Yes, something must supply the minimum magnetic field to activate the
oscillator - but the current determines the field, so it's
necessarily part of the drift characteristic. It also depends on
whether the YIG sphere is heated - usually to 80 deg C or so, to help
stabilize it.
Without any oth
That would certainly provide good distance capability and isolation,
but there may be a severe penalty in signal to noise ratio (and some
non-linearity) due to converting to optical and back. It may be
worthwhile considering the specs of the overall E-O link versus the
extra gain and SNR or NF
I agree - just tack a CMOS or LSTTL decade divider right inside the
equipment for now, then provide a fancy divider in your distribution
amp if you get around to it.
It's funny that entire extra instruments and programming
microcontrollers are being discussed to replace a simple fifty year
ol
I recently picked up an interesting early 1970s vintage WWVB
receiver, Model 630, made by "Specific Products" of Monrovia, CA -
that's what the adhesive sticker on the front says, and the name "1
MHz Time Base Calibrator (Utilizes WWVB accuracy of 2 parts in
10^11)." There's also a pair of bana
The wireless data links in those R/C sensor type things don't operate
near GPS carriers, but their harmonics can land there. The
transmitted power allowed should be too small to interfere with
anyone's receiver farther away - yours is probably pretty close. I
believe that the remote senders do
Whatever you do, don't apply power to the pins indicated as "VCXO
Supply." I'm pretty sure that is the internal regulated supply that's
accessible only to connect a pot so that you can remotely trim the
frequency - if it has the feature, including a varicap diode in the
oscillator. One end of t
If the Rb cell "drifted" enough (maybe if it was filled with water)
to de-tune the mechanical cavity resonator, it wouldn't work at all.
Only a small amount of the RF power in the cavity is coupled into the
Rb gas. The bandwidth of the Rb resonance is a fraction of a Hz (Q in
the millions), whi
Yes, very nice pictures. That thing is really built and looks like it
should be easy to work on and experiment with.
I still have to say that I doubt the cavity is off-tune unless
something serious happened to it mechanically. Is it even adjustable?
If so, maybe someone previously tried to adj
Ed,
I downloaded that service manual - an interesting read. So much stuff
was well-figured out even back then.
You should look closely at section 4.4.7.1. regarding the presence of
the 2f (310 Hz) signal.
Ed Breya
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cond harmonic signal should show up large
enough for the circuit to detect sufficient S/N ratio and provide a
valid lock indication.
Ed Breya
Ed Palmer wrote:
Could the drift be at least partially responsible for the lack of second
harmonic? A message on the list (
<http://www.febo.com/pipe
You may want to look at how that was done many years ago with
frequency difference multiplication as in the old Tracor meters - I
think the 528 was the main one. They synthesized a 9 MHz reference
from one input, and then subtracted it from the other to get a 1 MHz
result, which was used as a r
I have some SPTB-100 units, which are similar to M100 units, which
may be similar to yours. A few years ago, one failed to lock,
regardless of adjustment, and I found that one of the integrator
capacitors in the OCXO control loop was very leaky. I don't recall
which one, and couldn't even ident
Magnus, is that the same little transformer that I sent you a while
back? If so, did you add the PTC current limiter that I included?
That should have saved it from failure of the driver transistors. I
think there's a problem with that circuit, so I don't think you
should take a chance on any m
The PNP bipolar and P-channel MOSFET architectures do provide the
best low-dropout performance, but as I understand, do not provide the
best HF line rejection. Looking at the overall circuit - a high gain,
band-limited amplifier driving a "P" pass device puts it in a
common-base (or -gate) mode
Tightening up a connector may make a few pSec difference, in terms of
absolute delay length, but it could have a very large effect if it
caused enough reflection - then the entire time-length of the cable,
or some multiple of it, would come into play.
Ed
_
Thanks, Nigel, I think your history description is about right - I
vaguely recall seeing the Rockland brand too. I guess PTS is the
current survivor - the PTS D310 seems quite new, and the company
seems to be still in business in their niche.
Ignacio sent me a pinout page for the PTS 040/160/2
I don't remember which owns which, but some PTS models are under the
Wavetek brand. I have a Wavetek 5135A, which looks and acts just like
the PTS 160. I also have a PTS D310 that I plan to fix up with two
sets of wheel switches to be built into the front panel, but don't
recall if I already fo
That approximate frequency exists in Rb oscillators, but it is only
one of many harmonics, and very small in amplitude. The Rb system
doesn't (can't) count it - it sees only the difference between a
certain harmonic and the natural resonance, and a phase locked loop adjusts it.
Ed
__
Could it be that since they are much older (on average) than the
10811s, that (if they've been running) they would have much more
accumulated time, so in a more stable part of the long term drift curve?
Ed
Mark Sims wrote
Mon Jan 30 18:50:36 UTC 2012
I have had several HP-5370's with the 1054
I think the 10811 was the newer improved replacement for the 10544,
with the same connections and external signals, and a little better
performance. In that era of equipment you may see either one. They
should be interchangeable, and the manuals and specs for both are
readily available.
Ed
The lower bits can be pulse width modulated to get finer resolution,
but it gets harder to maintain monotonicity. Eventually you run out
of processing resolution, or the control signal falls into the noise
floor, whether the system is digital, analog, or both.
Ed
Javier Herrero wrote:
Sat Jan
Yes, those are handy amplifier modules - I always save any that I
find in surplus RF gear. You can easily replicate the functions with
modern gain blocks, or your own circuit using discrete parts, if you
don't need the "drop-in" hermetic package style.
The ones with about 10 dB gain are single
Yes, they are Schottkys, just like the ones used in most mixers - but
much bigger and slower. They would have to be properly impedance
matched, and could be driven to higher power levels, with higher
diode conductance, so (I think) much lower noise. Of course,
amplifying up to higher power will
That was a very interesting article. It would have been nice if they
tried other devices in their custom version mixer too, like bigger
diodes. I think the commercial mixers are optimized for wideband use
at typical power levels, but one specifically for low frequency like
5 or 10 MHz could be
Oops. That last message was supposed to be off-list. Sorry. Ed
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Hi Bill,
I may be interested in the Z3801s. Are you selling them locally only,
or can you ship them? I'm in California. How much would you want for them?
Ed Breya
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Thanks for all the help guys. I have enough info now to utilize any
of these PMTs. The "/SQ" and "/SN1" suffixes apparently are custom
connection versions of the basic parts. These have small circuit
boards soldered to leads that are welded to the tube pins, to adapt
for hookup with in-line squ
I just picked up a bunch of nice apparently "new" condition Photonis
brand PMTs, models XP3312/SQ, XP3212/SQ, XP5312/SN1, and XP5212/SN1.
I found their website but it appears they don't make PMTs anymore,
and have no info on their own former products.
Searching around for the XP3312 so far, I
Most gear probably won't care whether it's sinusoidal or "square" as
long as the amplitude is right, but if you try to send square waves,
then the question is how square do they need to be. Sharp edges may
convey better timing information, but may also cause ringing and
other effects. I think r
Yes - especially don't rub any cats on it or it may damage some electronics.
BTW for machining, any fine-toothed saw blade works well for straight
cuts. A metal hacksaw blade is usually stiff enough by itself to make
accurate, clean finish cuts on "quality" styrofoam. For drilling
round holes
That stuff at Home Depot is the way to go. You can use regular
styrofoam from coolers and cold shipping boxes, but there are a lot
of grades, ranging from crappy to great, and some are even
biodegradable - not good for this application. The construction types
are made to last, but also may have
Anyone contemplating building an analog loop for a GPSDO should
consider that it can be very tricky and expensive to attain great
performance. That's why the commercial ones are primarily digital -
it puts the most severe performance requirements in the least amount
of analog circuitry - the DA
I have a number of RF mixer modules mounted in junk microwave IF
converter blocks. They are labeled "MLP-102" in either KDI or EMCO
brands, circa mid-1980s date codes. I'm planning to use some for a
project, but can't find any info or anything even close on these
apparently obscure units. I hav
I just found the 5110B manual right at the Agilent website - I didn't
find it way back when I first got the thing. I guess I need to check
through there once in a while, since there's still a lot I need to
find that maybe shows up eventually.
Ed
While looking for something in my OCXO department I ran across this
old piece from the 1960s. I had saved it from an HP5110 synthesizer
carcass years ago, but only the crystal oven unit remained - no
oscillator or control circuits.
Just thought I'd ask here if anyone has info or a source of a
I have some M100s, which are similar, I think. A while back one of
them wouldn't lock, although the oscillator didn't stop. I found a
leaky high-K ceramic cap in the OCXO control loop. I don't have the
correct schematics, so was just shotgunning stuff. I would suspect
those parts and any tantal
My guess is that the drone was on one mission out of many over Iran,
and one of these scenarios occurred:
1. It had a major internal failure and auto-landed or crashed, and
was then spotted and grabbed.
2. There was operator error or guidance failure, causing same result.
3. The Iranians fin
Yes, you don't want to send un-buffered (or unprotected) signals -
especially right out of a filter - out for distribution. I have found
that some pieces of equipment will only take the external reference
over a certain small level range, so the distribution amplifier needs
to have an assortmen
I reported a filter design I was working on back in November, using
10 base T LAN filter modules. The first experimental air-wired unit
with two modules got to about -75 dBc at 30 MHz, rising to -65 dBc at 70 MHz.
After building the same circuit with shielded compartments, it ran
about -85 dBc
I looked at your first post again and noticed there were apparently
lots of TTL circuitry, so it could be an IRIG code receiver, and you
should be able talk to it. If you don't have a source readily
available, you may be able to fool it into responding a little to
gibberish applied from a modul
I doubt that you will ever find a manual or schematics, but you
should be able to decipher enough of the circuitry to figure out how
to fire it up and talk to it. The digits should be arranged in either
a counter or individually addressable. If it's a counter, you should
be able to find a 1 PPS
When looking at harmonic distortion of the 10 MHz, also consider the
distortion of the SA itself. I rebuilt my filter made from LAN
components that I described a while back, and achieved about 85 dB
rejection from 30 MHz to 70 MHz, which should have made harmonics of
even a crappy sine wave all
I would just combine these recommendations - see if the local XO can
be adjusted to lock. If so, problem solved. If not, then try to
return and replace the unit.
Ed
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How about a new thread with a more appropriate name to replace what
was: "Clocking a PIC16F628A from a Rubidium Standard?"
I don't think anyone will be interfacing anything associated with
their Rb standards directly to the AC line, except for unusual cases.
Regarding components: There are m
How did such a trivial circuit function for a one-unit application
trigger such a large philosophical discourse? I guess I'll put my
one-cent's worth in too. If you were designing to make a
mission-critical item, or millions of units, then every part and
every penny would count, so the finesse
Off topic: Actually, you can make almost anything withstand almost
any conditions TEMPORARILY - it depends on the packaging too. If you
wrap a circuit that can work at 100 deg C in a water jacket wrapped
in high temperature insulation, you can keep it going until most of
the water has boiled aw
I recently started setting up to design the distribution amplifier
system for my 10 MHz, so I've been rounding up the various parts I
had set aside over the years. I had planned to use various
transformers pulled from ethernet cards and routers, figuring they
would be good at 10 MHz, but I didn
The shunt regulator also serves to isolate load current fluctuations
from the main supply, since it makes it appear as a constant
resistance, current, or power load, depending on the design. This can
eliminate cross-talk between various circuitry.
For example, I just made one for my new 5065A
You can add a crystal filter using a common 10 MHz crystal in series
with a low noise, high impedance amplifier. Terminate the input side
with about 50 ohms, and set the Q of the filter with the load
impedance. Since you're only worried about harmonics, the Q can be
fairly low, making the exact
Look at 2N5744 and see if it looks like what you have. Sometimes it's
that simple. It could be a specific brand or package version of a
common device, especially if it's a power Q. Ed
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Fascinating stories. It looks like they covered all the bases, so if
correct, then it should have a big impact on physics. I can only
conclude one of the following:
1. There is some undiscovered measurement error or effect that
accounts for the discrepancy.
2. The data are correct and the neut
I am not familiar with the experiment, so I have to ask some dumb questions:
First, I wonder how the "beam" is generated at the source, and then
detected at the receiving end, and how the launch and arrival events
are determined with high certainty in the first place. I assume the
neutrinos co
If this "polyfuse" being discussed is what I know as a positive
tempco thermistor (PTC) current limiter, it could be either
detrimental or ideal for the application - it all depends on the
resistance vs. temperature characteristic. PTCs for protection are
commonly used as "resettable" fuses, bu
I may have that part in stock somewhere. Years ago I parted out the
un-needed guts of the 5065A I'm now using to transplant a Z3801A. I
likely would have saved the major parts from the boards, stripped en
masse on my solder machine. If you or anyone happens to have a good
picture of it, please
Just finished rebuilding the digital clock, and all is well. The
original clock IC was still good, so the display board stayed with
minimal rework - only new interface and power system needed. Made a
number of improvements:
1. Eliminated original power/interface board and clock setting buttons
Yes Bert, the "three-board" type uses the counting scheme that you
described, but the other type is as I described. On the "two-board"
version the "set" mode is permanent, and there is no external counter
or logic. The 555 is a normally a one-shot for stretching the narrow
1 PPS pulses from the
The original clock IC is probably OK - I needed to ID it to figure
out how to modify the circuit for new power and interface. I have a
couple of (probably OK) pulled MM5315s also, which could sub with a
slight pinout rearrangement if needed.
After looking at the manual, I realized that I did l
Thanks for the leads, guys. I did indeed find the .pdf manual at
www.to-way.com
and starting to study it.
Ed
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I am restarting an old project to transplant my HP Z3801A guts into a
5065A carcass, and now designing the power system. I'd like to keep
the original LED clock function, but with all new power and
interface. I traced out the circuit partially a few years ago, and am
going by the notes I made b
I don't think any "healing process" is necessary unless the capacitor
experiences voltage breakdown. This is unlikely in a low voltage circuit.
Longer integration times are available by changing the resistors
instead of the capacitors. Modern opamps are available that can run
rings around the
If you have a definite ground-loop problem, you can reduce the
sensitivity to direct triggering on it with the counter settings, but
that doesn't necessarily eliminate the interfering signal or its
possible effects - if it happens just at the right time on one of the
desired edges it will still
Actually, it is possible to legally buy and use small quantities of
CFC refrigerants, which are exempt from the regulations for
scientific or laboratory use - as evidenced by filling out a special
EPA form along with your order. R-11 is trichlorofluoromethane, the
closest sub for R-114, which s
One last thing regarding oil-filling. My previous comment was made
picturing oil inside the oscillator block only - not outside, or
between the outer parts - if there is a resistance wire heater (I
think it's heated with Qs only on the 10811) it is held together with
various tapes and adhesives
I think mineral oil would be just fine thermally and chemically - the
problem would be in keeping it where it belongs, leak-free. Some
things may need modification or adjustment, since the higher
dielectric constant would cause all inter-node capacitances to
increase, compared to air. The trim
Yes, running everything chilled would be better if low temperature
crystal turnovers were available. It is more complicated to chill
than heat, of course, even today, but way back when they started
temperature stabilizing things it was nearly impossible on a small
scale - or at least very impra
If your 100 MHz is already at HCMOS levels, then just use a 74AC
family decade divider or D-FF for the downconversion to 10 MHz - very
straightforward. A small series damping resistor may be needed if the
100 MHz signal has to be carried very far from its source.
Ed
_
For aircraft-related stuff you may send your official Navigation
Equipment Performance Variance Report form to your illustrious
president o'bama via the FAA Inter-Agency Regulatory Communications
Dept. All other non-military cases go to the FCC Office of Regulatory
Review. You must include proo
If the 100 MHz VCTCXO is fundamentally "better" than the 10 MHz VC?XO
in the Tbolt, then I would go with Chuck's idea to just use it with a
divide by 10 in front, as the main oscillator. You will still have a
good 10 MHz signal available from the divider - just buffer it up
and maybe harmonic
There are phase detectors available that can easily run at 50 MHz.
The output signal contains the information you want, but you have to
filter it and decode it according to the response time needed.
Ed
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You're right, Max, I didn't think about subsampling for this - that
would give a more efficient implementation - no LPF, say two 74HC390s
to divide by 10,000, a 74HC74 with one half as a divide by two to get
to 20,000, the other half as the sampler/downconverter, and a
74HC4046A PLL. So, four c
If you just want to get it to an integer value, I recommend, for
example, that you find or make a 6.000 MHz VCXO using a common 6
MHz crystal, and mix it with the 6.000300 MHz using a 74HC86 XOR,
then the 300 Hz IF can easily be low-pass filtered out and used as
the feedback to a PLL (like
That was a very interesting article. I'd vote for the neutrinos -
they must be good for something. Hey, what if neutrinos are actually
what makes radioactive decay possible, and the randomness of the
decays is just the randomness of arrival of the right kind of
neutrino or combinations of them
I agree that the extra converter is to provide isolation and input
voltage flexibility. Mine runs on 24V, and I assume that the first
converter is the only difference from the more common 48V units.
Also, each stage of conversion should provide additional power supply
rejection performance. It
I also hate wearing any kind of jewelry - watchbands and rings seem
to cut off circulation, even when sized right. A few years ago I
accidentally wrecked the nice Seiko that my wife gave me. Since then
I have used cheap no-brand watches attached to my 30 year old Speidel
Twistoflex band - the o
If you don't need the 26 and 19.2 to be exactly phase locked to the
10, and you can find crystals at those frequencies, I would suggest
that you go straight digital. There are a number of simple divide,
mix, multiply, and filter combinations that would make those
frequencies directly. The main
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