Re: [time-nuts] TymServe TS2100 dead power supply

[Bob Martin]

Many thanks for the replies on this one.

Before I made the first post, I'd pulled the supply, given it a visual and 
nasal inspection, checked the outputs for shorts, and powered it up on the 
bench. Dead (and dead quiet, not even the tick-tick-tick of a switcher with a 
shorted output).

In my perusal of the archives, someone observed that it was a standard Astec 
LPT-42 supply. Lo and behold, a label on the primary filter cap of my dead 
switcher identifies it as an ASTEC LPT42.

I looked around -- Mouser and Digi-Key were within $1 of each other. Not too 
surprising, actually, pretty much ALL the sellers on eBay wanted more for units 
of dubious heritage than Mouser and Digi-Key wanted for a new one.

Already had some bits and pieces I needed from Digi Key so I added a new LPT-42 
on to the order.

New supply arrived. Installed, connected power, turned it on and things light 
up. Pulled the fuse out of the old supply to save and tossed the old supply in 
the bin. Last time I got a good electrical shock (if there is such a thing) was 
from a faulty switching power supply; another reason to diagnose this one with 
my wallet!

Back in operation again. Yes, I *still* have to deal with the old GPS module 
and the issues it creates. But my TS2100 is back on the air, driving my IRIG 
displays and providing 10 MHz to various pieces of equipment.

RANDOM QUESTION -- does anybody know of software to *generate* IRIG time code? 
Something in C that's adaptable to a modern micro would be good. In something 
like a Raspberry Pi 3, IRIG generation would make a nice addition to Lady 
Heather...

cheers and 73,

Bob K6RTM

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[time-nuts] TymServe TS2100 dead power supply

[Bob Martin]

We had a brief power outage a few days ago.

My TS2100 didn't power up afterwards. Fuses are fine, AC power delivered to 
power supply, which is producing nothing. Nothing looks/smells fried on the 
power supply.

Couldn't find data on what the power supply output voltages should be; not in 
the meagre documentation, .

I'd appreciate help from someone with a TS2100 while I look for faults in this 
little switching power supply. Looks like three voltages, +5 and what else? Is 
this a more or less standard supply?

Appreciate any help I can get!

Bob K6RTM



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Re: [time-nuts] Designing an embedded precision GPS time

[Bob Martin]

One can minimize temperature change which affects things like 
regulated voltages, CMOS transition points for those converting

sine to TTL with gates, etc. in addition to the oscillators.

The November issue of Nuts and Volts Magazine has an article on an
Arduino based PID controller which might interest someone who wants 
to experiment with reducing temperature effects by controlling 
temperature.


Bob M

On 10/31/2017 8:42 PM, jimlux wrote:

On 10/31/17 1:47 PM, Bob kb8tq wrote:

HI

TCXO is a very loosely defined term. A part that does +/- 5 ppm 
-40 to +85C
is a TCXO. A part that does +/- 5x10^-9 over 0 to 50C may also be 
a TCXO.


Dividing the total deviation of either one by the temperature 
range to come

up with a “delta frequency per degree” number would be a mistake. You
would get a number that is much better than the real part exhibits.

Working all this back into a holdover spec in an unknown temperature
environment is not at all easy.



Very much so - most of the TCXO curves I've seen tend to be "much" 
better than the spec over the central part of the frequency range 
(which makes sense, the underlying crystal is a cubic with temp, 
most likely)


Retrace and hysteresis might be your dominant uncertainty.
I've attached a typical TCXO data plot for your viewing pleasure..
(that's an expensive oscillator, because it's for space, but I don't 
think space or not changes the underlying performance)




Bob





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Re: [time-nuts] I've been thinking about a GPS receiver experiment

[Bob Martin]

Terrific points. There are so many levels of sophistication.

My own experience is with catastrophic signal loss on the reference.
Determining degradation on your primary reference can present 
challenges.  I once designed a device that compared three Cesiums 
and switched the reference within one cycle if the amplitude of the 
Cesium that was acting as the reference changed or the zero crossing 
(10 MHZ) was a few nanoseconds out of spec relative to the other two 
Cesiums. Nowadays they create ensembles of Cesiums and use them to 
steer their timing systems while the Cesiums are steered by GPS.
Sophisticated Kalman filters are used to steer the signals based on 
the properties of the signal sources.


The Microsemi 4145 Ultraclean Oscillator is designed for 
catastrophic signal loss and freezes the DAC that controls the BVA 
oscillator. This works well because even the DAC is ovenized. It 
will also go into holdover if the input reference drifts too quickly.


It is pretty easy to make a simple temperature controlled box to 
house your temperature sensitive references. Just provide lots of 
insulation and control it at a temperature higher than your highest 
expected ambient.


I never measured the temperature of oscillators and used the 
information to compensate holdover but it makes sense with a 
specific oscillator and enough run time to collect the data
to categorize the oscillator for temperature and ageing. This is 
easier to accomplish when the DAC is is directly controlling the 
oscillator. Since I prefer analog control loops, it could also be 
done when the analog loop controls the oscillator if the DAC tracks 
the analog loop control voltage. A comparator compares the DAC 
output to the analog loop voltage. The DAC is adjusted to track and 
thereby characterized so that it can be set to the correct value 
when switched to holdover. As Bob pointed out this may or may not be 
the last value of the DAC depending on the mode of failure of the 
reference signal.


As Bob points out, there are very sophisticated ways of doing 
temperature compensation today. As an example of his point, I was 
told that the Microsemi CSAC (chip-scale atomic clock) uses 
temperature compensation at many places in the design to achieve its 
performance specs. I imagine that is the current ultimate in 
temperature compensation for commercial products!


Bob M


On 10/26/2017 8:33 AM, Bob kb8tq wrote:

Hi

Most GPSDO’s do some sort of “slew” to an average DAC value when they go into 
holdover.
Freezing at the last value is not (in general) a good idea. Often things 
degrade before there
is a dropout. Your final DAC value may not be a good one to maximize holdover 
duration.

Some setups try to “learn” temperature or aging. That gets fed into the DAC 
when in holdover.
The value of this depends a lot on the quality of the training process. 
Separating this and that
input to get a good value for a specific parameter is rarely done with good 
accuracy. The exception
to that rule are oscillators that have a large TC or a very high drift rate. In 
most cases those are not
the ones you pick for a GPSDO.

Bob


On Oct 25, 2017, at 7:46 PM, Bob Martin <aph...@comcast.net> wrote:

  The holdover state is a DAC set to the last value of the analog control 
voltage that adjusts the oscillator frequency. Some designs
use an analog control loop and switch the DAC into the control loop.
Others use the DAC to set the control voltage at all times. This can result in 
a steps in the control voltage (output frequency).
I've used both methods and prefer the latter.

Bob M

On 10/25/2017 5:30 PM, Mark Sims wrote:

  No, you set up an oscillator so that is why you have that problem.

I hooked the two rubidiums together just to see what would happen.   It pretty 
much did what I expected... chaos...   the time-nut equivalent of a naughty 
schoolboy putting a microphone up to the speaker of the public address system.  
I't's a tough job, but somebody gotta do it  ;-)

  No, not really. The rubidium would be the real hold-over clock.

Symmetricom calls the disciplining state where it can't lock to the 1PPS signal the 
"holdover" state.  It's sort of like a GPSDO holdover state.  Their discipline 
firmware does let you set the time constant and damping values.  I tried a little playing 
around with them, but never found any settings that worked consistently well with the 
LEA-5T.
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Re: [time-nuts] I've been thinking about a GPS receiver experiment

[Bob Martin]

Sorry, my mistake, change that to the former!  I have used DACs that 
were monotonic with decent results but prefer analog loops when the 
time constants are short enough.


Bob M

On 10/25/2017 5:46 PM, Bob Martin wrote:
   The holdover state is a DAC set to the last value of the analog 
control voltage that adjusts the oscillator frequency. Some designs

use an analog control loop and switch the DAC into the control loop.
Others use the DAC to set the control voltage at all times. This can 
result in a steps in the control voltage (output frequency).

I've used both methods and prefer the latter.

Bob M

On 10/25/2017 5:30 PM, Mark Sims wrote:

  No, you set up an oscillator so that is why you have that problem.


I hooked the two rubidiums together just to see what would 
happen.   It pretty much did what I expected... chaos...   the 
time-nut equivalent of a naughty schoolboy putting a microphone up 
to the speaker of the public address system.  I't's a tough job, 
but somebody gotta do it  ;-)




  No, not really. The rubidium would be the real hold-over clock.


Symmetricom calls the disciplining state where it can't lock to 
the 1PPS signal the "holdover" state.  It's sort of like a GPSDO 
holdover state.  Their discipline firmware does let you set the 
time constant and damping values.  I tried a little playing around 
with them, but never found any settings that worked consistently 
well with the LEA-5T.

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Re: [time-nuts] I've been thinking about a GPS receiver experiment

[Bob Martin]

  The holdover state is a DAC set to the last value of the analog 
control voltage that adjusts the oscillator frequency. Some designs

use an analog control loop and switch the DAC into the control loop.
Others use the DAC to set the control voltage at all times. This can 
result in a steps in the control voltage (output frequency).

I've used both methods and prefer the latter.

Bob M

On 10/25/2017 5:30 PM, Mark Sims wrote:

  No, you set up an oscillator so that is why you have that problem.


I hooked the two rubidiums together just to see what would happen.   It pretty 
much did what I expected... chaos...   the time-nut equivalent of a naughty 
schoolboy putting a microphone up to the speaker of the public address system.  
I't's a tough job, but somebody gotta do it  ;-)



  No, not really. The rubidium would be the real hold-over clock.


Symmetricom calls the disciplining state where it can't lock to the 1PPS signal the 
"holdover" state.  It's sort of like a GPSDO holdover state.  Their discipline 
firmware does let you set the time constant and damping values.  I tried a little playing 
around with them, but never found any settings that worked consistently well with the 
LEA-5T.
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Re: [time-nuts] Spice simulation of PSRR and phase noise

[Bob Martin]

I never had much luck with current feedback amplifiers such as the 
LMH6702.  Their input current noise (at the time) was too high for 
my needs and their output peaks at higher frequencies if the 
feedback resistors aren't optimal for the part.


 I had the best results with voltage feedback op amps like the 
MAX4104/MAX3404 when I needed gain on the input stage and the 
LMH6609 when I needed a buffer.


 My applications were broadband. If I remember correctly, 
aggressive bandwidth limiting can cause phase shift problems due to 
temperature changes unless one is careful in the design of the filter.


 I've successfully put as many as four op amps in parallel in an 
input stage to reduce phase noise.



Bob M (another bob)

On 10/24/2017 6:24 AM, Bob kb8tq wrote:

Hi

One would guess that they put them in parallel to get more drive. If that’s 
correct,
details of the loading are going to get into the simulation pretty quickly.

In a lot of cases, these amplifiers were designed against a specific need. If 
you have
a signal source that is in the -180 dbc / Hz range, they are unlikely do 
perform well.
In many cases a floor in the -140 dbc / Hz range was considered “good enough”.
If you are simply driving common test gear, it probably *is* good enough. If the
application was video rather than a standard the specs could have been very 
different.

In the case of an amp with a LMH6702, you are not going to get super  close in
phase noise. The device is *very* noisy under 1 MHz. It also starts to increase 
distortion
by 10 MHz so you will see up conversion. It probably did quite well against the 
intended
design spec.

=

If you need a system that will distribute one frequency today and a totally 
different
frequency tomorrow, broadband makes sense. For the more common task of
something like “only 10 MHz”, it does not make much sense at all. Gain other
  frequencies is just going to spread around noise from this or that source
of crud. Driving filters with op amps can be problematic. It often is easier to 
go another
way.

Bob


On Oct 24, 2017, at 6:09 AM, Anders Wallin  wrote:

FWIW I recently took a peek inside a commercial distribution-amplifier and
it seems to use two LMH6702 op-amps in parallel.
There are two of these dual-LMH6702 stages with a 1:2 splitter after the
first, and then a 1:4 splitter after the second stage. 8 outputs in total,
with an additional op-amp driving each output.
A simulation that shows the difference in PN between a single LMH6702 and
the dual-op-amp idea would be nice.
For far-out (>100Hz from carrier?) PN only SNR might matter, so a SPICE
noise-simulation giving noise PSD at relevant (5-10MHz) frequencies might
give something?

Anders
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Re: [time-nuts] Need advice regarding rubidium oscillator

[Bob Martin]

Roman--

You'll find a lot of information on the care and feeding of rubidiums such as 
the LPRO-101 on the list, and referenced websites.

A specific reference for the LPRO-101 is: 
http://www.ka7oei.com/10meg_rubidium1.html 

that page has links to a lot of information on rubidiums, and on the LPRO-101 
-- links to this list, the KO4BB website, manuals, and more.

In general:
   Rubidium packages have a finite operating life. The ones we get from eBay 
are usually telecoms pulls of unknown age.
   Rubidium packages need heat sinks!
   The outputs of some rubidium packages are cleaner than others

Have fun. Let us know what works and what doesn't -- that helps the next person 
to trod this path avoid the simple mistakes, and instead get right to the 
complex ones that are more interesting.

bob k6rtm

(using a rubidium reference for my Elecraft K3S for amateur radio Field Day)

> On 2017/06/23, at 9:00 , time-nuts-requ...@febo.com wrote:
> 
> Message: 13
> Date: Fri, 23 Jun 2017 12:47:59 +0400
> From: Roman >
> To: Time-nuts@febo.com 
> Subject: [time-nuts] Need advice regarding rubidium oscillator
> Message-ID:
>   

[time-nuts] FS: ThunderBolt

[Bob Martin]

U.S. only, will ship in well packaged USPS Priority Mail box. $220.

E-mail me off-list if interested.

This is my back-up Trimble ThunderBolt with rev 3.0 firmware. It's been sitting 
unused in a box for too long; it should be in some time-nut's lab listening to 
birds.

Obviously used with tape residue on the case. Sad to part with it, but I'm not 
likely to put it to use any time soon.

73,

Bob K6RTM

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Re: [time-nuts] UPS, battery backup, and connectors

[Bob Martin]

A lot of ham radio operators, particularly those in involved in emergency 
services use Anderson Powerpole connectors. Easy to install, reliable, 
available. A standard configuration exists for 12 VDC emergency communications 
and mobile work.

bob k6rtm

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[time-nuts] End of the World, or beginning of a new one?

[Bob Martin]

As I look at my Tymserve 2100 sitting in the rack to my left, the date it's 
displaying is JUL 02 2015.

So the week rollover bug was coupled to the leap second? No wine to drink today 
(it's still early)...

Anyone else with a TS2100 that's suddenly acting strange, er, correct for the 
first time in a while?

bob k6rtm




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[time-nuts] Tymserve 2100 thinks it's 1995?

[Bob Martin]

My Tymserve 2100 gps unit (Rev 4.1) thinks it's 1995 -- September 17, 1995.

But a restart (connect via telnet and give the commands util restart) brings it 
back to the correct time and date -- for a while? I haven't caught it dropping 
back, so i don't know if it's doing this on the hour, after an hour, or what, 
but I noticed it last night, and I've restarted it a few times today.

Any clues?

I know about the off-by-a-second issue with the pending leap second. This one 
is more interesting!

So far I've just been issuing software restarts. The next time I'll power cycle 
the sucker and see if that does any good.

GPS signal isn't the issue; the 2100 shares an external GPS antenna with my 
Thunderbolts through a Symmetricom 58536A GPS splitter, and the Thunderbolts 
are as happy as a Thunderbolt can be.

cheers

bob k6rtm


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Re: [time-nuts] Tymserve 2100 thinks it's 1995?

[Bob Martin]

Additional information --

Power cycling (leaving it off for about 5 minutes) didn't do any good.

Once at the correct time/date, it bounces back to 1995 at about 30 seconds 
after the hour (now to Sep 18, 1995).



My Tymserve 2100 gps unit (Rev 4.1) thinks it's 1995 -- September 17, 1995.

But a restart (connect via telnet and give the commands util restart) brings it 
back to the correct time and date -- for a while? I haven't caught it dropping 
back, so i don't know if it's doing this on the hour, after an hour, or what, 
but I noticed it last night, and I've restarted it a few times today.

Any clues?

I know about the off-by-a-second issue with the pending leap second. This one 
is more interesting!

So far I've just been issuing software restarts. The next time I'll power cycle 
the sucker and see if that does any good.

GPS signal isn't the issue; the 2100 shares an external GPS antenna with my 
Thunderbolts through a Symmetricom 58536A GPS splitter, and the Thunderbolts 
are as happy as a Thunderbolt can be.

cheers

bob k6rtm


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Re: [time-nuts] TS2100 thinks it's 1995...

[Bob Martin]

Middle of the night I had a worry this was a rollover bug... And that seems to 
be confirmed, 1024 weeks.

As I mentioned in an electronic conversation with another TS2100 user, I have 
the feeling our TS2100s have turned into turnips.

Well, I can use the 1U space in that rack... Don't recall what processor they 
use in the thing, but life is too short to go digging through decades old 
assembly code.

I will miss the IRIG time display mounted above my main LCDs though. While the 
time is accurate (well, it's off a second due the TS2100 leap pending bug), the 
day of the year is off by a bit.

--bob k6rtm

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Re: [time-nuts] Off topic project sort of heart rate monitor

[Bob Martin]

Being left-handed, I'll offer a left-handed suggestion --

Ditch the direct connection.  Go with a commercially available heart rate 
sensor, such as a transmitting chest strap heart rate monitor from Polar.

You can buy receivers for this (low carrier frequency) signal that connect up 
to Arduinos and such:

https://www.sparkfun.com/products/8661

This board even does noise filtering and some averaging for you, as well as 
providing raw outputs.

No wires between subject and monitoring gear. Seems like a winner to me.

Bob K6RTM


On 2013/02/19, at 17:01 , time-nuts-requ...@febo.com wrote:

 Off topic project sort of heart rate monitor

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Re: [time-nuts] Embedded NTP server ideas and feature - POE

[Bob Martin]

Full-blown 802.3af POE (IEEE 802.3af-2003 for example) is not a simple beast. 

The Arduino world uses a standard module, the Silvertel Ag9000-S.

Silvertel shows them as $10.64 each for a module that puts out 9W max and is 
802.3af compliant.

Bob K6RTM




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Re: [time-nuts] Nifty MINI TIC for DMTD work

[Bob Martin]

SIgn me up for one!

Bob K6RTM in sunny Silicon Valley 

 --
 
 Message: 3
 Date: Mon, 19 Nov 2012 14:53:16 -0500 (EST)
 From: ewkeh...@aol.com
 To: time-nuts@febo.com
 Subject: Re: [time-nuts] Nifty MINI TIC for DMTD work
 Message-ID: 2822f.5cd0eab7.3ddbe...@aol.com
 Content-Type: text/plain; charset=US-ASCII
 
 Don
 lets see how much interest and which counter and in the 2 channel it is 3  
 PIC's and 1 G/A and the 4 channel 5 PIC's and 2 G/A. Easy to solder Juerg 
 and I  are 70+ so soldering is a key consideration
 Bert Kehren.
 


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Re: [time-nuts] XL-DC Antenna Requirements

[Bob Martin]

Chris--

The 58532A is somewhat higher gain (30dBi or better) than most mag-mount 
antennas (26dBi typ IIRC).  The pointy nature of the 58532A also serves as an 
avian deterrent, reducing the accumulation of attenuating deposits...

Running two receivers, I would highly recommend a real GPS distribution amp 
such as the 58535A.  Such a beast will let you run both receivers from one 
antenna, while providing isolation between the receivers.  I just happen to 
have one handy, having recently pulled it out of service and replaced it with a 
4-port model to better support my time-nuttiness.  Contact me off list if you 
would be interested.

73 Bob k6...@arrl.net


On Jul 16, 2012, at 16:01, time-nuts-requ...@febo.com wrote:

 Message: 1
 Date: Mon, 16 Jul 2012 14:59:52 -0700
 From: Chris Hoffman cq.k...@gmail.com
 To: time-nuts@febo.com
 Subject: [time-nuts] XL-DC Antenna Requirements
 Message-ID: 0208b173-9f7b-49b9-ae83-ee231ebba...@gmail.com
 Content-Type: text/plain; charset=us-ascii
 
 All,
 
 Though somewhat outmoded, looking forward to starting my own time shop with 
 two XL-DC controllers that I have been lucky enough to pick up recently. 
 
 My question: Do I really need to invest in the likes of the HP 58532A 
 antennae, or will my surplus Trimble magnetic antennae -- magnetically 
 attached to a random ferrous backplane -- do? 
 
 I guess what I am really asking: what are the relevant antenna design 
 requirements here, and does the advent of as 32-satellite-constellation have 
 any effect upon the antenna choice (i.e. design downgrade) for the TrueTime 
 XL-DC? 
 
 -CH
 
 Chris Hoffman
 cq.k...@gmail.com
 http://ar.ctur.us

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[time-nuts] About that Leap Second...

[Bob Martin]

After all the waiting...

I set up a video camera to capture the LCD on my Datum/Tymserve 2100 GPS NTP 
box, and another camera to watch a different GPS-slaved IRIG-B display.

But for all the build-up, no 60 to be seen -- the video of the 2100 clearly 
shows the 23:59:59 hanging around for wy too long, but that's it.

I'll edit and post the videos anyway; the background music and the 
disappointment at not seeing a 60 on one of the displays is somewhat 
entertaining.

The kids think their dad is nuts (but they came in to watch). Still, it was 
fun!  Another afternoon in the life of a time-nut!

Bob K6RTM in sunny Silicon Valley
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[time-nuts] The Elusive 74AC175PC

[Bob Martin]

Summary: I found some, 50 or so, 20 cents each.  Contact me off-list (at 
k6...@arrl.net) if you are interested.

The longer version:

My travels had me near a surplus place I hadn't visited in a while.  Wandering 
the aisles, I thought to myself, Self, there's a part we need for the PICTIC 
II -- what was it?  A quick Google search, and wandering down the aisles...

Ah, the elusive 74AC175PC! Probably 50 or so, in tubes.  I picked up a tube of 
9 for 20 cents each.  National Semiconductor logo, 16 pin DIP, date code 
P9312AB so not quite as old as my kids, leads all shiny and bright.

I still need programmed PICs for my boards. Horse trading, anyone? Let me know 
if you need some of these parts.

73, Bob K6RTM in sunny Silicon Valley
preferred email: k6...@arrl.net
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Re: [time-nuts] Opinion Of Attached - Possible HPSDR GPSDO

[Bob Martin]

John--

Who do we make the checks to?  Having been reasonably successful at today's 
flea market, would small bills be preferable?

(This is an expression of interest!)

73, Bob K6RTM


On Apr 14, 2012, at 18:11, time-nuts-requ...@febo.com wrote:

 --
 
 Message: 1
 Date: Sat, 14 Apr 2012 18:10:28 -0700
 From: John Westmoreland j...@westmorelandengineering.com
 To: time-nuts@febo.com
 Subject: [time-nuts] Opinion Of Attached - Possible HPSDR GPSDO
   'Engine'
 Message-ID:
   CAFtYB4z=bmeidqkeudk63hduoklakcrrhnjao_z9jataucp...@mail.gmail.com
 Content-Type: text/plain; charset=iso-8859-1
 
 Hello Fellow Time-Nuts,
 
 I am new to the group - and was asked by someone from HPSDR/TAPR to get an
 opinion, good/bad, of the attached PDF which I hope doesn't exceed the
 allowable byte size of posts.
 
 Jackson Labs has given me a verbal on the attached as sub $300.00 QTY 1.
 We are seeing if there is interest in a possible 'bulk' buy.
 
 I will post more on the HPSDR Wiki as soon as I sort out my password - and
 will post an e-mail regarding the other files associated with the GPSTCXO.
 
 If there is sufficient interest we may do a spin of the HPSDR Excalibur
 project or perhaps just do a new project with the attached device.  It
 should be easy to interface
 directly to the Alex Bus in the OpenHPSDR Architecture.
 
 Thanks and 73's,
 John W.
 San Jose, CA
 AJ6BC (Ham Call Sign)
 -- next part --

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