Re: [time-nuts] Does doubling a frequency alter the original ADEV of the frequency?

[davidh]

Charles,

Thanks for the reminder about this... it will neatly solve a problem I 
have at hand. Can you advise which core you used for the transformer?


Thanks,

david


On 10/07/2016 07:57, Charles Steinmetz wrote:

James wrote:


Is there a preferred frequency doubler circuit which would do the
least harm to the ADEV of the oscillator?  The signal can be a square
wave and does not need to be a sine wave.  Thanks.  Jim Robbins


A quadrature-fed DBM produces the lowest jitter and noise.  My
implementation can be found at:




A well-designed push-push frequency doubler is probably second (but note
that many push-push designs you find on the web have various common
design flaws).  My implementation can be found at:




Best regards,

Charles





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Re: [time-nuts] PRS10 C900 replacement

[davidh]

Hi All,

I used the TAP225K035SRW, from Mouser, and have the PRS10 running again. 
In the process of pulling it apart I managed to break one of the glass 
thermistors (Mouser replacement from US Sensor, part number 104JG1F). Doh.


Whether it was the lamp temperature change (thermistor) or mechanical 
alignment now being a bit different, the frequency moved by about 
300E-12 (measured by locking to my GPSDO 1PPS and comparing old to new 
"SF" values).


I've also added a cooling fan so the base plate is now below 40dC. I 
guess that could also affect the frequency.


Cheers,

david


On 20/01/2016 4:59 PM, Charles Steinmetz wrote:

david wrote:


It's a 2.2uF cap, with a 0.125" lead spacing, and I'm looking for
125dC temp rating. I wondered if there were other characteristics such
as ESR/ESL I need to keep in mind.


You're on the right track.  Get the highest temperature rating available
(which is probably 125C), buy only caps manufactured by one of the
known-good manufacturers, and select from a parts series the
manufacturer designates as "high reliability" (or equivalent).

If it is a solid tantalum, I like the Vishay 199D Series.  The AVX TAP
Series and the Kemet "T" Series ("UltraDip II") are also high quality.
(This list isn't exhaustive -- these are just the ones I've had occasion
to qualify.)

Best regards,

Charles





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[time-nuts] PRS10 C900 replacement

[davidh]

Hi All,

While still appearing to function normally, my PRS10 started to smell: 
C900 in the lamp assembly has self destructed.


The SRS parts manual merely says "Capacitor, Tantalum, 35V, 20%, Rad", 
so I'd appreciate any advice on what additional parameters I should be 
looking at in selecting a replacement.


Thanks,

david

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Re: [time-nuts] PRS10 C900 replacement

[davidh]

Folks,

It's a 2.2uF cap, with a 0.125" lead spacing, and I'm looking for 125dC 
temp rating. I wondered if there were other characteristics such as 
ESR/ESL I need to keep in mind.



d.


On 20 Jan 2016 14:32, Dan Harboe Burer wrote:

Hi,

You need one more piece of info: its value! E.g. 1uf, 0.35uF, 2.2uF,
10uF? That is quite important :)

Just don't use too old tantalum caps - they tend to absorb moisture over
time (when stored incorrectly) - and self destruct as you have
experienced..
I just experienced the same while renovating a Tek 475 'scope.

Regards
Dan (A newbie from Denmark)

-Oprindelig meddelelse- From: davidh
Sent: Tuesday, January 19, 2016 11:21 PM
To: time-nuts-jsktletq...@public.gmane.org
Subject: [time-nuts] PRS10 C900 replacement

Hi All,

While still appearing to function normally, my PRS10 started to smell:
C900 in the lamp assembly has self destructed.

The SRS parts manual merely says "Capacitor, Tantalum, 35V, 20%, Rad",
so I'd appreciate any advice on what additional parameters I should be
looking at in selecting a replacement.

Thanks,

david

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[time-nuts] PRS10 Heatsink Temperature

[davidh]

Hi All,

I'm moving a PRS10 Rb to a new case. In the current case, the heatsink's 
getting to around 60dC, which is getting close to the maximum operating 
spec of 65dC.


I plan to add a small temperature controlled fan to limit the heatsink 
temperature. Can anyone recommend a suitable setpoint for the heatsink?


Thanks,

david



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Re: [time-nuts] PRS10 Heatsink Temperature

[davidh]

Charles and Bob,

Thanks. I'll report back on how it works out.

david



n 24/11/2015 10:33 AM, Charles Steinmetz wrote:

David wrote:


I plan to add a small temperature controlled fan to limit the heatsink
temperature. Can anyone recommend a suitable setpoint for the heatsink?


An SRS engineer once told me to keep the PRS10's baseplate temperature
below 40C.

Best regards,

Charles





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[time-nuts] PM6681 and Timelab (was: PM6680 or 53131A for TimePod)

[davidh]

Hi Angus,

I have three 6681s operating concurrently under a single instance of 
timelab beta. It operates perfectly, even live n-cornered measurements. 
Kudos to John!


The only downside (and I understand why it's this way) is that each 
counter needs a unique GPIB interface, but this is a timelab requirement 
and nothing to do with the counters.


My only fear regarding the counters is that I'll lose the cal one day, 
so I'm keen to discover how we can calibrate them ourselves.


Cheers,

david


On 17/11/2015 7:32 AM, Angus wrote:

Hi,

PM6681's turn up at quite a good price too, and you get a lot of
extras over the 6680 - does anyone know if Timelab will work with a
6681?

Angus.



On Sun, 15 Nov 2015 15:10:42 -0800, you wrote:





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Re: [time-nuts] Troubleshooting Fluke PM6681

[davidh]

Magnus,

I have a few of these counters and would love to see the details of the 
calibration process you mention.


Cheers.

david

On 17/08/2015 5:16 AM, Magnus Danielson wrote:

Ole,

I checked with a former Pendulum employee, and free off memory, he
recommend trimming up the 100 MHz until Error 2 does not show. Sensing
it directly can be difficult, FET-probe essentially mandatory.
Indirectly a 10 MHz is possible. A problem is that trimming with the
hood off causes a different thermal setup than when the hood is on. If
you dare, make a hole in the hood so that you can trim it with the hood
on, that is what they did.

CMOS backup battery eventually fails, and then you need to replace it
and re-calibrate it. I have the details jotted down, but it seems that
this is not your issue.

Cheers,
Magnus

On 08/16/2015 12:20 PM, Ole Petter Ronningen wrote:

Hello.

I have a Fluke PM6681 that has issues. When I got it, it gave results all
over the place, but after adjusting the 100Mhz multiplier-chain, it seems
to be much better; at least I get std.deviationwell within spec using a
split pulse to input A and B, 100 samples. I'd like to get it
professionally calibrated, but I don't want to send it in with known
issues
- the cost of calibration will not be refunded if the instrument can
not be
calibrated, and I believe it is no longer repairable.

So, the issue is that it fails the ASIC test (test 6), with err 2.The
service-guide lists a number of signals to be checked in test-mode, but I
am not able to see any of them. Since the counter seems to function, I
can
only conclude that the signals are not present due to this error.. (Or
that
I am mistreading the guide and looking in the wrong place, probably at
least as likely..)

Anyway, I cant seem to find a description of this particular error, does
anyone know what it means?

Thanks,
Ole
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Re: [time-nuts] 3048A software question

[davidh]

Hi All,

Using the A.01.01 DOS version of the 3048A code and the B.01.01 version 
of the HP-IB Command Library (thanks Adrian), with an 82335 GPIB card, 
works with DOS6.22, DOS7.1 (WIN98) and FREEDOS1.1. All that's required 
is to load the HPIB.SYS (config.sys) and ensure the selected ROM address 
and IRQ are available.


It does not work in a win98 command windows; I spent no time trying to 
figure our why.


It does not work with later GPIB cards (82340), as these are I/O mapped, 
and the B.01.01 drivers require memory mapped cards.


Not having an old PC around, I used an Agilent 54845A, with the HDD 
reconfigured for dual booting. It's kinda cool having the PC in the rack 
with the 3048A kit, but there was a bit to learn to get the scope to run 
two GPIB cards. I upgraded the scope's HDD to an SSD, as the old drive 
had *LOTS* of hours on it.


The overall result is a bit disappointing, given what I set out to 
accomplish. I can now compare the results from PN3048 in baseband noise 
mode to get absolute measurements, which will be useful. The DOS code 
produces calibration and result files which are unreadable to the RMB 
version and PN3048, so my master plan to use the DOS cal data with 
RMB/PN3048 has been foiled.


On the positive side, I know the 3048A hardware is good, the system 
meets its performance specs, and I can do the 3-cornered hat 
measurements on my 100MHz PLLs which PN3048 can't do.


All good clean fun, but at pennies per hour, a timepod looks like a bargain.

Cheers,

david



David,

the 82335 drivers came with the complete SW package that I sent you.
I don't know if the drivers and SW are running with any more recent or
non MS versions than MS-DOS 6.0.
But, it's as easy to find out as it gets. Back in the day the whole OS
fitted on a floppy disk and 640k of memory, together with a 33 MHz 486
did the job.

Btw. a modern 2,000 MHz or something clocked PC with 4,000,000k of
memory doesn't seem to work any faster...
And, no, even if you get MS-DOS installed on it, you're not gonna have
much fun.

Adrian


davidh schrieb:



Folks,

I'm also working on getting the MSDOS version running. What is the
most recent version of DOS that people have found to work with the A
01.01 version.

Also, can anyone advise where the command drivers for the 82335 can be
found?

Cheers,

david


Hi Adrian,

Got the spec lines working now, thanks!

Yes, the DOS version. I was hoping for an updated user manual for
that version as the manual describes the other software version, and
maybe a slightly later sw version. Oh well.

Thanks for you help!
Said



On Feb 17, 2012, at 5:06, Adrian
rfnuts-kvp5wt2u2u0-xmd5yjdbdmrexy1tmh2...@public.gmane.org wrote:


Said,

are you using the Opt. 311 (MS-DOS) software?
I don't know of any more recent versions.

To answer your initial question:
You can not change anything on the diagram _after_ the measurement,
not even the title.
The spec lines will be visible only when you have defined them prior
to starting the measurement.

Regards,
Adrian


saidjack-ydxpq3io04c-xmd5yjdbdmrexy1tmh2...@public.gmane.org schrieb:

Hello team,

I am trying to get an HP 3048A system up and running, and I am having
problems with enabling spec limit lines on the graph.

I can enter the spec line data under the manipulate results then
spec
lines menu, but the lines I entered are not visible. There are the
standard
spec lines visible when I do the internal noise floor test, so I
know this
should work.

Does anyone know how to enable these properly? The user manual
doesn't talk
   about this, and it is written for an older version of the software
anyway's.

Also, I have software version A 01.01 from 1994, does anyone have
any more
recent software version?

Thanks in advance,
Said
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Re: [time-nuts] 3048A software question

[davidh]

Folks,

I'm also working on getting the MSDOS version running. What is the most 
recent version of DOS that people have found to work with the A 01.01 
version.


Also, can anyone advise where the command drivers for the 82335 can be 
found?


Cheers,

david


Hi Adrian,

Got the spec lines working now, thanks!

Yes, the DOS version. I was hoping for an updated user manual for that version 
as the manual describes the other software version, and maybe a slightly later 
sw version. Oh well.

Thanks for you help!
Said



On Feb 17, 2012, at 5:06, Adrian rfnuts-kvp5wt2u...@public.gmane.org wrote:


Said,

are you using the Opt. 311 (MS-DOS) software?
I don't know of any more recent versions.

To answer your initial question:
You can not change anything on the diagram _after_ the measurement, not even 
the title.
The spec lines will be visible only when you have defined them prior to 
starting the measurement.

Regards,
Adrian


saidjack-ydxpq3io...@public.gmane.org schrieb:

Hello team,

I am trying to get an HP 3048A system up and running, and I am having
problems with enabling spec limit lines on the graph.

I can enter the spec line data under the manipulate results then spec
lines menu, but the lines I entered are not visible. There are the standard
spec lines visible when I do the internal noise floor test, so I know this
should work.

Does anyone know how to enable these properly? The user manual doesn't talk
  about this, and it is written for an older version of the software
anyway's.

Also, I have software version A 01.01 from 1994, does anyone have any more
recent software version?

Thanks in advance,
Said
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[time-nuts] USB Serial ports, was Re: LTE-Lite

[davidh]

Hi,

For Windows, ComPortMan does a great job of managing comm port 
assignments. Available at http://www.uwe-sieber.de/comportman_e.html


Cheers,

david

On 29/11/2014 9:42 AM, Hal Murray wrote:


kb8tq-wyfad0z3...@public.gmane.org said:

The “new chip ID, new com port” thing is pretty typical for the FTDI
drivers. If you plug the old LTE back in there’s a good chance it will come
back up as COMM 5. Usually they are pretty good about only adding ports for
devices they have not seen before.


Most/some of the FTDI usb to serial chips have a serial number.  I don't know
how it works on Windows, but on Linux, you can use the udev rules to make an
alias so your software can refer to something with a filename like /dev/LITE
rather than /dev/ttyUSB2.  It works no matter which slot you plug it into
and/or still works after it gets unplugged and reconnected.

lsusb -v will show things like:
   idVendor   0x0403 Future Technology Devices International, Ltd
   idProduct  0x6001 FT232 USB-Serial (UART) IC
   bcdDevice6.00
   iManufacturer   1 FTDI
   iProduct2 FT232R USB UART
   iSerial 3 A102GX1N

/var/log/messages or /var/log/syslog will contain something like:
Nov 28 15:12:00 deb kernel: [1392082.791230] usb 3-3: Product: FT232R USB UART
Nov 28 15:12:00 deb kernel: [1392082.791235] usb 3-3: Manufacturer: FTDI
Nov 28 15:12:00 deb kernel: [1392082.791240] usb 3-3: SerialNumber: A102GX1N
Nov 28 15:12:00 deb kernel: [1392082.799337] ftdi_sio 3-3:1.0: FTDI USB
Serial Device converter detected
Nov 28 15:12:00 deb kernel: [1392082.799447] usb 3-3: Detected FT232RL

Nov 28 15:12:00 deb kernel: [1392082.805436] usb 3-3: FTDI USB Serial Device
converter now attached to ttyUSB3


This is what I put in /etc/udev/rules.d/35-hgm.rules

# LTE LITE Eval Board
KERNEL==ttyUSB*, ATTRS{serial}==A102GX1N, MODE=0666, SYMLINK+=LITE


I use the same approach with my Rigol scope and Prologic USB-GPIB.







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Re: [time-nuts] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale

[davidh]

Hi Pete,

I'll take a couple of these of your hands if possible.

I'm in Australia, but using a shipping agent in California, so it'll 
just be domestic freight.


Let me know.

david

dho...@gmail.com


I've acquired a few new in the box Leica/AeroAntennas. Some boxes have been
opened.

https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313

The complete assemble is Leica P/N 10147

The 'puck' antenna is P/N 10160

I would like to have Time-Nuts get first dibs

Does $100 + shipping sound reasonable ?

The box is 16 x 16 x 16 and weighs 11 lbs.

-pete
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Re: [time-nuts] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale

[davidh]

Sorry Everyone,

I thought I replied only to Pete.

david




Hi Pete,

I'll take a couple of these of your hands if possible.

I'm in Australia, but using a shipping agent in California, so it'll
just be domestic freight.

Let me know.

david

dho...@gmail.com


I've acquired a few new in the box Leica/AeroAntennas. Some boxes have
been
opened.

https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313


The complete assemble is Leica P/N 10147

The 'puck' antenna is P/N 10160

I would like to have Time-Nuts get first dibs

Does $100 + shipping sound reasonable ?

The box is 16 x 16 x 16 and weighs 11 lbs.

-pete
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Re: [time-nuts] 10811 Thermal fuse?

[davidh]

Dan,

On Ebay you'll find a seller called newdeparture2010 who has a good 
range of fuses. He saved me a bucket load of money when I needed 
replacement LittleFuses to repair my 11848A, before I learnt the right 
way to apply the K23 to power supply measurements.


Cheers.

david

On 3/09/2014 5:23 AM, Dan Rae wrote:

I'm sure this has been discussed to death before, but does anyone know
of a source of thermal fuses small enough to fit in the -hp- 10811?  I
have found plenty of larger ones, none of which will fit and would
rather not just link it out.

Dan
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Re: [time-nuts] Symmetricom 1111C OCXO question

[davidh]

Hi All,

Can anyone advise the supply voltage and range of the control voltage 
for these gadgets?


Cheers,

david




On 03.04.2014 18:25, Azelio Boriani wrote:

Other idea than leaving the 6K8 resistor?

Yes... I would prefer to know why the little thing has stopped working.
The 6k8 resistor has also probed to be a marginal solution. The
operational amplifier is a Burr-Brown one (don't have the p/n at hand
now), and since it was my first suspect, I replaced it with a similar
(but not the same) part from Linear Technology that I had at hand. With
this one, I tested the resistor trick. After concluding that the
original opamp was ok, I have put it back. With the original one, the
resistor trick did no longer work, so it was not only a dirty solution,
but also very marginal. So... I would prefer to find and solve the real
failure :)

Regards,

Javier



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Re: [time-nuts] ARM boards for low-cost GPSDOs

[davidh]

Hi All,

I've used the STM32F4 for a few projects, and was considering it for a 
time tagger for a DMTD system. I have a question about the clocking 
though that someone may be able to help me with.


The 32F4 (like lots of similar ARMs) uses a PLL to generate the internal 
clocks from much lower frequency clock or crystal. Has anyone quantified 
the stability of the synthesised clock?


Thanks,

david


On 11/04/2014 8:02 AM, Alberto di Bene wrote:

On 4/10/2014 11:38 PM, Hal Murray wrote:


Does anybody have a favorite low-cost ARM board?  I'm looking for a
simple
Arduino like setup rather than something that runs Linux.  The idea is
to get
32 bit counters so a bunch of the recent discussion can be ingnored.


==

I can't recommend warmly enough the Discovery board from STM.
It sports a Cortex ARM M4F that can run at 180 MHz, has a native
IEEE compliant floating point core, 2MB flash and 256 kB RAM,
and a wealth of interesting peripherals on chip, TFT display touch
enabled included.  And at 23.52 USD is cheaper than a much
less powerful Arduino...

I implemented on it a fully featured SDR, without using any opsys,
talking directly to the bare metal using the Keil IDE/compiler.
A joy to use. Look here :

http://www.st.com/web/catalog/tools/FM116/SC959/SS1532/LN1848/PF259090

73  Alberto  I2PHD




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Re: [time-nuts] GPSDO control system

[davidh]

Howdy Charles,

Could you tell us more about the PLL, what sort of phase comparator, 
filters and so forth. I'd be keen to duplicate and test your configuration.


Thanks,

david



David wrote:


How do you lock your OCXO to the PRS10?


I just use a 1:1 PLL.  Some will argue that phase locking two
oscillators running at the same frequency is not optimal, but I have
found that it can work very well.  YMMV.  Perhaps locking a 100 MHz OCXO
to the PRS10 and dividing its output down to 10 MHz could yield better
results (and perhaps not) -- but I have no desire to start collecting
100 MHz OCXOs and culling them to find the best one, so that hypothesis
is left for someone else to investigate.

Best regards,

Charles






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Re: [time-nuts] GPSDO control system

[davidh]

Hi Charles,

How do you lock your OCXO to the PRS10?

Thanks,

david



I've lost track now of who it was, but someone asked if there was a
better strategy than a GPS disciplined quartz oscillator or a GPS
disciplined rubidium.  My best standard uses an SRS PRS10 rubidium
disciplined by GPS PPS at tau = VERY long ( ~12 hours), using the
PRS10's internal PPS locking.  The rubidium, in turn, disciplines my
best OCXO at tau 300 seconds.  So, for tau less than ~300 seconds the
stability is determined by the OCXO; for tau greater than ~300 seconds
and less than ~12 hours, the stability is determined by the rubidium;
and for tau  ~12 hours, the stability is determined by GPS.  I have
found that this works very well.

Note that the PRS10's digital PPS PLL has a bewildering array of
adjustable parameters.  One can easily get lost exploring different
combinations.  My advice is to keep it as simple as possible.

Best regards,

Charles





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[time-nuts] L1/L2 GPS Receiver

[davidh]

Folks,

I've stumbled across a Novatel 720L, so would like a new receiver module 
which supports L1/L2.


The main goal is to start learning about GPS/Galileo/Beidou. I may use 
the derived 1pps as input to my PRS10/10811D reference (or may continue 
using the 58503A). My budget is quite limited.


Thanks,

david

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