Re: Slightly off topic puzzle
Of course, this was the first thought, unfortunately I don¡¯t have an extender for these boards... A pretty weird type of connectors, the board is female and the motherboard is male, I don¡¯t think they are standard.
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Re: HP AN/USM 281A Oscilliscope needs repair (San Antonio TX)
Look to be sure you have switched to internal sweep, switch settings are good to double check.
Dennis
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On Sat, 10/7/17, andremajic@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
Subject: [hp_agilent_equipment] HP AN/USM 281A Oscilliscope needs repair (San Antonio TX)
To: hp_agilent_equipment@...
Date: Saturday, October 7, 2017, 11:45 AM
Hello all,
I am completely new to oscilliscopes,
and I just acquired one of these for free, since it was not
working. Cool thing is that the technical manual is
downloadable and the user manual as well, since this is a
military unit.
Now the rub: I have never used an
oscilliscope, and might not ever use one, however I'm
learning electronics repair and my Dad is telling me that
this could be an invaluable piece of troubleshooting
equipment. Another problem is that you normally need a
couple things to troubleshoot an oscilliscope, such as a
frequency generator and - another
oscilliscope.
I've used the flow chart on the
technical manual and it appears that the horizontal signal
board needs to be repaired. The CRT projects a beam only
when I press the TEST button and only vertical adjustments
are possible. Horizontal adjustments while holding the
test? button down do nothing.
Anyone in the San Antonio TX area
willing to help a newbie out? I work long hours (3am - 8pm
mostly) so the time I get off is usually weekends.
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Re: Affordable VNA Cal Kit in 12~15Ghz
"I used to do J.D. Jackson¡¯s Classical Electrodynamics end chapter problems to do brain workout although I¡¯m not a physicist:)"
That's a pretty serious amusement! The following is more for the benefit of other readers. You obviously will figure all the rest of this once you read the paper.
The paper is solving classic least squares solution of:
Gm=d
where
d=data measurements
m=correction parameters
G=system of equations to be solved
There are probably MATLAB programs for doing this that already have the G matrix built. It seems to me a pretty obvious graduate level homework problem. Building the G matrix is the hard part. But the paper gives all the details, although I'd strongly suggest that you work through the algebra by hand to verify there are no typos.
Make up 2-4 of the stripline boards shown in the paper as close to identical as possible using your normal construction techniques and measure them. Making 4 will cut the variance of your calibration coefficient estimates in half. Then do a short write up for QEX.
If you decide to do this, get in touch with me directly and I'll see what the L1 solution looks like. I drop in and out of the list because of the traffic level and shifting interests. I also like to play guitar: jazz, blues, folk and traditional country ballads.
Another alternative would be the 6 port network of Engen & Hoer. Once I get a VNA, making and characterizing standards will be one of my first projects. The EEVblog metrology group might be a good place to check on the matter.
Have Fun!
Reg
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Re: HP AN/USM 281A Oscilliscope needs repair (San Antonio TX)
Hi there
firstly welcome to the group but could you
please include your name at the end of your posting
Now to your problem?
You are very lucky that the military service
/ operating information includes the CCT diagrams ?I trust you Have
volumes 1 and 2
it appears that the AN/USM 281A is a ruggedized
version of the HP 180? and this is a very good old oscilloscope and very
reparable
?
At this time I suggest you repeat your posting
as HP 180 Oscilloscope needs help with repair this might receive more postings
The horizontal board is next to the tube
and has Very High voltage, The lack
of horizontal deflection is normally due to component frailer
the 2 drive transistors that provide the
deflection to the tube and there drivers are the usual ones that fail
?
regards Paul B????
south cost UK
From:
hp_agilent_equipment@...
[mailto:hp_agilent_equipment@...]
Sent: 07 October 2017 16:46
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] HP
AN/USM 281A Oscilliscope needs repair (San
Antonio TX)
?
?
Hello
all,
I am
completely new to oscilliscopes, and I just acquired one of these for free,
since it was not working. Cool thing is that the technical manual is
downloadable and the user manual as well, since this is a military unit.
Now the
rub: I have never used an oscilliscope, and might not ever use one, however I'm
learning electronics repair and my Dad is telling me that this could be an
invaluable piece of troubleshooting equipment. Another problem is that you
normally need a couple things to troubleshoot an oscilliscope, such as a
frequency generator and - another oscilliscope.
I've used
the flow chart on the technical manual and it appears that the horizontal
signal board needs to be repaired. The CRT projects a beam only when I press
the TEST button and only vertical adjustments are possible. Horizontal
adjustments while holding the test? button down do nothing.
Anyone in
the San Antonio TX area willing to help a newbie out? I work
long hours (3am - 8pm mostly) so the time I get off is usually weekends.
No virus found in this message.
Checked by AVG -
Version: 2016.0.8013 / Virus Database: 4782/15015 - Release Date: 10/07/17
|
Re: Affordable VNA Cal Kit in 12~15Ghz
Hi,
It depends on what you want to do. If you need measurements you need a cal kit with known coefficents, if you just want to adjust for "best" performance you can get away with less.
I don't think anyone was saying you can't make your own cal kit, just that Dave's kit is probably a more cost effective option overall. You could aquire all the components, check them as best you can and then send for calibration only to find one or more was out of limits and off you go again. Don't forget you need a calibration measurement device at least 3 times better than your required accuracy of the cal kit. I had a play with this to produce just a open / short / load (OSL) set for scalar measurements (no phase or length) to 1GHz. I had access to a modern 8GHz VNA and cal kit (a Kirby one) and was amazed how bad anything other than a proper calibration load (and most the used calibration ones I tried) were in terms of return loss.
Dave will do higher frequency SMA kits to special order You should contact him.
No connection to Dave, just a happy customer.
Robert G8RPI.
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Re: Slightly off topic puzzle
Hi,
No, I don?t think so. For best possible long term performance
an oven controlled crystal oscillator shall run continuously with power on. Otherwise,
turning power off and later turning power on again, you will get the retrace phenomenon.
There seems to be a temperature issue with some component. You
may find the culprit by using cooling spray on one component at a time. And
start with the first divider in the counter chain for example...
?
G?ran
|
Hi Adam
Regarding 70000 I have not spent any time
on the subject over the summer due to other commitments so
Firstly could you let the group have your
general location so that local help might be found as I am no expert?
?
I am told you require a HP 9000 computer
system running basic 5.1 or later a hard drive and a floppy either 5.25 or 3.5 and
I am well on the way to achieving this
Please note the hard and floppy drives for
the HP 9000 computer system are very fragile and I haven¡¯t found any replacements
?
Regards Paul B
From:
hp_agilent_equipment@...
[mailto:hp_agilent_equipment@...]
Sent: 08 October 2017 03:41
To: hp_agilent_equipment@...
Subject: Re:
[hp_agilent_equipment] Re: Hp 70909A vs 70910A
?
Paul
Responding to your older post about the 70910A Receiver Personality
software.? I have it loaded on my system and desire to archive it.?
Perhaps someone here can offer me some ideas on how to do this/talk me through
it?? I'm concerned that I don't corrupt or accidentally delete any of the
files while I'm at it.? I have a couple 32KB cards, but the total size of
the files is about 700K or so.? I don't have the 9122 series floppy
drive.? Any thoughts on copying these files over the GPIB to hard disc so
I can post them to KO4BB for posterity (and system safety/longevity)?
Adam
No virus found in this message.
Checked by AVG -
Version: 2016.0.8013 / Virus Database: 4782/15017 - Release Date: 10/08/17
|
Re: Affordable VNA Cal Kit in 12~15Ghz
Thank you for all responses guys!
I did look at Dave¡¯s cal kit but the SMA version doesn¡¯t cover my frequency range.
Reginald, I will look at the paper you indicated. I¡¯m not afraid of math. I used to do J.D. Jackson¡¯s Classical Electrodynamics end chapter problems to do brain workout although I¡¯m not a physicist:)
I use my VNA to do some casual measurement of some 15ghz filters and couplers, surprisingly the uncorrected measurement result matched the manufacturer¡¯s data sheet nicely. I guess I could just live with that. I understand that I can¡¯t reach the full potential of my 8510C without a cal kit, oh well¡I¡¯m not doing academic research nor making a filter for a missile:)
Regards, Calvin
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On 10/07/2017 08:13 PM, Mel Swanberg?wa6jbd@...
[hp_agilent_equipment] wrote:
> I'll make a third recommendation for Kirkby Microwave cal kits. I've purchased two of them, and the proof is in the verification tests. When my measurements closely match the supplied verification device, it just doesn't get better than that.?
>?
> One of my kits even came with custom coefficients for a number of different frequencies that I specified. When compared to what else is out there, you'd be hard pressed to find a better option.?
I have two as well, good stuff.
-Dave
--?
Dave McGuire, AK4HZ
New Kensington, PA
|
Re: Slightly off topic puzzle
?
I believe the oven stays on all the time but the
oscillator?powers down.
----- Original Message -----
Sent: Saturday, October 07, 2017 11:10
PM
Subject: [hp_agilent_equipment] Re:
Slightly off topic puzzle
?
Note: the flicker source is not in the ovenized crystal oscillator; the
oven is powered even in standby. When powering up from standby, the
synthesizer is spot on the frequencies up to 20ghz for about 10 minutes, then
the tuning voltage jumps are starting and the frequency offsets are
occurring.?
This will be a fun repair, after the nightmare of replacing the mixer
(was literally melted) and a blown power supply (wire bonded, so I had to get
creative) in the band 0 downconverter.?
|
Re: Slightly off topic puzzle
Note: the flicker source is not in the ovenized crystal oscillator; the oven is powered even in standby. When powering up from standby, the synthesizer is spot on the frequencies up to 20ghz for about 10 minutes, then the tuning voltage jumps are starting and the frequency offsets are occurring.?
This will be a fun repair, after the nightmare of replacing the mixer (was literally melted) and a blown power supply (wire bonded, so I had to get creative) in the band 0 downconverter.?
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Re: Slightly off topic puzzle
Meantime the puzzle was solved. The bug is in the 6747B synthesizer, the reference loop (10MHZ), although reported as locked, it ¡°flickers¡±. Easy to see if monitoring the VCO tuning voltage, it quickly changes quite a bit, after the instrument warms up. These flickers create spurious components at the output which in turn falsely trigger the counter gate. Before warming up, the frequencies are dead on.
The root cause of the flickers is not yet known, just in case I ordered the two boards a6 (Vco and loop gain) and a7 (reference divider). I already tried replacing the opamp, still the same. It could be the 500MHz SAW oscillator (unobtanium, but can be replaced by a maxim max2609 Vco plus a gain stage, plus some dc (bias, tuning) scaling,?there¡¯s room enough on the board) or the ECL and schottky counters/flip-flops and gates in the divider and phase detector. My bet goes toward the SAW oscillator hybrid, but fixing the current boards will happen later, I have to fix the synthesizer first.
|
Paul
Responding to your older post about the 70910A Receiver Personality software.? I have it loaded on my system and desire to archive it.? Perhaps someone here can offer me some ideas on how to do this/talk me through it?? I'm concerned that I don't corrupt or accidentally delete any of the files while I'm at it.? I have a couple 32KB cards, but the total size of the files is about 700K or so.? I don't have the 9122 series floppy drive.? Any thoughts on copying these files over the GPIB to hard disc so I can post them to KO4BB for posterity (and system safety/longevity)?
Adam
|
Re: 53131A, 53132A, 53181A Extra Channel option upgrade/downgrade
Hi all, OK - I've stuffed up. my eeprom got erased during this process. I've?done a recal except for the time interval fine.?However my eeprom is pretty much blank now and doesn't have?the header words. Are they at the end of the 8K?
Could I trouble someone for an eeprom image please to compare with what I have now?
I assume the header was at the end of the eeprom as the instructions are to change the start of the eeprom, my eeprom is FF from 0x01 through 0x1F with the firmware revision at 0x28?(3944). It's then blank from 0x200 through 0x1FFF.
My unit has no freq extenders (at the moment), I'm designing my own 12 GHz unit. The 12GHz e*ay units must use the default divide by 128 as?they're not changing the?eeprom so they're trying to get almost 100MHz through the ribbon cable,?which means they are probably pumping a lot of volts down that line to get those 2n3904 transistors to work at that frequency (ft=250Mhz) and given the main channels are divide by 4 before they get to the fpga which has a max clock speed of around 80Mhz,?means the fpga probably isn't expected to work beyond 60Mhz or so.
Thanks Greg
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Re: 8901B Power level zeroisation
On 10/07/2017 08:50 AM, Peter Gottlieb hpnpilot@... [hp_agilent_equipment] wrote: There was definitely a wave of these going cheap.? That seems to happen with a
lot of stuff, 99.9% of which I miss when looking for something. Damn. I missed it too. But I bought my 8901B a very long time ago. The reason I'm not a big fan of this instrument is because although it can do
many things it doesn't seem great at any of them.? Correct me if I'm wrong.? As
a frequency counter a 5334B totally blows it away, as does a Racal 1992.? In
digits, sensitivity, response speed and of course versatility.? I even have a
5335 which I put one of those cheap cell site rubidium oscillators in because
there's so much space inside.? As a power meter the 437/438 and of course the
E4418B seem far superior and are all available, like the 5334 and 5335 counters,
dirt cheap.? That leaves modulation meter, which is why I picked up the 8901B in
the first place.? Unless you're calibrating some piece of gear, a scope (for AM)
or a 53310A (for FM) are far easier and quicker to use and give you more
information.
So, while I have the nice clean 8901B, it mostly serves to keep the rack it's
mounted in from being too easy to move around.? I'm not even incentivized enough
to track down why a good power sensor doesn't work right with the thing. The 8901B is a fine instrument; it helps to not think of it as a "do everything" box, though it does do a lot of random stuff. When I want to measure RF power, I turn on a power meter. When I want to measure frequency, I turn on a frequency counter. The fact that the 8901B does these things is almost incidental; they got at least some of that functionality "for free" in designing a modulation analyzer. So, it helps to think of it as just that...a modulation analyzer. For that, it does very well. But don't be tempted by its "I'll replace everything on your bench" feature list. Right tool for the job, etc. That said, though, for my applications, I can't tell you the last time I modulated a carrier "analog". ;) For that reason, my pristine 8901B sees almost no use. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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On Fri, Oct 6, 2017 at 11:35 PM, Jeremy Nichols <jn6wfo@...> wrote: The 411A is the older, vacuum tube version of the 3406, vintage the same as the 400D/H/L AC and the 412 DC voltmeters. They are really very different. The 411A uses a traditional diode detector, that is supposedly linearized through the use of a matched feedback diode. The 3406A uses a fast sampler to convert the RF input to an IF frequency for measurement, which is a much more accurate technique.
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Re: Affordable VNA Cal Kit in 12~15Ghz
On 10/07/2017 08:13 PM, Mel Swanberg wa6jbd@... [hp_agilent_equipment] wrote: I'll make a third recommendation for Kirkby Microwave cal kits. I've purchased two of them, and the proof is in the verification tests. When my measurements closely match the supplied verification device, it just doesn't get better than that.
One of my kits even came with custom coefficients for a number of different frequencies that I specified. When compared to what else is out there, you'd be hard pressed to find a better option. I have two as well, good stuff. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
|
Re: Affordable VNA Cal Kit in 12~15Ghz
I'll make a third recommendation for Kirkby Microwave cal kits. I've purchased two of them, and the proof is in the verification tests. When my measurements closely match the supplied verification device, it just doesn't get better than that.
One of my kits even came with custom coefficients for a number of different frequencies that I specified. When compared to what else is out there, you'd be hard pressed to find a better option.
Mel - WA6JBD
--------------------------------------------
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On Sat, 10/7/17, robert8rpi@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:
Subject: Re: [hp_agilent_equipment] Affordable VNA Cal Kit in 12~15Ghz
To: hp_agilent_equipment@...
Date: Saturday, October 7, 2017, 7:55 AM
Hi,
It's not a simple job to
measure a cal kit, most cal labs will not
"calibrate" an unknown set of components.
I second the recommendation for Kirby
Microwave. Dave's kits are excellent and a much better
option than some unkown overpriced kit bought on ebay.
Search the group for more information, it's all been
said before.
Robert
G8RPI.
|
Re: Affordable VNA Cal Kit in 12~15Ghz
I'm interested.
I think I can get access to the a cal kit through work.
6GHz would be plenty since I don't have equipment that goes past
3GHz.
Ed
???
Hi Calvin
depending on your frequency range of interest, you can
make your own cal kit. I made a SMA kit which works fine
up to 6GHz, and a N kit which works to approx. 7GHz.
However, to calibrate your own cal kit, you need to have
access once to a 'real' cal kit, then measure your own
standards.
If you are interested, I can tell you more details
about this.
Tobias HB9FSX
-------- Original message --------
Date: 10/7/17 05:03 (GMT+01:00)
Subject: [hp_agilent_equipment] Affordable VNA Cal Kit
in 12~15Ghz
???
Hi there,
I need to measure and tune some of the RF
passive components i.e. filters, DC, ring
resonators etc I made for my hobby projects. I
would like to get some more precision but I
don't have $5000+ laying around for a
calibration kit.
Looking at ebay, there are some DC-26.5g HP
calkit offered at $2500 range and claiming
"fully working". How would I know if it is
"working" without sending it to Keysight for a
verification?
Is there any Cal Kit in the 12~15 ghz range
that doesn't cost an arm and a leg, and provide
definition files that I can load to a 8510C VNA?
Have anyone tried to make their own open,
short, load, through, then rent a calibrated VNA
to characterize them to make their own poorman's
cal kit?
Thanks,
Calvin
|
Re: Affordable VNA Cal Kit in 12~15Ghz
I hope this won't be taken personally. But I think the OP is being done a disservice by being told he needs to buy something that he is clearly skilled enough to make himself.
It was said is that someone like Transcat won't measure S parameters for a set of passive components over a specified frequency range. That may be true, but I find it rather amazing if it is. NIST certainly will, but I expect that they're a lot more expensive. This is vastly less work than an instrument calibration, so it should be cheaper. There are no adjustments to be made.
As for the feasibility, that is not an issue as was noted by others. For bleeding edge work there are references that get sent from lab to lab. The measurements are then reviewed and discussed at length.
I'm quite certain that David's kits are a much better choice than name brand stuff bought on eBay in unknown condition. I would expect he provides a set of calibration sweeps to compensate for the unavoidable errors in the standards. He certainly is no more able to make perfect standards than anyone else. Are David's calibration sweeps as good as Keysight's? Quite unlikely. They can afford to get in house references measured by NIST. Keysight's price for their references reflects the costs and the sales volume.
If the test fixture is designed to probe microstrip devices, then the article I cited is clearly the way to go. I was driving most of the day and doing algebra in my head without paper and pencil is unreliable at best. So I've not worked out the algebra for multiple devices with multiple connectors. An assumption of connector equivalence may be required to account for connector terms. At the moment I don't know.
There is a vast literature on the problem of quantifying instrument and reference errors. All you need is as many measurements as there are errors in the references. And a willingness to let yourself get beat up for awhile by the algebra.
It is certainly true, that in a commercial setting buying a set of references from Keysight is the prudent approach. But for a hobbyist it's silly.
A story from a different realm.
A salesman was calling on a company. While chatting with one of the employees he asked what they made. "Gears of all types." "Really? I thought you had to buy those."
Yeah, I'm a reflection seismologist, not an EE. But 1D (transmission line) problems are the first thing we have to learn. After that we spend most of our time on 2D and 3D issues because the earth is not 1D. It's not EM, but the algebra is the same. I've been quite surprised at how intimidated people are by matrix algebra.
Have Fun!
Reg
-
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Re: Need HP transformer IDs
Thanks Vladan. Being audio types would make sense, since some of the windings have very large L, that is even out of range of my 4276A. They may also be inductors - one has only two terminals (out of six) that had actually been soldered to. I don't know if simple inductors could be included in this part prefix - maybe they used a transformer winding as a big choke. I thought that these may have been from an old 740A that I junked out years ago, but can't find a manual for that. The 740B manual seems to show use of one of this style package for a dual 500 H choke in the front-end filter, but it's a different part number (9110-0197).
I've been doing some large scale garage cleanout, and rediscovering stuff that I hadn't seen in years, or didn't even know I had. Nowadays I mark most big parts that I keep with what they came from, whatever other info is evident, and the date. Back then I didn't, except for a few things that were very unusual.
Ed
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Paul Bicknell
G?ran Krusell
Dave McGuire