Saw the plot in the June 12 post.
Pretty much limited by the 3816 up to 10K Seconds.
Would be interesting to see a long plot of the two 5065 against each
other!
Cheers,
Corby
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Joe,
"What is mounted on top of the 10811?"
That is a Clifton Labs Z1 buffer amp.
Still made but by another company.
Mounted on a small right angle bracket that is mounted using the existing
screws on the back of the 10811 adaptor assy.
It's input is connected to the 10Mhz out pins of the
Attila,
I will send you some raw data.
Attached is a combined plot of a recent successful filter installation.
Only 20 to 25% of units will be improved with the filter mod.
Two things to look for.
1- The short term stability at 1 Sec (Allan Deviation) should drop from
the 2X10-12th range down
Paul,
I agree with Bob, the small telecom ones to include the Efratom ones have
a lifetime that is just a guess at this point.
A brand new PRS10 with a warranty and the original owner repair discount
would be a good bet, they do however have lamp assy problems unless that
has been redesigned.
Th
Hi,
I'm cleaning out a BUNCH of modules from HP 5061A/B. See listing on eBay
below.
More lots of other modules to follow in groups that will fit into flat
rate boxes.
If you have specific wants contact me off list!
Cheers,
Corby
https://www.ebay.com/itm/HP5061A-5051B-A7-AC-amplifier-modules-
Here is an clip from one of the space qualified ones Bob mentioned.
"The RAFS employs classical rubidium gas cell atomic frequency standard
principles. It utilizes a physics package with a discrete isotopic filter
cell for best stability. The relatively large, cool absorption cell
provides excepti
I agree with Bert,
I always remove the battery.
They will cause grief eventually!
Use either in UPS or the separate DC input jack on the rear.
One note, if the battery is removed and the battery charge switch is in
the position to light the front panel lamp you will degrade the stability
of the
Well I hunted up the change pages for the A9.
The cap is polycarbonate, the original A9 was polyester.
If I can't find the polycarbonate I'll look into the PPS.
Cheers,
Corby
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Hi,
I'm working to make some replacement A9 boards for the HP 5065A to the
new style schematic.
Will share the Gerber file when done.
The integrator capacitor is a 1986 vintage TRW 5.0ufd 50V 10% .42"DX1.0"L
axial.
Of course it has an HP part number and no manufactures #.
Any guess as to what
First, full disclosure, I have no vested or financial interest in the
5065A he is selling.
Now the 2816A prefix is the last series built so the most modern.
The last one I remember on eBay went for OVER $4000.00
Comparing a 5065A to a Cesium (except maybe a working 5071A for the same
price)\is wo
Perrier,
The telecom Rubidiums don't leave much meat on the bone for improvements
as they sacrificed pretty much everything else to be cheap, small, and
low power consumption.
Most of these tradeoffs work directly against trying to get better short
term stability out of them.
Bummer.
Cheers,
C
Hi,
My current Tally of "Known" HP 5065A is 120 units!
Cheers,
Corby
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Attila,
The Child and oven windings were destroyed pulling the oven cylinders out
of the potting.
I suppose you could replicate them and try to repot but I'm never going
to try!
Cheers,
Corby
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Paul,
You do NOT want to take one apart to this level!
It's never going to operate again.
If you look at the lamp in the PIX you will see a white coil wrapped
around the bulb.
This is the tank for the 90Mhz drive and it sits cocked at a 45 degree
angle.
The lamp assy can be removed easily via
Found a cosmetically nice HP 107BR on eBay right now.
Hewlett Packard HP 107BR Quartz Oscillator Vintage
Cheers,
Corby
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Hi,
Anyone priced a Rakon HSO-14 option 8.
It's the Oscilloquartz 8607 option 8 replacement.
I'm almost afraid to ask!
Cheers,
Corby
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Luciano,
I don't know of a commercial version.
As you have seen as the two signals move away from close phase
coincidence the system noise level will increase.
This is because the common offset oscillator noise will only cancel when
the phases are closely matching.
This is mainly important for
The Efratom/Tektronix PTB-100 took the 10Mhz sine out of the FRK brick,
AC coupled it to the input of an 74LS14 biased with a votage divider from
+5 to ground.
4 parts!
Cheers,
Corby
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Luciano,
Not sure what you mean by "two measures made on the same DUT never
coincide".
The plotter program takes out wraps which since your phase gain is so
large are due to happen.
For lower Tau measurements just adjust the phase for close to equal and
run shorter plots.
These can be spliced
Hi,
Attached is a schematic of the changes made to the stock 10811 for use in
the HP 5071A.
Also while I recently had two of them opened I noticed wavy lockwashers
under the nut attaching the tuning capacitor. If you have ever had to
open one up to retighten this nut you would wish all of them ha
Hi,
Saw this on the EEVblog and wondered if it could be done for the 53132A??
https://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimete
r-i-did-it-)/
I'd just be happy with 7 segment hi efficiency LEDs and just a few of the
annunciators!!
Cheers,
Corby
Ulf,
The new A9 was only installed in units that had the 10811 installed so HP
was not concerned with it working with the 105 oscillator.
In the 10811 interface the EFC from A9 goes thru a 316K resistor to a
147K (nominal) resistor to ground. This forms a voltage divider the feed
the 10811 EFC pi
Hi,
I've worked at Vandenberg AFB since 1971 and have seen LOTS of launches
over those years.
I was tracking the Iridium 4 launch so could not go outside and watch.
However someone made a video that is just Awesome.
https://www.youtube.com/watch?v=UU5KpfOT-_Y
You see the rocket come over a loc
When working on the A4 assy. the ONLY adjustments you should make are:
- Cavity frequency, unscrew locking ring and while looking at the A7 J1
signal or 2nd harmonic reading adjust for max and then lock down.
- Attenuator, Unlock with allen, adjust for same, usually pulled all the
way out. Rememb
Here is the schematic of the new style A9.
Cheers,
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Ulf,
Forrest is correct.
I'd try the LT1793.
It's an SOIC but if you are making your own board that would not be a
problem.
It is $4.87 at DigiKey.
Cheers,
Corby
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Bob,
The cardboard is impregnated with the foam insulation goop and then
sealed under the foam layer.
It is totally sealed off from any environmental effects.
Cheers,
Corby
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Made some measurements on a 5065A optical unit.
-There are 3 layers in the magnetic shield.
-There is about 1/8" of insulation between the
outer and middle, and between the middle and inner shields.
-The C-field winding is wound on a cardboard form that
fits tightly into the inner shield.
-Ther
Ulf,
Be careful if you are going to duplicate the new style A9 for
use in a chassis that was built for the old style!
On the old style chassis one of the resistors is mounted
on the rear of the front panel loop switch. This resistor
is mounted on the A9 module for the new style chassis.
Which t
HP5065A C-field mods and optical unit mods
The contribution of the temperature coefficients of the fixed resistors
and the pot (which is a 21 turn bulk metal foil 10PPM/Deg C pot) show up
as frequency errors as shown for several combinations.
Note that the pot does not cover the entire 2X10-9 fr
Warren,
Most all Rubidium standards do not have active current drive.
The HP 5065A is the exception. However the mod I installed is not active.
The C-field coils are roughly temperature compensated as they are near
the cell oven that is regulated.
If you check out Poul-Hennings "hacking the 5065
Attached is the schematic of the C-field supply.
Cheers,
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HP5065A C-field mods and optical unit mods
In addition to the power supply mods:
-removed AC components
-power now supplied with an external DC lab grade low noise
highly regulated supply.
-temperature coefficient of +20 Volt supply adjusted to be
below 1PPM/deg C
See: https://www.febo.com/pip
Ulf,
You either should replace the -6010 old style A7 or if building one from
scratch build the late style.
The new style has a BP filter on the 2nd harmonic that makes the 2nd
harmonic reading a better indication.
On the old style as you adjust the CF (in open loop) you will see the 2nd
harmonic
HP5065A +20V supply and C-field circuit mods
I'm doing some more work on the 5065A and thought I'd share the results
of a
modification (one of several that will be done on this unit).
I measured the +20V P/S temperature coefficient and got -13.5ppm per
degree C.
This equates well with the 1N938
Well I did some research and found my new best friend!
If you remember I needed: "I have a square aluminum tube 5" X 5" with a
.25" wall it's 8 1/2" long.
I need 20 holes in each end tapped for 4/40 and 1/2" deep."
This for a Rubidium standard I am working on.
I found all about self forming ta
Donald,
Will look forward to seeing your Allan Deviation plots before and after.
That will be the only way to verify your modification will make any
improvement.
I suspect the improvement at a few seconds will degrade it at other Tau.
Cheers,
Corby
_
Donald,
HP changed from 12.631771.6 Mhz to 12.631772.5 Mhz in the later days.
The Zeeman frequency changed to correspond from 42.82Khz to 53.53Khz.
The 5071A uses a Zeeman frequency of 39.949Khz.
I believe they liked the stability a bit more at the different C-field
current.
Either way will pu
Thanks everyone.
Not looking for a redesign, just figuring out how to get the holes
drilled and tapped.
I have come up with a scheme that looks promising and will let you know
how it goes.
The enclosure only has to hold +.1PSI of dry nitrogen without leaking.
It will have a pressure sensor insi
Well that generated a lot of advice and thanks for it!
I think I might do it myself and go with a 1/2" hole depth and 1/4"
threaded depth.
I'll get some of that Aluminum Tap magic, some new taps and new drill
bits.
Good idea about drilling the end plates first and drilling thru to match.
Between th
Hi,
I have a square aluminum tube 5" X 5" with a .25" wall it's 8 1/2" long.
I need 20 holes in each end tapped for 4/40 and 1/2" deep.
This is for a Rubidium project.
The local machine shop want's $360.00
Anyone have a machining setup that could do the work a bit cheaper?
If not I'll giv
Attached is a plot showing the measured floor of the sine wave loop
in the 5061A/B and also in the 5065A, along with plot of an HP 5061B
with a high performance tube.
The tube is the limiting factor.
As you can see the margin provided by the current design is substantial.
Also if you look at t
A friend asked me a while ago why the FTS Cesium tubes were so light.
Since they were designed from the beginning to fit in a 5.25" high
chassis that cut quite a bit of the weight.
However a large amount of weight was saved by using a Ramsey cavity that
was not milled from a massive block of co
Attached is a PIX showing (CW from top left) the:
>ionizer filament
>Oven filaments (STD oven)
>standard oven assy
>high perm oven assy
The HiPerf oven filament is the sealed spiral wound tube on the face of
the oven.
The posts on the top edge of the ovens is the connection to burn a hole
in the
Donald,
I agree with John, remove the gearing gizmo from the 10811 assy. the
adjust hole lines up any way so no need to drill a hole. you just need a
long insulated tuning tool. Also agree that a quick indication of tube
operation can be seen if the beam current rises when the mod is turned
off.
Things to be careful about!
"I think the final vacuum improvement can be achieved more
quickly if the cesium oven is on."
The outgassing in a tube that has been off for an extended time
is almost all from the oven filaments and the ionizer filament.
The metal surfaces are virtual "sponges" and g
If you cannot get the ion current below 50ua or so after a week at 5kV
then you are out of luck.
Most likely you have resistive deposits on the ion pump insulator.
If you can get the tube to give a decent SN at those levels then you can
run with the alarm circuit bypassed.
I have run tubes a couple
Looks like Oscilloquartz is getting ready to sell this commercially!
Will give the 5071A a run for the money!
Reliability should go way up as:
-No electron multiplier
-No ionizer filament
-No state selection magnets
Also all the fiddley bits (laser diodes and photodetectors) are external
to the tu
Skip,
If you are setting against GPS then you are done.
For most applications either Zeeman frequency- synthesizer setting will
be fine.
What the Zeeman adjust lets you do is set the frequency (via the C-field)
to within the accuracy specs for the instrument without having to use
another referen
Very cool!
Thanks for sharing.
You could probably use any of the large vintage neon bulbs to replace the
missing lamp.
Cheers,
Corby
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Pete,
That is a VERY early unit.
Those early ones did not have the TED device.
I have only seen one unit with an earlier SN!
Ohm the lamp oven windings to the threaded post protruding from the end
of the optical unit. (should be open)
Also check across the oven winding (50 Ohm)
If the windin
Well I thought that would get your attention!
It's not quite as simple as that, however it CAN be done.
First you need a good "mini" tube scavenged out of a 5061A/B.
These smaller diameter tubes HP made for 5061A/B replacements
are essentially a 5071A tube with different connectors.
Then you need
Paul,
The Zeeman frequency you use depends on what synthesizer frequency your
unit is set for.
Either 48.82Khz or 53.53Khz.
See: https://www.febo.com/pipermail/time-nuts/2008-July/032378.html
The Zeeman coil is close to a short. You set the amplitude to the spot
that gives you the best look at
Scott,
The resistor should be 12 Ohms nominal, I'd try installing a 12 Ohm and
see what happens.
The lamp should light within 10 seconds or so of applying power.
If you have a spectrum analyzer you can place a loose wire close to the
lamp assy and see the approx 120Mhz signal if it's oscillatin
Scott,
If you pull the SMB lamp connector off of the chassis jack you can Ohm
out between the center pin and shield.
Try both polarities of the leads.
If the 1330 Ohm resistor is good you should read around 3330 Ohms.
This is the sum of the 1330 and a 2000 Ohm resistor.
The 12 Ohm (selected) r
Hi,
The tiny coil inside the beam path is the low frequency coil used for DC
testing of the tube.
The tube shown is a standard performance tube and has no degaussing coil.
The flat windings on top of the shield are the C-field winding.
The high performance cavity is even "prettier".
You can se
David,
I would let it set on the peg in Cs off mode for a fewdays.
It can take a long time for some tubes.
An external HV supply can also be tried if it does not come down in a few
days.
If it does come down turn the switch to operate to turn the filaments on.
The ion pump should peg again, th
I've been doing some work on testing some HP 5061A/B tubes
and came across something that's not making any sense!
The R11 and R12 values marked on the tubes for use with the
new style A11 are supposed to reflect a parallel value
that is 10X larger than the thermistor reading.
This to agree with th
Dick,
The AC connector used depends on if the unit is an option 010 or not!
Regular unit MS3106-14S-5S
Option 010 MS3126F14-12S
Service manual PN is 05062-90029
Cheers,
Corby
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"Copper has a quite high temperature expansion, so could you servo
that via the cavity temperature ?"
To answer, both Copper and Aluminum cavities use the temperature setting
to coarse tune the cavity.
Fine tuning is via Varactor diode and modern Masers do servo "Auto-tune"
the cavity to reduce d
Tim,
The EFOS2 uses an Aluminum cavity! So machining would be easier than
Copper!
The complete manuals with schematics are on Tom's Leapsecond.com site.
Making a homebrew Maser was bandied about a few years ago on TimeNuts.
Cheers,
Corby
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time-nu
Happy Birthday EFOS2 Maser!
The EFOS2 active hydrogen Maser at my place just turned 34 years old!
Pretty impressive reliability.
It is an Oscilloquartz Maser, they are now called T4 Science.
I know a guy in Norway that bought the refurbished EFOS3 Maser last
year directly from T4 Science! It is 3
Hi,
I have Seven HP5062C chassis collected over the years.
Not sure how many tubes are installed (I can check) or their condition.
I'm pretty sure most of the quartz oscillators are missing but I see two
sitting by the pile.
Might be a very few modules missing.
Most of the top and bottom covers ar
Back in June I picked up the mystery oven assy that turned out to be the
oscillator assy. of an HP 106A.
Since then I have repaired it and another 106B oscillator assy for a
friend.
My oscillators main problem was that one of the inner oven windings was
open.
Just for testing I installed an array
Thanks to a reply from Angus the 53131A is sending data every sample
now!!!
"Something to check - in the 'Utility' menu, if the HP-IB is set to
'Talk' rather than a numeric address, it does just what you describe
and only sends data every few seconds.
Angus.
Thanks
Corby
___
Scott,
Tried reversing connections and the count goes from 4ms to 900+ms which
is correct.
update goes from about 3 seconds to about 5 seconds with them switched.
So the connections were correct with the 4ms reading.
Found out that the RS232 is talk only so it would not need any commands
or fee
I've tried all the parameters and the update rate still drops to about
once every 3 seconds when I turn print on!
You still see the 1pps strobing the input channels every transition even
with print on.
I was using just pins 2, 3 and 5 on the rs232 and switched to a "full"
cable with no improvement.
I reconfigured for TI with +.7V level 50Ohm and I get a good count.
With a TI of around 43milliSec between two 1pps signals the display is
updating every second.
However if I turn print on the display update slows way down and no
longer displays consecutive counts!
I know I had this working once!!!
Hi,
I have not played with my 53131A RS232 for a couple years and have a
question.
I want to configure it to "talk" to Hyperterminal so I can log some
readings.
I did the 5 items to configure it:
HW pacing (disabled)
print on
baud rate (19200)
parity
SW pacing (none)
with a 5Mhz input I only get
The EFOS2 has a small (approx. 4" X 10") aluminium compressed gas bottle.
I fill it to about 450PSI and it lasts about 3 years.
Most modern Masers use Hydride supplies like the Hydrostik I'm working to
install.
They can last up to 10 years.
This all predicated that you have no leaks!
Cheers,
Corby
Well it's been an education!
First finding out how to identify if the Swagelok fitting is Metric by
sight and now how carefully the tubing has to be made to use compression
fittings!
I just went ahead and got the short section from McMaster Carr.
Want to make sure it's right if I'm at 400+ PSI with
Bob,
That's the cheapest I have been able to find it.
I'll probably go that route with the expensive version as it's specified
for compression.
I know the original setup mixes copper and stainless but I have read that
is not recommended???
Cheers,
Corby
___
This sound off topic but it's for a Hydrogen Maser modification!
The EFOS2 Maser is running low on Hydrogen and this time rather than
refill the compressed gas bottle I'd like to install a Hydrostik in its
place.
I have obtained all the fittings I need but have hit a snag!
I need a few short pieces
Skip,
The easiest way to determine the oven resistor values for an unmarked
tube is to directly measure the oven temperature and select a resistance
to set it at the temperature you want.
Your tube is a STD tube so I'd set it at 90 degrees C.
Take a thermocouple meter and thermocouple and cut the
Anton,
To answer both questions:
You can use a Laser in place of the Rubidium lamp, however assuming the
problem is the lamp it would be cheaper to buy several LPRO units to
scavenge for a replacement lamp.
How did you determine it's the lamp that is dead?
Using a Laser is more complicated t
I have worked on these and the electronics is almost always working, or
easily repaired.
The mechanical can cause problems depending on how much "time" it has on
the clock mechanics.
No XTAL in these as the drive is external.
The case is hermetic and has dessicant inside.
Cheers,
Corby Dawson
__
Ruslan,
Yes you can conserve tube life my operating in the Cs off mode (for 5061A
and B).
This mode still powers the ion pump and helps maintain the vacuum.
If the tube is exposed to high temperatures for a long period the Cesium
will slowly escape the oven assy. and reduce the life of the tube.
A
Christopher,
The only way is to open the oscillator up and reselect the capacitor they
used to set it on frequency.
I've done it once or twice long ago, not easy to do!
I have a 1200 with the same problem however it does tune to 1Hz low so I
use it as the offset oscillator for my DMTD unit!
Che
Perry,
The 3010A prefix identifies that date it was made.
It should also have a 10811A marking.
The resistor value is for applications needing precise EFC.
Usually found in HP 5065A, 5061A, and 5061B.
If it also has a 60109 marking it has slightly better short term
stability at one Tau.
Hi,
I've had this booklet for quite a few years and whenever someone posts
about the HP5071A I think of sharing it.
Finally got around to scanning it and Tom VanBaak was kind enough to host
it on his website.
It's at http://leapsecond.com/corby/5071comb.pdf
Enjoy!
Corby Dawson
___
Hi,
I posted an AD plot of a good FE405B back on Jun 7th.
A plot just completed today after an additional month of running is
essentially the same.
I did however measure the aging rate and it is currently 1.15X10-11th per
day!
Cheers,
Corby
___
time
Ole,
Spin exchange tuning for a classic (non-autotuned) Maser is performed to
put the cavity to the frequency that corresponds to the point that
eliminates the frequency shift caused by changes in the Hydrogen flux.
This enhances the short term stability at short time scales. This tunes
the cavity
Hi,
I need a couple resistance readings at the A11 oven controller jack.
Does anyone have one available that they could measure for me?
Cheers,
Corby
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Herbert,
If you find my original post and also look at the HP5065B info on
leapsecond. com you will find that the pre/post performance is closer to
that listed below.
I belive Luciano missread the plots!
Cheers,
Corby Dawson
Typical ADEV improvement
Seconds BeforeAfter
1 1.4x10-1
Attila,
All oscillators are not the same!
Although I find the yield to be better for the FE405B than say the 10811
some are duds like the top trace in Toms data, some are very good like
the bottom trace, and some are even better, my plot.
I've been very impressed by the 405B performance as I hav
The FE405B AD plot I recently posted used a simple (non 50% duty cycle)
divide by 3 using a 74ls74 and 74ls02 (if I remember correctly).
I used the HP board from the pair used in the 5065A or 5061A/B.
The existing 74ls74 was piggy backed with the 74ls02 and connections made
with tiny wire. The non
Well, This is probably not the original but I remember using one "in the
day"
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Attached here is a long term AD plot of an FE405B.
Stays in the 10-13ths all the way up to 10,000 seconds!
This unit has only been operating for about 2 weeks.
In a month I'll repeat this plot and also include the aging rate.
I have found that these oscillators exhibit less drift than most othe
Hi,
Saw this while trolling for goodies!
http://www.mullardmagic.co.uk/racal-ma259-frequency-standard-ra17-ra117-r
af-navy-goldfinger-james-bond-ra1218-ra1772-ra1792-ma50-ra181
RACAL MA259 FREQUENCY STANDARD FROM 1965
Looks neat
Cheers,
Corby
_
Thanks for all the info.
They are the 1/4-32 (S-93 compatible) Microdot !!!
I ordered a double ended cable and will cut it in half to give me the two
connections I need (5Mhz out and EFC in).
Cheers,
Corby
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Well the checkout of the 106A oscillator section is going well.
I ran it for 6 hours and the outer oven came down OK, will have to wait
until I can do a longer attended run for the inner oven as it takes 8 1/2
hours per the manual to come down!
This unit was not built with the fine adjust via an
Got an email from someone who has the main unit!
Found out that the assy. is from an O-451A/U.
Possibly coast guard.
It is supposedly a double ovened unit.
Does anyone have any info on it?
Cheers,
Corby
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Peter,
Thanks for the heads up!
I purchased both units and they arrived yesterday.
I was worried for a moment as the HP106 assy. also had an HP107 part
number on a label on the side.
I realized that it was too big in diameter to fit a 107 but wonder why HP
put that label on it???
Carefully dis
Angus,
The M100 barometric data data is attached, the FRK should be the same.
Not sure what the time constant would be however.
So those units at least should have repeatable performance as far as
Barometric pressure is concerned.
Not sure about any of the other smaller units.
Cheers,
Corby___
Angus,
The HP 5065A has a fairly open path from atmosphere to the cells as far a
barometric pressure is concerned.
Response is rapid to a change.
The mechanism is "oil-canning" of the windows on the ends of the cell.
Depends on diameter of the cell, thickness of the windows, and stiffness
of th
Nice data Wulf.
Once I finish reducing the temp effects I'll post a couple long term AD
plots with and without the Barometric pressure compensation and with and
without the temperature modifications.
Will be interesting to see what kind of difference I get.
Cheers,
Corby
__
Luciano.
Hi,
1) it is difficult to read the frequency value on the plot. Can you
specify?
The plot is averaged to get the signal out of the noise, The P-P
calibration offset on the left allows you to estimate the deviation of
the other parts of the plot. The short term stability of the 5065A at
HP 5065A Environmental sensitivity
First here is a comparison between the specified sensitivities of various
Rubidium units.
Barometric per mbar Temperature per degree C
HP 5065A6.3X10-14 1.6X10-12
M100 FRK 8.7x10-1
The oscillator used in the 5360A is the same one used in the early 105A,
the 5061A and the 5065A.
I just call them the 105 style oscillator. They have a 115 volt
thermoswitch controlled fast warmup heater that is set to switch out once
it gets close to the set point of the proportional controller o
I'm changing the topic from best rubidium frequency standard for this
post.
Most repairs I make to the 5065A run well below $250.00, sometimes as low
as $100.00.
A "crazy bad" repair might run $400.00 or so but out of over 50 repairs
only two needed that level of help.
As far a tempco goes, unle
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