 
common mode, in which case transformers or capacitors can provide 
isolation. I prefer to use differential amps when possible, and for some 
reason the 1 GHz differential probe is often used in the lab.


As a reference, Ethernet is designed to work in an isolation BN setup, 
because the Ethernet connections often span over an office building, 
between different branches of the power distribution for which the 
grounding wires can have quite different potential and hence there being 
a potential difference that can produce a sizeable current. It also runs 
in environments where typical does not understand grounding issues, and 
where by local code and design of equipment, they have a star grounding 
network and no concept of interconnection between consumers (think of 
lamps, radiators, kitchen stoves and ovens and similar "simple" devices).


Also recall that the first rule of thumb for electrical safety is that 
the first connection you make to a box is ground, and the last 
connection you remove is to ground. Thus, a box shall at least be 
grounded for safety, and only when grounded it will receive power, from 
anywhere.


There is more war-stories to be told.

Cheers,
Magnus

On 12/19/2015 03:23 PM, Tim Shoppa wrote:

I think there is a valid heritage in transformer isolation in time and
frequency distribution, and it goes back to when telephone wiring was
used to distribute audio-type IRIG signals around a campus or other
facility. Even if a bunch of 60Hz or a local AM station was leaking
through the IRIG signaling was quite impervious to it. (Heh, the
aircraft VHF radio getting into Spinal Tap's lead guitar was hardly
noticeable at that air force base, for that matter!!!)

But something feels "off" with lifting grounds on coax if the
environment is just a test lab.

CAT 5/6 and Ethernet transformers work great at 10MHz but most all test
equipment is expecting coax and a BNC.

Tim N3QE

On Sat, Dec 19, 2015 at 8:29 AM, Magnus Danielson
> wrote:

Transformer isolation isn't helping much at RF, as you will
capacitively couple through the transformer. I've been bitten by
that in real life, as I was called in 

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Magnus Danielson]

Poul-Henning,

On 12/19/2015 03:58 PM, Poul-Henning Kamp wrote:


In message <56755ba1.7000...@rubidium.dyndns.org>, Magnus Danielson writes:


There is an over believe in isolation, as it only takes one mistake to
break the system. Another approach is to ground everything, cross-ground
etc. and bring the DC/power-spurs down through conduction.


Tony Waldron argued similar for audio systems:

http://www.fragrantsword.com/twaudio/



Haven't seen those, but it looks like a nice reading.
He uses the mesh-BN terminology.

One document to read is the ITU-T K.27 which is for free download here:
https://www.itu.int/rec/T-REC-K.27/en

The ISO/IEC/CENELEC standards often referred to is something you have to 
pay for, but the ITU-T stuff is for free, so it's a good starting point.


Cheers,
Magnus
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Magnus Danielson]

Poul-Henning,

On 12/19/2015 10:11 PM, Poul-Henning Kamp wrote:


In message <56757344.2020...@rubidium.se>, Magnus Danielson writes:


The isolation strategy says that the various equipments should only be
power grounded, as required for personal safety, and then have all other
grounding paths "galvanically separated" (thus, DC and power frequencies
separated in common mode).

The mesh strategy says that you extend the grounding of the power ground
with additional grounding with every cable and additional grounding
cables.


Please bear in mind that there is a *huge* difference between
single-ended (as in: RF-Coax-BNC) and balanced (as in: Audio-Twinax-XLR)
for both of these scenarios.

While you can get away with the isolation strategy with balanced,
because you have high CMRR inputs, there is nothing to "take care
of" the ground potentials in the single-ended mode.


Oh yes, indeed. I've worked both fields.


As a reference, Ethernet is designed to work in an isolation BN setup,
[...]


That is actually a new thing, the original Ethernet was 1/2" coax
and ground-loops and lightning damage was the order of the day.


Well, it's been a long time since that was Ethernet.


The main reason Ethernet went balanced was actually for fault
isolation (star-topology vs. bus) and signal quality (IT people
were horrible at "sharking" and crimping coax.)


The way they destroyed yellow cable with their attempts to drill for 
their vampire... yes. I've seen that too.


Cheers,
Magnus
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bob Camp]

Hi

There is a very significant difference between coax and twisted pair when it 
comes
to magnetic induction. The twist “cancels out” the signal on the pair. The 
shield has
the signal induced on it’s outer surface. Transformers work better on twisted 
pair than
on coax. If you look at a “normal” ethernet twisted pair interface (magnetics) 
you will 
likely see both a transformer and a common mode choke inside. That of course 
assumes
that the schematic is showing you what really is in there. Even with twisted 
pair the 
choke helps.

Bob


> On Dec 19, 2015, at 9:23 AM, Tim Shoppa  wrote:
> 
> I think there is a valid heritage in transformer isolation in time and
> frequency distribution, and it goes back to when telephone wiring was used
> to distribute audio-type IRIG signals around a campus or other facility.
> Even if a bunch of 60Hz or a local AM station was leaking through the IRIG
> signaling was quite impervious to it. (Heh, the aircraft VHF radio getting
> into Spinal Tap's lead guitar was hardly noticeable at that air force base,
> for that matter!!!)
> 
> But something feels "off" with lifting grounds on coax if the environment
> is just a test lab.
> 
> CAT 5/6 and Ethernet transformers work great at 10MHz but most all test
> equipment is expecting coax and a BNC.
> 
> Tim N3QE
> 
> On Sat, Dec 19, 2015 at 8:29 AM, Magnus Danielson <
> mag...@rubidium.dyndns.org> wrote:
> 
>> Transformer isolation isn't helping much at RF, as you will capacitively
>> couple through the transformer. I've been bitten by that in real life, as I
>> was called in to solve issues in someone elses design. It was only when I
>> introduced an RF choke that we got conducted noise battled. It's also not
>> enough, as the RF choke needs an RF path to ground in order to start
>> rejecting effectively, which was the issue another time, so you want an RF
>> choke with caps to ground on the inside.
>> 
>> The galvanic isolation can be done using transformer or capacitors after
>> that.
>> 
>> There is an over believe in isolation, as it only takes one mistake to
>> break the system. Another approach is to ground everything, cross-ground
>> etc. and bring the DC/power-spurs down through conduction. It have proven
>> itself easier to ensure RF properties when shield and chassi is tied hard
>> to each other, as it provides good RF conduction and the cable does not act
>> like an antenna against the shield for the RF power being unbalanced. The
>> RF choke then acts to separate the chassi RF from that of the board,
>> assisting in the balance.
>> 
>> Transformers can provide RF shielding, if they have double shields between
>> the coils, and where the shield of each side is connected to it's ground.
>> That way each coil will capacitively terminate in it's own shield, and the
>> remaining capacitive coupling will mainly be between the shields and hence
>> grounds. I rarely see people doing this.
>> 
>> I've been bitten multiple times by the capacitive coupling in
>> transformers, and only when I found a way to handle it things have started
>> to work. It's not all magnetics.
>> 
>> Cheers,
>> Magnus
>> 
>> 
>> On 12/19/2015 12:33 AM, Tim Shoppa wrote:
>> 
>>> All the inputs and outputs were deliberately transformer isolated. Why
>>> break the isolation by using capacitor from coax shield to chassis ground?
>>> 
>>> I do realize that some isolation transformers have "extra floating turns"
>>> to give transformer action that cancels stray capacitive coupling. I don't
>>> think the capacitors tying coax shield to chassis ground can serve that
>>> purpose.
>>> 
>>> Tim N3QE
>>> 
>>> On Mon, Nov 30, 2015 at 3:02 PM, Anders Wallin <
>>> anders.e.e.wal...@gmail.com>
>>> wrote:
>>> 
>>> HI all,
 I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
 maybe 5MHz) and instead of reinventing the wheel I decided to try to
 modernize the TADD-1 into an all (almost) SMD design. Here are some draft
 sketches:
 
 
 http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/
 
 Does this sound/look reasonable or crazy?
 Any suggestions for op-amps to try and/or compare to the AD8055?
 What causes the extra phase-noise below 1 Hz offset in John A's result:
 
 https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png
 
 Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied
 to
 this board will most likely come from a switched-mode PSU, so filtering
 of
 common-mode noise is mandatory.
 I found the TI LP38798 shown in the schematic by googling - if someone
 has
 a proven a measured design that would be a safer choice. In any case more
 filtering (e.g. ferriites) is probably a good idea.
 
 This design will be available on my blog or on github when it is done -
 if
 anyone is interested.
 
 Thanks,
 Anders
 

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Poul-Henning Kamp]

In message <56757344.2020...@rubidium.se>, Magnus Danielson writes:

>The isolation strategy says that the various equipments should only be 
>power grounded, as required for personal safety, and then have all other 
>grounding paths "galvanically separated" (thus, DC and power frequencies 
>separated in common mode).
>
>The mesh strategy says that you extend the grounding of the power ground 
>with additional grounding with every cable and additional grounding 
>cables.

Please bear in mind that there is a *huge* difference between
single-ended (as in: RF-Coax-BNC) and balanced (as in: Audio-Twinax-XLR)
for both of these scenarios.

While you can get away with the isolation strategy with balanced,
because you have high CMRR inputs, there is nothing to "take care
of" the ground potentials in the single-ended mode.

>As a reference, Ethernet is designed to work in an isolation BN setup, 
>[...]

That is actually a new thing, the original Ethernet was 1/2" coax
and ground-loops and lightning damage was the order of the day.

The main reason Ethernet went balanced was actually for fault
isolation (star-topology vs. bus) and signal quality (IT people
were horrible at "sharking" and crimping coax.)

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Hal Murray]

p...@phk.freebsd.dk said:
> The main reason Ethernet went balanced was actually for fault isolation
> (star-topology vs. bus) and signal quality (IT people were horrible at
> "sharking" and crimping coax.) 

The reason Ethernet switched to a star topology was to take advantage of the 
wires that were already installed in most buildings.

The electronics at each end were cheap compared to the cost of installing a 
new wire in the ceiling.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Magnus Danielson]

Transformer isolation isn't helping much at RF, as you will capacitively 
couple through the transformer. I've been bitten by that in real life, 
as I was called in to solve issues in someone elses design. It was only 
when I introduced an RF choke that we got conducted noise battled. It's 
also not enough, as the RF choke needs an RF path to ground in order to 
start rejecting effectively, which was the issue another time, so you 
want an RF choke with caps to ground on the inside.


The galvanic isolation can be done using transformer or capacitors after 
that.


There is an over believe in isolation, as it only takes one mistake to 
break the system. Another approach is to ground everything, cross-ground 
etc. and bring the DC/power-spurs down through conduction. It have 
proven itself easier to ensure RF properties when shield and chassi is 
tied hard to each other, as it provides good RF conduction and the cable 
does not act like an antenna against the shield for the RF power being 
unbalanced. The RF choke then acts to separate the chassi RF from that 
of the board, assisting in the balance.


Transformers can provide RF shielding, if they have double shields 
between the coils, and where the shield of each side is connected to 
it's ground. That way each coil will capacitively terminate in it's own 
shield, and the remaining capacitive coupling will mainly be between the 
shields and hence grounds. I rarely see people doing this.


I've been bitten multiple times by the capacitive coupling in 
transformers, and only when I found a way to handle it things have 
started to work. It's not all magnetics.


Cheers,
Magnus

On 12/19/2015 12:33 AM, Tim Shoppa wrote:

All the inputs and outputs were deliberately transformer isolated. Why
break the isolation by using capacitor from coax shield to chassis ground?

I do realize that some isolation transformers have "extra floating turns"
to give transformer action that cancels stray capacitive coupling. I don't
think the capacitors tying coax shield to chassis ground can serve that
purpose.

Tim N3QE

On Mon, Nov 30, 2015 at 3:02 PM, Anders Wallin 
wrote:


HI all,
I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
maybe 5MHz) and instead of reinventing the wheel I decided to try to
modernize the TADD-1 into an all (almost) SMD design. Here are some draft
sketches:

http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/

Does this sound/look reasonable or crazy?
Any suggestions for op-amps to try and/or compare to the AD8055?
What causes the extra phase-noise below 1 Hz offset in John A's result:
https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png

Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
this board will most likely come from a switched-mode PSU, so filtering of
common-mode noise is mandatory.
I found the TI LP38798 shown in the schematic by googling - if someone has
a proven a measured design that would be a safer choice. In any case more
filtering (e.g. ferriites) is probably a good idea.

This design will be available on my blog or on github when it is done - if
anyone is interested.

Thanks,
Anders
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Poul-Henning Kamp]

In message <56755ba1.7000...@rubidium.dyndns.org>, Magnus Danielson writes:

>There is an over believe in isolation, as it only takes one mistake to 
>break the system. Another approach is to ground everything, cross-ground 
>etc. and bring the DC/power-spurs down through conduction. 

Tony Waldron argued similar for audio systems:

http://www.fragrantsword.com/twaudio/

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Tim Shoppa]

I think there is a valid heritage in transformer isolation in time and
frequency distribution, and it goes back to when telephone wiring was used
to distribute audio-type IRIG signals around a campus or other facility.
Even if a bunch of 60Hz or a local AM station was leaking through the IRIG
signaling was quite impervious to it. (Heh, the aircraft VHF radio getting
into Spinal Tap's lead guitar was hardly noticeable at that air force base,
for that matter!!!)

But something feels "off" with lifting grounds on coax if the environment
is just a test lab.

CAT 5/6 and Ethernet transformers work great at 10MHz but most all test
equipment is expecting coax and a BNC.

Tim N3QE

On Sat, Dec 19, 2015 at 8:29 AM, Magnus Danielson <
mag...@rubidium.dyndns.org> wrote:

> Transformer isolation isn't helping much at RF, as you will capacitively
> couple through the transformer. I've been bitten by that in real life, as I
> was called in to solve issues in someone elses design. It was only when I
> introduced an RF choke that we got conducted noise battled. It's also not
> enough, as the RF choke needs an RF path to ground in order to start
> rejecting effectively, which was the issue another time, so you want an RF
> choke with caps to ground on the inside.
>
> The galvanic isolation can be done using transformer or capacitors after
> that.
>
> There is an over believe in isolation, as it only takes one mistake to
> break the system. Another approach is to ground everything, cross-ground
> etc. and bring the DC/power-spurs down through conduction. It have proven
> itself easier to ensure RF properties when shield and chassi is tied hard
> to each other, as it provides good RF conduction and the cable does not act
> like an antenna against the shield for the RF power being unbalanced. The
> RF choke then acts to separate the chassi RF from that of the board,
> assisting in the balance.
>
> Transformers can provide RF shielding, if they have double shields between
> the coils, and where the shield of each side is connected to it's ground.
> That way each coil will capacitively terminate in it's own shield, and the
> remaining capacitive coupling will mainly be between the shields and hence
> grounds. I rarely see people doing this.
>
> I've been bitten multiple times by the capacitive coupling in
> transformers, and only when I found a way to handle it things have started
> to work. It's not all magnetics.
>
> Cheers,
> Magnus
>
>
> On 12/19/2015 12:33 AM, Tim Shoppa wrote:
>
>> All the inputs and outputs were deliberately transformer isolated. Why
>> break the isolation by using capacitor from coax shield to chassis ground?
>>
>> I do realize that some isolation transformers have "extra floating turns"
>> to give transformer action that cancels stray capacitive coupling. I don't
>> think the capacitors tying coax shield to chassis ground can serve that
>> purpose.
>>
>> Tim N3QE
>>
>> On Mon, Nov 30, 2015 at 3:02 PM, Anders Wallin <
>> anders.e.e.wal...@gmail.com>
>> wrote:
>>
>> HI all,
>>> I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
>>> maybe 5MHz) and instead of reinventing the wheel I decided to try to
>>> modernize the TADD-1 into an all (almost) SMD design. Here are some draft
>>> sketches:
>>>
>>>
>>> http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/
>>>
>>> Does this sound/look reasonable or crazy?
>>> Any suggestions for op-amps to try and/or compare to the AD8055?
>>> What causes the extra phase-noise below 1 Hz offset in John A's result:
>>>
>>> https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png
>>>
>>> Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied
>>> to
>>> this board will most likely come from a switched-mode PSU, so filtering
>>> of
>>> common-mode noise is mandatory.
>>> I found the TI LP38798 shown in the schematic by googling - if someone
>>> has
>>> a proven a measured design that would be a safer choice. In any case more
>>> filtering (e.g. ferriites) is probably a good idea.
>>>
>>> This design will be available on my blog or on github when it is done -
>>> if
>>> anyone is interested.
>>>
>>> Thanks,
>>> Anders
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
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>>>
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bob Camp]

Hi

Another way to look at coax ….

You can (easily) have signals flowing on the *outside* of the shield. In an 
ideal world with perfect coax outside would be
outside and inside inside. Ideally the two signal sets would never interact. 
Once you put an isolated transformer on the end
of the cable, the “outside” signal shows up on the capacitive coupling. Since 
you are open circuit terminating the outer current,
you likely have a voltage peak at this point. Maximizing voltage on the 
capacitor pretty much guarantees maximum signal 
transfer. Since the transformer now has both the “inside” and “outside” signals 
on it, you have a problem. 

One solution to this is a common mode choke (the other term for the “outside” 
signal). Ferrite lumps are one way to do this, there
are other ways (coil up the cable). The idea here is to provide a high(er) 
impedance to the signal you do not want. In the case of 
ferrites, you may be able to provide a resistive component and convert them 
into heat. Just as you can buy cheap little RF transformers
these days, you can also buy cheap little common mode chokes as well. The down 
side is that they are designed for VHF and up 
type frequencies (cell phones …) rather than 10 MHz. For lower frequencies you 
generally are stuck with winding a number of turns
on a cheap core. The only way I know to get cores cheap is to buy them by the 
pound. That makes the design more of a “use what you 
have” deal than anything else.

Bob


> On Dec 19, 2015, at 8:29 AM, Magnus Danielson  
> wrote:
> 
> Transformer isolation isn't helping much at RF, as you will capacitively 
> couple through the transformer. I've been bitten by that in real life, as I 
> was called in to solve issues in someone elses design. It was only when I 
> introduced an RF choke that we got conducted noise battled. It's also not 
> enough, as the RF choke needs an RF path to ground in order to start 
> rejecting effectively, which was the issue another time, so you want an RF 
> choke with caps to ground on the inside.
> 
> The galvanic isolation can be done using transformer or capacitors after that.
> 
> There is an over believe in isolation, as it only takes one mistake to break 
> the system. Another approach is to ground everything, cross-ground etc. and 
> bring the DC/power-spurs down through conduction. It have proven itself 
> easier to ensure RF properties when shield and chassi is tied hard to each 
> other, as it provides good RF conduction and the cable does not act like an 
> antenna against the shield for the RF power being unbalanced. The RF choke 
> then acts to separate the chassi RF from that of the board, assisting in the 
> balance.
> 
> Transformers can provide RF shielding, if they have double shields between 
> the coils, and where the shield of each side is connected to it's ground. 
> That way each coil will capacitively terminate in it's own shield, and the 
> remaining capacitive coupling will mainly be between the shields and hence 
> grounds. I rarely see people doing this.
> 
> I've been bitten multiple times by the capacitive coupling in transformers, 
> and only when I found a way to handle it things have started to work. It's 
> not all magnetics.
> 
> Cheers,
> Magnus
> 
> On 12/19/2015 12:33 AM, Tim Shoppa wrote:
>> All the inputs and outputs were deliberately transformer isolated. Why
>> break the isolation by using capacitor from coax shield to chassis ground?
>> 
>> I do realize that some isolation transformers have "extra floating turns"
>> to give transformer action that cancels stray capacitive coupling. I don't
>> think the capacitors tying coax shield to chassis ground can serve that
>> purpose.
>> 
>> Tim N3QE
>> 
>> On Mon, Nov 30, 2015 at 3:02 PM, Anders Wallin 
>> wrote:
>> 
>>> HI all,
>>> I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
>>> maybe 5MHz) and instead of reinventing the wheel I decided to try to
>>> modernize the TADD-1 into an all (almost) SMD design. Here are some draft
>>> sketches:
>>> 
>>> http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/
>>> 
>>> Does this sound/look reasonable or crazy?
>>> Any suggestions for op-amps to try and/or compare to the AD8055?
>>> What causes the extra phase-noise below 1 Hz offset in John A's result:
>>> https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png
>>> 
>>> Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
>>> this board will most likely come from a switched-mode PSU, so filtering of
>>> common-mode noise is mandatory.
>>> I found the TI LP38798 shown in the schematic by googling - if someone has
>>> a proven a measured design that would be a safer choice. In any case more
>>> filtering (e.g. ferriites) is probably a good idea.
>>> 
>>> This design will be available on my blog or on github when it is done - if
>>> anyone is interested.
>>> 

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Chuck Harris]

One of my other hats involves advising electronics scrap and
recycling companies, and the repair of all manner of electronics
equipment.

In all of the equipment I have rummaged through I can state the
following without reservation:

I have never seen any sign of damage caused by properly float charged
sealed lead acid batteries.

I have seen lots of serious damage caused by trickle charged nicads.

I have seen some very serious damage caused by lithium iodide pacemaker
cells at end-of-life.

I have seen lots of damage caused by carbon-zinc, and alkaline cells.

Lithium ion cells behave like electrolytic capacitors.  They want to
have their initial inrush current limited to about 1C, and they must
have their final charge voltage limited to 4.2V.  They will tolerate
being floated at 4.2V for quite a while, but that will ultimately lead
to their capacity being compromised.

A simple backup charger for a LiIon cell would be a constant voltage,
current roll back supply that is controlled by a timer that charges
the cell every time power is restored, and several times a year if
power doesn't fail.

Discharge must be abruptly stopped when the cell voltage drops below
around 2V... the exact value varies by the manufacturer.

-Chuck Harris

Dr. David Kirkby (Kirkby Microwave Ltd) wrote:

On 17 Dec 2015 21:00, "Anders Wallin"  wrote:


First prototype assembled today, tested with 12 VDC SMPS wall-wart supply
and with 12 V lead-acid battery.



Anders


Is the lead acid battery supposed to be there so the unit continues to
function if power is removed?

If do, I believe that the choice of a lead acid battery is a poor one.  I
believe that even the sealed ones release very small amounts of sulphuric
acid and when contained in equipment the acid results in damage in the
long-term. I believe that people have reported damage to oscillators like
the HP 10811A even on this list.

I believe NiCd would be a better choice.  That said I somewhere read they
were banned in Europe but that might have been for general consumer use, as
I note that they are still shipped in some products - e.g. sone emergency
lights I bought in the UK from Farnell,  although the lights were made in
China. One can certainly still buy NiCd cells in Europe.

I don't know if there is any simple way of slowly charging Lithium Metal
Hydride batteries. Commercial chargers from reputable manufacturers have
temperature sensors, voltage sensors and I assume a microprocessor to
determine how to charge them and when to stop charging.  You don't need to
fast-charge a distribution amplifier,  but I don't know if there's any
relatively simple way of charging them.

Dave.

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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Poul-Henning Kamp]

In message 
, "Dr. 
David Kirkby (Kirkby Microwave
 Ltd)" writes:

I belive in the instant case Lead-Acid was used as a noise-free power
source rather than as backup.

>If do, I believe that the choice of a lead acid battery is a poor one.  I
>believe that even the sealed ones release very small amounts of sulphuric
>acid [...]

Lead-acids, sealed or not, shall always be ventilated.

The main problem is actually not sulphuric acid but rather hydrogen.

Apart from the potential to explode if it accumulates, hydrogen is
bad for pretty much all metals, which it penetrates easily.

(The way one filters hydrogen is to pump it through a filter consisting
of a 2mm thick massive slab of Rhodium, and it isn't particularly hard.)

>That said I somewhere read they were banned in Europe [...]

Anything involving Cadmium is banned under ROHS and for good reasons.

You can still get approval to use them in specialized applications
where there are no realistic choice, provided you make provisions
for their safe recycling.  Few such approvals have been given.

A lot of the stuff which says "NiCd" these days is actually
Nickel-metalhydride where the marketing department hasn't got the
memo.

>I don't know if there is any simple way of slowly charging Lithium Metal
>Hydride batteries.

There isn't.  They're almost the worst possible kind of battery for
float-service.

Lead-acid is still the best way to go.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Poul-Henning Kamp]

In message <17836e4f4318bf8d2e5b6028224a0068.squir...@email.powweb.com>, "Chris 
Caudle" writes:

>A better layout would be to have the power and input connectors on the
>same side of the PCB as the output connectors, and make  provision for all
>of the connectors to be snugged down tight to a metal enclosure, or at
>least a metal plate, so that any parasitic currents flowing on the shields
>can stay on the shields and won't be forced across the PCB.

A significant reason for the TADD-1 existing in the first place was to
break groundloops.  This is incompatible with tying all the BNC's together.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 17 Dec 2015 21:00, "Anders Wallin"  wrote:
>
> First prototype assembled today, tested with 12 VDC SMPS wall-wart supply
> and with 12 V lead-acid battery.

> Anders

Is the lead acid battery supposed to be there so the unit continues to
function if power is removed?

If do, I believe that the choice of a lead acid battery is a poor one.  I
believe that even the sealed ones release very small amounts of sulphuric
acid and when contained in equipment the acid results in damage in the
long-term. I believe that people have reported damage to oscillators like
the HP 10811A even on this list.

I believe NiCd would be a better choice.  That said I somewhere read they
were banned in Europe but that might have been for general consumer use, as
I note that they are still shipped in some products - e.g. sone emergency
lights I bought in the UK from Farnell,  although the lights were made in
China. One can certainly still buy NiCd cells in Europe.

I don't know if there is any simple way of slowly charging Lithium Metal
Hydride batteries. Commercial chargers from reputable manufacturers have
temperature sensors, voltage sensors and I assume a microprocessor to
determine how to charge them and when to stop charging.  You don't need to
fast-charge a distribution amplifier,  but I don't know if there's any
relatively simple way of charging them.

Dave.
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Pete Lancashire]

When I used a Lead acid battery as a low noise and isolated power source I
raided the kitchen. Put the batter inside
a polyethylene container they type with a 'snap tight' lid. Then found in
my junk a nylon barb to threaded fitting and
some Tygon tubing to create an external vent. In another junk box a sealed
MS socket and its mating plug.

It solved three things venting to where it didn't matter, sealed becoming
not sealed and puking and solving
shorting from touching things.





On Fri, Dec 18, 2015 at 7:22 AM, Chuck Harris  wrote:

> One of my other hats involves advising electronics scrap and
> recycling companies, and the repair of all manner of electronics
> equipment.
>
> In all of the equipment I have rummaged through I can state the
> following without reservation:
>
> I have never seen any sign of damage caused by properly float charged
> sealed lead acid batteries.
>
> I have seen lots of serious damage caused by trickle charged nicads.
>
> I have seen some very serious damage caused by lithium iodide pacemaker
> cells at end-of-life.
>
> I have seen lots of damage caused by carbon-zinc, and alkaline cells.
>
> Lithium ion cells behave like electrolytic capacitors.  They want to
> have their initial inrush current limited to about 1C, and they must
> have their final charge voltage limited to 4.2V.  They will tolerate
> being floated at 4.2V for quite a while, but that will ultimately lead
> to their capacity being compromised.
>
> A simple backup charger for a LiIon cell would be a constant voltage,
> current roll back supply that is controlled by a timer that charges
> the cell every time power is restored, and several times a year if
> power doesn't fail.
>
> Discharge must be abruptly stopped when the cell voltage drops below
> around 2V... the exact value varies by the manufacturer.
>
> -Chuck Harris
>
>
> Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
>
>> On 17 Dec 2015 21:00, "Anders Wallin" 
>> wrote:
>>
>>>
>>> First prototype assembled today, tested with 12 VDC SMPS wall-wart supply
>>> and with 12 V lead-acid battery.
>>>
>>
>> Anders
>>>
>>
>> Is the lead acid battery supposed to be there so the unit continues to
>> function if power is removed?
>>
>> If do, I believe that the choice of a lead acid battery is a poor one.  I
>> believe that even the sealed ones release very small amounts of sulphuric
>> acid and when contained in equipment the acid results in damage in the
>> long-term. I believe that people have reported damage to oscillators like
>> the HP 10811A even on this list.
>>
>> I believe NiCd would be a better choice.  That said I somewhere read they
>> were banned in Europe but that might have been for general consumer use,
>> as
>> I note that they are still shipped in some products - e.g. sone emergency
>> lights I bought in the UK from Farnell,  although the lights were made in
>> China. One can certainly still buy NiCd cells in Europe.
>>
>> I don't know if there is any simple way of slowly charging Lithium Metal
>> Hydride batteries. Commercial chargers from reputable manufacturers have
>> temperature sensors, voltage sensors and I assume a microprocessor to
>> determine how to charge them and when to stop charging.  You don't need to
>> fast-charge a distribution amplifier,  but I don't know if there's any
>> relatively simple way of charging them.
>>
>> Dave.
>>
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Chris Caudle]

On Fri, December 18, 2015 3:38 am, Poul-Henning Kamp wrote:
> A significant reason for the TADD-1 existing in the first place was to
> break groundloops.  This is incompatible with tying all the BNC's
> together.

Assuming you mean power line frequency currents flowing between equipment,
the way telecom equipment vendors solved that problem was BNC connectors
which have the shells connected to the chassis contact through low
inductance capacitor structures, so that the BNC shell was connected to
chassis at RF frequencies, but isolated by a relatively large impedance at
low multiples of 50 Hz or 60 Hz.
Even in that case it is better to have the connectors on the same side so
that the high frequency shield currents are not forced across the PCB.

-- 
Chris Caudle


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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Tim Shoppa]

All the inputs and outputs were deliberately transformer isolated. Why
break the isolation by using capacitor from coax shield to chassis ground?

I do realize that some isolation transformers have "extra floating turns"
to give transformer action that cancels capacitive coupling. I don't think
the capacitors tying coax shield to chassis ground can serve that purpose.

Tim N3QE

On Mon, Nov 30, 2015 at 3:02 PM, Anders Wallin 
wrote:

> HI all,
> I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
> maybe 5MHz) and instead of reinventing the wheel I decided to try to
> modernize the TADD-1 into an all (almost) SMD design. Here are some draft
> sketches:
>
> http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/
>
> Does this sound/look reasonable or crazy?
> Any suggestions for op-amps to try and/or compare to the AD8055?
> What causes the extra phase-noise below 1 Hz offset in John A's result:
> https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png
>
> Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
> this board will most likely come from a switched-mode PSU, so filtering of
> common-mode noise is mandatory.
> I found the TI LP38798 shown in the schematic by googling - if someone has
> a proven a measured design that would be a safer choice. In any case more
> filtering (e.g. ferriites) is probably a good idea.
>
> This design will be available on my blog or on github when it is done - if
> anyone is interested.
>
> Thanks,
> Anders
> ___
> time-nuts mailing list -- time-nuts@febo.com
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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bruce Griffiths]

On Friday, December 18, 2015 10:46:46 PM Anders Wallin wrote:
> Thanks for all the useful comments!
> Things improved quite a bit just by wrapping the (insulated) board in
> aluminium foil:
> http://www.anderswallin.net/wp-content/uploads/2015/12/alufoil_and_battery.p
> ng
> 
> Op-Amps:
> Maybe it wasn't clear enough on schematic, but I used the AD8055 (as in
> TADD-1). The TL071 is there just because it comes standard with KiCad -
> sorry for the confusion.
> OPA827 doesn't have the slew-rate for +10 or +20 dBm at 10 MHz.

The OPA827 was merely used to illustrate the preferred gain setting and 
biasing architecture not the opamp to be used.

> I was looking at ADA4899-1, but with the exposed pad it's not a direct
> replacement and might require a new board.
> 
> Biasing:
> I didn't understand why a "T" of resistors is better than a simple voltage
> divider? The extra resistor is R3 in Bruce's second attachment.
> What is the noise contribution of the biasing resistors?

T configuration   allows bypassing of residual power supply noise.
Divider only allows minimal filtering via the coupling capacitor.
You could also bias the bottom end of the transformer secondary and directly 
connect the noninverting input of the input amp to the other end of the 
transformer secondary.

> 
> Battery:
> The lead acid battery was only used as a convenient DC source in the lab. I
> would need to find a quiet SMPS or linear supply for permanent
> installation.
> Additional filtering on the 12VDC input might be still be required. Results
> with the battery are good, so does that 'prove' the schematic is OK after
> the linear regulator?
> 
> Isolation measurements:
> Not done yet. I want to get one good channel first ;)
> Would this be done by feeding a known amplitude RF (at 10.1 MHz or
> something?) to an output-channel, and looking at the feedthrough to an
> another output-channel or to the amplifier input with e.g. a spectrum
> analyzer?
> 
> Far-out PN/AM is still 7dB short of the 6502!
> Looks like an SNR issue to me, rather than some issue with the linear
> regulator noise feeding through?!
> AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
> input-referred voltage noise PSD (if I calculated correctly..)

With +10dBm input the corresponding SSB PN floor should be  around -163dBc/Hz.


> With an ADA4899-1 and lower value resistors I get about -4.5 dB improvement
> to 3.4 nV/sqrt(Hz) input-referred

Corresponds to an SSB PN noise floor of around -168dBc/Hz.

> Could they run two or more amplifiers in parallel on the 6502 to get
> 1/sqrt(N) type improvements - or are there still cheap gains to be made
> with my circuit?
> 

Try using an input stepup transformer eg 1:2 (voltage ratio) perhaps with a 
centre tapped secondary to allow use with higher input signal levels via tap 
selection. The use of a stepup input transformer reduces the required amplifier 
gain as well as reducing its effective input noise. As long as the input 
currentt noise isnt excessive the SSB PN floor should be reduced by about 
6dBc/Hz.
 
> thanks,
> Anders
> 

Bruce

> 
> On Fri, Dec 18, 2015 at 6:32 PM, Pete Lancashire 
> 
> wrote:
> > When I used a Lead acid battery as a low noise and isolated power source I
> > raided the kitchen. Put the batter inside
> > a polyethylene container they type with a 'snap tight' lid. Then found in
> > my junk a nylon barb to threaded fitting and
> > some Tygon tubing to create an external vent. In another junk box a sealed
> > MS socket and its mating plug.
> > 
> > It solved three things venting to where it didn't matter, sealed becoming
> > not sealed and puking and solving
> > shorting from touching things.
> > 
> > On Fri, Dec 18, 2015 at 7:22 AM, Chuck Harris  wrote:
> > > One of my other hats involves advising electronics scrap and
> > > recycling companies, and the repair of all manner of electronics
> > > equipment.
> > > 
> > > In all of the equipment I have rummaged through I can state the
> > > following without reservation:
> > > 
> > > I have never seen any sign of damage caused by properly float charged
> > > sealed lead acid batteries.
> > > 
> > > I have seen lots of serious damage caused by trickle charged nicads.
> > > 
> > > I have seen some very serious damage caused by lithium iodide pacemaker
> > > cells at end-of-life.
> > > 
> > > I have seen lots of damage caused by carbon-zinc, and alkaline cells.
> > > 
> > > Lithium ion cells behave like electrolytic capacitors.  They want to
> > > have their initial inrush current limited to about 1C, and they must
> > > have their final charge voltage limited to 4.2V.  They will tolerate
> > > being floated at 4.2V for quite a while, but that will ultimately lead
> > > to their capacity being compromised.
> > > 
> > > A simple backup charger for a LiIon cell would be a constant voltage,
> > > current roll back supply that is controlled by a timer that charges
> > > the cell every 

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Tim Shoppa]

All the inputs and outputs were deliberately transformer isolated. Why
break the isolation by using capacitor from coax shield to chassis ground?

I do realize that some isolation transformers have "extra floating turns"
to give transformer action that cancels stray capacitive coupling. I don't
think the capacitors tying coax shield to chassis ground can serve that
purpose.

Tim N3QE

On Mon, Nov 30, 2015 at 3:02 PM, Anders Wallin 
wrote:

> HI all,
> I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
> maybe 5MHz) and instead of reinventing the wheel I decided to try to
> modernize the TADD-1 into an all (almost) SMD design. Here are some draft
> sketches:
>
> http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/
>
> Does this sound/look reasonable or crazy?
> Any suggestions for op-amps to try and/or compare to the AD8055?
> What causes the extra phase-noise below 1 Hz offset in John A's result:
> https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png
>
> Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
> this board will most likely come from a switched-mode PSU, so filtering of
> common-mode noise is mandatory.
> I found the TI LP38798 shown in the schematic by googling - if someone has
> a proven a measured design that would be a safer choice. In any case more
> filtering (e.g. ferriites) is probably a good idea.
>
> This design will be available on my blog or on github when it is done - if
> anyone is interested.
>
> Thanks,
> Anders
> ___
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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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>
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Anders Wallin]

Thanks for all the useful comments!
Things improved quite a bit just by wrapping the (insulated) board in
aluminium foil:
http://www.anderswallin.net/wp-content/uploads/2015/12/alufoil_and_battery.png

Op-Amps:
Maybe it wasn't clear enough on schematic, but I used the AD8055 (as in
TADD-1). The TL071 is there just because it comes standard with KiCad -
sorry for the confusion.
OPA827 doesn't have the slew-rate for +10 or +20 dBm at 10 MHz.
I was looking at ADA4899-1, but with the exposed pad it's not a direct
replacement and might require a new board.

Biasing:
I didn't understand why a "T" of resistors is better than a simple voltage
divider? The extra resistor is R3 in Bruce's second attachment.
What is the noise contribution of the biasing resistors?

Battery:
The lead acid battery was only used as a convenient DC source in the lab. I
would need to find a quiet SMPS or linear supply for permanent
installation.
Additional filtering on the 12VDC input might be still be required. Results
with the battery are good, so does that 'prove' the schematic is OK after
the linear regulator?

Isolation measurements:
Not done yet. I want to get one good channel first ;)
Would this be done by feeding a known amplitude RF (at 10.1 MHz or
something?) to an output-channel, and looking at the feedthrough to an
another output-channel or to the amplifier input with e.g. a spectrum
analyzer?

Far-out PN/AM is still 7dB short of the 6502!
Looks like an SNR issue to me, rather than some issue with the linear
regulator noise feeding through?!
AD8055 in non-inverting circuit with 1+2k7/2k7 gain has 9.6 nV/sqrt(Hz)
input-referred voltage noise PSD (if I calculated correctly..)
With an ADA4899-1 and lower value resistors I get about -4.5 dB improvement
to 3.4 nV/sqrt(Hz) input-referred
Could they run two or more amplifiers in parallel on the 6502 to get
1/sqrt(N) type improvements - or are there still cheap gains to be made
with my circuit?

thanks,
Anders


On Fri, Dec 18, 2015 at 6:32 PM, Pete Lancashire 
wrote:

> When I used a Lead acid battery as a low noise and isolated power source I
> raided the kitchen. Put the batter inside
> a polyethylene container they type with a 'snap tight' lid. Then found in
> my junk a nylon barb to threaded fitting and
> some Tygon tubing to create an external vent. In another junk box a sealed
> MS socket and its mating plug.
>
> It solved three things venting to where it didn't matter, sealed becoming
> not sealed and puking and solving
> shorting from touching things.
>
>
>
>
>
> On Fri, Dec 18, 2015 at 7:22 AM, Chuck Harris  wrote:
>
> > One of my other hats involves advising electronics scrap and
> > recycling companies, and the repair of all manner of electronics
> > equipment.
> >
> > In all of the equipment I have rummaged through I can state the
> > following without reservation:
> >
> > I have never seen any sign of damage caused by properly float charged
> > sealed lead acid batteries.
> >
> > I have seen lots of serious damage caused by trickle charged nicads.
> >
> > I have seen some very serious damage caused by lithium iodide pacemaker
> > cells at end-of-life.
> >
> > I have seen lots of damage caused by carbon-zinc, and alkaline cells.
> >
> > Lithium ion cells behave like electrolytic capacitors.  They want to
> > have their initial inrush current limited to about 1C, and they must
> > have their final charge voltage limited to 4.2V.  They will tolerate
> > being floated at 4.2V for quite a while, but that will ultimately lead
> > to their capacity being compromised.
> >
> > A simple backup charger for a LiIon cell would be a constant voltage,
> > current roll back supply that is controlled by a timer that charges
> > the cell every time power is restored, and several times a year if
> > power doesn't fail.
> >
> > Discharge must be abruptly stopped when the cell voltage drops below
> > around 2V... the exact value varies by the manufacturer.
> >
> > -Chuck Harris
> >
> >
> > Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
> >
> >> On 17 Dec 2015 21:00, "Anders Wallin" 
> >> wrote:
> >>
> >>>
> >>> First prototype assembled today, tested with 12 VDC SMPS wall-wart
> supply
> >>> and with 12 V lead-acid battery.
> >>>
> >>
> >> Anders
> >>>
> >>
> >> Is the lead acid battery supposed to be there so the unit continues to
> >> function if power is removed?
> >>
> >> If do, I believe that the choice of a lead acid battery is a poor one.
> I
> >> believe that even the sealed ones release very small amounts of
> sulphuric
> >> acid and when contained in equipment the acid results in damage in the
> >> long-term. I believe that people have reported damage to oscillators
> like
> >> the HP 10811A even on this list.
> >>
> >> I believe NiCd would be a better choice.  That said I somewhere read
> they
> >> were banned in Europe but that might have been for general consumer use,
> >> as
> >> I note that they are 

Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Anders Wallin]

First prototype assembled today, tested with 12 VDC SMPS wall-wart supply
and with 12 V lead-acid battery.
Compared against a SRS FS710 and a Symmetricom 6502 and John Ackermann's
2007 plot:
http://www.anderswallin.net/2015/12/frequency-distribution-amplifier-first-tests/

What does the 6502 do differently? It is maybe 5 to 8 dBc/Hz better both in
PN and AM from around 1 kHz and out.

My 'ultra-low-noise DC-supply' in the form of a lead-acid battery improves
things somewhat, but some spurs still remain:
http://www.anderswallin.net/wp-content/uploads/2015/12/2015-12-17_fda_spurs_and_comments.png
interpretations and explanations are welcome!
The board was not enclosed in a metal can for these tests.

The regulator is an LP38798
http://www.ti.com/lit/ds/symlink/lp38798.pdf


Anders


On Tue, Dec 1, 2015 at 12:54 AM, Bruce Griffiths  wrote:

> Anders
> U101 only needs to have a gain of 1 at dc so replace R104 and R105 with a
> capacitor connected to ground.
> Adjust the other components of the gain determining network
> accordingly.Also the junction of the power supply divider R102 and R103
> should be heavily capacitively bypassed to ground and a resistor placed
> between this junction and U101's noninverting input.
>
> Excess Sub Hz PN is usually due power supply noise or thermal fluctuations
> due to air currents/ convection.
> Most of the so called super regulator circuits  should be more than quiet
> enough with an LM329 reference.A damped LCR filter at the input will
> improve the PSRR at switchmode output frequencies.
>
> Bruce
>
>
>
> On Tuesday, 1 December 2015 9:02 AM, Anders Wallin <
> anders.e.e.wal...@gmail.com> wrote:
>
>
>  HI all,
> I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
> maybe 5MHz) and instead of reinventing the wheel I decided to try to
> modernize the TADD-1 into an all (almost) SMD design. Here are some draft
> sketches:
>
> http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/
>
> Does this sound/look reasonable or crazy?
> Any suggestions for op-amps to try and/or compare to the AD8055?
> What causes the extra phase-noise below 1 Hz offset in John A's result:
> https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png
>
> Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
> this board will most likely come from a switched-mode PSU, so filtering of
> common-mode noise is mandatory.
> I found the TI LP38798 shown in the schematic by googling - if someone has
> a proven a measured design that would be a safer choice. In any case more
> filtering (e.g. ferriites) is probably a good idea.
>
> This design will be available on my blog or on github when it is done - if
> anyone is interested.
>
> Thanks,
> Anders
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Alex Pummer]

That noise could come also from the environment, even trough ground-loop 
with the cox cable [ if the cable is connected between two grounds and 
the cable is long enough it will pick up noise since the noise-current 
generates voltage drop along the cable's shield, but the same field does 
not drives current trough the internal conductor of the cable thus 
causes noise voltage difference at the end of the cable between the 
shield and the internal connector.
Take a piece of coax cable put a connector[ preferable an N connector] 
to one end of the cable, short the internal connector of the cable to 
the shield at the other end and touch that connected shield/internal 
connector cable end to a larger metal
object, while the N connector end is connected to a spectrum-analyzer 
input, set the spectrum-analyzer to high sensitivity and you will see 
all the local AM and FM stations "coming out" from a perfectly shielded 
coax cable...
Also the power supply of the amplifier needs a good filtering [chokes, 
damping resistors damping ferrites, feed trough capacitors with relative 
large value up to 0,1microFarad range. and any wire loop works as an 
Antenna, therfore twist the power wires and keep close to metal surfaces

The box of the amplifier need to be closed without any small slots
to get good shielding with more than 120dB attenuation is not trivial,
73
KJ6UHN
Alex
On 12/17/2015 7:20 PM, Bruce Griffiths wrote:

Also add

1) BNX002
(attenuates noise in 1MHz to 1GHZ region) between the dc input and the input to:
2) Simple LCR filter - attenuates from 10kHz to 10MHz (see attachment)
Output of which is connected to the regulator input.

3) Like all the so called RF regulators with internal low pass filters your 
regulator is exceptionally noisy at low frequencies.
Try substituting something else - a good one should be at least 20dB quieter at 
low frequencies

4) Change the input amplifier to something like that depicted in 2nd 
attachment. Reduces complexity and effect of residual power supply noise. 
Reduce feedback resistor values.

Bruce
 On Friday, 18 December 2015 12:08 PM, Poul-Henning Kamp 
 wrote:
  


  
In message 
, Anders 
Wallin writes:


My 'ultra-low-noise DC-supply' in the form of a lead-acid battery improves
things somewhat, but some spurs still remain:
http://www.anderswallin.net/wp-content/uploads/2015/12/2015-12-17_fda_spurs_and_comments.png
interpretations and explanations are welcome!
The board was not enclosed in a metal can for these tests.

Isn't that the explanation ?

Any SMPS in the vicinity is going to show up...




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-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.7294 / Virus Database: 4489/11202 - Release Date: 12/18/15


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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Poul-Henning Kamp]

In message 
, Anders 
Wallin writes:

>My 'ultra-low-noise DC-supply' in the form of a lead-acid battery improves
>things somewhat, but some spurs still remain:
>http://www.anderswallin.net/wp-content/uploads/2015/12/2015-12-17_fda_spurs_and_comments.png
>interpretations and explanations are welcome!
>The board was not enclosed in a metal can for these tests.

Isn't that the explanation ?

Any SMPS in the vicinity is going to show up...


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[John Miles]

Those spurs are reminiscent of what happens when you lift the ground of a coax 
cable at one end and turn it into an antenna, in my experience.  It is almost 
always a bad idea to do this.  Try shorting out the capacitor(s) at your input 
and output jacks. 

-- john, KE5FX
Miles Design LLC
 
> My 'ultra-low-noise DC-supply' in the form of a lead-acid battery improves
> things somewhat, but some spurs still remain:
> http://www.anderswallin.net/wp-content/uploads/2015/12/2015-12-
> 17_fda_spurs_and_comments.png
> interpretations and explanations are welcome!
> The board was not enclosed in a metal can for these tests.
> 

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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Jörg Logemann]

Anders,
the TL071 is not the right choice as it has a unity gain bandwidth of
only 3MHz! You should use an OP with a unity gain bandwidth of ten times
the wanted frequency at least (I guess 10MHz, so a 100MHz OP). Modern
OPs are AD8045 (preferable), AD8099 (too fast and too good for this
purpose;-), OPA847 and many others. The AD8045 can drive 70mA, so you
could drive up to 15 outputs with 0dBm or up to 5 outputs with +10dBm
simply by serial resistors (50 Ohm) from the OP output to each
coaxconnector (+dc-block).

Joerg, DL2NI

Am 17.12.2015 um 20:44 schrieb Anders Wallin:
> First prototype assembled today, tested with 12 VDC SMPS wall-wart supply
> and with 12 V lead-acid battery.
> Compared against a SRS FS710 and a Symmetricom 6502 and John Ackermann's
> 2007 plot:
> http://www.anderswallin.net/2015/12/frequency-distribution-amplifier-first-tests/
>
> What does the 6502 do differently? It is maybe 5 to 8 dBc/Hz better both in
> PN and AM from around 1 kHz and out.
>
> My 'ultra-low-noise DC-supply' in the form of a lead-acid battery improves
> things somewhat, but some spurs still remain:
> http://www.anderswallin.net/wp-content/uploads/2015/12/2015-12-17_fda_spurs_and_comments.png
> interpretations and explanations are welcome!
> The board was not enclosed in a metal can for these tests.
>
> The regulator is an LP38798
> http://www.ti.com/lit/ds/symlink/lp38798.pdf
>
>
> Anders
>
>
> On Tue, Dec 1, 2015 at 12:54 AM, Bruce Griffiths > wrote:
>> Anders
>> U101 only needs to have a gain of 1 at dc so replace R104 and R105 with a
>> capacitor connected to ground.
>> Adjust the other components of the gain determining network
>> accordingly.Also the junction of the power supply divider R102 and R103
>> should be heavily capacitively bypassed to ground and a resistor placed
>> between this junction and U101's noninverting input.
>>
>> Excess Sub Hz PN is usually due power supply noise or thermal fluctuations
>> due to air currents/ convection.
>> Most of the so called super regulator circuits  should be more than quiet
>> enough with an LM329 reference.A damped LCR filter at the input will
>> improve the PSRR at switchmode output frequencies.
>>
>> Bruce
>>
>>
>>
>> On Tuesday, 1 December 2015 9:02 AM, Anders Wallin <
>> anders.e.e.wal...@gmail.com> wrote:
>>
>>
>>  HI all,
>> I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
>> maybe 5MHz) and instead of reinventing the wheel I decided to try to
>> modernize the TADD-1 into an all (almost) SMD design. Here are some draft
>> sketches:
>>
>> http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/
>>
>> Does this sound/look reasonable or crazy?
>> Any suggestions for op-amps to try and/or compare to the AD8055?
>> What causes the extra phase-noise below 1 Hz offset in John A's result:
>> https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png
>>
>> Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
>> this board will most likely come from a switched-mode PSU, so filtering of
>> common-mode noise is mandatory.
>> I found the TI LP38798 shown in the schematic by googling - if someone has
>> a proven a measured design that would be a safer choice. In any case more
>> filtering (e.g. ferriites) is probably a good idea.
>>
>> This design will be available on my blog or on github when it is done - if
>> anyone is interested.
>>
>> Thanks,
>> Anders
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>>
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
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>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
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-- 
Dipl.Ing.(FH) Jörg Logemann 
Veilchenstraße 3 
D-89150 Laichingen 
Germany 
Tel. +49 7333 922506 
Mobil  +49 171 2814359
Fax. +49 7333 922507 
mail: joerg.logem...@t-online.de

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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Chris Caudle]

On Thu, December 17, 2015 3:47 pm, John Miles wrote:
> Those spurs are reminiscent of what happens when you lift the ground of a
> coax cable at one end and turn it into an antenna, in my experience.

This came up several weeks ago, I don't remember whether an original
TADD-1 or some other distribution amp, where I pointed out that the
measurements provided were with the board connectors run on two short
pigtails to panel mount connectors which were mounted side by side on a
metal enclosure.  I think the question was why was there so much more
noise on the measurements done with the cables just hanging off the PCB.

With the layout of the new board shown any shield currents are going to
flow right across the PCB from the input connector to the output
connectors, causing voltage fluctuations across the ground plane.
A better layout would be to have the power and input connectors on the
same side of the PCB as the output connectors, and make  provision for all
of the connectors to be snugged down tight to a metal enclosure, or at
least a metal plate, so that any parasitic currents flowing on the shields
can stay on the shields and won't be forced across the PCB.
-- 
Chris Caudle


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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bruce Griffiths]

Also add 

1) BNX002
(attenuates noise in 1MHz to 1GHZ region) between the dc input and the input to:
2) Simple LCR filter - attenuates from 10kHz to 10MHz (see attachment)
Output of which is connected to the regulator input. 

3) Like all the so called RF regulators with internal low pass filters your 
regulator is exceptionally noisy at low frequencies. 
Try substituting something else - a good one should be at least 20dB quieter at 
low frequencies

4) Change the input amplifier to something like that depicted in 2nd 
attachment. Reduces complexity and effect of residual power supply noise. 
Reduce feedback resistor values.

Bruce
On Friday, 18 December 2015 12:08 PM, Poul-Henning Kamp 
 wrote:
 

 
In message 
, Anders 
Wallin writes:

>My 'ultra-low-noise DC-supply' in the form of a lead-acid battery improves
>things somewhat, but some spurs still remain:
>http://www.anderswallin.net/wp-content/uploads/2015/12/2015-12-17_fda_spurs_and_comments.png
>interpretations and explanations are welcome!
>The board was not enclosed in a metal can for these tests.

Isn't that the explanation ?

Any SMPS in the vicinity is going to show up...


-- 
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
p...@freebsd.org        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bob Camp]

Hi

Somethings to consider:  

How quiet are the sources you will be running through this amplifier?

How predictable are the levels of the sources? 

How important is isolation?

Do you need lowpass / bandpass filtering (are there other RF sources running 
around?)?

Is ESD on the coax an issue (do you need a high value resistor here or there?) ?

Bob

> On Nov 30, 2015, at 3:02 PM, Anders Wallin  
> wrote:
> 
> HI all,
> I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
> maybe 5MHz) and instead of reinventing the wheel I decided to try to
> modernize the TADD-1 into an all (almost) SMD design. Here are some draft
> sketches:
> http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/
> 
> Does this sound/look reasonable or crazy?
> Any suggestions for op-amps to try and/or compare to the AD8055?
> What causes the extra phase-noise below 1 Hz offset in John A's result:
> https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png
> 
> Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
> this board will most likely come from a switched-mode PSU, so filtering of
> common-mode noise is mandatory.
> I found the TI LP38798 shown in the schematic by googling - if someone has
> a proven a measured design that would be a safer choice. In any case more
> filtering (e.g. ferriites) is probably a good idea.
> 
> This design will be available on my blog or on github when it is done - if
> anyone is interested.
> 
> Thanks,
> Anders
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[time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Anders Wallin]

HI all,
I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
maybe 5MHz) and instead of reinventing the wheel I decided to try to
modernize the TADD-1 into an all (almost) SMD design. Here are some draft
sketches:
http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/

Does this sound/look reasonable or crazy?
Any suggestions for op-amps to try and/or compare to the AD8055?
What causes the extra phase-noise below 1 Hz offset in John A's result:
https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png

Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
this board will most likely come from a switched-mode PSU, so filtering of
common-mode noise is mandatory.
I found the TI LP38798 shown in the schematic by googling - if someone has
a proven a measured design that would be a safer choice. In any case more
filtering (e.g. ferriites) is probably a good idea.

This design will be available on my blog or on github when it is done - if
anyone is interested.

Thanks,
Anders
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bruce Griffiths]

Anders
U101 only needs to have a gain of 1 at dc so replace R104 and R105 with a 
capacitor connected to ground.
Adjust the other components of the gain determining network accordingly.Also 
the junction of the power supply divider R102 and R103 should be heavily 
capacitively bypassed to ground and a resistor placed between this junction and 
U101's noninverting input.

Excess Sub Hz PN is usually due power supply noise or thermal fluctuations due 
to air currents/ convection.
Most of the so called super regulator circuits  should be more than quiet 
enough with an LM329 reference.A damped LCR filter at the input will improve 
the PSRR at switchmode output frequencies.

Bruce
 


On Tuesday, 1 December 2015 9:02 AM, Anders Wallin 
 wrote:
 

 HI all,
I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
maybe 5MHz) and instead of reinventing the wheel I decided to try to
modernize the TADD-1 into an all (almost) SMD design. Here are some draft
sketches:
http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/

Does this sound/look reasonable or crazy?
Any suggestions for op-amps to try and/or compare to the AD8055?
What causes the extra phase-noise below 1 Hz offset in John A's result:
https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png

Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
this board will most likely come from a switched-mode PSU, so filtering of
common-mode noise is mandatory.
I found the TI LP38798 shown in the schematic by googling - if someone has
a proven a measured design that would be a safer choice. In any case more
filtering (e.g. ferriites) is probably a good idea.

This design will be available on my blog or on github when it is done - if
anyone is interested.

Thanks,
Anders
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