Re: Frequency calibration?
Right there with ya.. -Dave On 10/10/2017 04:11 PM, `Richard Knoppow dickburk@... [hp_agilent_equipment] wrote:
?????? There are many of us who are slaves to coffee. Have few other bad
habits but I can't even talk in the morning before drinking a cup.
On 10/10/2017 11:02 AM, Bob Bownes bownes@...
[hp_agilent_equipment] wrote:
Correct! Need more caffeinated beverage. Thanks!
--
Richard Knoppow
dickburk@...
WB6KBL
-- Dave McGuire, AK4HZ New Kensington, PA
|
Here are some random notes on the expansion options for the
89410A/89441A, for the sake of the archives.
Second Channel
--------------
It's possible to add the second input channel option in the field. An
input channel (either one) consists of a pair of boards, A10 and A21.
The board pairs are identical between channel one and channel two. It's
possible to take a channel one board set from one 89410A/89441A and add
it as a channel two board set in another unit. The firmware will
recalibrate the ADC on the first power-up with the new board set
installed, which takes several minutes.
The only configuration change required to use the second input channel
is a jumper on the A35 source board. Several of the self-tests and the
calibration routine will fail unless you move this jumper. It's a
wider-than-usual black plastic jumper near the connector along one edge.
There are two positions; one position is for a single-channel system
and the other is for a two-channel system. If you add a second channel
and forget to move this jumper, and see the self-test failures, just
power down, extract the A35 module, move the jumper, and start it up
again. It will now work, assuming the added board set is functional.
Memory
------
Options UFG and UTH are nearly identical; both options add more I/O
(an Ethernet port, for one) and additional RAM and take the form of the
topmost board in the backplane that's accessible from the rear of the
instrument. How they differ is in the amount of RAM that they provide;
UFG adds 4MB, while UTH adds 20MB. There's 4MB on the option board, and
a 72-pin SIMM socket that's either empty in the case of option UFG, or
populated with a 16MB SIMM in the case of option UTH.
One can remove an option UFG board and install an option UTH board,
and the system will see it with no configuration changes required. One
can also add a 16MB SIMM to an option UFG board and turn it into an
option UTH board; no configuration changes are required on either the
board or on the system.
It's possible that there's an earlier revision of the option UFG board
that lacks the SIMM socket, but I've not confirmed this.
I've not yet determined what type of SIMMs these boards use, though
they look pretty ordinary. I've also not yet determined if it will take
larger SIMMs.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
|
Re: HP AN/USM 281A Oscilliscope needs repair (San Antonio TX)
One last question for the night. Is there a component failure that would cause the beam/dot not to show on the screen when I apply low voltage to the test leads (1.5v battery) I have to hold the TEST button to find the FIND BEAM button to see anything other than the backlight, and I wish I had 3 hands, but this shouldn't be necessary.
It might just be a switch or knob that I haven't adjusted correctly, so I'm trying to set it up correctly for testing in order to figure out if there is anything malfunctioning.
Best Regards,
Andrew
--------------------------------------------
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Show quoted text
On Tue, 10/10/17, Andrew Maich andremajic@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
Subject: RE: [hp_agilent_equipment] HP AN/USM 281A Oscilliscope needs repair (San Antonio TX)
To: hp_agilent_equipment@...
Date: Tuesday, October 10, 2017, 8:15 PM
?
Cool. Thank you for the tip on where to check.
I'm still trying to figure out if there are any settings
I need to try without cracking the case open. I'll save
this email for reference when I open it up.
Andrew
--------------------------------------------
On Sun, 10/8/17, knener@... [hp_agilent_equipment]
<hp_agilent_equipment@...> wrote:
Subject: RE: [hp_agilent_equipment] HP AN/USM 281A
Oscilliscope needs repair (San Antonio TX)
To: hp_agilent_equipment@...
Date: Sunday, October 8, 2017, 12:44 PM
?
The resistors in the deflection amplifier output
stages (in this case the horizontal deflection
amplifier)
have an annoying tendency to drift much higher in value
and
eventually fail open. This is also an issue with the
HP853A,
I have repaired three or four of these with essentially
the
same failure. You can check the resistors easily with an
ohmmeter - if you measure higher resistance than the
value
shown in the schematic, then the resistor has failed.
Suitable replacements are available from DigiKey or
Mouser
at low cost. If you find a failed resistor of a specific
type, then change all of the resistors of that type in
the
deflection amplifier output stage (even the
"good"
ones). I have repaired at least one unit where all of
the
deflection amplifier output stage resistors were
open-circuit on both the horizontal and vertical
amplifiers.
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|
Re: HP AN/USM 281A Oscilliscope needs repair (San Antonio TX)
Cool. Thank you for the tip on where to check.
I'm still trying to figure out if there are any settings I need to try without cracking the case open. I'll save this email for reference when I open it up.
Andrew
--------------------------------------------
toggle quoted message
Show quoted text
On Sun, 10/8/17, knener@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
Subject: RE: [hp_agilent_equipment] HP AN/USM 281A Oscilliscope needs repair (San Antonio TX)
To: hp_agilent_equipment@...
Date: Sunday, October 8, 2017, 12:44 PM
?
The resistors in the deflection amplifier output
stages (in this case the horizontal deflection amplifier)
have an annoying tendency to drift much higher in value and
eventually fail open. This is also an issue with the HP853A,
I have repaired three or four of these with essentially the
same failure. You can check the resistors easily with an
ohmmeter - if you measure higher resistance than the value
shown in the schematic, then the resistor has failed.
Suitable replacements are available from DigiKey or Mouser
at low cost. If you find a failed resistor of a specific
type, then change all of the resistors of that type in the
deflection amplifier output stage (even the "good"
ones). I have repaired at least one unit where all of the
deflection amplifier output stage resistors were
open-circuit on both the horizontal and vertical
amplifiers.
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Re: HP AN/USM 281A Oscilliscope needs repair (San Antonio TX)
Thanks for the help. What can I use for a signal? I don't have a signal generator. I tried testing it with a 3v 800ma wall wart using the EXT INPUT and didn't get a dot or anything.
I tried using a 1.5v battery on the lower left input probe and, while holding the test button down I could see the dot jump up and down 1.5 square up each time I contacted the battery terminal. I can't get a dot to appear without holding the test button, so I feel like the knobs and switches probably aren't adjusted correctly.
It worked the same way with the lower left INPUT when I tried the wall wart. The dot jumped up 3 squares, but only when holding the test beam button.
Do you think I'm doing the test correctly, or are there other switches and knobs I need to try different settings with?
Thank again!
Andrew
--------------------------------------------
toggle quoted message
Show quoted text
On Sun, 10/8/17, 'Paul Bicknell' paul@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
Subject: RE: [hp_agilent_equipment] HP AN/USM 281A Oscilliscope needs repair (San Antonio TX)
To: hp_agilent_equipment@...
Date: Sunday, October 8, 2017, 1:05 PM
?
Hi re
fixing 180 from memory
Before
removing the transistors a simple
test
Have
you tested all the power supply rails
on the pcb for the main frame for this test I would remove
the plugging just in
case they are causing any problems ?
?
Display
switch on right hand side 3rd
one down turn it clock wise this puts the X amplifier into
external with the intensity
turned up you should have a spot
turning
the pot fully clock wise gives
maximum sensitivity ?( right hand side 2rd one
down magnifier
should be set to 1 )
now
connect a signal into the external ?BNC
input below ?I just held a length of wire and put into the
bnc socket ?you
should see a horizontal line if not it is probably the drive
transistors
if
you have movement connect the BNC input
below ?to the calibration terminal you should see 2 dots
one on left one
on right if one hasten moved then it is that pare of
transistors that has a
fault
?
this
was my first HP scope to repair ?Paul
B
From:
hp_agilent_equipment@...
[mailto: hp_agilent_equipment@... ]
Sent: 08
October 2017 18:02
To:
hp_agilent_equipment@...
Subject: RE:
[hp_agilent_equipment] HP AN/USM 281A Oscilliscope needs
repair ( San Antonio TX )
?
?
I have a fluke
digital multimeter, a weller soldering
station, and not much else. I'm slowly building up what
I can when I have a
specific need or find a good deal.
I bought a set of probes for it off ebay
There's no rush for me to fix it, so I can take the next
10 years if need be. Should
I de-solder the transistors for testing?
I heard that with very high voltages, the thickness of the
gloves are what's
important. That's why lineman's gloves and spark
plug boots are so thick.
I have a thick pair of rubber gloves that I'll probably
be wearing for safety
after leaving it unplugged for a while.
I also need to make a high resistance capacitor discharge
tool. I believe I
have some high capacity resistors I've salvaged from
some equipment.
Thanks for the tips. Any further help is appreciated.
Andrew
--------------------------------------------
On Sun, 10/8/17, Reginald Beardsley pulaskite@...
[hp_agilent_equipment]
< hp_agilent_equipment@... >
wrote:
Subject: RE: [hp_agilent_equipment] HP AN/USM 281A
Oscilliscope needs repair ( San Antonio TX )
To: hp_agilent_equipment@...
Date: Sunday, October 8, 2017, 11:30 AM
?
What test gear do you have? That will help people
advise you. Did it come with a probe?
The manual suggests approaches appropriate to a
commercial
environment where labor is expensive and parts are
readily
obtained. In your case labor is actually what you're
after. Except you'll call it "experience"
after you're done. Being able to say you have
repaired
a 100 MHz analog scope is non-trivial. That's a good
scope, though old age will make it a bit cranky. It will
serve you well even when you get newer gear.
You can make a limited test of the transistors by
measuring
the forward resistance of the B-E and B-C junctions with
an
ohmmeter. The B-C resistance will be smaller than the B-E
resistance because the larger area of the collector
trumps
the higher doping level of the emitter. Use the highest
resistance ranges. You may encounter problems with DMMs
that don't supply sufficient voltage to turn on the
transistor. I learned this trick using an analog VOM. It
doesn't work with the Harbor Freight cheapy DMMs.
If you've got one of the Harbor Freight DMMs that
they
give away, measure hFE with it. That should suffice for
testing the two transistors, But beware of the crappy
transistor sockets, You should probably solder some leads
with grabbers or alligator clips. I just tried two red
ones. One worked, the other didn't, but both were
intermittent. An old yellow HF DMM had a better socket
and
worked just fine (once I plugged it in correctly ;-)
Connect to the probe compensation signal for testing.
Make
sure you know where the high voltages are and stay away
from
them. I've heard it's rather painful at best and
lethal at worst. If you do need to work near it, keep
your
left hand in your pocket and wear rubber sole shoes. HF
nitrile gloves might not be a bad idea, though I
don't
know how good they'd be. Not quite sure what is
recommended for southpaws. Be aware that the HV
capacitors
and the CRT can hold a charge for quite a while. Before
you
EVER touch anything in the HV section, ground it with a
screwdriver first with the unit unplugged.
Whenever you get tired or confused, stop. It took me over
a
week to fix the horizontal section in my Dumont
working a
couple of hours each evening.
Most important....
Have Fun!
Reg
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Re: Frequency calibration?
Unless there is a reason for extreme precision in your frequency measuring, you don't need to spend too much money adjusting the oscillator to a reasonable precision. The old method using WWV with a radio receiver can be quite good.?
I have been using GPS for the last dozen years and before that WWVB on 60 kHz, but I do a lot of work requiring high accuracy at microwave frequencies.
?
I recently bought an all new (small) 10 MHz output GPS receiver, used for work away from my lab. It is made in China, and comes with a power supply (small "wall-wart") and antenna for $130 delivered (eBay item?262981677836). This provides far better accuracy than any reasonable person would probably need, at the cost of a new crystal oven. The construction appears to be excellent. It locks quickly even with the antenna on the work bench.
Stuart
K6YAZ
West Hills, (Los Angeles)
California
StuartL73@...
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Re: [TekScopes] Fast Rise/Fall Time Pulser
Mine arrived today. Alas, it uses a USB B connector instead of a more common USB mini or micro; I gotta get a cable.
Mine has the comparator IC marked only, "AJK BAA." Yes, this is an Analog Devices ADCMP572 or ADCMP573 Ultrafast SiGe comparator. I'm not sure which output configuration is used yet, but likely is the 572 with CML output drivers.
The controller IC is a 18F25K50 PIC with integral USB. Level programming software is available on the Leo Bodnar website for download.
The board was supplied with a test result data sheet from a Tektronix CSA803A (website picture shows a SD30 40 GHz sampling head used) showing the pulser rise time as 38.91 ps and the fall time as 33.20 ps with about 950 mv P-P.
It's a lovely looking board; lots of thought went into the layout. I can't tell if it is multi-layer. Now for that B cable...
Larry
toggle quoted message
Show quoted text
On 10/10/2017 12:19 PM, Larry McDavid lmcdavid@... [TekScopes] wrote: There has been discussion recently about generating fast rise/fall time
pulses by various means. Here is a link to a Leo Bodnar device that will
provide <40 ps rise/fall time, 50% duty cycle, 10 MHz pulses:
This is built on a small PWB with integral BNC connector, powered by 5
vdc through a USB B connector; a trigger output is provided. Price is US$68.
I've ordered one of these for testing.
Is anyone here using one of these?
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
-- Best wishes, Larry McDavid W6FUB Anaheim, California (SE of Los Angeles, near Disneyland)
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
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Re: Frequency calibration?
What's wrong with my Rubidium reference that would make me choose a GPS disciplined? Costed me $75 on EPay, but still needs a power supply, case and diastribution amplifiers, yet another project to boot...
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Re: Frequency calibration?
I have the same equipment and don't need insane accuracy (1Hz in 100MHz is more the sufficient - 10e-8). ?I will put the 1PPS signal into the A input, the 10MHz from the ref osc out on the back into the B input and use the B/A ratio mode and set the resolution to get the desired LSD resolution. ? It will pretty much stay on 10000000.0 for hours with an occaisional blip up or down the LSD. ?When it jitters up as often as down, I'm close enough for my hobby use. ?Better signal lock results in less jitter (outdoor antenna is better than one of those fingernail sized things indoors).
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Re: Frequency calibration?
They say coffee helps you live longer, I don’t know about how true that is but I do know that it definitely makes me enjoy the time I do have much more!
toggle quoted message
Show quoted text
?
?? There are many of us who are slaves to coffee.
Have few other bad habits but I can't even talk in the morning
before drinking a cup.
On 10/10/2017 11:02 AM, Bob Bownes
bownes@... [hp_agilent_equipment] wrote:
Correct!
Need more caffeinated beverage. Thanks!
--
Richard Knoppow
dickburk@...
WB6KBL
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Re: Frequency calibration?
?????? There are many of us who are slaves to coffee.
Have few other bad habits but I can't even talk in the morning
before drinking a cup.
On 10/10/2017 11:02 AM, Bob Bownes
bownes@... [hp_agilent_equipment] wrote:
Correct!
Need more caffeinated beverage. Thanks!
--
Richard Knoppow
dickburk@...
WB6KBL
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Re: Fast Rise/Fall Time Pulser
Yes, works as advertised as far as I can tell.? There is plenty of discussion and many screenshots here:
?
There has been discussion recently about generating fast rise/fall time
pulses by various means. Here is a link to a Leo Bodnar device that will
provide <40 ps rise/fall time, 50% duty cycle, 10 MHz pulses:
This is built on a small PWB with integral BNC connector, powered by 5
vdc through a USB B connector; a trigger output is provided. Price is US$68.
I've ordered one of these for testing.
Is anyone here using one of these?
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
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Re: Frequency calibration?
Two questions for the original poster: How accurate do you need (want) to be? and what are you using the counter for?
Time and frequency precision can become an obsession - Time Nuttery.
Robert G8RPI.
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Fast Rise/Fall Time Pulser
There has been discussion recently about generating fast rise/fall time pulses by various means. Here is a link to a Leo Bodnar device that will provide <40 ps rise/fall time, 50% duty cycle, 10 MHz pulses:
This is built on a small PWB with integral BNC connector, powered by 5 vdc through a USB B connector; a trigger output is provided. Price is US$68.
I've ordered one of these for testing.
Is anyone here using one of these?
--
Best wishes,
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
|
Re: Frequency calibration?
Correct! Need more caffeinated beverage. Thanks!
?
?? On a standard scope with the same signal on X and
Y in phase is a line at 45degrees to the right, 180degrees out of
phase is a straight line tilted 45 degrees to the left, a circle
is 90 degrees out of phase. This assumes equal phase response of
of the X and Y amplifiers in the scope.
??? If there is drift the pattern will rotate.
On 10/10/2017 7:38 AM, Bob Bownes
bownes@... [hp_agilent_equipment] wrote:
?
Another is feed one into X, one into
Y of an oscilloscope. In phase is a circle. Out of phase
is a diagonal line.?
frequency multiples will show pretty
patterns from your favorite SciFi movies of the 50's and
60's.
--
Richard Knoppow
dickburk@...
WB6KBL
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Re: Frequency calibration?
?????? On a standard scope with the same signal on X and
Y in phase is a line at 45degrees to the right, 180degrees out of
phase is a straight line tilted 45 degrees to the left, a circle
is 90 degrees out of phase. This assumes equal phase response of
of the X and Y amplifiers in the scope.
????????? If there is drift the pattern will rotate.
On 10/10/2017 7:38 AM, Bob Bownes
bownes@... [hp_agilent_equipment] wrote:
???
Another is feed one into X, one into
Y of an oscilloscope. In phase is a circle. Out of phase
is a diagonal line.???
frequency multiples will show pretty
patterns from your favorite SciFi movies of the 50's and
60's.
--
Richard Knoppow
dickburk@...
WB6KBL
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Re: VNA design engineer on the list?
Dr. Joel Dunsmore hangs out in the Forums on HP/Agilent/Keysight.
?
If anyone here designed commercial VNAs, I'd like to call attention to some recent posts I've made to the EEVblog metrology forum on the topic of using an SA and a computer to measure amplitude and phase.
If the names Wiener, Levinson and Hilbert are unfamiliar it's not likely to make any sense.
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VNA design engineer on the list?
If anyone here designed commercial VNAs, I'd like to call attention to some recent posts I've made to the EEVblog metrology forum on the topic of using an SA and a computer to measure amplitude and phase.
If the names Wiener, Levinson and Hilbert are unfamiliar it's not likely to make any sense.
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Re: Frequency calibration?
By far and away the best choice is going to be a GPS disciplined oscillator such as an HP 3801A or a Thunderbolt. A good GPSDO should be good to at least 1x10^-10 ? (1ppb) over the course of a day. ? It will be the simplest as well. Take the 10MHz output and feed into the Ext Reference input on pretty much all of your lab equipment. Any good counter, signal generator, even bench scopes will have one. A simple video distribution amplifier will serve just fine to ship the signal to all of them at once. Don't forget to put one on the workbench someplace to plug it into whatever you are working on. :)
There are a variety of ways to to check the accuracy of your reference. One of the better ones is to look at jitter and phase difference over time. Feed one into the trigger on a time interval counter such as an HP5370 , the other into the input. The time interval between the two shouldn't change (it will), but the change over time and the jitter between the two will be very instructive. Using this, you can see changes over the course of days or weeks (depending on what data you save). There is a good HP App Note on jitter.
Another is feed one into X, one into Y of an oscilloscope. In phase is a circle. Out of phase is a diagonal line.? frequency multiples will show pretty patterns from your favorite SciFi movies of the 50's and 60's.
This is a subject many have been drawn into very deeply. There is, in fact an entire mailing list devoted to the subject.
Beware however. It is a subject that can cost you a great deal of time and money. A man with one watch knows what time it is. A man with two is never sure. A man with 3 can make a very good guess however! That thinking can lead to owning several GPSDO's, a rubidium, and a cesium beam standard. Or several of each. Really. And taking your kids up mountains to prove relativity. Really. .
Bob
?
I can't recall where, but someone posted a comment to the effect that the PPS output of their GPS unit had significant (~20 nS) jitter.
I'd suggest feeding the output of the reference to be checked to an MCU such as an STM32F4xx Discovery board along with the PPS from the GPS and counting the number of transitions between PPS outputs.
Have Fun!
Reg
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Re: Schematics for HP 8558B SA
As Dave from Artek says, it is helpful to know the serial number of the unit. What you most likely want is the "Operation and Service Manual" for this unit. The part number for the manual is 08558-90102.
Keysight probably still has this posted on their website as that is where I got mine, but it is not perfect and there are a few schematic pages that are not scanned completely/properly. If Dave at Artek has this manual, I would consider ordering it from him - Dave's manuals are, well, pretty much perfect.
Is there a specific issue you are having with your 8558B? I have several of them in service and might be able to assist you with debug and replacement parts (other than wafer-switch rotors).
Ken
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Dave McGuire
bownes