... for those who would like to participate in HDL discussions that aren't
on-topic for existing lists:
http://groups.yahoo.com/group/HDLTalk
Any VHDL or Verilog HDL-related topics are welcome.
To keep spammers away, new member signups require moderator approval. For
this reason, please
At 12:29 PM 4/14/2009 , John Miles wrote:
... for those who would like to participate in HDL discussions
that aren't
on-topic for existing lists:
http://groups.yahoo.com/group/HDLTalk
Any VHDL or Verilog HDL-related topics are welcome.
How will this compare to comp.lang.verilog
Michael Sokolov skrev:
John Miles jmi...@pop.net wrote:
Not everybody can stomach Google's perversion of Usenet (which
admittedly
was no small engineering feat in itself).
Aren't there still non-Google ways of accessing Usenet?
There is. Find the Wikipedia page for Usenet to find
Google didn't do anything to usenet. They did provide a web based
interface into usenet, and bought the dejanews archive of all
non-binary groups.
If you were a hardcore DejaNews user, as I was, you were probably not very
happy with the way Google handled the archive and its user interface.
Hi Everyone
Sorry for the off topic post. I have received such great advice in the
past with regard to instrumentation purchases, I just can't resist. The
caliber of knowledge on this list is second to none.
I am looking for a low cost chip programmer(under $300, preferably under
$200).
I believe having STD in parts of 10-14th is fairly respectable for
amateur designs..
It depends on whether it's due to the counter or the DUT. Keep in mind the
5370's own jitter is about 15-20 ps for a best-case unit (and they all seem
to be a bit different).
For an application like an ADC
I'm still curious to hear if anyone else is seeing the same ~1E-10 error in
their 9390's 10 MHz output. I don't really care that much about the
front-panel clock, but the fact that it seems to be locking the rubidium
oscillator at the wrong frequency is more of a concern.
-- john, KE5FX
There's an HP 5062C closing on eBay soon!
Corby
Thanks for the heads-up, Corby, even if it incited a bidding war. :) I
bought it and got it working without much trouble. The problem turned out
to be a resistor that had drifted high and crowbarred the oven-temp shutdown
circuit.
Its cesium
John,
Is that, now unusable tube a surplus for You? I'd have some use
for it...
(sectioned, as a display for an University lab)..
Predrag Dukic
University of Split
Croatia
Sure, Predrag, you're welcome to it. Someone might as well get some use out
of it. Send me your address
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of Thomas Folkers
Sent: Monday, March 23, 2009 12:11 PM
To: time-nuts@febo.com
Subject: [time-nuts] Datum 9390 Problems
On Mar 22, 00:00 UT, both of our Datum 9390 model GPS
paperwork to do the shipment?
Dave
- Original Message -
From: John Miles jmi...@pop.net
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Monday, March 23, 2009 12:53 PM
Subject: Re: [time-nuts] 5062C
John,
Is that, now unusable tube a surplus
Hmm, looks like there is no problem for domestic shipments but some
potential red tape for international shipments. Predrag, I'll look into it
a bit and let you know offline if it appears to be feasible to ship it to
you.
-- john, KE5FX
-Original Message-
From:
The /q= command-line argument lets you expand the plot queue size. Looks
like the default is 86400 entries for one day's worth of data taken at
one-second intervals.
Mark -- at one time it apparently was set to 3 days in the Windows version,
but not now? Do you remember why it was backed down
Hello Said,
Attached is a screen dump of a run that John Miles did. You can
see that the envelope of the DAC voltage follows the temperature
curve (inversely). On a finer scale the DAC voltage follows the
PPS error. This plot was done with the unit locked to GPS. I
believe the time
Rest assured, you are not going to get the 3048A system (or pretty much
anything else) working with a Softmark adapter.
-- john, KE5FX
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of Don Latham
Sent: Monday, March 02, 2009 9:14 AM
no
way to make HTBasic talk to a Softmark or even a Prologix board.)
-- john, KE5FX
-Original Message-
From: John Miles [mailto:jmi...@pop.net]
Sent: Monday, March 02, 2009 10:49 AM
To: Discussion of precise time and frequency measurement
Subject: RE: [time-nuts] HP3048A Phase Noise
Can TAPR put together a group buy on these?
http://www.teachspin.com/instruments/optical_pumping/index.shtml
-- john, KE5FX
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HOWEVER-- if I close the LH display and open it back
up shortly thereafter, all my T-bolt running parameters
start fluctuating wildly and going off-scale. Even the
yellow temp line goes off scale and PPS OADEV and OSC OADEV
both drop back to a high e-12.
At what tau values, though? The
I believe that the blue trace (#3) on the last figure from John Miles'
page [3] is with the integrated 24 to -12, +12, +5 V PSU. So you are
better off buying a cheap barebones Thunderbolt and a cheap linear PSU.
That's my thinking, assuming the currently-available surplus ones all have
good
Hmm. Are you following the example shown in the readme file? What is the
exact command line you're using where multiple options aren't working?
I normally use
C:\Heather\heather.exe /i=10 /mt=130
... myself.
-- john, KE5FX
But, I have been unable to get more than one switch to
Hmm. No, I have no idea what would do that. :( There's some sort of
handshaking incompatibility, it sounds like. Try a fully-populated serial
cable, just to see if it makes a difference.
-- john, KE5FX
-Original Message-
From: time-nuts-boun...@febo.com
The parameters need to be outside the quotes, or they're considered part of
the executable filename itself. (When I posted the latest version the other
day, I added an example -- see http://www.ke5fx.com/heather/readme.htm and
click on the small image of the shortcut dialog.)
-- john, KE5FX
, 2009 6:01 PM
To: Discussion of precise time and frequency measurement
Cc: John Miles
Subject: Re: [time-nuts] Lady Heather command line modification
question...
John,
I just started playing around with Lady Heather (for some reason, that
sounds kinky :-) )
Any chance of adding
The NLB-300 and NBB-300 series MMICs from RFMD work very at up to 13GHz
or so, certainly far better than a Mini-circuits ERA- whose gain will
start to roll off at higher frequencies. Designing a broadband gain
stage to work up to 12GHz+ may not be as easy as it seems. However it
is made
Hmm... in /vl mode there might be room for a large-format digital clock
display. Not quite enough free space in the normal or /vs modes, I don't
think.
-- john, KE5FX
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of Michael Baker
Thanks for the confirmation -- I don't believe anyone else has tried it on
Windows 7 before. Did you have to run it as admin?
Christopher, I imagine there's either a WoW64 compatibility problem or (more
likely) the unit you're using isn't 100% compatible with Trimble's TSIP
implementation for
John -
I did have to run it as Admin. I tried a few things on a Guest logon
including a
USB serial port but got the 0x02 error. Just clicking on the
Lady Heather
icon
worked on the first try using a real serial port..
So if you have a real serial port you don't need to run as admin,
Mark and I have unified the Lady Heather code base between the DOS and
Windows versions, fixed various bugs and UI issues, and added some useful
features. This is my version 1.0 release:
http://www.ke5fx.com/heather/readme.htm
The app is a decent graphical replacement for tboltmon.exe at this
By the way, I can't run the DOS version here at all, so let me know if
anything looks significantly different.
-- john, KE5FX
-Original Message-
From: John Miles [mailto:jmi...@pop.net]
Sent: Sunday, February 01, 2009 4:50 AM
To: Discussion of precise time and frequency measurement
Here's my quick-and-dirty Windows port (including the modified source code):
http://www.ke5fx.com/tbolt/setup.exe (600K)
Tested on XP, should be fine on Win9x/2K, no telling with Vista.
As with Mark's original program, the default is COM1; you'll need to modify
your Windows shortcut to run
to me! :D
Cheers,
Magnus
Stijn PE1RKS
John Miles schreef:
Here's my quick-and-dirty Windows port (including the modified
source code):
http://www.ke5fx.com/tbolt/setup.exe (600K)
Tested on XP, should be fine on Win9x/2K, no telling with Vista.
As with Mark's original program
The DOS version had a bug that caused it to ignore the /2 altogether (it
hardwired the COM port back to 1 after parsing the command-line arts).
That's fixed in the Windows build.
Mark: the Windows source code should still be able to compile for DOS at
your end, if you change the #define back. If
01, 2009 4:18 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Lady Heather Question
John Miles skrev:
The DOS version had a bug that caused it to ignore the /2 altogether (it
hardwired the COM port back to 1 after parsing the command-line args).
That's
I think a more flexible fashion of setting size would be a good thing.
The preferred fasion is always being able to do standard resize by
dragging the edge, but saying x*y size at command line kind of works.
Yep, the code could support arbitrary x*y sizes, but he has several groups
of related
I'm trying to bring the Win32 version up to date with the graphical version,
but am dealing with a bug that apparently puts the Thunderbolt into some
kind of mode where it returns junk data over the serial line. My Win32
build runs for a minute or so, draws some graphs that don't make sense, and
I'd be inclined to take the error message at face value; you have some
corruption in EPROM or flash memory that isn't in an area that gets used
during the measurements you're making. Contacting an Agilent rep would make
sense, as the 53132A is new enough that there might be an easy way to
: [time-nuts] Wenzel Oscillator Repair
Now I understand! I was planning to reuse the case. It didn't occur to
me to sacrifice the case and put the oscillator in another box.
Thanks for the idea, John.
Ed
Message: 3
Date: Mon, 19 Jan 2009 21:20:54 -0800
From: John Miles jmi...@pop.net
The problem with the oscillator turned out to be even easier to fix than
I could have hoped for. There's a ferrite transformer on the output -
possibly a balun. The wire is about the thickness of a hair. The
ferrite isn't tied down - it's just held by the leads. I don't know if
it took a
I had a similar problem with a 5 MHz OCXO from their ULN series. There was
a bad solder joint on the output connection, easy enough to fix once I got
the unit open.
In my case I used a Dremel tool to cut the seam. Suggest wearing a dust
mask, obviously, and keep your cuts close to the perimeter
cutter? The case on mine looks to be about 20 ga. tin-plated
steel (~0.04 thick). The gap is so small it might have been a friction
fit to start with.
Ed
From: John Miles jmi...@pop.net
Subject: Re: [time-nuts] Wenzel Oscillator Repair
To: Discussion of precise time and frequency
Phase Noise and Frequency Stability in Oscillators:
http://www.amazon.com/gp/product/0521886775/
The UPS driver handed it to me 30 seconds ago, and I can already give it a
favorable review after opening it to a random page. Exercise 6.2 on page
191: Hack as many microwave oscillators as you can.
I'd like to see a similar test conducted against a local Cs clock (and/or
maser), just to get everything on one graph.
-- john, KE5FX
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of Bruce Griffiths
Sent: Friday, January 09, 2009
Even though the ISE/Webpack toolchain is considered somewhat buggier and
less-capable than the competing Altera freeware, I prefer it because the
Altera package requires product activation. Call it paranoia on my part,
but I see a lot of HPSDR experimenters who are going to be unhappy campers
I've got a very clean late-production HP 8663A signal generator up for sale,
in case anyone is looking. This description page will be posted to eBay
next week unless sold offline first:
http://www.ke5fx.com/8663a.htm
Will be packaged safely for shipment in a wooden crate. Asking $3000, US
Well, sure, it's more accurate than the undisciplined OCXO in the counter,
that's the idea behind the Thunderbolt. :)
-- john, KE5FX
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of n3...@aol.com
Sent: Friday, December 19, 2008 12:07
More info on the LO chain:
1) 5MHz Wenzel OCXO --Custom Osc for me.
2) MSA-1105 buffer MMIC and lumped LPF
3) 5MHz to 10MHz 1N5711 diode based doubler
4) MSA-1105 buffer and lumped LPF
5) 10MHz to 20MHz 1N5711 diode based doubler
6) 20MHz BPF
What kind of BPF? A really narrow crystal
Maybe I'm missing the decimal point. What's the bandwidth of a crystal
filter relative to the spectrum out of the same crystal used as an osc?
The oscillator's noise floor itself is superb, near -180 dBc/Hz beyond 1
kHz. That is only true until you do something with it. The idea behind the
The painful part is probably the first few stages, if you are starting at 5
MHz. You probably want to do some HP 8662A-like tricks using crystal
filters to shave off the broadband noise below 1 GHz, and maybe SAW filters
above that. This will do nothing for noise within 1 kHz, though... do you
The Symmetricom 5120A does something very clever to alleviate this
problem. Explained in US patent 7,227,346 and Direct-Digital
Phase-Noise
Measurement; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig,
and
S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and
The date code is not a production date, necessarily, but the date of that
particular design revision (presumably when it was released to
manufacturing). It sets a lower bound, but your unit could potentially be
several years newer. You can get a better idea by looking for the latest
date code on
Hadley's site has this one: http://to-way.com/tf.html
-- john, KE5FX
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Quigg, Stephen
Sent: Monday, December 08, 2008 8:06 PM
To: time-nuts@febo.com
Subject: [time-nuts] Ball-Efratom FRK-L manual
I went ahead and bought the 5062C service manual from Manuals Plus. I'll
contact Dave at Artek Media next week sometime to see if he's interested in
scanning the whole thing...
-- john, KE5FX
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Corby Dawson
Actually your earlier advice proved golden. I believe I've been able to
verify that the tube is at least within throwing distance of its factory
spec (see test results at http://www.ke5fx.com/cs.htm including the
configuration details).
I haven't tried playing with the low-frequency test coil at
I recently found a tube from a 5062C on eBay in unknown condition for not
*too* much money, and thought it would be interesting to power it up on the
bench. Once I got it and saw the 19xx-prefix serial number, I wasn't too
optimistic, since it could potentially be 25 years old or more. Things
Hmm! I appreciate the tip. I'll confess it didn't occur to me to try to
force more current through the ion pump. The supply I was using was limited
to about 300 uA, but I took your advice and tried a beefier one, set to 3
kV. As I increased the current limit from 0 towards 5 mA, the ion-pump
http://www.amendez.com/Noahs%20Ark...
I'm sure there's a more appropriate list for this bogosity.
-- john, KE5FX
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and
That's a Winsock HOST UNREACHABLE error. If you're moving the Prologix
board from one subnet to another, are you reconfiguring its IP address?
-- john, KE5FX
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Bruce Griffiths
Sent: Sunday, November 23,
] Im Auftrag von Dan Rae
Gesendet: Donnerstag, 20. November 2008 18:58
An: time-nuts@febo.com
Betreff: [time-nuts] To improve a Tbolt?
I have been reading with interest John Miles' page about his Tbolt
'upgrade'.
http://www.thegleam.com/ke5fx/tbolt.htm
I have a newly acquired
On your rubidium comment, one needs to be a little careful about
expectations. For short tau (say 0.1 to 10 seconds) your average
cheap eBay surplus telecom Rb will have far less performance
than a good OCXO. Yet mid-term (say 10 to 10^4 seconds), a
Rb-GPSDO will win. However, long-term the
What power supply did the TAPR Thunderbolt use?
The green, orange, and red traces used the supply module that came with the
TAPR order. You can see the characteristic hump around 3 kHz that appears
in many of Tom's plots with this supply as well.
The blue trace was the old-style packaged
Unless you are going to use a different OCXO, there is nothing to do except
perhaps tell it to save the self-survey results and set your foilage mode
if desired. They are plug and play.
-5 V/Hz is the correct kvco parameter; any changes will either degrade the
phase margin and give you a hump in
Anyone got a .PDF of the 5062C op/service manual, before I fall back to
Manuals Plus?
-- john, KE5FX
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and follow the
Along the same lines (and this may have come up before), is there a good
Allan-deviation application for Windows that talks to the 5370B?
-- john, KE5FX
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Heinzmann, Stefan (ALC NetworX GmbH)
Sent: Friday,
Couple of (somewhat naive) questions here:
It's similar to asynchronous switching inside a digital computer.
You can
add levels of flip flops to synchronize across two asynchronous
time-domains,
but all you are doing is decreasing the possibility of a
meta-stable failure to
make it
I can't find much fundamental research on this at all; and if
even Mr. Vig
says the phenomenon is not well understood.. But there are
(propriatary) ways
to probe for the susceptibility of a particular unit to do this.
John told me once that an easy way to deal with many classes
of
Javier Serrano wrote:
Dear nuts,
I would like to know if there is a clear explanation somewhere with
considerations on how to choose an upper frequency limit when
integrating phase noise to find jitter. Let's say I'm interested in
the raw jitter measurement which comes from integrating phase
A high-quality crystal oscillator's broadband floor will be
sufficiently quiet (typically better than -160 dBc/Hz) that it won't
matter
much whether
you integrate out to 100 kHz or to 1 MHz. The difference will be on
the order of attoseconds.
Sorry, should have said femtoseconds here.
Sounds like you're doing everything right. 9390s are plug-and-play by
nature, so I'd have to wonder if there's some front-end damage to the GPS
receiver.
-- john, KE5FX
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Myers, Charlie
Sent: Monday,
You don't normally listen to a CW signal at zero beat, so many receivers
apply a BFO offset to make the CW tone audible at a comfortable frequency.
This is usually more like 800 Hz than 4 kHz, though, so you could still have
a calibration error somewhere.
-- john, KE5FX
-Original
It (LTSpice) has some severe limitations for most of the simulations I
have done.
You might bring those up with Mike Engelhardt (the author). He doesn't miss
many tricks.
These need to be supplemented with on board filtering as they aren't
quite as quiet as you need.
Either the NIST style
Following the good advice I received about increasing the value of the
trimmer capacitor, I replaced the trimmer which was originally
3-12pF, with
another one which was 2-22pF.
This has given the additional adjustment range to allow me to pull the
crystal to meet the specification.
It's
How's the filament voltage at the 7587 socket, by the way? A shorted
turn in your power transformer might account for some lack of
enthusiasm on the Nuvistor's part.
I'd expect a shorted turn on a power transformer to let the smoke out.
Depends on a lot of things, but yes, usually.
Is this a double-oven cubicle, or the less-stable single-oven model with the
bang-bang controller (i.e., the boss holding a gun to your head)?
Seriously, that's great that not all of the old guard has retired. The 8640
came along in the early 70s, so I'd bet that guy has seen a lot.
-- john,
I'm not familiar with any GPIB bugs on the 5370A, but I moved your code over
to C and ran it on my 5370B via a GPIB-LAN adapter. The test app failed
after ~6 hours with a Winsock timeout error. I'm thinking that was caused
by a power glitch, though, because I actually had to power-cycle the
The elevation mask might also come into play. Ordinarily you don't want to
consider input from satellites too near the horizon, as terrestrial features
can distort the signal's timing.
I think it can be stated with confidence that there's nothing wrong with a
(normally functioning) Thunderbolt's
I just got one of the new networked GPIB controllers, and I've been
having some issues. I'm not sure if it's the Prologix or the
instruments, or both.
With the 5370A, I can get samples for some period of time ranging from
about 2 to 4 hours before the GPIB controller stops responding. I
LO phase noise is almost always what limits the noise floor at close-in
offsets, because of the narrow RBW (either analog or digital) typically used
at those offsets to keep the carrier out of the measurement.
Occasionally a high degree of RF attenuation might raise the equivalent
front-end noise
Yes, but kind of puzzles me a bit since I would
be expecting phase noises more than 10x worst on a
SA covering DC to 1GHz (+/-)
(since the LO for this is an YIG oscillator circa 3GHz locked to a
reference)
comparing with an FFT analyzer that uses a few tens MHz sample rate.
Phase noise is
Perhaps the local oscillator isn't the limiting factor for the low
frequency analysers.
The claimed noise floor is in the vicinity (within 10dB) of -120dBc/Hz
for the analysers for which I checked the specs.
If the 10MHz reference has a phase noise floor of around -160dBc/Hz
this is only
The R+S FMU36 has a phase noise floor of around -143dBc/Hz (offset
10kHz) with a 10MHz input.
Whereas the R+S FSU67 has a phase noise floor of around -133dBcdBc/Hz
(offset = 10kHz) with a 640Mhz input.
There is a definite improvement at lower frequencies but not quite as
much as one might
Most synthesizers regardless of technology still end up with broadband
floors in the -150 dBc/Hz neighborhood, so now you're back to circa -120
dBc/Hz inband... which is what the PSA-series spec sheets show.
I didn't phrase that very well; I meant to say that the broadband floor of
your phase
It's sort of a religious matter, but if you are looking for an easy-to-use
part with great, free C/C++ support, you'd most likely be happy with the
AtMEGA series.
-- john, KE5FX
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jim Palfreyman
Sent:
If you don't want pushbutton convenience, you can measure the close-in phase
noise with not much more than a $5 mixer and $2 opamp. It will take a lot
of sweat equity, and you will need to build two of whatever you're
measuring, or buy/borrow a known-cleaner source at the same frequency.
TSC
These tests were made with the GPS antenna connected? At t 100 seconds,
they should all look about the same, because that's where GPS disciplining
comes in, no? They should not be uncorrelated in the long run.
To the extent one Z3801 looks worse than the other at large values of tau,
I'd
Hi John,
On Sat, 2008-08-09 at 17:48 -0400, John Ackermann N8UR wrote:
The longer tau readings are interesting mainly to see how the GPS loop
kicks in; tau below about 1000 seconds seem related to OCXO performance
on the TBolts, while the Z3801A seems to have a longer time constant,
I don't have any of the 10811-60158s, but I did buy two of the 10811-60168s
that were up for auction recently. The -60168s seem to be really good
performers (from memory, -106 dBc/Hz at 1 Hz, -139 at 10, -155 at 100, -164
at 1000, when I measured them against each other.) I have never seen any
Tom or JohnA, have either of you run any Allan plots on a
10811-60268? I'd
be curious to see how they do.
Er, -60168, that is.
-- john, KE5FX
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-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of [EMAIL PROTECTED]
Sent: Friday, August 08, 2008 4:17 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Double-Oven Thunderbolt on Ebay
I was actually talking about
In any event, if you actually test real comparators, you will
find them to be universally lousy. I will be happy to be proven
wrong if someone is aware of a good comparator. It's just that
I have never met I comparator I liked :-)
I think you're right about that. About the best thing you
I do agree with Richard, comparators are quite bad...
Having played with interfacing signals to FPGA 'ad nausea'
I found that the only simple scheme that works
better than biased (or feedback) cmos gates and of
course much better than ECL line receivers or comparators
(even cmos gates
Modern ECL parts aren't necessarily that bad compared to the old MECL
stuff.
My experience goes all the way back to the MECL 1000 series that was
discontinued 30 years ago. I designed many synthesizers around them
for Zeta Labs. Every newer family of ECL line receivers has been faster
I've played with the Hittite chips before and obtained PN results in the
same ballpark (see http://www.ke5fx.com/hpll.htm ), but at 8 GHz rather than
6 GHz. To save further head-scratching, the figure of merit on these chips
works like this:
In-band phase noise in dBc/Hz = FOM + 10*log(Fcomp) +
Yeah, those Noritake parts are very nice. I wouldn't expect trouble from
one.
There is a slight possibility of additional EMI versus an LCD, obviously
nothing that would cause trouble at the end of an RS232 cable.
-- john, KE5FX
-Original Message-
From: [EMAIL PROTECTED]
I don't know about sending edges that slow into a CMOS chip. Is that
considered kosher for HC-series logic?
-- john, KE5FX
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of David C. Partridge
Sent: Tuesday, July 15, 2008 10:16 AM
To: 'Discussion of
,
This is just DC selection of which MUX line is active.
Am I missing something here?
Dave
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of John Miles
Sent: 15 July 2008 18:30
To: Discussion of precise time and frequency measurement
Subject: Re: [time
eBay has partitioned itself lately into items with excessive starting bids,
and items which are real bargains. But yeah, I already paid for all the
Cs/Rb sources flying around overhead, damned if I'm not going to use 'em!
-- john
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From: [EMAIL PROTECTED]
I believe the Allan variance graph in Trimble's data sheet was taken before
Selective Availability was turned off. I'm not sure what impact this would
have; I wouldn't expect any at all at tau 100s.
A pronounced hump in the ADEV plot could suggest that the disciplining loop
is underdamped.
I am not a big fan of BNC connectors on the PC board itself, because I am
not a big fan of attaching PC boards directly to panels in most cases.
There are usually some BNC bulkhead connectors on eBay that terminate in
SMA/SMB/SMC pigtails, which are great for panel mounting.
There is nothing special about the 5087A's amplifier cards. The 5087A
design is not especially quiet; in fact, it will degrade the broadband floor
of a Thunderbolt by a good 7 or 8 dB from what I have seen.
I'd say grab some PCB prototyping stock and a Dremel tool, and surf through
Bruce's notes
Just watch for the odd error in those references.
eg in the first reference (.../498.pdf) the captions for figure 2 and
figure 3 should be swapped.
If anyone wants to try it, I have an even quieter, lower distortion 3
transistor isolation amplifier design that runs from a 12V supply.
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