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Re: E4401B No 50MHZ Cal signal

 

Without reading through all of this again... you have a decent scope, correct? You should be able to measure the 50 MHz cal signal with that. (around 20 mV or so) And also follow its path.
I have yet to see problems with the front end on these but I'm sure it happens.

I also have (more than one!) SDR used as a spectrum analyzer for signals above 3 GHz. (I have E4402 & E4403) They will work BUT if you do not know the frequency of interest they can be
pretty slow. (say sweeping from 1 to 6 GHz)

Mark
Re: E4401B No 50MHZ Cal signal

 

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Typo:

?

That sentence should read:

?

? Running without the cap, I notice that the noise floor is higher than it should be, and that changes to levels of the input signal DO NOT cause corresponding changes in display on the spectrum analyzer.? This is telling me that the gain is still too high in the IF stage.

?

The change that I see in the spectrum analyzer are a multiple of the change at the input.? ¨C A 10 db change in the input results in a displayed 20 db change in the SA.? I also see a lot of harmonics of the 50MHz test signal when input is set to the internal 50MHz signal.

?

-- Mike

?

?

?

From: <[email protected]> on behalf of "Michael Williams via Groups.Io" <mike@...>
Reply-To: "[email protected]" <[email protected]>
Date: Monday, April 15, 2019 at 11:02 AM
To: "[email protected]" <[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] E4401B No 50MHZ Cal signal

?

? Running without the cap, I notice that the noise floor is higher than it should be, and that changes to levels of the input signal do cause corresponding changes in display on the spectrum analyzer.? This is telling me that the gain is still too high in the IF stage.
Re: E4401B No 50MHZ Cal signal

 

¿ªÔÆÌåÓý

Nope.? While the scope functions with the cap removed, putting a good replacement back in reproduces the failure.? I suspect that the cap is part of an attenuator/filter.? Removing it is raising the test signal high enough for it to get detected during the alignment procedure.? Running without the cap, I notice that the noise floor is higher than it should be, and that changes to levels of the input signal do cause corresponding changes in display on the spectrum analyzer.? This is telling me that the gain is still too high in the IF stage.

?

?

My current theory is that the front end is blown out and I will need to replace some component in the 1st mixer or amplifier.?? I suspect that the 50MHz test signal is present, but too low for me to measure with current equipment.? Which component(s) are blown at this point is the question.? Next steps are to probe the 1st IF, which I currently don¡¯t have any suitable equipment to measure.

?

I have ordered a LimeSDR which is supposedly capable of measuring up to 3 GHz to use as a stand-in spectrum analyzer.? I know it¡¯s not a calibrated spectrum analyzer, but I am hoping it should give me enough to check relative levels and presence of the IF signals.? I will also be ordering a 54701a active probe today.?

?

This whole process has been a humbling experience.? I¡¯ve got lots of experience with lower frequency gear ¨C oscilloscopes, DVms, radios, etc.? These spectrum analyzers are a very different beast and require very different troubleshooting and probing techniques.

?

-- Mike

?

?

From: <[email protected]> on behalf of "Mark Bielman via Groups.Io" <mbielman@...>
Reply-To: "[email protected]" <[email protected]>
Date: Monday, April 15, 2019 at 10:49 AM
To: "[email protected]" <[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] E4401B No 50MHZ Cal signal

?

Mike - The cap (C448) was not the problem? Rats.

Re: hp3586a selective voltmeter jammed

 

I have an HP8165A which had the same problem. The backup battery behind the front panel was dead. Replacing the battery cured the problem.



On 2019-Apr-13 4:42 PM, cc@... wrote:
Hello,
have you ever experienced this fault?
This unit is now stuck at this leve. Earlier it was jammed as well but only with annunciator LEDs (no LED display) then I moved and disconnected the front panel A98 and I don't know why something changed like shown in this video.



I tried with an oscilloscope but in the most of cases I only notice a single change of a digital state level and nothing else¡­ it is so hard to troubleshoot this type of signal :-( and also very hard to find spare parts.

Thank you
Ciro

---
This email has been checked for viruses by AVG.
Re: E4401B No 50MHZ Cal signal

 

Mike - The cap (C448) was not the problem? Rats.
Re: My $25 "In Poor Shape" 3468A has arrived

 

Alex,
Most definitely you need to ZERO cal the ohms ranges.? ?You can do that with confidence that the gain cals will not be affected..? ?ZERO cal the ohms.? Make sure after installing the jumpers you wait a few minutes for the temperature of the jumpers and input terminals to stabilize.? The heat from your fingers transferred to the jumpers during installation can cause slight thermal errors.

Set the cal switch on the back of the 3468A to cal position? ? ?Switch #8? DOWN
Put meter in manual range and select the range to be caled -- start with lowest range and work up
press from panel:? ?BLUE? SHIFT - CAL(local)
meter will display 000000?
press:? SGL? TRIG
wait for cal to finish

Then see what the RED DEVIL resistors I sent you read to see how good the gain cal is.? Should be on the values I gave you from the measurement on my 3458A at the temperature I wrote down.? 2-W or 4-W should be the same if the resistors are installed very close to the input terminals.? ?Good luck.
?
George
Re: Type of coax for Impedance Analyzer Test Fixtures

 

I just noticed in an earlier post the desire for a cable set in a common sheath. You can use salvaged VGA monitor cables - the kind that are "better" quality and fatter, that have coax rather than just a bundle of wires or twisted pairs. With the right VGA cable stock, you can get four coax (RGB and sync), of the preferable (to me) 75 ohms. You would have to put your own BNCs on - just use 50 ohm BNCs - it won't matter. There are also pre-made sheathed cable sets for various other monitor types, especially from the old days. I have often found nice salvaged BNC cable bundles in various lengths, even up to several meters. For my purposes, I usually have one end of the cables permanently attached to the fixture, and the other end BNC to the LCZ meter. From one long BNC RGB&S set, I can make two good cables, ready to go.

Ed
Re: E4401B No 50MHZ Cal signal

 

¿ªÔÆÌåÓý

Sadly, C448 was not the actual culprit.? When I replaced what I thought was the defective cap, the malfunction returned.

?

At this point, I suspect the 1st IF mixer, or the amplifier post-mixer.? I am waiting on the tools to properly probe the signal path to know for sure.? Once I have the equipment to test, and have more info, I will post it here.

?

-- Mike

?

From: <[email protected]> on behalf of "Alex via Groups.Io" <hpagilentgroup@...>
Reply-To: "[email protected]" <[email protected]>
Date: Monday, April 15, 2019 at 9:56 AM
To: "[email protected]" <[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] E4401B No 50MHZ Cal signal

?

For what it is worth, and to give you guys an idea I have a good background servicing Motorola and other brands of LMR 2-way radio equipment for over 40 years. I use a R2001H service monitor on the bench as most of my customers with big radio fleets are still on analog. Besides the R2001H (1GHz), for tracing I do have a Fluke 85 RF probe, which has a upper -3dB limit of 500MHz, and among other scopes have a Tek 2465B with P6137 400MHz probes, and several 1.1GHz frequency counters which I check and recal as needed with a 10MHz rubidium oscillator. Plus the obligatory 3468, 3478 and several 974/975 handheld DVMs. Not sure that would stack the odds enough in my favor towards being prepared to find the RF problem in that 4411B.

But just in case I would definitively check C448 first, although I doubt will be this lucky.

Re: Type of coax for Impedance Analyzer Test Fixtures

 

The zero and open setups should compensate for cable lengths and fixture characteristics - up to a point. At higher frequencies, and in certain instruments, it may be that specific cable types and lengths are expected by the equipment. My 4276A runs up to only 20 kHz, so is fairly easy to set up over a wide range. There is a maximum cable load capacitance that it can handle, maybe 150-200 pF, so I use 75 ohm cable for all my home-made fixtures. This gives lower C, allowing for longer cables if needed. There is no impedance matching issue here - it's all about the range of parasitic R, L, and C that can be accommodated.

Ed
Re: E4401B No 50MHZ Cal signal

 

On Mon, Apr 15, 2019 at 07:43 AM, ArtekManuals wrote:
The CLIP stands for "Component Level Information Package" Beginning in
the 1990's ( for the most part) HP/Agilent stopped publishing what we
all used to know as full up service manuals. At that point in time most
of the service manuals only? had test and adjustment info but not
schematics , no board part locators nor parts list . For roughly the
next 10 years if you wanted schematics you had to purchase a CLIP ( at a
price of $250-$500 !!!) . Trouble shooting trees as we knew them
disappeared all together for the most part . After 2000 they even
stopped ( for the most part) publishing the CLIPS. Typically CLIPS do
not cover GHZ level RF circuits, YIGS etc. Most do not cover the power
supplies and CRT ( or LCD) display units both of which HP had stopped
making and were 3rd party drops ins.

Dave
manuals@...
--
Dave
Manuals@...
www.ArtekManuals.com

Thank you Dave.

Do you have anything available for the 4411B in terms of service aid literature?
Maybe its time to make another purchase from you.
Re: E4401B No 50MHZ Cal signal

 

For what it is worth, and to give you guys an idea I have a good background servicing Motorola and other brands of LMR 2-way radio equipment for over 40 years. I use a R2001H service monitor on the bench as most of my customers with big radio fleets are still on analog. Besides the R2001H (1GHz), for tracing I do have a Fluke 85 RF probe, which has a upper -3dB limit of 500MHz, and among other scopes have a Tek 2465B with P6137 400MHz probes, and several 1.1GHz frequency counters which I check and recal as needed with a 10MHz rubidium oscillator. Plus the obligatory 3468, 3478 and several 974/975 handheld DVMs. Not sure that would stack the odds enough in my favor towards being prepared to find the RF problem in that 4411B.

But just in case I would definitively check C448 first, although I doubt will be this lucky.
Re: E4401B No 50MHZ Cal signal

 

The CLIP stands for "Component Level Information Package" Beginning in the 1990's ( for the most part) HP/Agilent stopped publishing what we all used to know as full up service manuals. At that point in time most of the service manuals only? had test and adjustment info but not schematics , no board part locators nor parts list . For roughly the next 10 years if you wanted schematics you had to purchase a CLIP ( at a price of $250-$500 !!!) . Trouble shooting trees as we knew them disappeared all together for the most part . After 2000 they even stopped ( for the most part) publishing the CLIPS. Typically CLIPS do not cover GHZ level RF circuits, YIGS etc. Most do not cover the power supplies and CRT ( or LCD) display units both of which HP had stopped making and were 3rd party drops ins.

Dave
manuals@...

On 4/15/2019 10:28 AM, Alex wrote:
Thank you Mark and Mike for the insightful answers.

Unfortunately I don't have access to this particular unit yet, I only saw the error message on one of the pictures sent to me. The selling price is around the $500 mark shipping to FL included. Normally I would feel adventurous in trying to find and ultimately fix this problem, but given the big complexity of these units in this case I am not so sure I really want having to go into the jungle from the get go. Unless someone more experienced in these ESA units thinks the price would still be a good deal, I guess will wait for the next one. Or would anyone care to suggests a counteroffer I could send that would make sense and minimize my risk given the unknowns?

BTW wanted to ask what is the "CLIP" that has been mentioned several times in this thread? Sounds like an extension to the service manual, or some sort of diagnostic hardware. Maybe I should think of getting it ahead of purchasing one of these units. Can't even find a PDF service manual yet.

Thanks again.
--
Dave
Manuals@...
www.ArtekManuals.com
Re: E4401B No 50MHZ Cal signal

 

Thank you Mark and Mike for the insightful answers.

Unfortunately I don't have access to this particular unit yet, I only saw the error message on one of the pictures sent to me. The selling price is around the $500 mark shipping to FL included. Normally I would feel adventurous in trying to find and ultimately fix this problem, but given the big complexity of these units in this case I am not so sure I really want having to go into the jungle from the get go. Unless someone more experienced in these ESA units thinks the price would still be a good deal, I guess will wait for the next one. Or would anyone care to suggests a counteroffer I could send that would make sense and minimize my risk given the unknowns?

BTW wanted to ask what is the "CLIP" that has been mentioned several times in this thread? Sounds like an extension to the service manual, or some sort of diagnostic hardware. Maybe I should think of getting it ahead of purchasing one of these units. Can't even find a PDF service manual yet.

Thanks again.
Re: Type of coax for Impedance Analyzer Test Fixtures

Dr. David Kirkby from Kirkby Microwave Ltd
 

On Sun, 14 Apr 2019 at 22:17, peter bunge <bunge.pjp@...> wrote:
Does anyone have any idea what kind of coax is used for the 16048A, example below, or other test fixtures.

The data is in the impedance handbook. It is coax. I think its a polyethylene dielectric.?

Its not obvious where the 1 m is measured from. I do have a couple of original test leads / fixtures so can check.

If anyone knows why the cables need to be a specific length, please let me know. I would have thought the short/open calibration would have removed the effects of the cables, but I am obviously missing something.

I managed to get a free option 006 (support for 4 m cables) for my 4284A from Keysight.?

I¡¯ve yet to work out how to properly calibrate my 4285A. The manual is far from clear. It needs a 4TP 100 ohm resistor which i have.

Dave

HP say not to substitute. They are in various colours.
Are they 50 ohm or just shielded wire? Perhaps low capacity?
My dielectric test fixture is near completion and I need cables. It would be nice to have the four coax in one sheath.

--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD, Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100
Re: Type of coax for Impedance Analyzer Test Fixtures

 

Is this a guess or do you have real knowledge?
Do you think it is microphone cable?
Peter

On Sun, Apr 14, 2019 at 10:29 PM pianovt via Groups.Io <pianovt=[email protected]> wrote:
50 Ohm, 105 pF/m

Vladan


On Sun, Apr 14, 2019 at 02:17 PM, peter bunge wrote:
Does anyone have any idea what kind of coax is used for the 16048A, example below, or other test fixtures.
HP say not to substitute. They are in various colours.
Are they 50 ohm or just shielded wire? Perhaps low capacity?
Wanted: HP 10509A Loop Antenna, part of HP 117A VLF Comparator

 

Wanted: HP 10509A Loop Antenna in good physical condition, don't care if preamplifier is serviceable.

Contact me directly at whitreeve@... with details.

Whit
Re: Type of coax for Impedance Analyzer Test Fixtures

 

RG-174A/U shows as 50 ohms 102 pF/m

That's pretty darn close!

On 4/14/2019 10:29 PM, pianovt via Groups.Io wrote:
50 Ohm, 105 pF/m

Vladan


On Sun, Apr 14, 2019 at 02:17 PM, peter bunge wrote:

Does anyone have any idea what kind of coax is used for the 16048A,
example below, or other test fixtures.
HP say not to substitute. They are in various colours.
Are they 50 ohm or just shielded wire? Perhaps low capacity?
Re: Type of coax for Impedance Analyzer Test Fixtures

 

50 Ohm, 105 pF/m

Vladan


On Sun, Apr 14, 2019 at 02:17 PM, peter bunge wrote:
Does anyone have any idea what kind of coax is used for the 16048A, example below, or other test fixtures.
HP say not to substitute. They are in various colours.
Are they 50 ohm or just shielded wire? Perhaps low capacity?
Re: Type of coax for Impedance Analyzer Test Fixtures

 

MV and HV utility cables also have layers of semiconducting insulation, but for a different reason.


Peter

On Apr 14, 2019, at 7:46 PM, Chuck Harris <cfharris@...> wrote:

That is just standard microphone cable... Very messy stuff
to strip.

-Chuck Harris

Paul Bicknell wrote:
Hi the only thought I have is as follows



Coax cables used for charge amps as in Pc / volt often have carbon type of
material over the dielectric then the screen to reduce any mechanical noise




Just a thought

Re: Type of coax for Impedance Analyzer Test Fixtures

 

That is just standard microphone cable... Very messy stuff
to strip.

-Chuck Harris

Paul Bicknell wrote:

Hi the only thought I have is as follows



Coax cables used for charge amps as in Pc / volt often have carbon type of
material over the dielectric then the screen to reduce any mechanical noise




Just a thought

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