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Re: Strange spurious in 8568B

 

Curiosity

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Scott McGrath
Sent: Saturday, 23 February 2019 9:49 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Strange spurious in 8568B

Y

Content by Scott
Typos by Siri
Re: hp8595A faulty

Maurizio IZ1MDJ
 

Hi Dave many thanks , I will try to isolate the fault subassy.
Maurizio
IZ1MDJ
HP 86603A question...

 

First, would anyone have a spare attenuator knob for this series of RF heads--mine was damaged as purchased.

Second, why do some versions have a push button to disable the freq. doubler? over the range of 650 to 1300 MHz?
Was this needed only for the A and B versions of the 8660?? Mine is? a D.

Also have an 86601A that has low RF output until it warms up for a few hours. Meter goes from 1/4 scale to normal.
Is that a common problem?'

Pete W1BR
Re: HP 3478A - working

 

Mine has a metal frame.? Not sure when they switched, but earlier ones had the metal frame.

Daun
Daun E. Yeagley II, N8ASB

On 2/23/2019 12:23 AM, Dave McGuire wrote:
On 2/22/19 11:42 PM, Don Bitters via Groups.Io wrote:
Just a brief comment on your bent corner frame. The frame is heat/pressure cast powdered aluminum, magnesium. If you heat it and apply pressure to the bend it will likely break the corner off. I have had mixed success bending corners of the 85660, 85680, and 85662 from frames. The technique I used was about 60-70% successful - a sharp, abrupt shock caused the deformation without breaking the frame, another abrupt shock should reverse some of the damage without breaking the frame. Remove the frame, support the corner in a solid right angled bracket (like a piece of heavier steel angle stock in a vise. Take another piece of square stock and place it on the inside of the deformation and then smack the square stock with a hammer hard close to the deformation. This should remove most of the bending, but note again my success rate is not 100%. The next best choices are live with it, or find another sacrificial unit.
I didn't look at the OP's pic this time around (busy few days here),
but every 3468/3478 I've seen has had a plastic frame.

-Dave
Re: 5385A: LCD Backlight?

 

At 2019-02-22 08:44 PM, Mark Bielman wrote:
Picked up an HP 5385A Frequency Counter for my collection. Seems to work well BUT the display is hard to see in dim light.
Wondering if it's possible to add some back lighting to the LCD. (like LED strips maybe) Have not opened it up yet... just arrived today.

I've wondered the same about my HP4263A LCR meter. It's been a while, but IIRC I opened it up and concluded it wasn't really feasible. Keep in mind that there are three types of LCDs:

1) Transparent - almost have to be backlit to be visible.
2) Reflective - opaque reflective backing, only a front light will do.
3) Transflective - somewhere in between.

I don't remember for sure, but I think I concluded either that mine are (2), but it may have been that there just wasn't any place to squeeze in an LED.

Steve Hendrix

Re: Strange spurious in 8568B

 

Y

Content by Scott
Typos by Siri
Re: 8970B Problem

 

¿ªÔÆÌåÓý

More likely too much blood in your caffeine stream? My 8970B takes about 40 minutes to settle from a cold start but then it's fine. The time taken for the NF display to settle is affected by the value of the smoothing factor you've set of course.

Adrian

On 2/23/2019 8:20 AM, kevin kearns wrote:

Sorry too early for me this morning!
?
Gain reads -6.01dB, got there in the end.
?
Kevin
Re: 8970B Problem

kevin kearns
 

?
Sorry too early for me this morning!
?
Gain reads -6.01dB, got there in the end.
?
Kevin

----- Original Message -----
Sent: Saturday, February 23, 2019 8:16 AM
Subject: Re: [HP-Agilent-Keysight-equipment] 8970B Problem

Gain reads -6.10db!
----- Original Message -----
Sent: Saturday, February 23, 2019 8:11 AM
Subject: Re: [HP-Agilent-Keysight-equipment] 8970B Problem

Hi All,?
?
?Does anyone else notice that it takes longer?for the NF reading to stabilize?compared with?the gain figure on the 8970B? When you calibrate the machine after a few minutes after switch on, gain reads zero and is stable. NF will read zero straight after cal?but drifts a bit, so it takes 10 mins warm up or so for the reading to?stay at zero after cal.
?
Checking the machine with a precision 6.0 dB attenuator, Gain reads 6.01dB and NF reads 6.10 dB when all warmed up.

Kevin
----- Original Message -----
Sent: Friday, February 22, 2019 11:26 PM
Subject: Re: [HP-Agilent-Keysight-equipment] 8970B Problem

Dear All,

Many thanks for your advice, especially to ¡°nj902¡± who pointed me to the explanation.

I¡¯ve now verified what happens as gain/NF of the measured object is changed and it is nice to find that this is not a fault.

Regards,

Alwyn

From:?nj902
Date: Thu, 21 Feb 2019 21:22:23 PST?

Apparently, this is normal.

Look up Agilent (Keysight) Application Note 1484? "Non-Zero Noise Figure After Calibration"

_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.

Tel.: +44 (0) 20 7376 4110


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________
Re: 8970B Problem

kevin kearns
 

?
Gain reads -6.10db!

----- Original Message -----
Sent: Saturday, February 23, 2019 8:11 AM
Subject: Re: [HP-Agilent-Keysight-equipment] 8970B Problem

Hi All,?
?
?Does anyone else notice that it takes longer?for the NF reading to stabilize?compared with?the gain figure on the 8970B? When you calibrate the machine after a few minutes after switch on, gain reads zero and is stable. NF will read zero straight after cal?but drifts a bit, so it takes 10 mins warm up or so for the reading to?stay at zero after cal.
?
Checking the machine with a precision 6.0 dB attenuator, Gain reads 6.01dB and NF reads 6.10 dB when all warmed up.

Kevin
----- Original Message -----
Sent: Friday, February 22, 2019 11:26 PM
Subject: Re: [HP-Agilent-Keysight-equipment] 8970B Problem

Dear All,

Many thanks for your advice, especially to ¡°nj902¡± who pointed me to the explanation.

I¡¯ve now verified what happens as gain/NF of the measured object is changed and it is nice to find that this is not a fault.

Regards,

Alwyn

From:?nj902
Date: Thu, 21 Feb 2019 21:22:23 PST?

Apparently, this is normal.

Look up Agilent (Keysight) Application Note 1484? "Non-Zero Noise Figure After Calibration"

_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.

Tel.: +44 (0) 20 7376 4110


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________
Re: 8970B Problem

kevin kearns
 

?
Hi All,?
?
?Does anyone else notice that it takes longer?for the NF reading to stabilize?compared with?the gain figure on the 8970B? When you calibrate the machine after a few minutes after switch on, gain reads zero and is stable. NF will read zero straight after cal?but drifts a bit, so it takes 10 mins warm up or so for the reading to?stay at zero after cal.
?
Checking the machine with a precision 6.0 dB attenuator, Gain reads 6.01dB and NF reads 6.10 dB when all warmed up.

Kevin

----- Original Message -----
Sent: Friday, February 22, 2019 11:26 PM
Subject: Re: [HP-Agilent-Keysight-equipment] 8970B Problem

Dear All,

Many thanks for your advice, especially to ¡°nj902¡± who pointed me to the explanation.

I¡¯ve now verified what happens as gain/NF of the measured object is changed and it is nice to find that this is not a fault.

Regards,

Alwyn

From:?nj902
Date: Thu, 21 Feb 2019 21:22:23 PST?

Apparently, this is normal.

Look up Agilent (Keysight) Application Note 1484? "Non-Zero Noise Figure After Calibration"

_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.

Tel.: +44 (0) 20 7376 4110


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________
Re: hp8595A faulty

 

Maurizio
Sorry.... NO ..... dramatically different beasts the 95A and the 95E
Dave
NR1DX
manuals@...

On 2/22/2019 2:50 AM, Maurizio IZ1MDJ wrote:
Hi to all , I have a spectrum analyzer hp8595A and I suspect the RF assembly has a problem.
Can I replace this assembly , whith one from an hp8595E ?
Many thanks in advance for your help
Best regards

Maurizio IZ1MDJ
--
Dave
Manuals@...
www.ArtekManuals.com
Re: 8970B Problem

kevin kearns
 

?
Thanks Dario

----- Original Message -----
Sent: Saturday, February 23, 2019 7:07 AM
Subject: Re: [HP-Agilent-Keysight-equipment] 8970B Problem

Hi Kevin, this is the link for AN1484 (and other info, manual, etc.):

Dario IU3ARP

?
Il 23 febbraio 2019 alle 7.53 kevin kearns <kkyahoo@...> ha scritto:

Got a link to AN1484?
?
Kevin
----- Original Message -----
Sent: Friday, February 22, 2019 11:30 PM
Subject: Re: [HP-Agilent-Keysight-equipment] 8970B Problem

Dear Dave,

Thanks.

Yes, uncorrected NF is normal.

The explanation proved to be that given in AN1484.

So I¡¯ve learned something, for which I am most grateful.

Regards,

Alwyn

IIRC there is an IF output on the rear. Have a look at that with a spectrum analyzer. I had an 8970B which showed stability issues.?

Is the uncorrelated noise figure in spec? I believe its about 6-8 dB depending on frequency.?

BTW, I believe someone has created a device that makes an 8970A/B show a negative noise figure by it having a negative input resistance.?
_____________________________________________________

Alwyn Seeds, Director
114 Beaufort Street (Management) Company Ltd.,
114 Beaufort Street,
London,
SW3 6BU

+44 020 7376 4110

114 Beaufort Street (Management) Company Ltd., Registered in England and Wales: No. 02797775 Registered Office Address: 114 Beaufort Street, London, SW3 6BU
______________________________________________________


?

?
Re: 8970B Problem

 

Hi Kevin, this is the link for AN1484 (and other info, manual, etc.):

Dario IU3ARP

?

Il 23 febbraio 2019 alle 7.53 kevin kearns <kkyahoo@...> ha scritto:

Got a link to AN1484?
?
Kevin
----- Original Message -----
Sent: Friday, February 22, 2019 11:30 PM
Subject: Re: [HP-Agilent-Keysight-equipment] 8970B Problem

Dear Dave,

Thanks.

Yes, uncorrected NF is normal.

The explanation proved to be that given in AN1484.

So I¡¯ve learned something, for which I am most grateful.

Regards,

Alwyn

IIRC there is an IF output on the rear. Have a look at that with a spectrum analyzer. I had an 8970B which showed stability issues.?

Is the uncorrelated noise figure in spec? I believe its about 6-8 dB depending on frequency.?

BTW, I believe someone has created a device that makes an 8970A/B show a negative noise figure by it having a negative input resistance.?
_____________________________________________________

Alwyn Seeds, Director
114 Beaufort Street (Management) Company Ltd.,
114 Beaufort Street,
London,
SW3 6BU

+44 020 7376 4110

114 Beaufort Street (Management) Company Ltd., Registered in England and Wales: No. 02797775 Registered Office Address: 114 Beaufort Street, London, SW3 6BU
______________________________________________________


?

?
Re: 8970B Problem

kevin kearns
 

?
Got a link to AN1484?
?
Kevin

----- Original Message -----
Sent: Friday, February 22, 2019 11:30 PM
Subject: Re: [HP-Agilent-Keysight-equipment] 8970B Problem

Dear Dave,

Thanks.

Yes, uncorrected NF is normal.

The explanation proved to be that given in AN1484.

So I¡¯ve learned something, for which I am most grateful.

Regards,

Alwyn

IIRC there is an IF output on the rear. Have a look at that with a spectrum analyzer. I had an 8970B which showed stability issues.?

Is the uncorrelated noise figure in spec? I believe its about 6-8 dB depending on frequency.?

BTW, I believe someone has created a device that makes an 8970A/B show a negative noise figure by it having a negative input resistance.?
_____________________________________________________

Alwyn Seeds, Director
114 Beaufort Street (Management) Company Ltd.,
114 Beaufort Street,
London,
SW3 6BU

+44 020 7376 4110

114 Beaufort Street (Management) Company Ltd., Registered in England and Wales: No. 02797775 Registered Office Address: 114 Beaufort Street, London, SW3 6BU
______________________________________________________
Re: HP 3478A - working

 

The bezel around the front panel (which is what is shown and described) is indeed plastic on my unit, as is the rear bezel.? There is no metal construction except for the 3-sided chassis and of course the wraparound cover.
Re: HP 3478A - working

 

On 2/22/19 11:42 PM, Don Bitters via Groups.Io wrote:
Just a brief comment on your bent corner frame. The frame is heat/pressure cast powdered aluminum, magnesium. If you heat it and apply pressure to the bend it will likely break the corner off. I have had mixed success bending corners of the 85660, 85680, and 85662 from frames. The technique I used was about 60-70% successful - a sharp, abrupt shock caused the deformation without breaking the frame, another abrupt shock should reverse some of the damage without breaking the frame. Remove the frame, support the corner in a solid right angled bracket (like a piece of heavier steel angle stock in a vise. Take another piece of square stock and place it on the inside of the deformation and then smack the square stock with a hammer hard close to the deformation. This should remove most of the bending, but note again my success rate is not 100%. The next best choices are live with it, or find another sacrificial unit.
I didn't look at the OP's pic this time around (busy few days here),
but every 3468/3478 I've seen has had a plastic frame.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
5385A: LCD Backlight?

 

Hello group! New member here. So glad I found you.

Picked up an HP 5385A Frequency Counter for my collection. Seems to work well BUT the display is hard to see in dim light.
Wondering if it's possible to add some back lighting to the LCD. (like LED strips maybe) Have not opened it up yet... just arrived today.

Maybe some experiments are in order. If I/we find something, perhaps use it on my 3468A DMM as well?

Mark
hp8595A faulty

 

Hi to all , I have a spectrum analyzer hp8595A and I suspect the RF assembly has a problem.
Can I replace this assembly , whith one from an hp8595E ?
Many thanks in advance for your help
Best regards

Maurizio IZ1MDJ
Re: HP 3478A - working

 

Just a brief comment on your bent corner frame. The frame is heat/pressure cast powdered aluminum, magnesium. If you heat it and apply pressure to the bend it will likely break the corner off. I have had mixed success bending corners of the 85660, 85680, and 85662 from frames. The technique I used was about 60-70% successful - a sharp, abrupt shock caused the deformation without breaking the frame, another abrupt shock should reverse some of the damage without breaking the frame. Remove the frame, support the corner in a solid right angled bracket (like a piece of heavier steel angle stock in a vise. Take another piece of square stock and place it on the inside of the deformation and then smack the square stock with a hammer hard close to the deformation. This should remove most of the bending, but note again my success rate is not 100%. The next best choices are live with it, or find another sacrificial unit.
Don Bitters
Re: Strange spurious in 8568B

 

¿ªÔÆÌåÓý

Ernst,

?

The input level is higher than you should be using, but ?I think you may still have a fault because some are saying they can¡¯t replicate this issue on their HP 8568B spectrum analysers.

?

I only have access to the HP70000 series (which also have a last IF of 21.4MHz) but they seem to perform quite well in rejection of half IF except with high input levels as you suggest.

?

?

FOR CONSIDERATION? (SUPER HETERODYNE RECEIVERS GENERALLY) ¨C FIXED FREQUENCY

?

Single or multiple conversion radios will have a tuned bandpass frontend and some designers only consider the image rejection because balanced mixers reject even order harmonics.

?

The half IF spurious response issue can happen with multiple conversion radios as well, it just depends on the design.

?

First IF bandwidth, local oscillator(s) purity, mixer(s) type balanced or other types, IF amplifier linearity all factor in to spurious response performance

?

Field strength meters, also used in testing, tune to fixed frequencies and have variable bandwidth and can usually both demodulate the signal and display the received signal level.

?

?

IN THIS INSTANCE HOWEVER WE ARE TALKING ABOUT A SPECTRUM ANALYSER. ??(You have to get your head around the difference between fixed and swept measurements.)

?

So the signal presented to the mixer via a low pass (<1500MHz) filter is effectively up converted a high frequency IF. The image frequency would be somewhat higher again. ??

?

The operation after the first mixer is effectively a field strength meter (FSM) on a fixed frequency with more bandwidth options with the level displayed on a screen rather than a meter.

?

As the first LO sweeps into the first mixer, it is effectively doing the reverse of the receiver spurious test, because whilst the RF input signal to the spectrum analyser remains constant, the FSM is being presented with changing frequencies such that the ¡°half IF¡± response is at some point presented to it.

?

At that instant any stage in the FSM that can cause distortion to that signal and create second harmonic makes it possible for that harmonic to mix with the second harmonic of the last LO.

?

?

THE UPPER LIMIT OF THE OBSERVED ¡°ISSUE¡± AT -64dBm.

?

I really am not sure, but remember that the IF amplification changes automatically when you change reference level to keep the input signal level to top of screen.

?

So maybe the point at which the second harmonic is being generated is presented a constant input above -10dBm.

?

Regards Noel

?

From: [email protected] [mailto:[email protected]] On Behalf Of amirb
Sent: Saturday, 23 February 2019 3:02 AM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Strange spurious in 8568B

?

he didn't say the spur amplitude didn't change with input rf signal amplitude
it does change: going from -74dbm at -20dBm RF to -64dBm at -10dBm Rf but remains constant after that

however, the half IF issue that people are talking about only occurs in single conversion radios
and it requires the second harmonic of input signal. None of these are the case here...

On Fri, Feb 22, 2019 at 10:55 AM, Chuck Harris wrote:

It is improbable that the mixing element in whatever
is going to cause a 10.7 MHz image response (in a 21.4MHz
If'd receiver) is going to be such a hard limiter that
the displayed spur can't change amplitude when the
input signal changes amplitude.

What I am hearing said is that there is no 10.7 spur
on the display when there is no signal, but when a
signal is applied (from any generator, at any frequency),
a 10.7MHz spur appears below the generator's signal on
the SA display... and no matter what the generator's
signal's amplitude, the spur is -63dBm

That is not the sort of behavior one comes to associate
with large household appliances.

I think a more probable explanation is that the OP is
using a 10MHz reference throughout his lab, and that
reference is leaking into the SA somehow. The 10MHz
is being mistaken or misrepresented on the SA as 10.7MHz.

-Chuck Harris

Noel VK3NH wrote:

Chuck,

I don¡¯t follow that logic unless you are talking about the second harmonic output of the generator into the input stage then I agree.
The fundamental is what goes through the various mixers and causes second harmonics in later stages, probably gain compressed.
I suspect the issue is excessive second harmonic in the final mixer combined perhaps with distortion/overload before the final mixer stage.

One thing that is for sure, the levels involved are way higher than should be applied with the attenuator set to zero.
As stated in the specifications, optimum performance happens at <-30dBm.

Regards Noel

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Chuck Harris
Sent: Friday, 22 February 2019 3:59 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Strange spurious in 8568B

Not really, that pretty much tells you that the spur
doesn't actually come from the input signal.

-Chuck Harris


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