Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Tom Van Baak]

> Please forgive my ignorance but what is a TICC?
> Regards
> John P

Short answer:

https://www.febo.com/pages/TICC/

https://www.tapr.org/kits_ticc.html

Long answer:

When working with precise time one of the very first instruments you'll want is 
a frequency counter. But when your clocks get accurate enough that your counter 
always reads 9.999 or 9.99 or 10.0 a different measurement approach 
is called for. This is where a phase meter or Time Interval Counter (TIC) is 
useful: instead of making a frequency measurement for a fixed duration (gate 
time), you can instead continuously monitor the slow and steady drift in phase 
(time) between two sources; over seconds, over hundreds of seconds, even over 
days. Programs like Stable32 or TimeLab can make phase, frequency, or stability 
plots from the data set.

That's why a TIC can be used to measure coax temperature coefficient. A 
frequency counter can't do that.

Most of us get our counters from eBay where the favorite TIC's are SR 620, hp 
5335, hp 5370, hp 53132. But it has always been a challenge to make a modern, 
cheap, homebrew TIC that matches commercial instruments in performance. Over 
the years a number of time nuts have tried to make sub-nanosecond counters. The 
most recent time interval counter by John Ackermann, the "TICC", is a winner. 
See the links above for details.

By using a recent off-the-shelf TDC (time to digital) chip from ti.com John 
avoided the complexity and analog calibration of earlier amateur designs. In 
order to allow arbitrary range of interval, he actually uses two TDC chips; one 
to precisely time the start pulse, and another to time the stop pulse.

Moreover, John's "TICC" exposes the underlying start and stop channel 
timestamps so that the board not only acts like a simple start=A stop=B TIC, 
but can also be used as a dual-channel time-stamping counter (TSC). Unlike 
commercial counters, both the A and B inputs can collect data simultaneously 
and independently if you want. This avoids certain deadtime, collision and 
sampling issues that many commercial TIC's have. So it's a very nice design, 
and low cost, and open source.

/tvb


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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[John Ponsonby]

Please forgive my ignorance but what is a TICC?
Regards
John P
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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Alex Pummer]

most likely the cooper is much ticker than the penetration of the lowest 
frequency for which the cable is used, therefore the high frequency 
"does not" see the steel inside of the cooper, that steel could cause 
problem if the coax also used to carry some power -- DC or AC -- because 
at lower frequency or DC the cable's current carried mostly in the 
cooper, and while the cooper constitute just a small fraction of the 
center wire cross section, a cable with "steel core" could carry much 
less current, than a cable with full cooper. But the steel core cable 
has one advantage it is usually stronger than a full cooper cable and 
therefore it is usable for outside installation with larger support 
distance.


73
KJ6UHN,  [a former engineer of a cable manufacturer ]
Alex

On 4/19/2017 11:57 AM, Hal Murray wrote:

kb...@n1k.org said:

I’d want to be pretty sure what the center conductor was made out of. I’ve
seen some stuff in coax that “one would think� should not be there (copper
over steel …).

Does that effect the propagation time?

If I gave you a good scope picture of a pulse after going through chunk of
coax, could you figure out the ratio of copper to steel?  Would you need to
know the length or could you figure that out too?



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-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.8012 / Virus Database: 4769/14347 - Release Date: 04/19/17


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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Scott Stobbe]

A table of a bunch of rg6 catv permutations,
http://www.texcan.com/media/import/pdf/Electronic_Cable_RG6_RG59.pdf

At least on this list if it has a solid copper core, it also has a copper
braid shield. I'm sure there is many more permutations out there.

On Wed, Apr 19, 2017 at 7:00 PM Will Kimber  wrote:

> TV co-ax these days for satellite or UHF is almost all steel wire with
> copper plating.  In fact the 'F' connector that is used is designed to
> use that stiff wire as the center pin of the connector!
>
>
> Will
>
>
> On 04/20/2017 06:57 AM, Hal Murray wrote:
> > kb...@n1k.org said:
> >> I’d want to be pretty sure what the center conductor was made out of.
> I’ve
> >> seen some stuff in coax that “one would think† should not be there
> (copper
> >> over steel …).
> > Does that effect the propagation time?
> >
> > If I gave you a good scope picture of a pulse after going through chunk
> of
> > coax, could you figure out the ratio of copper to steel?  Would you need
> to
> > know the length or could you figure that out too?
> >
> >
> >
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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Alan Melia]

MMmm interesting but what about skindepth ?? surely the "R" is not DC R so 
would it matter? RF currents travelling in the copper anyway.  I suspect 
that a steel inner might increase the L/unit length?, maybe this is more 
significant or not as is sceened by copper??


Alan
G3NYK

- Original Message - 
From: "jimlux" <jim...@earthlink.net>

To: <time-nuts@febo.com>
Sent: Wednesday, April 19, 2017 11:17 PM
Subject: Re: [time-nuts] Measuring coax temperature coefficient with a TICC



On 4/19/17 11:57 AM, Hal Murray wrote:


kb...@n1k.org said:
I’d want to be pretty sure what the center conductor was made out of. 
I’ve
seen some stuff in coax that “one would think” should not be there 
(copper

over steel …).


Does that effect the propagation time?

If I gave you a good scope picture of a pulse after going through chunk 
of
coax, could you figure out the ratio of copper to steel?  Would you need 
to

know the length or could you figure that out too?



This being timenuts, I think you might do it with just timing 
measurements.


Let's see - the different candidate materials all have different thermal 
resistance coefficients.  So you can make some DC measurements.  If you 
knew it was some combination of copper and steel, for instance, you could 
probably determine the ratio from that alone (or, for that matter, doing 
it at a single temperature, if you can *measure* the diameter of the 
conductor).


There is some variation in material properties (not all copper is the 
same, and, in particular, steel varies widely depending on alloy and 
manufacturing).




The propagation equation has a dependence on both R and G as well as  L 
and C


Is the change in prop speed due to the change in R bigger or smaller than 
the change due to L and C (from dimensional changes)?


The L and C terms both have a frequency dependent (linear in frequency) 
term.  The R term has a fairly complex dependency on frequency, in terms 
of skin depth relative to the diameter of the conductor.  The G term also 
has a frequency dependence.



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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Bob kb8tq]

Hi


> On Apr 19, 2017, at 2:57 PM, Hal Murray  wrote:
> 
> 
> kb...@n1k.org said:
>> I’d want to be pretty sure what the center conductor was made out of. I’ve
>> seen some stuff in coax that “one would think” should not be there (copper
>> over steel …). 
> 
> Does that effect the propagation time?
> 
> If I gave you a good scope picture of a pulse after going through chunk of 
> coax, could you figure out the ratio of copper to steel?  Would you need to 
> know the length or could you figure that out too?
> 

The issue is skin depth. On something like TV coax operated at the normal 
frequencies, a copper jacket is likely as good as full coper. The skin depth is 
such
that the signals never “see” the iron core to any real extent. 

With a pulse that has a fast edge things are quite so cut and dried. Most of 
the 
“signal” that you are measuring in that fast rising edge is at high 
frequencies. That
would suggest that the skin depth stuff would get you there as well. 

Best way to do it would be at low frequencies either DC or a LF sine wave.

Bob


> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Will Kimber]

TV co-ax these days for satellite or UHF is almost all steel wire with
copper plating.  In fact the 'F' connector that is used is designed to
use that stiff wire as the center pin of the connector!


Will


On 04/20/2017 06:57 AM, Hal Murray wrote:
> kb...@n1k.org said:
>> I’d want to be pretty sure what the center conductor was made out of. 
>> I’ve
>> seen some stuff in coax that “one would think� should not be there 
>> (copper
>> over steel …). 
> Does that effect the propagation time?
>
> If I gave you a good scope picture of a pulse after going through chunk of 
> coax, could you figure out the ratio of copper to steel?  Would you need to 
> know the length or could you figure that out too?
>
>
>
> ___
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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[jimlux]

On 4/19/17 11:57 AM, Hal Murray wrote:


kb...@n1k.org said:

I’d want to be pretty sure what the center conductor was made out of. I’ve
seen some stuff in coax that “one would think” should not be there (copper
over steel …).


Does that effect the propagation time?

If I gave you a good scope picture of a pulse after going through chunk of
coax, could you figure out the ratio of copper to steel?  Would you need to
know the length or could you figure that out too?



This being timenuts, I think you might do it with just timing measurements.

Let's see - the different candidate materials all have different thermal 
resistance coefficients.  So you can make some DC measurements.  If you 
knew it was some combination of copper and steel, for instance, you 
could probably determine the ratio from that alone (or, for that matter, 
doing it at a single temperature, if you can *measure* the diameter of 
the conductor).


There is some variation in material properties (not all copper is the 
same, and, in particular, steel varies widely depending on alloy and 
manufacturing).




The propagation equation has a dependence on both R and G as well as  L 
and C


Is the change in prop speed due to the change in R bigger or smaller 
than the change due to L and C (from dimensional changes)?


The L and C terms both have a frequency dependent (linear in frequency) 
term.  The R term has a fairly complex dependency on frequency, in terms 
of skin depth relative to the diameter of the conductor.  The G term 
also has a frequency dependence.



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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Hal Murray]

kb...@n1k.org said:
> I’d want to be pretty sure what the center conductor was made out of. I’ve
> seen some stuff in coax that “one would think” should not be there (copper
> over steel …). 

Does that effect the propagation time?

If I gave you a good scope picture of a pulse after going through chunk of 
coax, could you figure out the ratio of copper to steel?  Would you need to 
know the length or could you figure that out too?

-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Bob kb8tq]

Hi

One of the easiest ways to get a slow ramp it to toss the foam box full of 
cable out the back door. 
Assuming it stays in the shade, you can often get a pretty good 24 hour 
temperature cycle. You 
still need to monitor things to know what the ramp is. Generally it’s slow 
enough that you can be
pretty sure everything is isothermal during the test. Yes, there are some 
practical issues with 
doing it this way (thunderstorms, cables to hook it up, bugs, alligators ….)

Bob

> On Apr 19, 2017, at 9:01 AM, Mark Sims  wrote:
> 
> Yes, for a variety of reasons, I would not expect the best results with coax 
> on a spool.   The coax that I tested was a loose coil of coax pre-fabbed with 
> BNC connectors.  It should not have any significant stresses on it than a 
> laid out 100 foot run would.  The main purpose of the experiment was just to 
> see how well the TICC could detect temperature effects on a hunk of coax.  I 
> just  found a small styrofoam insulated shipping box (I think it might have 
> been  used for shipping pies) that should make for a better cable testing box.
> 
> 
> 
>> I would question how much the results will relate to real-world use of coax, 
>> where its not
> normal to have great real of it.
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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[jimlux]

On 4/19/17 3:34 AM, Bob kb8tq wrote:

Hi



On Apr 18, 2017, at 8:33 PM, jimlux  wrote:

On 4/18/17 3:55 PM, Bob kb8tq wrote:

Hi

On something like a 500’ spool of coax, the question will always be “what 
temperature is it where in the spool”. A single sensor will
only give you precise information if the temperature ramp is *very* slow (as in 
days …).



measure the DC resistance of the spool, and you'll be able to get a sort of 
"average" temperature.


I’d want to be pretty sure what the center conductor was made out of. I’ve seen 
some stuff
in coax that “one would think” should not be there (copper over steel …).



One would want to calibrate your "coax as temp sensor" just in case 
you've got some exotic stuff with silver plated over stainless steel 
(used in cryo applications).  But you could probably do that with a 
short length.


Copper is about 0.4% /degree
Iron is about 0.6%

So, over a -10 to 60 degree swing you'd see about significant (30-40%) 
change in the resistance, and it would be easy to tell if it's copper or 
iron or NiCr or something really exotic.


The Belden catalog says that RG58/U type coax is about 7-8 ohms/1000 ft. 
So a 10 foot length is 0.07 ohms - A bit tricky to measure that low, but 
not impossible, and certainly within the scope of a time-nut skilled in 
the electronics arts.






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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 15 April 2017 at 02:34, Mark Sims  wrote:

> I finally got around to using a TICC to measure the temperature
> coefficient of 100 feet of generic RG-58 coax using a TICC.   The TICC was
> clocked by a HP 5071A 10 MHz output.  The 1PPS output was connected to the
> input of the coax and the TICC chB input.  The TICC chA input was connected
> to the coax output via an inline terminator.   The TICC was set to "debug"
> mode  and Lady Heather plotted the chB-chA timestamp difference (hence the
> negative cable delay values).
>
> The coax had been chilled down for 2 hours in a 5 degrees F in a freezer,
> connected to the TICC, and left to warm up in a 75 degree F room.   Over
> the 10F to 70F temperature range (measured with an IR thermometer) the coax
> delay spanned around 300 ps... so figure around 5 ps per degree F (10 ps
> per degree C) for 100 feet of cable.
>
> I'm adding currently adding the ability for Heather to use an external
> temperature sensor...
>

I would not assume that a reel of coax that is coiled up will behave the
same as when used in  in a lab environment in the usual way. So whilst this
might be an interesting experiment, I believe some caution would need to be
applied before assuming that such a measurement is representative of how
coax is normally used. When not on a reel, a heated coax is free to expand
radially with no external pressure force applied, apart from that due to
air pressure. When on a reel, that's not the case, as the coax is the
middle of the reel is going to have forces applied that are much greater
due to the mass of the coax. To take an extreme example, if you use a foam
dielectric coax, when on a  real, the airgaps in the foam are likely to
become smaller as the cable will experience mechanical forces as it tries
to expand, constrained by the coax around it.

Also, when the coax tries to expand under heat, it is likely to deform to
take up the space between the turns on the reel, so possibly become more
square.

Unfortunately cable is likely to behave very differently at 10 MHz than 10
GHz, so it not necessarily useful to repeat a measurement with a small
piece of coax at 10 GHz, where its phase change could easily be measured on
a vector network analyzer.

Another spanner in the works is that the impedance of coax (usually 50
Ohms), is given by the equation

Z=sqrt( (R + 2 pi f L)/(G + 2 Pi f C) )

where R is the resistance per unit length, L is the inductance per unit
length, G is the conductance per unit length and C is the capacitance per
unit length. The high frequency approximation is that 2 pi f L >> R, and 2
Pi f C >> G, so it simplifies to sqrt(L/C). Those two assumptions become
less valid at low frequencies.

Overall, what you are doing seems interesting, but I would question how
much the results will relate to real-world use of coax, where its not
normal to have great real of it.

Dr. David Kirkby Ph.D CEng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT,
UK.
Registered in England and Wales, company number 08914892.
http://www.kirkbymicrowave.co.uk/
Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Bob kb8tq]

Hi


> On Apr 18, 2017, at 8:33 PM, jimlux  wrote:
> 
> On 4/18/17 3:55 PM, Bob kb8tq wrote:
>> Hi
>> 
>> On something like a 500’ spool of coax, the question will always be “what 
>> temperature is it where in the spool”. A single sensor will
>> only give you precise information if the temperature ramp is *very* slow (as 
>> in days …).
>> 
> 
> measure the DC resistance of the spool, and you'll be able to get a sort of 
> "average" temperature.

I’d want to be pretty sure what the center conductor was made out of. I’ve seen 
some stuff
in coax that “one would think” should not be there (copper over steel …).

Bob

> 
> 
> 
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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[jimlux]

On 4/18/17 3:55 PM, Bob kb8tq wrote:

Hi

On something like a 500’ spool of coax, the question will always be “what 
temperature is it where in the spool”. A single sensor will
only give you precise information if the temperature ramp is *very* slow (as in 
days …).



measure the DC resistance of the spool, and you'll be able to get a sort 
of "average" temperature.




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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Bob kb8tq]

Hi

On something like a 500’ spool of coax, the question will always be “what 
temperature is it where in the spool”. A single sensor will
only give you precise information if the temperature ramp is *very* slow (as in 
days …). 

Bob

> On Apr 18, 2017, at 11:50 AM, Mark Sims  wrote:
> 
> Unfortunately I did not have the ability to log temperature at the time I did 
> that test.   I just added support to Lady Heather for an environmental sensor 
> so I should be able to do that later on.  Currently my environmental sensor 
> code only does two channels of temperature.  I am going to build a board with 
> an ATMEGA 328 chip and BMP280 for humidity and pressure along with support 
> for a couple of temperature sensors (should be able to do type K 
> thermocouples and RTD1000's)
> 
> -
> 
>> maybe you can recalculate your results in PPM and plot against temperature,
> to compare with the mw-journal plots?
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Re: [time-nuts] Measuring coax temperature coefficient with a TICC

[Anders Wallin]

The recent supplement to Microwave journal has a piece on phase stability
of cables (predictably - written by a vendor of said cables..):
http://www.microwavejournal.com/publications/1/editions/223

maybe you can recalculate your results in PPM and plot against temperature,
to compare with the mw-journal plots?

Anders

On Sat, Apr 15, 2017 at 4:34 AM, Mark Sims  wrote:

> I finally got around to using a TICC to measure the temperature
> coefficient of 100 feet of generic RG-58 coax using a TICC.   The TICC was
> clocked by a HP 5071A 10 MHz output.  The 1PPS output was connected to the
> input of the coax and the TICC chB input.  The TICC chA input was connected
> to the coax output via an inline terminator.   The TICC was set to "debug"
> mode  and Lady Heather plotted the chB-chA timestamp difference (hence the
> negative cable delay values).
>
> The coax had been chilled down for 2 hours in a 5 degrees F in a freezer,
> connected to the TICC, and left to warm up in a 75 degree F room.   Over
> the 10F to 70F temperature range (measured with an IR thermometer) the coax
> delay spanned around 300 ps... so figure around 5 ps per degree F (10 ps
> per degree C) for 100 feet of cable.
>
> I'm adding currently adding the ability for Heather to use an external
> temperature sensor...
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