[time-nuts] PN9000 software?

[AC0XU (Jim)]

I recently purchased an Aeroflex PN9000 system with the correct modules for 
doing phase noise measurements. However, I haven't been able to figure out how 
to get the software for this system. The only digital interface is GPIB. 

I believe that from the factory the system came with a Dell workstation with a 
GPIB card and an A2D card. I haven't seen any of these workstations or the 
software for sale. I have other GPIB and A2D cards, but no software.

If I can't get the software, then reverse-engineering the system seems possible 
theoretically but could be difficult, especially since there does not appear to 
be a service manual or any kind of GPIB ICD for the system.

Advice?  

Thanks- Jim

___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] About 10 MHz Optical Distro

[AC0XU (Jim)]

Thanks to all the posters. Especially to Dana -  That is exactly what I was 
looking for - suggestions for parts and/or circuits to do the job. I was 
originally thinking that I would go with a digital circuit (sine to square to 
sine), but maybe analog/sinewave would be simpler and perform about as well.

Anyway, I have ordered some of the recommended optical transceivers. We'll see 
how that works out.

One or two posters mentioned that phase noise and/or thermal stability may be 
issues. The referenced research papers don't seem to indicate that phase noise 
is a problem. I don't think that thermal effects will be a big problem for me - 
I just need to check the phase calibration from time to time. Certainly there 
are expensive commerical optical clock distribution systems with excellent 
properties. Maybe the devil is in the details... 

My specifical application at the moment is putting several SDRs at diverse 
antenna locs and feeding the IF via ethernet-converted-to-optical to my 
computer. I may want to transmit at some point but receiving is all I want to 
do for now. Still need a way to get a stable ref clock to each radio to provide 
phase coherence I only need 50-60 meters but an optical solution with 
single mode fibers can go many km if I ever wanted to scale up. Anyway, my plan 
is to have only power carried by copper.

I don't want to go with coax, twisted pair, or any other copper solution 
because of high ambient noise levels in my area and a desire to avoid adding to 
it. Stringing several 100 meters of copper about my yard, carrying 10 MHz clock 
signals, no matter if the cables are well shielded, doesn't seem like a great 
idea.

Overkill?  Probably.

BTW, I would NEVER try to do something like this with copper Ethernet. Even 
shielded Ethernet cables (Cat-7 and Cat-8) radiate badly when used for 1-G and 
10-G Ethernet.

Thanks again to all!

Jim
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Query about List and about 10 MHz Distro

[AC0XU (Jim)]

I am hoping that you can help me about a couple of things:

1) My time-nuts summaries sometimes appear unformatted and unreadable. All the 
text from all the postings is crammed together without spacing. How can I fix 
it?

2) I want to distribute 10 MHz references by fiber. There are RF-over-Fiber 
products available, but too expensive for me (thousands of $$$ per xmit/rcv 
set).  I am thinking that it should be possible to use fiber Ethernet 
components to do this. I don't mean IEEE 1588 but a much simpler, 
no-computer-required, solution. Possibly just converting sine wave (coax) to 
square wave (fiber) to sine wave (coax). I am looking for a low cost solution. 
Any thoughts or recommendations??

Thanks!

Jim
___
time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an 
email to time-nuts-le...@lists.febo.com
To unsubscribe, go to and follow the instructions there.

[time-nuts] Query about insulated coax panel connectors?

[AC0XU (Jim)]

Time-nuts:

Having recently run into major ground loop noise issues, I have begun reworking 
some of my homemade pieces of equipment using insulated coax connectors. My 
goal is to have one ground connection only in the cases, and that is at the 
power entry point, either a power cord or the outer terminal of a DIN. I am 
also installing isolation baluns on inputs and/or outputs.

Insulated BNCs are readily available. Others not so. In some cases, there is 
not room to install an insulated BNC. I am not finding any insulated SMA, SMC,  
SSMA, or SSMC despite googling and searching catalogs.

Does anyone know of a source for insulated small threaded coax panel connectors?

Another option would be a compact insulating bushing that an SMA panel 
connector, for example, could be mounted in. I am not finding anything like 
that either...  In fact the ideal solution would be an insulated SMA with an 
integrated 1:1 balun.

And I am not thinking about using plastic cases - that would introduce a whole 
other set of problems. I think about my lab area at work where a bundle of 
dozens of gigabit ethernet cables run through the roof directly over the lab 
bench - the ambient noise level is quite high.

Suggestions???

The only idea I have some up with is to design something myself, possibly 3-D 
printed...  Any suggestions about how to get started on something like that?

Thanks in advance-
Jim



___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] 5065A phase noise

[AC0XU (Jim)]

Timenuts-

I was able to borrow a Holzworth HA7062C phase noise analyzer recently and used 
it to measure phase noise for several oscillators.

I have a few questions:

1) I noticed that ground loops can be a significant problem - generating noise 
peaks at multiples of 60Hz and/or multiples of 120Hz. If this were merely 
additive noise, then no noise peaks near the 5MHz or 10MHz carrier should 
result in the analyzer, so non-linearities must be involved. Where are those 
non-linearities arising and how can they be eliminated?

2) Using several 50 ohm baluns and disconneting power supplies from ground 
eliminated some of the 60Hz-related noise in my tests but not all. The attached 
is a phase noise plot of a 5065A, run into a Wenzel low-phase-noise doubler run 
off a battery, run through a balun into the analyzer. Some 60Hz-related peaks 
are still evident - should I assume they are produced internally by the 5065A?  
In this case I could imagine that some additive 60Hz noise on the output of the 
5065A gets nonlinearly transformed by the doubler. Unfortunately, the HA7062C 
lower frequency limit is 8MHz, so I had to use the doubler (or something 
similar).

3) See the 105B plot, which is drawn directly from the 10MHz OCXO (I modified 
the 105B, adding a TAPR buffer of the 10MHz OCXO to feed an external 
port),which has bad 60xN Hz peaks despite my using a balun to eliminate ground 
loops on the output.  So no doubler in this case - where are these 60Hz-related 
peaks coming from?

4) Both 5065A and 105B oscillators show peaks at 10KHz (multiples), 100KHz, 
1MHz, etc. Is this nonlinear feedback from the dividers in the OCXO devices?  I 
could remove the dividers to see if that has an effect...

Another question - I can't afford to buy the Holzworth analyzer for my personal 
use, but I would like to continue my phase noise experiments. Any advice on 
acquiring or building an adequately sensitive instrument that doesn't break the 
bank?

BTW, I recently visited the Holzworth factory. Their designs and manufacturing 
processes are impressive.

Thanks in advance-

Jim___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Query about 4060

[AC0XU (Jim)]

Time-nuts-

It has been a couple of years since I last worked on a 4060 so I have forgotten 
some of the details. Can someone remind me?

Operating the device in manual mode, I can adjust beam gain so that I get a 
reading. However, ramping the control voltage over its range (which does sweep 
the output below and above 10 MHz), the gain needle hardly moves on the front 
panel. Measuring  with a DVM on test point E26, it does seem that the voltage 
increases a bit as I tune through 10 MHz, but the voltage seems a bit unstable, 
and the unit won't lock up automatically.

I am going to check the power supply for open capacitors next.

Is there anything else I should be checking towards diagnosing the problem?

Thanks in advance-

Jim
 




___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Issues with Datum FTS 4065A cesium beam reference

[AC0XU (Jim)]

Time Nuts-

Having fixed the dead power supply on this Datum FTS 4065A, the control panel 
displays mostly "Major" fault, although this occasionally shifts to "Minor" 
fault for a brief time. It reports Cesium Module faults that vary from time to 
time. They are usually one of:

2,18
2,3,18
2,3,7,18

According to the 4065C manual, the codes mean:

2 - Voltage difference (symmetry check of clock transition) > 40 mV
or
Voltage difference (clock pedestal) >40 mV

3 - Voltage difference (Zeeman pedestal) >160 mV

7 -  DAC voltage < 5% or > 95% of input range

18 - Beam Gain DAC Near Limit

Is there a straightfoward way to determine whether the tube is dead or - how 
should I drill down??

All voltages displayed by the control panel seem to be within range. Oscillator 
shifts from 'COLD' to 'warm'. There is a 10 MHZX output signal but it is not 
especially stable.

Thanks in advance-

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] FTS 4065A schematics?

[AC0XU (Jim)]

Time Nuts-

Another project - have an FTS 4065A cesium beam reference with what appears to 
be a short in the -34V supply line. I have the 4065C Operators Guide, which has 
partial schematics. However, the C version apparently has only a +34V main 
supply, whereas the A version has both + and -34V.

Does anyone have manuals or schematics for the FTS 4065A?

Thanks!

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] time-nuts Digest, Vol 192, Issue 10

[AC0XU (Jim)]

Very helpful - thanks to Tom & Tom.

This unit does not have VR modules - the power controller is one circuit board 
about 6" long, and it has been badly burnt.

Schematic solves identity of CAPSUL 0616 black box - this is the backlight 
driver for the LCD backlight HV supply. Although there are 5 connections to the 
front display board wheras the schematic suggests only 4.

The "Start A+ Source" seems to +10V <200mA . "Run A+ Source" is also 
unregulated and no voltage specified, although since 1N914s are used, the 
current can't be much. I see "Start A+ Source", "Run A+ Source", and A+ sink 
labels, but no  indication as to what goes in between. Maybe the only purpose 
is powering U1.

OSC B+/RTN - isolated unregulated. Is this 24V?  That seems unexpected because 
C27 is only rated at 25V.

There seems to be +5V unreg major current. I'll have to figure out the current.

Linear VRs are listed as 78XX and 79XX and 7905 (U6-8) - they are not populated 
in this unit.

Someone already replaced CR15 in this unit with a much larger diode but it 
looks like CR14 was on fire at some point, as were R9, U1 and C1. They took out 
neighboring components when they went. Also, CR2 is definitely not a 1N4002 so 
that got replaced at some point with a larger part. Black soot on the topside, 
multiple carbonized components, and vaporized traces on the bottom suggest to 
me it is not worth the time to repair this thing.

Remaining questions-

1) OSC voltage? Did Austron really use 25V caps for a 24V line?  The oscillator 
is clearly labeled 15V but it has a separate LM350T VR. I would guess that 18V 
would be fine for it but I will check that with bench PS. Maybe the design 
voltage is 20V?

2) Can I modify the display board to use a standard DC backlight display power 
supply?

3) What is the purpose of the Start A+ Source and Run A+ Source?   Do they have 
any use outside the power controller board?  

As a general design strategy, I don't get the purpose of the multiple 
over/under-voltage circuits, crowbars, and alarms. None of that stuff prevented 
this thing from going up in smoke.










At 10:00 AM 7/6/2020, time-nuts-requ...@lists.febo.com wrote:
>Send time-nuts mailing list submissions to
>time-nuts@lists.febo.com
>
>To subscribe or unsubscribe via the World Wide Web, visit
>http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>or, via email, send a message with subject or body 'help' to
>time-nuts-requ...@lists.febo.com
>
>You can reach the person managing the list at
>time-nuts-ow...@lists.febo.com
>
>When replying, please edit your Subject line so it is more specific
>than "Re: Contents of time-nuts digest..."
>
>
>Today's Topics:
>
>   1. Re: Raspberry Pi NTP server (Steve Platt)
>   2. Re: Raspberry Pi NTP server (Tim Shoppa)
>   3. HP-5372A and  HP-5372A operation with no CRT display.
>  (Lester Veenstra)
>   4. ESE ES-188 Master Clock : Repair (Gregory Beat)
>   5. Re: HP-5372A and HP-5372A operation with no CRT display.
>  (Magnus Danielson)
>   6. 5071A (Bill Notfaded)
>   7. Re: 5071A (Bob kb8tq)
>   8. Re: 5071A (Tom Van Baak)
>   9. Austron 2110 schematics? (AC0XU (Jim))
>  10. Re: Austron 2110 schematics? (Tom Van Baak)
>  11. Re: Austron 2110 schematics? (Tom Knox)
>  12. Success replacing Oncore VP with Synergy SR-6Tf ? (Steve Jones)
>  13. Re: HP-5372A and HP-5372A operation with no CRT display.
>  (Lester Veenstra)
>  14. Re: HP-5372A and HP-5372A operation with no CRT display.
>  (Gary Woods)
>
>
>--
>
>Message: 1
>Date: Sun, 5 Jul 2020 15:53:00 +0100
>From: Steve Platt 
>To: time-nuts@lists.febo.com
>Subject: Re: [time-nuts] Raspberry Pi NTP server
>Message-ID: <70893931-f340-fee9-d518-924579c96...@ntlworld.com>
>Content-Type: text/plain; charset=utf-8; format=flowed
>
>On 03/07/2020 13:56, Andrew Hancock wrote:
>> But here's the weird thing, it starts out okay, from what I can tell, and I 
>> get 377 for both GPSD and PPS
>>
>>   remote   refid  st t when poll reach   delay   offset  
>> jitter
>> ==
>> *127.127.28.0.GPSD.   1 l   21   32   370.000   98.447  
>> 89.508
>> o127.127.22.0.PPS.0 l   20   32   170.000  -63.468  
>> 27.800
>
>That's NOT ok, IMHO :-)
>
>I think the offset and jitter for the PPS server are far too high. 
>Here's what my Raspberry Pi2 looks like:
>
>> $ ntpq -p
>>  remote?? refid? st t when poll reach?? delay offset? 
>> jitter
>> 

[time-nuts] Austron 2110 schematics?

[AC0XU (Jim)]

Time Nuts-

I have an Austron 2110 with a severely toasted power controller board. Probably 
not repairable. I plan to build a substitute with a more modern design.

Does anyway have schematics?  I noticed correspondence between Magnus Danielson 
and Harald Hauglin some years ago. Did the manula or schematics ever get posted?

Thanks in advance-
Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] GPSDOs with 10.23 MHz output?

[AC0XU (Jim)]

Time-nuts-

I recall seeing a few models of GPSDOs that have 10.23 MHz output. Now when I 
want one I am not having any luck. Any recommendations?

Thanks-
Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] GPSDO that isn't GPS locked for large time scales?

[AC0XU (Jim)]

Time Nuts-

I recently purchased (Ebay) a GPSDO from an overseas manufacturer. This is a 
new item and the Ebay description seemed quite encouraging. Having had one in 
the lab for several weeks what I observe is that:

1) ADEV for short to medium durations (Tau <1,000 sec) is comparable to or 
better than other GPSDOs in my lab. Not as good as the best undisciplined 
oscillators in my collection, as expected, but no problem here.

2) ADEV for longer durations (Tau>10,000 sec) is considerably worse than other 
GPSDOs and Cesiums in my lab. I measure  well over 1E-11 at tau=100,000 sec for 
the new unit. This is my problem with it. As far as I can see, it  behaves like 
it is not actually locked to GPS.

I queried the vendor about the apparent lack of synchronization with GPS and 
this was his response.

"I understand everything. When constructing this device, I was guided by the 
need to get a good 100 MHz and 10 MHz signal, which will be maintained with an 
accuracy better than 0.1 ppb throughout its life. I used the GPS signal to 
correct the frequency of the main OCXO as the elements ages. I tried to ensure 
that the frequent loss of GPS signal and its quality did not affect the 
parameters of OCXO itself. For this reason, the adaptive algorithm is very 
delicate in the final phase.
The frequency correction program causes it to stop regulating OCXO in some 
cases.
This happens when:

1. OCXO will achieve accuracy of 0.01 ppb.
2. No GPS signal.

The control system is temporarily frozen when the frequency accuracy of 0.01 
ppb is reached. Therefore, ADEV for T> 1000 seconds resembles the typical 
behavior of OCXO during free operation. These parameters do not change when the 
GPS signal appears suddenly after a long absence. When constructing the device, 
it was assumed that all stability will be dominated by OCXO, and a value better 
than 0.01 ppb is not needed in telecommunications applications. I would add 
that the value of 1E-13 has never been a goal to achieve, especially due to the 
additional costs. Maybe if I gave up the 100 MHz section, I could do it for the 
price."

It surprised and dismayed me that large-tau behavior is so poor in a GPSDO. The 
several other GPSDOs in my lab all have ADEV around 1E-13 at 100,000 secs 
(based on a mass assessment of the GPSDOs and cesium oscillators).  It makes me 
wonder what the point was in adding the GPS receiver to this device. Is there 
something that I am not understanding?

Thanks in advance for your comments - Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Quartz oscillator slow drift/aging

[AC0XU (Jim)]

Time Gurus-

I have a FPS 1150A quartz oscillator with the 1 PPS disciplining option. With 
the frequency control set to "manual" I can use the digital thumbwheel control 
to set 10 MHz correctly. However, for two weeks there has been a steady drift 
upwards of about 2E-10 per day. I have not seen this behavior in other similar 
oscillators - the magnitude of the drift seems greater than expected. Any ideas 
what could be happening?  I have no idea how long the unit was unpowered before 
I got it - it needed repairs - it may have been years. Is this normal? Should I 
 expect the drift to decrease over time? Etc?

Thanks!

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Service manuial for FTS 1050A or 1150A

[AC0XU (Jim)]

Does anyone have a service manual for either FTS 1050A or 1150A (they are 
almost identical)? I have an 1150A with a bad power board

Thanks!

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] HV PS Board for FTS 4060?

[AC0XU (Jim)]

Does anyone have a spare HV PS board (just the small board with the xformer and 
the two diode ladders in silicone potting) for an FTS 4060?   My +3kv circuit 
seems to have died and the board is not easy to repair due to the potting.

BTW, I did find that the board is not as hard to remove as it looks. Here is my 
procedure:

1) Remove the hex socket screws that hold the cesium tube assembly onto the 
outer chassis.

2) Detach the ribbon connector from the main PS board.

3) Slide the chassis out a few inches on the bottom side of the unit. (You may 
have to disconnect the distribution buffer assembly on the top side first).

4) Unscrew the two high voltage connectors and the plastic connector with the 
two orange wires (BTW, if anyone knows how to detach that connector please let 
me know - I ended up unsoldering the wires from the PC board).

5) Slide the whole power supply board out of the cesium assembly.

6) Remove the two screws and detach the small HV sub-board from the main PS 
board.  Voila!

I would be happy to send PayPal for item and shipping to Colorado.

Thanks!

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Dead 5061B

[AC0XU (Jim)]

Time Nuts-

Thanks to John, Corby, Skip and anyone else I missed who offered help.

John got it in one. The hot wire ionizer is open, as measured at the D 
connector coming out of the tube. I understand that this is a terminal 
condition. Too bad for me.

BTW, I found this note on antiqueradios.com:


There is a procedure for broken filaments also. The success rate of welding a 
filament is very low in my experience but has extended the life of a few 
expensive tubes for me. You apply high voltage to the filament pins and tap the 
tube to try to make the broken ends touch. If all works well, the filament 
fuses on contact and continuity is restored. I use a charged capacitor as the 
voltage source since it will discharge immediately so it will not burn the 
filament out again. 
It's pretty much the same procedure I use to restore open audio transformers 
for my 20's battery sets. I have over a 50% success rate with my audio 
transformers so far. 


Has this ever been tried on a cesium tube?

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Dead 5061B

[AC0XU (Jim)]

Time Nuts-

This 5061B was working fine until a recent power failure, after which the unit 
would not come on line (alarm light stayed lit).

Major symptoms now: 

Beam I  ; Second Harmonic;  Ion Pump Supply are all 0 on front panel.  All 
other front panel readings are normal. (except for battery, which th unit doe 
snot have).

L4P2 signal is 16.832 MHz 1.7 V p-p  (perfect - suggesting that A1 synthesizer 
is fine)

Going through 5-173 A12 Cesium Beam Tube Operational Checks:

5-175 Low Frequency Coil Check. Everything is fine except that tweaking the 
external oscillator frequence/amplitude has no effect. Beam I is always 0.

The text says "If the beam current is not restored, it indicates a problem in 
the the cesium beam tube power supplies (A11, A15, A18, or A19) or in the 
cesium beam tube itself.

A11 = Cesium Oven Controller - front panel reading is fine. Removed A11 from 
the chassis and made the tests in  5-141.
 Everything fine. +- 16V and -10V all fine; Cs oven voltage fine; the 
thermistor tests out at 435 ohm vs. the 430 ohm on the label.

A15 = Power Regulator Board - main +18.65V is fine

A18 = +3.5KV supply - measured and is fine

A19 = -2.5KV supply - measured and is fine

I am inclined to conclude that the tube is dead. I don't understand why that 
occurred suddenly in conjunction with a line power failure.

Can I have any hope that the tube is still o.k.?  Any ideas?

Thanks!

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Sulzer 5A Repair Notes

[AC0XU (Jim)]

Thanks to everyone who had a suggestion re replacing the broken fine frequency 
adjustment capacitor.

AFAIK, there are no glass trimmer caps still made that are the same size. By 
buying a large number of used/NOS trimmers on Ebay, I eventually found one the 
right diameter and close enough on length to work fine:

JFD VCJ1018

A few seconds with a hot air desolderer and the threaded end literally fell 
off, leaving the glass tube open at both ends, as required.

After reassembly, and a quick adjustment of the coarse trimmer, the 5A seems to 
be working o.k. 

One thing I noticed is that when heated up, the adjustment shaft gets much 
tighter than when cold. It is so tight that feeling when it is at the end of 
its normal range is difficult. My guess is that some previous user adjusted it 
too far and broke the capactitor.

I would be tempted to use some graphite lubricant except that having graphite 
bits floating around in the works doesn't seemlike a good idea...

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Cold Rubidium?

[AC0XU (Jim)]

Does anyone have any experience/first hand knowledge of this Cold Rubidium 
standard?

https://spectradynamics.com/products/crb-clock/

The specs look very good. The mfr claims that, unlike traditional rubidium 
oscillators, it has no long-term drift.
Thanks!
Jim
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Fine freq control glass capacitor for Sulzer 2.5/5A?

[AC0XU (Jim)]

I am looking for a replacement for C3, the fine frequency control capacitor for 
a Sulzer 5A. In the model 2.5A, this seems to have a special Sulzer part number 
(2.5-MP4); the actual capacitor in a model 5A is a modification of the JFD 
VCJ14.  Unfortunately, this glass piston capacitor is slightly smaller in 
diameter (5.5mm) than currently manufactured caps (6.3mm), and I haven;t been 
able to find the VCJ14 anywhere. Any suggestions?

Also, although I have the instruction manual for the 2.5 (which includes 
schematics and parts lists) I haven't found the 5A manual. Any suggestions 
there?

Thanks- Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] ZCD Article

[AC0XU (Jim)]

TNs - Bob Martin asked me to post this article reference about designing ZCD 
systems.

https://app.box.com/s/b7d45z2cpq0x5ilz4jtn7a424btzjdhm

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Jan-Derk's DDMTD

[AC0XU (Jim)]

Jan-Derk-

Excellent and exciting work!  Thanks for sharing with the newsgroup...

I have a couple of questions:

1.  The input bandwidth of the digitizer chip is 750 MHz (very impressive), but 
what happens to input noise that is aliased?  When sampling at 10MHz (plus 
offset) everything above 5MHz is aliased. Doesn't this suggest that high 
performance bandpass filters on the input, for whatever frequencies are of 
interest, would be helpful when measuring time stability (but not phase noise)? 
 I suppose it as a question of noise/instability added by the filter vs. noise 
removed from the input by the filter, and I haven't seen a published analysis 
of this...

2. You mentioned that you are decimating the data to get the sample rate down. 
Doesn't this raise the noise floor above what it could be if all the samples 
were processed?

3. What algorithm are you using for the digital ZCD?

4. How hard would it be to put an Ethernet interface on the output? Would it be 
easier to attached the device to a Raspberry Pi or sim as a USB-to-Ethernet 
converter?  In my lab I find USB to be annoyingly problematic, and prefer 
Ethernet...

I have been experimenting with DDMTD setups using commercial 14- and 16-bit 
simultaneous-sampling digitizer boards, and processing the phase data at the 
full rates (from a few MHz to 250 MHz or so sample rate) by correlation method 
instead of ZCD.  The results have been o.k. but not quite as good as I was 
hoping for.  There is a complex relationship between the sample rate and 
performance which I haven't quite worked out. Also, the number-crunching takes 
a while on conventional PC.

Thanks-

Jim


Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Overseas buying?

[AC0XU (Jim)]

Anyone have suggestions about how to buy equipment from out of the country 
without getting US Customs delays?  I have the impression that precision timing 
devices are on some kind of US list of sensitive technologies, but Customs 
seems to also be concerned about importing such items.

I recently purchased an Oscilloquartz OCXO from a seller in France and FEDEX 
delayed delivering the item, requesting documentation about the item and about 
the purchaser (me) over and over again. I found FEDEX's communications to be 
atrocious - 7 different FEDEX people wanted me to email them information, and 
they kept asking me to email documents to paperw...@fedex.com, which bounced 
everything I sent it. For a few days, it looked like FEDEX was going to return 
the package, because they kept complaining that I wasn't responding to their 
requests for more information. Emails to them bounced. My phone calls to them 
went unanswered. Eventually FEDEX did release the package but it took over a 
week.

This was a frustrating experience and I am wondering what I should advise 
sellers in the future about how to document items so as to get through US 
Customs more smoothly. Any suggestions?

Thanks! 
Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Docs for FE-1125A?

[AC0XU (Jim)]

Does anyone know where to find docs for FE-1125A quartz standard?

Thanks!

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Query about NRL Canvas source?

[AC0XU (Jim)]

Does anyone know how to obtain the NRL Canvas (clock analsis) software?  The 
widely published link

https://goby.nrl.navy.mil/canvas/

appears to be broken. Thanks!


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Query about Guidetech products

[AC0XU (Jim)]

Time Nuts-

Does anyone have experience or recommendations re. Guidetech products, either 
their TIC or CTIA products, for time stability measurements?

Thanks!

Jim]


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] LN RB

[AC0XU (Jim)]

John-

The LNRB had been powered on continously for several weeks prior to my tests. 
Also, the same antenna/LNA is feeding multiple GPSDOs (4 others) with Lady 
Heather connected and running continuously, and none of them exhibited any kind 
of strange behavior at the times of the anomalies in the LN RB timing.

It certainly appears that Jackson Labs did not design the LN RB to be stable in 
the presence of external temperature fluctuations. To be useful, this seems to 
imply that it needs an external environmental temperature control. Furthermore, 
it doesn't seem to be stable near the top end of its supported temperature 
range even when the external temperature is constant, so the external 
temperature needs to be fairly low (probably under 40C or so). One application 
I was interested in is a low SWaP timing reference for smallsats. Its 
sensitivity to temperature seems to make that application unlikely, because 
adding external temperature control would make the electrical power 
prohibitive, even if size and weight can be kept under control. As a lab 
reference, I expect I can implement an external temperature control and it may 
work well enough. Overall, I am very disappointed with the product. I have 
written to Jackson Labs about my concerns but I have not heard back from them.

Jim


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Behavior of a disciplined rubidium oscillator?

[AC0XU (Jim)]

Time Nuts-

Here is a reference to the LN RB spec sheet:

http://jackson-labs.com/index.php/products/ln_rubidium

It doesn't seem to give a temperature coefficient. It does say the baseplate 
temp range is -20 to +70C.

Again, my issue is that a slight change in temperature leads to a huge, if 
short term, time shift. That seems to me like very strange behavior. I will 
contact JL to see if they have an explanation. It does suggest that the unit 
should be installed in a temperature-controlled enclosure.

Jim



LnRb5071A_1pps.pdf
Description: Adobe PDF document
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] Behavior of a disciplined rubidium oscillator?

[AC0XU (Jim)]

Time Nuts-

I have been observing the relative time stability of a Jackson Labs Ln Rb GPS 
disciplined oscillator and a 5071A cesium reference (undisciplined) , as 
measured via the 1 PPS outputs and a TIC. See the attached plot for about 8 
days of history. Horizontal axis is seconds and vertical axis is nanoseconds.

The Ln Rb has very good specs, qualfied by Jackson Labs with "no vibration", 
"no air current", etc. I have been surprised to find that the unit responds 
rather violently to external temperature changes.

(A) represents fluctuations of 100 ns or so when the room ceiling fan is turned 
on or off. Upper case temperature was about 40C.

(B) represents fluctuations of about 200 ms when I put an insulating blanket 
around the unit. Case temperature went up to about 65C and remained constant 
until point (F). After applying the blanket, it took several hours for the 
timing to stabilize.

(C) represents a steady period with the blanket on and a case temperature of 
65C.

(D) represents a fluctuation of  almost 1 us, with no cause that I am aware of. 
There was no significant change in lab temperature, no mechanical shock or 
vibration, this is a mystery.

(E) represents a period of fluctuation up and down of size almost 100 ns with a 
period of around 2 hours. Again, I have no idea why the oscillator started 
behaving this way.

(F) represents my removing the insulating blanket and placing the unit on a 
very large heat sink. Upper case temperature dropped to 35C.

(G) represents steady operation on the large heat sink with an upper case temp 
of 35C.

I am assuming that this behavior (aside form the steady downward slope, which I 
expect is the 5071A needing some steering) is due to the Ln Rb oscillator, and 
not the 5071A, which was not subject to any fluctuation I am aware of during 
the test. Does anyone have an idea what might have caused the behaviors at (D) 
and (E)?

The behaviors at (A) (B) and (F) are evidently due to external temperature 
changes. It seems less than ideal to me that the device would be engineered so 
as to cause a large jump in the timing for a couple of hours after modest 
external temperature changes. A slowly turning ceiling fan 10 feet away does 
not seem like a big environmental factor. Shouldn't the rubidium oscillator 
and/or GPS be filtering that out? It appears that I would have to add external 
temperature control (i.e. environmental chamber) to this device to maintain 
reasonable stability.

Any thoughts?  Thanks!

Jim



LnRb5071A_1pps.pdf
Description: Adobe PDF document
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] 53230A TIC and TimeLab

[AC0XU (Jim)]

THANK YOU!

Thanks very much to all who responded to my query. Apparently, I was a bit 
naive in my expectations for the device. Since it am especially interested in 
measuring short-term stability, I am going to try using it the method described 
in  (who??):

http://www.efos3.com/53230A/HPAK53230A-High-speed-TI.html

I understand that at some point I will be seeing the noise/stability floor of 
the instrument. According to

http://www.anderswallin.net/2015/04/keysight-53230a-noise-floor-test/

that noise floor may be around 2e-11 at 0.1 sec and 2e-12 at 1 sec.  That is 
just about what I am aiming for.

Jim


 


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] 53230A TIC and TimeLab

[AC0XU (Jim)]

I have recently acquited a 53230A counter and have tried to measure ADEV of a 
GPSDO with it. I am suspicious of the ADEV numbers reported by TimeLab V1.31 
because

1) Timelab disagrees significantly with the ADEV numbers reported by the 53230A 
itself.  In this case, with 1 sec sample intervals, the 53230A reports an ADEV 
of about 370 micro Hz (or 3.7e-11). Time lab reports  1.5e-11 @0.01 sec sample 
period, 2e-11 @0.1 sec sample period, 6e-11 @1sec sample period - all at 
tau=1sec.

2) When I use TimeLab to select different sample intervals, the whole ADEV 
curve shifts left (with smaller sample intervals) or right (with larger sample 
intervals).

Its as if TimeLab does not correctly account for the sample interval, but am I 
just not using the Timelab/counter setup correctly?

Thanks!


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.