On 7/10/2022 10:14 AM, Lux, Jim via time-nuts wrote:
Yeah, but that virtual ground brings with it it's own set of problems.
For instance, it has to both sink and source current, so you can't just
use a 3 terminal regulator to create the midpoint, although I've seen
schemes with a resistor
Another great post from Bob (as usual). Bob's advice
is exactly correct. Unfortunately, the
HP 11848 phase noise test set (part of the HP 3048
PN measurement system) is poorly designed, and does
not break out the low gain non clipped signal.
I modified mine to bring out this signal and it
was MU
I think there is a severe misunderstanding of this issue.
First of all, "rapid warmup" is a red herring. The real
issue is "rapid frequency stabilization".
The time it takes for the oven to cut back (typically only
a minute or two) is a very minor part of the time budget
to get to frequency stab
On 6/9/2022 10:03 AM, Bruce Hunter via time-nuts wrote:
My only experience with SC-cut crystals is that time base oscillators in later
EIP/Phase-Matrix counters with SC-cut crystal oscillators seem to warm-up from
a cold start and stabilize more quickly than earlier AT-cut versions. I was
s
Yet another interesting time nuts conversation.
A few comments:
1 A number of comments stated as a "fact" that
higher unloaded Q for the resonator
corresponds to lower phase noise. This
idea evidentially comes from looking at analysis
of a so-called free running oscillator with a simple
LC ta
These types of devices have been around so long they can
be found in labs wearing the hp badge. Their uselessness
40 years ago compelled me to invent the workarounds in the copper
mountain ap note.
Rick N6RK
Keysight retiree, 2014.
On 5/26/2022 12:51 PM, Brooke Clarke via time-nuts wrote:
Hi
This was already SOP for any knowledgeable RF engineer by the
1940's. Somewhere I have a copy of Dishal's paper. I worked
for Zeta Labs in the 1970's and we sold lots of microwave filters
that were tuned this way. We didn't even have VNA's at Zeta.
We just used a directional detector (diode typ
On 5/26/2022 10:24 AM, Lux, Jim wrote:
https://www.mwrf.com/technologies/test-measurement/article/21849791/copper-mountain-technologies-make-accurate-impedance-measurements-using-a-vna
describes the various approaches
I don't know how long these methods have been in use, but I
indepen
I have had good results with the LCR Research tweezers.
Search "LCR Research" on Amazon. They work great on
anything you can pick up or probe with tweezers.
The general disclaimer on any kind of component measuring
device is:
Virtually all of them are ONLY suitable for measuring a
free-standing
When I was working on a cold atom Rb standard a few years ago,
I settled on the LT1028 with a 3.5 Hz (yes Hertz) noise corner and
noise floors of less than 1nV/sqrtHz and 1pA/sqrtHz. GBP>50 MHz.
Specified on the data sheet. In production now for ~40 years! I can
remember when it first came ou
I am seeing a lot of unsupported "theories" about what should be done to
make devices with low 1/f noise. It might be instructive for everyone
to read Marv Keshner's PhD dissertation (Stanford) discussing 1/f noise.
He looks at all kinds of theories and shows that there is no valid
cookbook
On 4/2/2022 6:16 PM, Hal Murray wrote:
rich...@karlquist.com said:
The tester they used for ADEV consisted of a special 10811 that was 500 Hz
off frequency driving a dual mixer box (Model 10514?) which produced a 500 Hz
beat note, which then drove an ADEV system (model 5490?). Only a few o
Yes, Jim Johnson (who worked for Len Cutler) worked on this hero
experiment. IMHO, it was a boondoggle from the get go. BTW,
this wasn't Jim's fault. I guess you could blame Len if you
needed to.
1. You might think that we had the capability to select 10811's
as they came off the line. Numbe
He should be looking at Wenzel Associates and NEL.
Wenzel specs -170 dBc at 100 Hz offset. Hope he has lots of money for
this one. Some of the NEL OCXO's are $5,000 and 6 months to 1 year
delivery. Both vendors also sell noisier cheaper versions.
He needs to trade off noise vs offset vs cost
No one mentioned tempco, so I will. Ideally you should do your
calibration at a temperature corresponding to the long term
average in your workshop. If the crystal is in a piece of
equipment with a temperate rise, it should be accounted for,
and then going forward you have to leave the equipment
Bob, you apparently know more about this than I do.
I was just repeating HP folklore.
Rick N6RK
On 3/27/2022 6:17 AM, Bob kb8tq wrote:
Hi
I was under the impression that the hammer blow gizmo was designed
to emulate the impact of a torpedo in a nearby compartment….. The
force it produces do
On 3/25/2022 12:41 PM, John Ackermann N8UR wrote:
PS -- an interesting feature of these oscillators is that they are an
"S12" variant that has a little accelerometer bolted on and hooked to
the EFC circuit to compensate for G forces. These were ship-board Cs
units, so I wonder if the acce
The clip on vacuum tube ammeter might be in contention.
Rick N6RK
On 1/16/2022 2:25 PM, Magnus Danielson via time-nuts wrote:
Hi,
No, not for HP. The HP200A through D products where separate products
for 8 years, then the 200A and 200B was merged to the 200AB and the 200C
and 200D merged int
On 12/26/2021 10:42 AM, Tom Van Baak wrote:
The correct link is:
https://febo.com/pipermail/time-nuts_lists.febo.com/2012-September/053009.html
/tvb
I think what I said here is self explanatory.
The loop amplifier or its resistors have noise that corrupts the AFC
loop. Or else the lo
AFC is not necessary just to make the oscillator play
for noise testing.
Rick N6RK
On 12/25/2021 9:38 PM, Bruce Griffiths wrote:
Was it related to the cause of the hump in the PN plot vs offset frequency that
the E1938A exhibits?
Bruce
On 26/12/2021 17:56 Richard (Rick) Karlquist wrote
I'm sure I said that ... a long time ago. I can't remember now what the
fix was, but I am fairly sure it would only apply to phase noise at
more than 1 kHz offset. If anyone can jog my memory about it I might
be able to remember the details.
Rick N6RK
On 12/25/2021 2:09 PM, Stewart Cobb wrote
When I designed the HP E1938A, I put a 2.5V reference IC inside the oven
and brought out both terminals of it. This was intended to provide a
reference voltage to the external DAC that generated the tuning voltage
for the loop that locked it loosely to GPS. It had its own return path
that
The news may be worse that you think.
I vaguely remember we had one of these
a long time ago at HP/Agilent. You pretty
much had to have the Dell workstation; the
software didn't run on just anything.
I know that the Agilent (now Keysight) PN system
came with its own computer and you got an
image o
I was working for HP in 1983 at the division that produced the 3561.
In those days everyone had "terminals" that were used to remotely
log in to shared computers. These terminals had a bunch of PC
cards with gold plated edge-card connectors. It was SOP that
one's terminal would stop working peri
I am looking for help choosing a potting compound that
has the following properties:
1. Good for 5,000VAC @ 1 MHz
2. Low RF losses.
3. Low permittivity is preferred
4. Low tempco of permittivity is a want.
5. Something I can implement in my home shop
without access to a vacuum pump etc. is a
Let me just mention that when I worked at the HP Santa Clara
Division counters section, they came out with a "feature"
that they called "continuous count". However, it was limited
to something like 3 MHz. So a 100 MHz counter would only
continuously count signals below 3 MHz.
So you need to ver
If still available, I'll take it.
I would be able to pick it up sometime this week.
Rick Karlquist
On 6/6/2021 4:52 PM, Bob L. wrote:
Hi folks,
I'm offering a late production HP 8405A RF Vector Voltmeter in fine
operating and cosmetic condition: $275 cash, pick-up only in Menlo Park, CA
On 4/1/2021 10:32 AM, Lux, Jim wrote:
And for what it's worth DROs have their microphonic problems too. We had
a breadboard deep space transponder and you could demodulate your voice
(poorly) using the spectrum analyzer's FM demod feature. Very cool.
Unimpressive to the folks who wanted to p
was the term) oscillator around 15 or 20 years ago.
It depended on some spool of fiber optic cable. I never thought
that was going to work, both because of basic principles and
because of the cable spool microphonics.
Rick N6RK
On 4/1/2021 9:06 AM, Chris Caudle wrote:
On 2021-03-31 14:27, Richa
On 3/31/2021 11:02 AM, Bob kb8tq wrote:
Hi
If you were going insane on a fountain, you likely would go with one of the
sapphire whispering gallery devices as the start of your chain. A good one
will blow a quartz crystal based part away ….
Bob
When I left Keysight in 2014, they were still
On 3/31/2021 11:57 AM, Lux, Jim wrote:
In some ways it's like high power laser labs. It's not the direct beam
you worry about - nobody is going to put their hand in the beam path.
It's the stray reflection when something gets bumped and falls across
the optical bench and reflects a stray
At HP, it was explained that a primary standard
could be built on a desert island containing no
frequency standards nor any GPS receivers, etc.
and it would be guaranteed by design to meet its
spec. It could have adjustments, either operated
by a technician or a computer controlled algorithm,
but
The ADEV of the 5071 follows the typical curve of
improving at a constant rate vs increasing Tau
until it levels out due to limiting by flicker. AFAIK,
this flicker noise never turns back up. There is
no observable aging either. Nor are there any
observable environmental effects.
The 5071's tr
On 12/11/2020 1:38 AM, Magnus Danielson wrote:
He keep insisting at referring to the ADEV as 2-sample deviation except
in introductory coarses.
Along that line, I recently learned that the "Van Allen
radiation belts" are called that everywhere except in
Iowa City, where they use the nomen
If I had thought about it, I would have assumed
David made fellow decades ago. He was already
a legend around the HP Precision Frequency section
when I started at HP 40 years ago. Maybe he was
just too modest and didn't do enough self
promotion. Anyway, I'm happy that the powers
that be finally
On 11/18/2020 5:27 PM, jimlux wrote:
The proposed mitigation technique relies on tracking the
rapid gain variations in the radiometer due to 1/f noise and
correcting them by generating a baseline state in the first
amplification stage of the low noise amplifier (LNA). The
proposed 1/f noise mi
I suspect that, whatever this is, only applies to 1/f mechanisms
specific to THz, based on the last sentence. One of my
former clients did a PhD at Stanford on 1/f noise and
his dissertation certainly had no magic bullets to
mitigate 1/f noise.
There is some frequency, which I am fairly sure is
On 10/30/2020 5:05 PM, Bob kb8tq wrote:
Hi
Gradients are a really big deal in an OCXO. Thermal mass works against
you if you are after quick warmup ….
Bob
I'll take this opportunity to plug my 1997 FCS paper:
"The Theory of Zero Gradient Ovens" explaining how
we got thermal gain over 1 mil
Diamond, graphite and graphene are all forms of the
element carbon. They all can have more conductivity
than silver.
Rick N6RK
On 10/30/2020 3:25 PM, Andy Talbot wrote:
Actually, diamond has five times better thermal conductivity than silver,
so is the most conductive element, although graphen
Yes, we want conductivity, and not heat capacity.
On 10/30/2020 3:06 PM, Luiz Alberto Saba wrote:
If my memory serves me, copper has the better conductivity of all the periodic
table...
Actually, carbon is at the top of the list.
Then silver, then copper.
Rick N6RK
Enviado do meu iPhone
On 10/23/2020 3:52 PM, paul swed wrote:
Corby
I have run into issues with the older coax essentially rotting internally.
It allows teh center conductor to tough the outer in the worst case. Is
FWIW, in those days HP had its own internal shop
that made wire and coax. This situation could
acc
I suspect that the stock 5065 chain has better
phase noise than this chip. I know for sure
that you can get much better phase noise than
this chip by using conventional architectures.
Of course they are more complicated, etc. Just
wanted to put this chip in perspective.
Rick N6RK
On 10/22/202
I would tend to agree with the assessment that the
SRD is not a high failure rate item. Also, it
could experience a faux failure where the fixturing
of it corroded such that it was not making good
electrical contact any more, but the underlying diode
was still good. Cleaning up the contact area
On 9/30/2020 12:47 PM, Magnus Danielson wrote:
This is all true, except for the last part, since you really need to
consider the duo of Jim Barnes and David Allan. If you look at the early
work, their work and contribution overlap. Some of the important math
was actually discovered by Jim Barn
On 9/29/2020 4:38 PM, Bob kb8tq wrote:
Hi
The gotcha with *any* SMT part is that stress / strain from the soldering
process gets into the
performance of the part for a *long* time. There is no mechanical “buffering”
in most parts. Whatever
the PCB does is what the guts of the part sees ….
G
The HP E1938A OCXO that I worked on had a feature where
we could set the oven temperature individually on each
oscillator to the exact turnover point of the crystal.
With all the temperature characterization we did, it
would seem like if there were a thermistor "aging"
process, we would have seen
Another great post, Tom.
Amplifying Tom's last paragraph:
1. The statistics of clocks are (take your pick)
a. Not gaussian, central limit theorem doesn't apply
b. Not stochastic
c. Not stationary
d. Not ergodic
e. Contain flicker of frequency processes that do not
average to zero; AKA 1/f
On 9/16/2020 5:59 PM, ed breya wrote:
Depending on the performance level, I'd tend to go with the crowd
recommending CATV distribution type stuff. If the trip is short, then
maybe you don't have to worry about 75 vs 50 ohms too much. If the trip
The RF2312 I mentioned IS a CATV type ampl
I also need ~200 MHz buffers for a client.
See:
State-of-the-Art RF Signal Generation
From Optical Frequency Division
Sept 2013 IEEE Trans UFFC, p 1796
In Table I (top of page 1798)
they list the RFMD RF2312 amplifier.
Table II top of page 1799 shows
that this is good for -150 dBc/Hz at 1 Hz
f
On 9/11/2020 10:04 PM, Lloyd Blythen wrote:
Thanks Bob.
About a month ago I looked at which free simulators were available. In case
it saves anyone doing the same ...
Micro-Cap was recommended consistently as having the best schematic-capture
and GUI. Trouble is, although it's now free, that
I was the project manager of the HP5334B, which is similar to
many other models regarding the input. IMHO, 1 megohm is ONLY
for scope probes. For everything else, use 50 ohms. Yes, an
advanced user (which doesn't sound like you) can play some
tricks with the 1 megohm input and a 50 ohm cable,
In the NIST paper available at the URL below:
http://pdfs.semanticscholar.org/47ac/742de238c0ece5e91ff7d12c515b9173eb60.pdf
At the beginning of page 2 (4th line) the paper
states:
"Note that the shield permeability is a nonlinear function of the
magnetization and increases to a maximum value
Decommissioning an old hard drive and found these> files. I don't
know if they are already in
circulation; I can't view the hpgl ones
See:
http://www.leapsecond.com/u/rk/
Rick N6RK
___
time-nuts mailing list -- time-nuts@lists.febo.com
To u
A DBM inherently does harmonic mixing...at no
extra charge :-). In this case, the third
harmonic of the LO mixes with the RF and
you get 15.0 MHz - 5.01 MHz = 9.99 MHz.
This signal be down 20 log N, where N=3, IOW,
-9.5dB. There is nothing you can do about this
as long as you use a DBM.
Are you filtering out the 10.01 MHz image?
Rick N6RK
On 7/23/2020 11:01 AM, cdel...@juno.com wrote:
Hi,
I'm feeding 5.0 MHZ and 5.01MHz into an HP10514A mixer.
A buffer and a 12dB attenuator feed each input and a 50 Ohm buffer amp
(10Mhz) is on the output.
I get a nice sine output bu
On 7/22/2020 7:35 AM, Rodger via time-nuts wrote:
Hey Ray,
Paul and I have a nice piece of code that generates the WWVB BPSK bit stream
using an Arduino and a ublox GPS module. (total cost under $30) You could
use this as a WWVB emulator while you're working on your code. Sorry, I
can't rea
On 7/21/2020 4:27 PM, Magnus Danielson wrote:
In capacitors, two things make them microphonic, voltage over the
capacitor and the high-dielectric constant as this makes it more
sensitive to mechanical stress, and this also tends to make them very
sentistive to thermal stress. So X7R is terri
On 7/18/2020 6:25 PM, Magnus Danielson wrote:
Hi,
A similar approach is used in the 10811 replacement oscillator setup for
the 5065, where a 7474 is used to divide 10 MHz to 5 MHz. Signal
conditioning consists of a DC-blocking cap and a pair of resistors to
bias the mid-point. The produced no
There's a lot of lore out there that, for instance, HP would put
oscillators with good long term stability in counters, but for things
like a spectrum analyzer or signal generator, you'd use an oscillator
with good close in phase noise, because absolute frequency accuracy
isn't as important
On 7/13/2020 11:34 AM, jimlux wrote:
There are also "frequency locked" devices that are not "phase locked" -
they essentially discipline an internal oscillator by adjusting its
frequency, but not with any sort of phase locked loop.
The 8640 famously worked (sort of) this way. The cavity
Good question; answer is not so simple. Here goes:
Signal generators and spectrum analyzers have to have a low phase
noise oscillator inside to be able to generate/detect spectrally
pure signals. Unlike counters, the 10811, etc has to be standard
equipment, not an option.
Therefore, in order t
On 7/13/2020 9:46 AM, Wes wrote:
Thanks again for your insight Rick. I'll be passing on acquiring one of
these.
Wes N7WS
I'm so glad you asked before buying.
I hate having to tell something they wasted their money.
Rick
___
time-nuts mailing l
On 7/13/2020 6:26 AM, Wes wrote:
Hi Magnus,
I did have the manual when I posed the original question but I had not
delved into the cal procedure until you mentioned it. It seems to be a
bit complicated for what it does. I wonder how stable this is and how
often might it need to be repeated
On 7/11/2020 3:51 PM, Wes wrote:
As I understand it this counter has an external reference input that
isn't used directly as the time base but injection locks the internal
time base. Does anyone here know how well this works. Is using a GPSDO
as a reference a worthwhile accuracy improvement?
The 74XX160/74XX162 is the decade divider that runs at maximum
clock rate for the chip. Meaning no external feedback is
necessary to make it work at divide by 5/10.
The 74XX161/74XX163 can only divide by powers of 2 at maximum
clock rate. You have to add feedback to divide by 5 and THAT
is what
The sum of propagation delay (~15 ns) and setup time (~5 ns)
in the 74AC161 gives just enough time to operate at 50 MHz,
based on the data sheet. Of course, at room temp, the chip
will beat the data sheet by an undetermined margin.
The fact that the clock frequency is specified at 103 MHz
applie
I designed a marine radio in 1976 that used 74LS161's.
They could do something like 15 MHz on a good day
at room temperature. I did a lot of characterization
on them. 100 MHz? In your dreams...
BTW, if you want to divide by ten in the LS family,
the 74LS160 is a better choice, because it will
On 6/30/2020 3:47 PM, dschuecker wrote:
Hi,
a divide by five should possible with a synchronous state-machine made
of 3 ( sufficiently fast-) JK-FlipFlops.
All 3 FFs are clocked with the input freq. , the outputs of the FFs are
fed back to the the JK-inputs, the divided freq. is output of
To divide by 5 with a '161/'163 counter, connect
the 8's bit output to the /preset enable input.
Then set the input bits to 12. The counter will
count: 12, 13, 14, 15, 0, 12, 13, 14, 15, 0 ...
This is the fastest configuration. It avoids
external gate delay and the slower carry output.
You can
See:
https://futurism.com/how-infamous-hydroelectric-dam-changed-earths-rotation
Of course, readers of this list know that the earth isn't stable to 60
ns/day in the first place. But this is an interesting calculation, at
least to time nuts.
Rick N6RK
On 6/27/2020 5:48 AM, Gerhard Hoffmann wrote:
Am 27.06.20 um 14:02 schrieb Michael Wouters:
What do other people do with their quartzes ? I thought I should ask
for some advice before attempting measurements.
A sand box? Literally? Some bags filled with sand really helped
with my turntab
On 6/18/2020 4:58 AM, Gilles Clement wrote:
Hi
I need to divide the output of an OCXO by a factor D=81 for testing purposes.
So with minimum added phase noise.
If you are using any kind of digital divider, let me
recommend that you first condition the signal to be
divided by using an ADI LT
I worked in the R&D section that designed the HP53132 series at the
time it was designed. This kind of stuff would be SOP where the
gate array designer (great engineer, I knew him well) does a proper
job, and then after the fact marketing/manufacturing adds on
the rear connect because some big c
On 5/26/2020 4:42 PM, Perry Sandeen via time-nuts wrote:
Learned Members,
While window shopping on Ebay sites of stuff -I'd- like- to- have -but- for
-now-dream-on I noticed that Alltest was selling over 8,000 items on Ebay.
I googled "Alltest" and came up with a bunch of similar
variant n
On 5/4/2020 8:36 AM, Tim Shoppa wrote:
Has anyone done any time-nuttery with the mechanical clocks available in
cars up through the 1970's?
My experience in the 1960's was that
it seemed like I don't remember any
car with one of these clocks that ever
worked reliably. Meaning, the time would
On 4/25/2020 6:06 PM, Bryan _ wrote:
They make quite a few models which one are you recommending?
For soldering, use the Metcal STTC-090 tip
($27.78 from Mouser SKU 745-STTC-090)
0.25mm tip diameter, perfect for 25 mil pitch
BE SURE TO GET THE WS1 AUTO-SLEEP WORKSTAND
TO SAVE THE TIP!
Fo
On 4/11/2020 2:25 PM, Bob kb8tq wrote:
Hi
Would you *really* want to read a book about how from August of 1986 to
January of 1993 AVX NPO’s had some sort of issue ( not that the issue is
clearly known, just that they are flakey) and that by 1994 the parts with
values below 220 pf in 0805 seeme
That caught my attention. Could you please say more.
A DDS introduces spurs. They move around as you change the adjustment
parameters.
Are the spurs small enough that they are not a problem with most applications?
What applications do/don't get along with spurs?
What do spurs look like on a
On 4/11/2020 12:15 AM, John Moran, Scawby Design wrote:
During my 50 years in the electronics industry I have always been puzzled about
one aspect of crystal oscillators. They go to great lengths to use a precise
piece of quartz as the heart, because of its unique properties, and then add
s
On 4/10/2020 12:51 PM, ed breya wrote:
looking for. Also, moving the frequency far away from "ideal" changes
the tempco, since it's no longer at the ideal center of the turnover
point. In reality, this may not matter much, since after all these
years, things may have drifted and aged way ou
On 4/10/2020 5:47 AM, Bob kb8tq wrote:
Hi
It is not at all uncommon to …. errr …. make that decision, regardless
of what the customer might think about it :)
Even with that sort of decision, the whole process of measuring a one
sigma and multiplying by 6 depends very much on the underlying
pr
On 4/9/2020 5:05 PM, Didier Juges wrote:
Perry,
Typically jitter is expressed in the time domain (so many ps peak to peak
for instance)
Phase noise is expressed as a power ratio in the frequency domain.
Otherwise they usually represent the same phenomenon.
Didier
On Thu, Apr 9, 2020, 6:29 P
On 4/9/2020 3:14 PM, Perry Sandeen via time-nuts wrote:
Learned Gentlemen,
Rick wrote:If you really need lower far out phase noise than the 10811 offers,you can redesign the
2nd and 3rd bufferamplifier stages. The 10811 designers knowingly degraded the phasenoise in those
stages because of requ
On 4/8/2020 3:33 PM, Dana Whitlow wrote:
Bob, what I' was getting at was: what do you do differently to make a
stable Rb versus one
that drifts a lot? Never mind price issues.
My understanding from working on the HP10816 Rb standard
is that aging (as opposed to temperature drift) is due
to t
On 4/8/2020 2:02 PM, Tom Holmes wrote:
Then what was the purpose of the inner oven?
Tom Holmes, N8ZM
-Original Message-
The inner oven has a thermal gain around
1,000. When my colleagues at HP proposed
to wrap a 2nd oven around it, I predicted
that the additional thermal gain due
On 4/8/2020 12:53 PM, Jarl Risum wrote:
I have been puzzled by a mistake which has been published recently on this
list and elsewhere as well. It concerns the operation of the HP 10811
double oven TCXO used in the HP Z3801 GPSDO.
It is claimed that the outer oven is only in use during start u
When I worked for Agilent, I had full access for "free" to
all these tools, and access to their designers, etc.
Nevertheless, the time commitment to learn these tools
is prohibitive to any engineer who is responsible for
designing the complete product, not just designing a chip.
I mainly only ever
Some vendors say "LF-1GHz" etc instead of the misleading "DC".
True DC coupled amplifiers are a different universe. They
must be differential. Search for differential amplifier IC'S
from the usual suspects. You will find that the NF will be
at least 7 dB and up. I'm not exactly sure why, but
On 3/26/2020 3:03 PM, Perry Sandeen via time-nuts wrote:
Learned Gentlemen,
Both the HP 106 and 107 have a post oscillator crystal filter. There is also a
10 MHz crystal filter used in my Tracor 527E FDM.
So the question I have is there anything to be gained by adding 10 MHz crystal
filters to
On 3/14/2020 1:57 PM, Hal Murray wrote:
rich...@karlquist.com said:
At one time, only cesium standards were considered truly primary because of
the definition of the second. However, the quantum mechanical constants of
other atoms such as Rb have been measured to much more accuracy than the
On 3/13/2020 11:00 PM, Greg Maxwell wrote:
On Sat, Mar 14, 2020 at 5:35 AM WB6BNQ wrote:
*By definition a Cesium frequency standard is just that, an absolute
primary reference ! The only difference between the 5061A and another
Cesium reference is a matter of degree of closeness to the abso
On 3/1/2020 5:58 PM, Alex Pummer wrote:
don't forget the oscillator is one amplifier with infinite gain on his
own frequency
73
KJ6UHN
Alex
Actually, the closed loop gain is not infinite, rather it is whatever is
needed to boost thermal noise enough to account for the
RF output level. I w
On 3/1/2020 3:03 PM, Hal Murray wrote:
OTOH, if you carefully adjust a couple of HP10811's to zero beat, you will
have to go to extraordinary measures to keep them from injection locking. A
lot more than just running them on individual voltage
How extraordinary? How likely are 2 GPSDOs s
On 3/1/2020 2:28 PM, John Moran, Scawby Design wrote:
My apologies if this is slightly off-topic, but it does concern crystal
oscillators.
However, I then remembered Huygens's discovery that 1S pendulums mounted on the
same wall, or beam, would synchronise and swing either in phase, or out
On 2/29/2020 1:58 PM, Attila Kinali wrote:
Different concept. Quartz oscillators are mechanical resonators.
Cryogenic sapphire oscillators are electro-magnetic resonators.
The problem with those is, that they are large and need liquid He
for cooling. Not only is He expensive, but it also need
Been there; done that!
Rick N6RK
On 2/27/2020 12:15 PM, David Van Horn via time-nuts wrote:
I remember opening up those military crystals and sanding them down with Ajax
cleaner to raise the frequency or rubbing a little solder on the plate to lower
it for CW transmitters.
High school days.
I seem to recall that crystals for frequency control (on a commercial
basis) were sort of a post WW2 thing (partly because of developments in
piezo hydrophones for sonar)
Crystals for radios were well established pre-WWII. There was an
FCS paper ~30 years ago about the WWII quartz shortage
OTOH, you could build a simple Colpitts
oscillator and see where it oscillates.
That's what they did back in the dark
ages.
Any time nut should be up for that.
Rick N6RK
On 2/27/2020 5:35 AM, Bob kb8tq wrote:
Hi
Ok, so just to run the math:
5 MHz / 2.9 = 1.724 MHz
If the Q at the fundamenta
A VERY long time ago, it was discovered that simply
degenerating a transistor with an emitter resistor
makes a worthwhile improvement in 1/f noise. I
want to say this was published in 1970 by Dick Baugh
of HP but don't hold me to it. Note that the resistor
was NOT bypassed: it's purpose was RF
You need to determine your requirements for phase
noise. You also need to coordinate this PLL with
the phase noise of the 3.125 GHz PLL, which will
need its own VCO.
The best VCXO's I have found are from Abracon,
COTS in distribution (DigiKey, etc) for only
about $25. Lucky for you that 125 MHz
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