Re: [time-nuts] Z3801A OCXO manual trimming

[Tom Curlee]

What is the rail to rail EFC voltage on the Z3801A?  Is it different than the 
single oven 10811?  My 10811 manual says that the EFC is -5V to +5V, while the 
EFC voltage on my ailing Z3801 is ~-2.0V with LH reporting the DAC at 
99.996902%.
Haven't had time to dig any further - been moving/installing antennas including 
one of my GPS antennas.


  From: Mark Sims 
 To: "time-nuts@febo.com"  
 Sent: Monday, March 5, 2018 7:36 PM
 Subject: [time-nuts] Z3801A OCXO manual trimming
   
Or, it you are sure it's the OCXO,  go shopping for a new one.    There is a 
reputable seller with them (the double oven version) for $100 on Ebay.

A couple of things to try...  monitor the EFC voltage, power up the unit, and 
see if it is changing as it attempts to lock.  If  it does not, you may have a 
DAC problem... I don't think the Z3801 remembers the last DAC voltage to speed 
up the initial lock, so it should be searching for the lock voltage.

Also monitor the OCXO output and see how it changes as it warms up.  It should 
start out several Hz off and converge to 10 MHz as it warms up.  



> Either tear into the OCXO or go shopping for a new(er) GPSDO.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


   
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

[time-nuts] Z3801A OCXO manual trimming

[Tom Curlee]

Since the Z3801A is being discussed, I thought I'd ask about an issue I'm 
having with my unit.  I use my Z3801 as my working lab standard for the usual 
pieces of RF test equipment.  In the past year or so I've had the unit drop out 
of lock and go into standby mode.  Resetting/cycling power would bring it back 
into lock for a while, but it generally got worse and now stays in hold over 
mode.  LH (thanks Mark Sims!!) reports that everything is operating normally 
except that the it has a PLL unlock.  The one highly suspicious item is that 
the DAC is at 99.996902% - full output.
The unit shows it has over 94.5K hours run time, so I suspect that the OCXO has 
aged to the point that the EFC can't pull it into lock.  I disassembled the 
OCXO to see if it had a trimmer capacitor like the standard 10811 units.  After 
removing the outer case and foam insulation, I see that the outer heater is one 
of the thin printed circuit serpentine heaters on what I think is Kapton.  That 
would need to be peeled off of the case to either get to the hole for the 
trimmer (if there is one) or to remove the cover for the inner case.
What I don't understand is the purpose of what looks like another coil or 
heater wrapped around the Kapton printed circuit heater stuck to the inner 
case.  This second coil/heater is 2 layers of 1/8" thick red foam wrapped 
completely around the inner case, with fine copper wires wrapped over each 
layer.  At least I think there are wires on each layer.  This whole second 
heater is taped down and I don't want to dig any further until I know a bit 
more about what I'm doing or find that there isn't a trimmer on the double oven 
10811 oscillators.
Any ideas on the purpose of the outer heater (or whatever it is)?  Does the 
double oven 10811 have a manual trimmer that I can adjust to bring the 
oscillator back to the center of the EFC range?  Assuming that I can manually 
adjust the OCXO back into adjustment range, will there be any issues with the 
Z3801 performance, things like phase noise, short term stability, etc?
Any suggestions will be most appreciated.
Thanks,
Tom
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] HP 4815 Vector Impedance Analyzer repair

[Tom Curlee]

The first thing I would do is replace all the power supply electrolytic 
capacitors on the internal boards.  If I remember correctly, the boards are 
plugged in and the replacing the capacitors is quite easy.  In my unit, at 
least one capacitor was shorted and was pulling down a power supply.  

Tom  WB6UZZ


  From: Richard (Rick) Karlquist 
 To: Discussion of precise time and frequency measurement  
 Sent: Tuesday, June 20, 2017 12:02 PM
 Subject: [time-nuts] HP 4815 Vector Impedance Analyzer repair
  
I have a non-functional HP 4815, don't know if it
is the probe or the box.  A long time ago, there
was a fellow named George Standford (something like
that) who repaired these.  My old contact information
for him is no good.  Does anyone know if he is still
in business, or if there is any other place that
repairs these things?

Rick N6RK
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


   
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] TAPR TICC boxed (input protection)

[Tom Curlee]

You need to be careful how you paint the package black.  My first electronics 
job was in a place that made, among other things, mass spectrometers.  We made 
very high input impedance electrometers for the mass specs using TO-5 can 
mosfet transistors.  One batch was found to be very photo sensitive through the 
glass/ceramic lead interface.  Someone had the idea to spray paint the bottom 
of the package with black paint.  Not a good idea. The black paint, likely 
loaded with carbon, decreased the electrometer input impedance by many orders 
of magnitude.  Considering that our electrometers had an input impedance of 
1E-12 to 10E-15, even a fingerprint made a huge difference.  The carbon filled 
black paint was practically a short.
Maybe an overcoat with silicone or some other type of low leakage sealant, then 
the black paint?
Tom


  From: David 
 To: Discussion of precise time and frequency measurement  
 Sent: Saturday, April 8, 2017 10:00 AM
 Subject: Re: [time-nuts] TAPR TICC boxed (input protection)
   
On Fri, 7 Apr 2017 01:06:17 -0400, you wrote:

controlling the offset voltage.

We ended up painting the diodes black after soldering.

I have also heard of it happening with metal TO-18 packages through
the lead interface under the package.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


   
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] OT: Eagle PC CAD now Autodesk, $500/year

[Tom Curlee]

KiCad is an open source pcd cad package that looks interesting.  Has some 
microwave/RF features, 8 layers (I think),  both schematic capture and layout.  
Just started to look at it.  Doesn't have the libraries that Eagle does, but 
you can create your own.  Worth looking at.
Considering how Autodesk works (pay ), I'm surprised that their Fusion 360 
3D cad package is free for hobbyists.  I use Solidworks at work, but definitely 
not going to pay $6K for home use.  Just starting to learn Fusion 360, and, at 
least at my level, it seems to have all the functionality of Solidworks.  My 
only beef is that it's cloud based, but it will work off line for a few weeks 
before needing to call home.  My fear is that some time in the future Autodesk 
will either discontinue the program or start wanting $$.  Again, well worth 
looking at.
Tom, WB6UZZ


  From: Richard (Rick) Karlquist 
 To: Discussion of precise time and frequency measurement  
 Sent: Thursday, January 19, 2017 7:52 PM
 Subject: [time-nuts] OT: Eagle PC CAD now Autodesk, $500/year
   
Off topic, but probably a lot of disgrunted Eagle users on this list.
Its official, you will now have to pay $500 per year for a
professional license from Autodesk.  The spin meistering of the
announcement would make George Orwell proud.  I don't see any way they
can keep me from just using the license I currently own, at least
on the OS's it supports.  (Parenthetically, like many users, I
am also digging in my heels in terms of staying at Windows 7).

Still, the question arises:  are there any affordable alternatives?
Don't have to be entirely free.  I am looking for any trends out
there as to what tool will attract a critical mass of users in
the future.  There is strength in numbers.

Comments?

Rick N6RK
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


   
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Thunderbolt Harmonics

[Tom Curlee]

I'm not sure what the Thunderbolt specs state for harmonics, but -60 dB seems 
quite good to me.


  From: Rhys D 
 To: Discussion of precise time and frequency measurement  
 Sent: Tuesday, January 17, 2017 6:40 PM
 Subject: [time-nuts] Thunderbolt Harmonics
   
Hi all,

Before I start, let me say I'm rather a newbie at this sort of stuff so
please be gentle.

I was looking at the output of my Trimble Thunderbolt GPSDO and was rather
surprised to see really "loud" harmonics in there. ~ 60dB down from the
10Mhz signal.

Can anyone here shed some light on what I am seeing here?
Surely this isn't what it is supposed to look like? Should I be trying to
filter these before going to my distribution amplifier?

Thanks for any light you can shed.

R


​
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

   
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Using GPSDO as a Refrence for Protable Amateur Radio Microwave Operations

[Tom Curlee]

I used one of the Jupiter GPS receivers that has a 10 KHz output to control my 
10 GHz LO to discipline one of the common "brick" type of microwave 
oscillators.  These oscillators have an internal crystal oscillator (106.6 MHz  
for a 10.224 GHz LO) that is multiplied up to the needed microwave frequency.  
I divided the 106.5 MHz oscillator frequency down to 10 KHz that was then 
compared to the 10 KHz output from the Jupiter.  The control loop is very 
simple: a single op amp, a resistor, and a large capacitor.  The response time 
is extremely slow - 5 to 10 seconds or more.  All I wanted was to nudge the 
crystal oscillator onto frequency.  

>From a warm GPS start, the LO is within 1 to 2 HZ at 10.224 GHZ within 45 to 
>60 seconds from power on.
The hardest part was designing the divider circuit to get 10 KHz from the 106.6 
MHz oscillator.

Tom 

WB6UZZ


  From: Eric Haskell 
 To: Time Nuts  
 Sent: Wednesday, December 21, 2016 11:06 AM
 Subject: [time-nuts] Using GPSDO as a Refrence for Protable Amateur Radio 
Microwave Operations
   
Hello Time Nuts,  I have been on the group and have promoted it to other folks 
for a while but this may be my first post here.

I am microwave amateur radio operator and I have question to pose relating to 
the use of GPSDO's with amateur radio for microwave communication.

First, the more generic question.  A friend was discussing using a eBay 
purchased Trimble 57963-D for providing a 10 MHz refrence for his portable 
microwave station  (primarly at 10GHz).  He wants a clean high stability 10 MHz 
refrence mainly to lock the station LO. First I think a GPSDO is overkill for 
this application and I am thinking that a good surplus ovenized crystal 
oscillator should get him to within a few Hz after warm up and a Rb could do 
better but may have short term stability that may degrade phase noise of the 
LO.  I am concerned that a GPSDO is not designed for portable operations.  
Moving it should probably force a new site  survey which may take a day or more 
 to complete before it goes into disciplining mode so you would loose any 
potential benefit of a GPSDO by moving around frequently.  If he wants to do 
this I think he should leave it connected at his home location for an extended 
time (several days at least), then when he want to go portable (roving), h
 e should
  disconnect the GPS antenna entirely to force the unit into holdover mode 
maintain continuous power with battery backup which should maintain the 
internal OCXO very close to the target frequence and allow the holdover 
algorithm to compensate for OCXO for aging and best it can.  I would guess that 
if he chooses to used the GPSDO with the antenna connected it would probably 
never exit the site survey mode and you would have the output default to the 
last known good DAC value when it was been disciplined so it would be operating 
as a OCXO only (although potentially starting from a very accurate starting 
point, if it had been in use at a fixed location for a good while) before going 
portable.  Is this a correct view of the situation?  Any recommendations?

I also know of a fellow who has developed some excellent open source Linux 
software to drive an Ettus Research USRP microwave SDR transceiver for amateur 
radio microwave applications.  His code also has features to calculate antenna 
baring and with other available code compensates for satellite Doppler shift 
and/or synchronize digital communication modes using the GPS coordinates and 
timing data.  He has a built in interface for a Trimble Thunderbolt for this 
purpose.  I think it also might be a better solution to use a OCXO for 10 MHz 
and a cheap USB GPS sensor for location?  Is there a cheep USB GPS that 
provides PPS?  Any recommendations?

I have seen simpler GPS controlled 10 MHz sources like the Miller design that 
divides down a 10 MHz ref and compares it to a 10 KHz output from a Jupiter T 
GPS to tweak the ref freq that may or may not be better suited to this 
application as it may add phase noise to the LO but would be more real time in 
it's GPS correction to the reference frequency.

Regards,


Norman Eric Haskell

KC4YOE

Keller, TX USA
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


   
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

[time-nuts] Trimble UCCM survey results

[Tom Curlee]

A couple of questions:
I've just started using  LH 5.0 with my 2  GPSDO units (Thanks Mark!) - a 
Trimble UCCM and a Z3801A.  Oddly, I'm very getting different survey altitude 
values.  The Z3801A is around 81 M, which agrees within 1 or 2 meters with 
Google maps (not a perfect source, but close), but the UCCM is usually around 
48M to 53M depending on which survey I want to believe.  Both receivers are 
locked and both are fed off the same antenna through a splitter.  I admit that 
the antenna placement is very poor - anything below 60 degrees elevation to the 
north is blocked (LH is great for antenna placement analysis).  Anyone have any 
ideas?
A question on LH usage.  When the UCCM is in the position hold mode, what 
happens when a precision survey is run?  Looking at the .lla file shows that 
every position, including the final processed location,  is the same as that 
shown as the position hold location on the main LH screen.  Do you need to take 
the receiver out of the hold mode to run a precision survey?  How?  How is the 
position scatter plot used with a survey?  I usually don't see any positions 
plotted, certainly not when running a precision survey.  I think I saw data 
plotted when I did an internal survey.
Many thanks for any info.  And thanks again to Mark and John for all the work.
Tom


___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] FRK-L Rubidium

[Tom Curlee]

I'll add my own FRK-L failure story.  I have a FRK that suddenly stopped 
locking.  The 10 MHz was there, but off frequency so much that I couldn't 
adjust it to sweep over 10 MHz.  It suddenly occurred to me that the crystal 
oven housing should be hotter than just barely warm to the touch (it's usually 
too hot to touch).  I found that the Darlington transistor that is used as a 
oven heater was bad.  Replacing the transistor fixed the problem.

Tom

--- On Sat, 2/9/13, Dan Rae dan...@verizon.net wrote:

From: Dan Rae dan...@verizon.net
Subject: Re: [time-nuts] FRK-L Rubidium
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Date: Saturday, February 9, 2013, 10:31 AM

Since we're offering up faults for the FRK, I'll add one that I've found: 
there's a CMOS 4060 oscillator that should go off at 8.128 kHz, set by an 
adjust on test R.  If this drifts off enough the lock will never happen.  It 
provides the FM frequency for the synth.

Dan
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] HP 10811 Tuning Diode

[Tom Curlee]

I'll second the interesting part. 

I have a problem with a 10 GHz brick oscillator LO that I converted to GPS 
lock.  I don't remember the instantaneous frequency jumps (around 200 - 400 HZ 
at 10 GHz) before I did the GPS lock (although it's possible).  Please note 
that this is NOT any type of GPS phase shift.  I built a extremely slow 
frequency lock circuit that has a loop time in seconds.  The jump is 
instantaneous and I can then see the control voltage slowly change to correct 
the error.  When the frequency jumps back, the control voltage slowly follows.  
Since this brick has the usual 106.5 MHz crystal (multiplied by 96 to get 
10.224 GHz for the LO), I'm seeing at most 400 HZ / 96 shift in the crystal 
oscillator.

I've wondered if I have a noisy varactor diode.  The diode selected was one I 
had around, selected only because it had a low-ish capacitance value.  I 
haven't gotten around to digging into the problem any farther.

Anyone have any more info or ideas?

73,

Tom  WB6UZZ

--- On Thu, 10/18/12, John Miles jmi...@pop.net wrote:

From: John Miles jmi...@pop.net
Subject: Re: [time-nuts] HP 10811 Tuning Diode
To: 'Discussion of precise time and frequency measurement' 
time-nuts@febo.com
Date: Thursday, October 18, 2012, 8:54 PM

That's extremely interesting, Adrian.  I've never heard of a noisy varactor,
but then I've never looked for one, either.  It'd be great if some of the
problems that have been blamed on jumping crystals were in fact caused by
the tuning diode.  What steps did you take to rule out the crystal and
narrow down the problem to the diode?  

-- john, KE5FX
Miles Design LLC

 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-
 boun...@febo.com] On Behalf Of Adrian
 Sent: Thursday, October 18, 2012 12:19 PM
 To: Discussion of precise time and frequency measurement
 Subject: [time-nuts] HP 10811 Tuning Diode
 
 Hello,
 
 I found the 10811 in my 8662A to be quite noisy and was able to trace
 the problem down to the tuning diode.
 Actually, the phase noise started to jump when the oven heated up. As a
 quick solution, I replaced it with a SMD type that I had at hands.
 
 I would appreciate any hint where to find an original diode (even though
 I could leave it as is).
 
 As by the manual, the original is a '0122-0244 DIODE-VVC 100PF 5%
 C4/C25-MIN=2 BVR-30V Mfr. 28480'
 Mfr. 28480 is listed as HP, but the diode is marked 'M' for Motorola and
 '0244' and '312'.
 
 Adrian
 
 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-
 bin/mailman/listinfo/time-nuts
 and follow the instructions there.


___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Why the fuss - GPS Interference...

[Tom Curlee]

I've also had some odd dealings with Rich Bailey.  Some time in the mid 1990's 
I was a contractor at a USN cal lab.  We had sent out a Datum time code 
generator for repair, and when it came back, one of the functions didn't work.  
I called Datum and after describing the problem, the tech support guy 
remembered that there had been a software upgrade, one that, for some unknown 
reason, had removed the function we needed.  He promptly sent me a set of PROMs 
that had the previous software version and all was well.  

Skip ahead 6 or 8 years, and I was at a family function and got to talking to 
my cousins husband.  He vaguely mentioned that he worked for a company that 
'made very accurate clocks'.  For some reason, I blurted out do you work for 
Datum?  He was shocked that I knew who, and what, they were.  We got to 
comparing notes, and, yep, same Rich Bailey that sent me the PROMs.  I agree, 
he really is a nice guy.  Last I heard, he was the sales manager for FEI-Zyfer.

Tom WB6UZZ

--- On Fri, 9/28/12, Burt I. Weiner b...@att.net wrote:

From: Burt I. Weiner b...@att.net
Subject: [time-nuts] Why the fuss - GPS Interference...
To: time-nuts@febo.com
Date: Friday, September 28, 2012, 9:20 AM

Yes, Rob, It was Rich Bailey. A good guy! He worked for DATUM in 
Anaheim, CA and as I recall, he lived in Riverside. I noticed that he 
didn't wear a watch and when I jokingly commented about it, 
considering what he did for a living, he told me that he had been so 
aware of precise time for so many years that he got tired of knowing 
precisely what time it was. We had fun together that day.

Burt, K6OQK


From: Rob Kimberley robkimber...@btinternet.com
To: 'Discussion of precise time and frequency measurement'
         time-nuts@febo.com
Subject: Re: [time-nuts] Why the fuss - GPS Interference...


Hi Burt,

This sounds familiar! It wasn't a guy called Rich Bailey was it? That's what
he suggested I do, but I got onto Trimble and got one of their Bullet
antennae with the 3 pole filter (Bullet III?).

That worked for us.

Rob

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
b...@att.net
www.biwa.cc
K6OQK 


___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Oh dear

[Tom Curlee]

Instead of making fun of the web site, we all need to be more entrepreneurial 
so that we can fleece, errr, that is, offer a superior product to the 
audiophiles out there.  Think of the add copy:

You don't want to rely on a drifty, low accuracy, secondary rubidium standard 
for your audio recording and playback needs.  Upgrade to our new Chip Scale 
Cesium Frequency Standard and hear the improved (insert audio buzz words here) 
that this new cutting edge technology provides.

And, you won't need to darken the edges of your CDs with a black felt tipped 
pen any longer.


--- On Sun, 5/6/12, Jim Palfreyman jim77...@gmail.com wrote:

From: Jim Palfreyman jim77...@gmail.com
Subject: [time-nuts] Oh dear
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Date: Sunday, May 6, 2012, 7:39 PM

http://www.ebay.com.au/itm/Antelope-Audio-Isochrone-10M-Rubidium-Atomic-Clock-/270809581736?pt=LH_DefaultDomain_0hash=item3f0d8248a8

Make sure you read the description to discover what it's being sold for.

My chuckle for the day.

Jim Palfreyman
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Service manual or schematic for Option 21 DVM in HP5328?

[Tom Curlee]

Chris:

The theory of operation, along with the usual block diagrams, schematics, etc, 
for the OPT 021 for the 5328B is in the 5328B service manual.  It may be the 
same, or at least close enough to, the 5328A.  It's worth a try.  You can 
download the 5328B manual here:  
http://128.238.9.201/~kurt/manuals/manuals/HP%20Agilent/HP%205328B%20Operation%20and%20Service.pdf

73,

Tom  WB6UZZ

--- On Sat, 1/28/12, Chris Albertson albertson.ch...@gmail.com wrote:

From: Chris Albertson albertson.ch...@gmail.com
Subject: [time-nuts] Service manual or schematic for Option 21 DVM in HP5328?
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Date: Saturday, January 28, 2012, 7:38 PM

Has anyone seen a sevice manual or a schematic for the HP-5328A Option
21 DVM.  I have the 5328A service manual but it says the DVM Option 21
is covered in a separate manual.  Without a schematic debugging could
take a long time as the DVM is spread over three plug-in boards.


Thanks,

Chris Albertson
Redondo Beach, California

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Building a GPSDO trouble using Jupiter-T

[Tom Curlee]

Ray:

I used a similar circuit to lock my 10 GHz LO to GPS.  I used a similar Jupiter 
GPS board receiver (not the 'T' version).  My 10 GHz LO is one of the older 
Microwave Associates brick type of oscillators.  It has an internal 106.5 
crystal oscillator that is in a crude oven.  The 106.5 is multiplied by 96 to 
get the 10.224 GHz LO frequency.  It would hold frequency fairly reasonably in 
my lab, but outside in the summer it would drift as much as 30 kHz.  I 
installed a varactor diode on the quartz oscillator to control the frequency.  
I divided the 106.5 MHz down to 10 kHz and compared it with the 10 kHz out of 
the Jupiter in an exclusive OR gate.  I used a one op amp filter circuit that 
had a time constant of 5 to 10 seconds - not critical, but just needs to be 
slow.  If the GPS was 'warmed up' (it had been on in the last few hours), the 
10 GHz LO will  lock to within a few Hz of the 10.224 GHz in less than a minute 
after power on.  I have some
 other frequency stability issues that I need to fix, but the GPS lock portion 
of the circuit works great.  

Look on eBay for GPS antennas.  I use one of the small mag mount units.  You 
can get one for around $6.00, shipping included.  Also look on www.halted.com 
and search for GPS antenna.  They have some (that I use) for $3.95, but charge 
$5.00 handling  for under $20 - 1 is $8.95, 2 is $12.90, etc

Let me know if I can help in any way.

73,

Tom  WB6UZZ

--- On Sat, 1/28/12, Ray Xu rayxu...@gmail.com wrote:

From: Ray Xu rayxu...@gmail.com
Subject: [time-nuts] Building a GPSDO  trouble using Jupiter-T
To: time-nuts@febo.com
Date: Saturday, January 28, 2012, 10:50 PM

Hi guys

I'm planning to build a GPSDO to use as a frequency ref for my GHz ventures.

I've done research in what other people have built - but I have no
experience working with long-term precision/stability products (nor do I
have the equipment to do so -- I think).

I'm using the Jupiter T (the one with the 10-pin header) GPS and its 10KHz
output in an analog PLL that controls a 10MHz VCXO.  It would be ideal for
me that if I were to multiply the 10MHz output up to 10GHz, I would get
about a few Hertz or so of inaccuracy.  It would also be ideal if I can
have a PLL lock time of a few minutes while maintaining accuracy.

However, right now as I am trying to design my project, I can't find enough
information on the web regarding the VCXO's (or the PLL oscillator, in this
case) short term accuracy effect on output frequency.  I know that its
short term accuracy depends on the response time of the PLL, which also
depends on the amount of jitter from the Jupiter-T's 10KHz output...  I
know that the longer the time constant for the PLL, the better accuracy,
but I do not want to wait, literally, hours for it to lock...

Also, what is the advantage of using a OCXO instead of a VCXO in terms of
short-term accuracy?  If the PLL time constant is only a few seconds, then
a crystal shouldn't deviate in frequency by too much within a few seconds,
assuming I'm using a crystal bought from a well-known manufacturer...or
could it? I am inclined towards using oscillators that do not require any
significant warm up time...

For those who have experience using the Jupiter T GPS:
I have bought this
http://www.ebay.com/itm/Navman-jupiter-T-Tu60-GPS-Kit-1pps-10khz-GPS-Module-/260790984470but
I could not get it to communicate via serial.  So far, I do not have
an
antenna available and so the antenna port is just left disconnected.  When
I turn it on, there is a 1pps and 10KHz signal and the TX line is at logic
high.  However, I cannot get it to communicate to anything else, even a
dumb terminal.  It does not respond to when I send a message ID to it.
(Because of computer difficulties, I am using the PicKit 2's UART tool).
Is my device a dud or am I doing something wrong?

Many inputs is highly appreciated.  Thanks

-- 
__
73, Ray Xu
KF5LJO
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] synch for pendulum clock....

[Tom Curlee]

Check the Scientific American Amateur Scientist index for clocks here:  
http://amasci.com/amateur/sciamdx.html#52-CC  It looks like the September 1974 
issue has the article on using discrete cmos logic to synchronize a pendulum 
clock to a quartz crystal.

Tom  WB6UZZ

--- On Sun, 12/11/11, Brian, WA1ZMS wa1...@att.net wrote:

From: Brian, WA1ZMS wa1...@att.net
Subject: [time-nuts] synch for pendulum clock
To: Time Nuts time-nuts@febo.com
Date: Sunday, December 11, 2011, 1:32 PM

This was talked about several years ago, but did anyone get a fully functional 
design running using electromagnets to synch at one or both ends of the travel?

In the meantime I am using a sensor to measure the time period of the pendulum 
for this particular new grandmother wall clock and from that, I can synthesize 
a pulse train from one of the 10MHz lab clocks to drive the electromagnets to 
cause a subtle synch at the end(s) of the pendulum travel. The pulse train freq 
is custom for a given clock.

Anyway.. that's my scheme for now.
Feedback welcome.

-Brian, WA1ZMS
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.