That
reminds me of a?really cool tip that most people haven't noticed yet.?
Amazon provides full-text searches of many of their books now,?including
technical books.? You can pull up the Rohde reference?just by
searching for "8662a" at ?and clicking on the page
number it gives you.? You will then be able to retrieve .PDF-quality images
of +/- 2 pages in either direction.?
?
No,
really, it's that simple.?
?
The
feature appears to be down at the moment.? ?I hope they haven't
figured out what a one-sided giveaway it is to offer a feature?like that
for technical/reference books that may be purchased only for a few specific
tidbits of information.? With the right cookie-deletion tricks, you can
probably read the whole book that way if you're patient
enough.
?
--
john KE5FX
?
toggle quoted message
Show quoted text
Thanks for the tip
John. Another list member was able to provide me with the schematic (from a
book by Ulrich Rhode), but of course no information on adjustment was
available. The main reason I obtained the 8662A was because of it’s low phase
noise characteristics. First, however, I need to get it working and without
these oscillators being in range the output loops do not lock. I will email
Tom and see what he may be able to come up with. Thanks again. 73 - Mike
?
?
?
Mike B. Feher,
N4FS
89 Arnold
Blvd.
Howell, NJ,
07731
732-901-9193
?
?
-----Original
Message-----
From: John Miles
[mailto:jmiles@...]
Sent: Friday, August 06, 2004 2:14
PM
To: hp_agilent_equipment@...
Subject: RE: [hp_agilent_equipment]
8662A
?
Mike,
you might write to Tom Bruhns (k7itm?(at) aol.com, or tom_bruhns (at)
agilent.com)?and see if he can hook you up with the in-house service
procedure.? He's an?Agilent?engineer who's frequently very
helpful on rec.radio.amateur.homebrew.? This?sounds like one of
those adjustment processes that really shouldn't be?done empirically for
fear of degrading the phase-noise specs.?
-----Original
Message-----
From: Mike
Feher [mailto:n4fs@...]
Sent: Friday, August 06, 2004 7:06
AM
To:
hp_agilent_equipment@...
Subject: [hp_agilent_equipment]
8662A
I have made
some progress since my initial post on my defunct 8662A. One of the 2N5397
JFETs in one of the oscillators was defective and now both oscillators need
to be aligned as they only operate in certain band segments. There are 3
miniature pots on each VCO, two of which adjust the IDS for each FET and the
other for the VS of the FETS. Has anyone repaired these VCOs in the past
that may be able to share their experience. I feel I am real close to
getting it to play. Thanks – Mike
?
Mike B. Feher,
N4FS
89 Arnold
Blvd.
Howell, NJ,
07731
732-901-9193
|
Thanks for the tip John. Another list member
was able to provide me with the schematic (from a book by Ulrich Rhode), but of
course no information on adjustment was available. The main reason I obtained
the 8662A was because of it’s low phase noise characteristics. First,
however, I need to get it working and without these oscillators being in range
the output loops do not lock. I will email Tom and see what he may be able to
come up with. Thanks again. 73 - Mike ?
?
?
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193
?
?
toggle quoted message
Show quoted text
-----Original Message-----
From: John Miles
[mailto:jmiles@...]
Sent: Friday, August 06, 2004 2:14
PM
To: hp_agilent_equipment@...
Subject: RE:
[hp_agilent_equipment] 8662A
?
Mike, you might write to
Tom Bruhns (k7itm?(at) aol.com, or tom_bruhns (at) agilent.com)?and
see if he can hook you up with the in-house service procedure.? He's
an?Agilent?engineer who's frequently very helpful on rec.radio.amateur.homebrew.?
This?sounds like one of those adjustment processes that really shouldn't
be?done empirically for fear of degrading the phase-noise specs.?
-----Original
Message-----
From: Mike Feher
[mailto:n4fs@...]
Sent: Friday, August 06, 2004 7:06
AM
To:
hp_agilent_equipment@...
Subject: [hp_agilent_equipment]
8662A
I have made
some progress since my initial post on my defunct 8662A. One of the 2N5397
JFETs in one of the oscillators was defective and now both oscillators need to
be aligned as they only operate in certain band segments. There are 3 miniature
pots on each VCO, two of which adjust the IDS for each FET and the other for
the VS of the FETS. Has anyone repaired these VCOs in the past that may be able
to share their experience. I feel I am real close to getting it to play. Thanks
– Mike
?
Mike B. Feher,
N4FS
89 Arnold
Blvd.
Howell, NJ,
07731
732-901-9193
|
Mike,
you might write to Tom Bruhns (k7itm?(at) aol.com, or tom_bruhns (at)
agilent.com)?and see if he can hook you up with the in-house service
procedure.? He's an?Agilent?engineer who's frequently very
helpful on rec.radio.amateur.homebrew.? This?sounds like one of those
adjustment processes that really shouldn't be?done empirically for fear of
degrading the phase-noise specs.?
?
--
john KE5FX
toggle quoted message
Show quoted text
I have made some progress since my
initial post on my defunct 8662A. One of the 2N5397 JFETs in one of the
oscillators was defective and now both oscillators need to be aligned as they
only operate in certain band segments. There are 3 miniature pots on each VCO,
two of which adjust the IDS for each FET and the other for the VS of the FETS.
Has anyone repaired these VCOs in the past that may be able to share their
experience. I feel I am real close to getting it to play. Thanks –
Mike
?
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193
|
George at www.glkinst.com can probably fab the cables for you (if not the
grabbers).
-- john KE5FX
toggle quoted message
Show quoted text
-----Original Message-----
From: Philip Pemberton [mailto:philpem@...]
Sent: Friday, August 06, 2004 10:28 AM
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] HP analyser cables?
Hi,
Does anyone have the part number for the woven cable that goes
between a HP
1650B series logic analyser and the pods?
Even better - does anyone have any spares? The cables consist
of a pair of
2x20 0.1-inch pitch connectors (they look like IDC40s) with grey
casing and a
woven cable connecting the two connectors together.
I also need some grabber probes (and maybe some replacement
data wires with
the compensation network built in) to fit the pods. Anyone got
some spares or
know of a source for them?
Thanks.
--
|
Hi,
Does anyone have the part number for the woven cable that goes between a HP
1650B series logic analyser and the pods?
Even better - does anyone have any spares? The cables consist of a pair of
2x20 0.1-inch pitch connectors (they look like IDC40s) with grey casing and a
woven cable connecting the two connectors together.
I also need some grabber probes (and maybe some replacement data wires with
the compensation network built in) to fit the pods. Anyone got some spares or
know of a source for them?
Thanks.
--
Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
philpem@... | ViewFinder, 10BaseT Ethernet, 2-slice,
| 48xCD, ARCINv6c IDE, SCSI
... Free Holiday in Holland for Girls send e-mail to address above for info.
|
I think the best old paper capacitor is a replaced one (with a modern
plastic type) however if you want to test them a Megger (high voltage
insulation tester) is very good for finding leakage at high voltage. Be
careful the test voltage doesn't exceed the capacitor rating. These
meters usually operate on open circuit voltages of 250, 500 or 1000
volts DC, often switchable.
Don Black.
Dave Faria wrote:
toggle quoted message
Show quoted text
Thanks Erik
-----
Original Message -----
Sent:
Wednesday, August 04, 2004 1:38 PM
Subject:
Re: [hp_agilent_equipment] Re: 8552B problem
Hello?Dave ,
?
In my many years of experience?in
?service / fault finding it is my opinion that only two good ways exist
for cap checking ...
1) knowing how the circuit works
and finding the fault by measuring voltages and waveforms under normal
operating conditions in order to detect the faulty component .? Of
course schematics wanted or at least electronic experience is a must .
?
2) Replacing the cap with a known
good one .? If the part of ?the circuit where you could isolate the
trouble is rather small in component count ,? replace them all .? For
older power supplies , if you want to keep the instrument reliable in
the future , best replace all elcos .? Specially those located near to
hot spots (transformers /larger transistors ).
?
Measuring capacitors is
troublesome?, this because in many cases the trouble is related to
applied voltage /waveform or current or temperature or ...?? so it is
very difficult to detect faulty one's unless they died completely of
course .
Moreover desoldering and
resoldering is also a factor that can cause new troubles.
?
Good luck ,
Erik
?
-----
Original Message -----
Sent:
Wednesday, August 04, 2004 10:48 PM
Subject:
Re: [hp_agilent_equipment] Re: 8552B problem
Dave I have a cap. checker built
into a vom.? Would I be able to test the cap.s in the circuit without
doing damage to surrounding componets?? The checker is a late model
Wavetech Meterman.? I know I will not get accurate readings but, will
an obviously bad cap. stand out?? I don't really want to pull loose one
end of the cap to test.? I don't have good de-soldering equipment.?
Also can I use a VOM and read DC resistance and get info that way??
Again would checking DC resistance damage associated componets?? I
don't want to cause any more problems and I'm being very careful with
every step.? Like I say I'm very new to working on SS and I don't want
to cause problems.
?
Thanks for ur help
Dave Faria/WA5TEZ
----- Original Message -----
Sent: Wednesday, August 04, 2004 8:53 AM
Subject: [hp_agilent_equipment] Re: 8552B
problem
Dave,
Interesting that you have that problem.? I have an
8552B that exhibits the same symptoms!? Or at least I
think it does.? My display (in log mode - linear mode
is not often useful in a spectrum analyzer) shows
about 20dB down from the intended calibrated level.
You are to be congratulated on narrowing it down to
the final amplifier - that's good troubleshooting.
Remember that if an amplifier fails, it does not block
all signals.? Instead, a single-stage amplifier may
change from a 15dB gain block (if that's what it was
intended to be) to a 15dB LOSS block - in my case,
that would explain the 30dB down symptom.
In a solid state amplifier, the first suspect is the
amplifying device itself - the transistor.? If the
amplifier is common-emitter, it may have a resistor
from emitter to ground, bypassed by a capacitor.? If
that capacitor fails open circuit, then the
amplifier's gain will be seriously degraded.
Particularly suspect would be any electrolytic
capacitors, at the age of these instruments.
How were you able to operate the IF section outside of
the mainframe?? Or did you plug the module into a
mainframe without an RF section and able to
troubleshoot from the little bit of topside access
that would get you?
As far as the vertical positioning question, remember
that a spectrum analyzer is not intended to be
zero-centered like a scope.? Instead, the bottom line
or the top line of the graticule is the reference.? In
linear mode, that means zero volts at the bottom of
the screen.? The analyzer uses a diode detector in
linear mode, so there's never negative voltage - just
RF envelope voltage.? In log mode, the top line is the
reference.? If you set the gain controls so that zero
dBm (one milliwatt into 50 ohms) is at the top of the
screen, then each division down from that is 2dB or
10dB depending on the setting of the log/lin switch.
With an oscilloscope, we move the vertical position
control around to get the signal on screen, and take
note of where zero landed.? The signal goes up and
down from zero.? On a spectrum analyzer, the absolute
position of the signal on screen is a part of the
measurement, so the zero volt line is at the bottom,
always, and the dB reference line is at the top,
always.
Good troubleshooting!
Dave
?
Date: Tue, 3 Aug 2004 15:06:34 -0700
From: "Dave Faria"
Subject: HP 8552b Problem
Good afternoon list.? I have an HP141T with the Hp
8553b and Hp 8552b
plug ins.? I am new to solid state test equipment and
need some help.? I
have down loaded all the manuals from the BAMA list.
The situation of
my unit is it appears to work in all aspects except it
does not have
sufficient vertical gain.? It will show its
calibration signal in all
modes 2db log, 10db log, and linear but, the display
will not show the
peaks at the levels that it should(7.1mv, -30db).? The
signals are abt 2/3
of what they should be on the .1uv and -60db scale.? I
have done the
test indicated in the 8552b manual to test the final
amp.? I injected a
3mhz signal at pin 14 of card XA4 with that card
pulled.? The test
indicated the amp was not working.? Where do I go from
here??? The down
loaded Hp manual is not that easy to use or read.
Another thing that I
don't understand is why would all functions continue
to work with a failed
amp.? One thing that may help someone who understands
this unit is when
I change the gain(db or mv) the entire trace will
shift either up or
down on the screen, sometimes out of the range of the
vertical position
control.? This problem would be corrected by a balance
control
adjustment on an old tube type scope.
Thanks for any help or comments
Dave Faria WA5TEZ
????? ?????
__________________________________
Do you Yahoo!?
Yahoo! Mail - 50x more storage than other providers!
|
I have made some progress since my initial
post on my defunct 8662A. One of the 2N5397 JFETs in one of the oscillators was
defective and now both oscillators need to be aligned as they only operate in
certain band segments. There are 3 miniature pots on each VCO, two of which
adjust the IDS for each FET and the other for the VS of the FETS. Has anyone
repaired these VCOs in the past that may be able to share their experience. I
feel I am real close to getting it to play. Thanks – Mike
?
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193
?
?
?
?
?
?
|
I have the blue face HP 8510B System.?
I was told it was configured that way for theft reasons.
?
Dan
toggle quoted message
Show quoted text
Hmm.? Yeah, that's pretty ugly (I
just looked).? My 436A is the standard HP color.? Interesting stuff;
I didn't know they made anything like that.
?
-- john KE5FX
I've noticed so far three 436A power meters on ebay with light blue
front faces, though everything else about the instrument seems to be in
normal HP colors.? I've seen a couple times a Fluke 8060A (or was it a
8062A?) in a light blue plastic case (although again, other bits like the
Lexan front label are normal colors) and it was associated with IBM.?
Was the 'blue' 436A a custom configuration for IBM also?? Why would IBM
go to such lengths?? A deterrent of some kind?
?
[Quite frankly, the 'blue gear' is rather ugly to me as nothing else
about the instrument's appearance is changed to be compatible with the
color.? I've got to believe that Fluke's and HP's industrial designers
had fits over the idea.]
?
Anyway, I'd love to hear the story....
?
Don
Beaverton, OR
|
Hmm.? Yeah, that's pretty ugly (I just
looked).? My 436A is the standard HP color.? Interesting stuff; I
didn't know they made anything like that.
?
-- john KE5FX
toggle quoted message
Show quoted text
I've noticed so far three 436A power meters on ebay with light blue front
faces, though everything else about the instrument seems to be in normal HP
colors.? I've seen a couple times a Fluke 8060A (or was it a 8062A?) in a
light blue plastic case (although again, other bits like the Lexan front label
are normal colors) and it was associated with IBM.? Was the 'blue' 436A a
custom configuration for IBM also?? Why would IBM go to such
lengths?? A deterrent of some kind?
?
[Quite frankly, the 'blue gear' is rather ugly to me as nothing else
about the instrument's appearance is changed to be compatible with the
color.? I've got to believe that Fluke's and HP's industrial designers
had fits over the idea.]
?
Anyway, I'd love to hear the story....
?
Don
Beaverton,
OR
|
I've noticed so far three 436A power meters on ebay with light blue front
faces, though everything else about the instrument seems to be in normal HP
colors.? I've seen a couple times a Fluke 8060A (or was it a 8062A?) in a
light blue plastic case (although again, other bits like the Lexan front label
are normal colors) and it was associated with IBM.? Was the 'blue' 436A a
custom configuration for IBM also?? Why would IBM go to such lengths??
A deterrent of some kind?
?
[Quite frankly, the 'blue gear' is rather ugly to me as nothing else about
the instrument's appearance is changed to be compatible with the color.?
I've got to believe that Fluke's and HP's industrial designers had fits over the
idea.]
?
Anyway, I'd love to hear the story....
?
Don
Beaverton, OR
|
Dave,
I know that you've already gotten the unit working. But, for future reference:
One thing that I usually do first, when checking electrolytic capacitors, is to test their ESR (equivalent series resistance). Apparently, for many (or most?) of their common failure modes, an electrolytic's ESR will rise. Also note that, in older equipment, the electrolytics are usually prime suspects for failure.
It is usually easy to check the ESR, in circuit. You could buy an ESR Meter, or a kit for one. But you can ALSO check it quite effectively with just an oscilloscope and a square wave generator (and some cables and a 50-Ohm terminator). I've already described how I normally do it, at:
And I learned about that method from a site that is "a must see" for anyone involved in electronic repair:
You can also use an oscilloscope with a "quick and dirty curve tracer", to really speed up the basic testing of semiconductors (and, actually, MOST or all types of components, in many cases). You can also use it to compare the displayed "signatures" of corresponding points in a unit under repair and those in an identical working unit, to (often) quickly zero-in on the problem area. The Q & D Curve Tracer is literally just two or three resistors, and a small-signal source, configured to display the current versus the voltage for two test points, on an X-Y scope display! You can probably throw one together in two or three minutes! It's detailed at:
I *STARTED* out with that exact same "quick and dirty" curve tracer. But I kept adding features, and re-designing, etc, until I ended up with THIS ONE:
Hehe.
Good luck with future troubleshooting.
Regards,
Tom Gootee (tomg AT fullnet.com)
-------------------------------------------- Original message:
Date: Wed, 4 Aug 2004 13:48:17 -0700
From: "Dave Faria" <dave_faria@...>
Subject: Re: Re: 8552B problem
Dave I have a cap. checker built into a vom. Would I be able to test the cap.s in the circuit without doing damage to surrounding componets? The checker is a late model Wavetech Meterman. I know I will not get accurate readings but, will an obviously bad cap. stand out? I don't really want to pull loose one end of the cap to test. I don't have good de-soldering equipment. Also can I use a VOM and read DC resistance and get info that way? Again would checking DC resistance damage associated componets? I don't want to cause any more problems and I'm being very careful with every step. Like I say I'm very new to working on SS and I don't want to cause problems.
Thanks for ur help
Dave Faria/WA5TEZ
<snipped>
|
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, August 04, 2004 6:01
PM
Subject: RE: [hp_agilent_equipment] Re:
8552B problem
Standard FAQ on the 141T equipment: put an extra washer under the
D-connectors that join the RF and IF plugins, and/or bend the fingers out a
little to improve the mating.? It will save you a lot of
befuddlement.?
?
--
john KE5FX
Hi Dave, well its going and working like its
suppose to.? I don't really know what I did except possibly clean the
card edge contacts by taking the cards out and putting them back in.?
The contacts looked great but its the only thing I can think that could have
changed.? Urs might have the same problem.
?
Good Luck
?
-----
|
Hi Dave, well its going and working like its
suppose to.? I don't really know what I did except possibly clean the card
edge contacts by taking the cards out and putting them back in.? The
contacts looked great but its the only thing I can think that could have
changed.? Urs might have the same problem.
?
Good Luck
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, August 04, 2004 8:53
AM
Subject: [hp_agilent_equipment] Re: 8552B
problem
Dave,
Interesting that you have that problem.?
I have an
8552B that exhibits the same symptoms!? Or at least
I
think it does.? My display (in log mode - linear mode
is not
often useful in a spectrum analyzer) shows
about 20dB down from the
intended calibrated level.
You are to be congratulated on narrowing it
down to
the final amplifier - that's good troubleshooting.
Remember
that if an amplifier fails, it does not block
all signals.? Instead, a
single-stage amplifier may
change from a 15dB gain block (if that's what it
was
intended to be) to a 15dB LOSS block - in my case,
that would
explain the 30dB down symptom.
In a solid state amplifier, the first
suspect is the
amplifying device itself - the transistor.? If
the
amplifier is common-emitter, it may have a resistor
from emitter to
ground, bypassed by a capacitor.? If
that capacitor fails open
circuit, then the
amplifier's gain will be seriously degraded.
Particularly suspect would be any electrolytic
capacitors, at the age
of these instruments.
How were you able to operate the IF section
outside of
the mainframe?? Or did you plug the module into
a
mainframe without an RF section and able to
troubleshoot from the
little bit of topside access
that would get you?
As far as the
vertical positioning question, remember
that a spectrum analyzer is not
intended to be
zero-centered like a scope.? Instead, the bottom
line
or the top line of the graticule is the reference.? In
linear
mode, that means zero volts at the bottom of
the screen.? The analyzer
uses a diode detector in
linear mode, so there's never negative voltage -
just
RF envelope voltage.? In log mode, the top line is
the
reference.? If you set the gain controls so that zero
dBm (one
milliwatt into 50 ohms) is at the top of the
screen, then each division
down from that is 2dB or
10dB depending on the setting of the log/lin
switch.
With an oscilloscope, we move the vertical position
control
around to get the signal on screen, and take
note of where zero
landed.? The signal goes up and
down from zero.? On a spectrum
analyzer, the absolute
position of the signal on screen is a part of
the
measurement, so the zero volt line is at the bottom,
always, and the
dB reference line is at the top,
always.
Good
troubleshooting!
Dave
?
Date: Tue, 3 Aug 2004 15:06:34
-0700
From: "Dave Faria"
Subject: HP
8552b Problem
Good afternoon list.? I have an HP141T with the
Hp
8553b and Hp 8552b
plug ins.? I am new to solid state test
equipment and
need some help.? I
have down loaded all the manuals
from the BAMA list.
The situation of
my unit is it appears to work in
all aspects except it
does not have
sufficient vertical gain.? It
will show its
calibration signal in all
modes 2db log, 10db log, and
linear but, the display
will not show the
peaks at the levels that it
should(7.1mv, -30db).? The
signals are abt 2/3
of what they should
be on the .1uv and -60db scale.? I
have done the
test indicated in
the 8552b manual to test the final
amp.? I injected a
3mhz signal
at pin 14 of card XA4 with that card
pulled.? The test
indicated
the amp was not working.? Where do I go from
here??? The down
loaded Hp manual is not that easy to use or read.
Another thing that I
don't understand is why would all functions continue
to work with a
failed
amp.? One thing that may help someone who understands
this
unit is when
I change the gain(db or mv) the entire trace will
shift
either up or
down on the screen, sometimes out of the range of
the
vertical position
control.? This problem would be corrected by
a balance
control
adjustment on an old tube type scope.
Thanks
for any help or comments
Dave Faria
WA5TEZ
?????
?????
__________________________________
Do
you Yahoo!?
Yahoo! Mail - 50x more storage than other providers!
|
I am trying to get my 8662A to work. I bought it knowing
that it had problems.? I now have most of it working but believe that one
of the VHF (320-640 MHz) VCOs is not behaving the way it should. There are two
of these VCOs in the unit, essentially identical. They use a pair of 2N5397 N
channel JFETs in an oscillator and it is varactor tuned. There is no info on
them at all in the manuals as it is a factory repair part only. I wonder if any
one on here has any experience with them that they could share. Thanks - Mike ??
?
?
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-901-9193
?
?
?
|
Standard FAQ on the 141T equipment: put an extra washer under the
D-connectors that join the RF and IF plugins, and/or bend the fingers out a
little to improve the mating.? It will save you a lot of
befuddlement.?
?
--
john KE5FX
toggle quoted message
Show quoted text
Hi Dave, well its going and working like its
suppose to.? I don't really know what I did except possibly clean the
card edge contacts by taking the cards out and putting them back in.? The
contacts looked great but its the only thing I can think that could have
changed.? Urs might have the same problem.
?
Good Luck
?
-----
|
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, August 04, 2004 1:38
PM
Subject: Re: [hp_agilent_equipment] Re:
8552B problem
Hello?Dave ,
?
In my many years of experience?in
?service / fault finding it is my opinion that only two good ways exist
for cap checking ...
1) knowing how the circuit works and finding the
fault by measuring voltages and waveforms under normal operating conditions in
order to detect the faulty component .? Of course schematics wanted or at
least electronic experience is a must .
?
2) Replacing the cap with a known good one
.? If the part of ?the circuit where you could isolate the trouble
is rather small in component count ,? replace them all .? For older
power supplies , if you want to keep the instrument reliable in the future ,
best replace all elcos .? Specially those located near to hot spots
(transformers /larger transistors ).
?
Measuring capacitors is troublesome?, this
because in many cases the trouble is related to applied voltage /waveform or
current or temperature or ...?? so it is very difficult to detect
faulty one's unless they died completely of course .
Moreover desoldering and resoldering is also a
factor that can cause new troubles.
?
Good luck ,
Erik
?
----- Original Message -----
Sent: Wednesday, August 04, 2004 10:48
PM
Subject: Re: [hp_agilent_equipment] Re:
8552B problem
Dave I have a cap. checker built into a
vom.? Would I be able to test the cap.s in the circuit without doing
damage to surrounding componets?? The checker is a late model Wavetech
Meterman.? I know I will not get accurate readings but, will an
obviously bad cap. stand out?? I don't really want to pull loose one
end of the cap to test.? I don't have good de-soldering
equipment.? Also can I use a VOM and read DC resistance and get info
that way?? Again would checking DC resistance damage associated
componets?? I don't want to cause any more problems and I'm being very
careful with every step.? Like I say I'm very new to working on SS and
I don't want to cause problems.
?
Thanks for ur help
Dave Faria/WA5TEZ
----- Original Message -----
Sent: Wednesday, August 04, 2004 8:53
AM
Subject: [hp_agilent_equipment] Re:
8552B problem
Dave,
Interesting that you have that
problem.? I have an
8552B that exhibits the same symptoms!?
Or at least I
think it does.? My display (in log mode - linear
mode
is not often useful in a spectrum analyzer) shows
about 20dB
down from the intended calibrated level.
You are to be
congratulated on narrowing it down to
the final amplifier - that's good
troubleshooting.
Remember that if an amplifier fails, it does not
block
all signals.? Instead, a single-stage amplifier
may
change from a 15dB gain block (if that's what it was
intended to
be) to a 15dB LOSS block - in my case,
that would explain the 30dB down
symptom.
In a solid state amplifier, the first suspect is
the
amplifying device itself - the transistor.? If
the
amplifier is common-emitter, it may have a resistor
from emitter
to ground, bypassed by a capacitor.? If
that capacitor fails open
circuit, then the
amplifier's gain will be seriously degraded.
Particularly suspect would be any electrolytic
capacitors, at the
age of these instruments.
How were you able to operate the IF
section outside of
the mainframe?? Or did you plug the module into
a
mainframe without an RF section and able to
troubleshoot from the
little bit of topside access
that would get you?
As far as the
vertical positioning question, remember
that a spectrum analyzer is not
intended to be
zero-centered like a scope.? Instead, the bottom
line
or the top line of the graticule is the reference.?
In
linear mode, that means zero volts at the bottom of
the
screen.? The analyzer uses a diode detector in
linear mode, so
there's never negative voltage - just
RF envelope voltage.? In log
mode, the top line is the
reference.? If you set the gain controls
so that zero
dBm (one milliwatt into 50 ohms) is at the top of
the
screen, then each division down from that is 2dB or
10dB
depending on the setting of the log/lin switch.
With an
oscilloscope, we move the vertical position
control around to get the
signal on screen, and take
note of where zero landed.? The signal
goes up and
down from zero.? On a spectrum analyzer, the
absolute
position of the signal on screen is a part of
the
measurement, so the zero volt line is at the bottom,
always, and
the dB reference line is at the top,
always.
Good
troubleshooting!
Dave
?
Date: Tue, 3 Aug 2004
15:06:34 -0700
From: "Dave Faria"
<dave_faria@...>
Subject: HP 8552b Problem
Good
afternoon list.? I have an HP141T with the Hp
8553b and Hp 8552b
plug ins.? I am new to solid state test equipment and
need
some help.? I
have down loaded all the manuals from the BAMA
list.
The situation of
my unit is it appears to work in all
aspects except it
does not have
sufficient vertical gain.? It
will show its
calibration signal in all
modes 2db log, 10db log,
and linear but, the display
will not show the
peaks at the levels
that it should(7.1mv, -30db).? The
signals are abt 2/3
of what
they should be on the .1uv and -60db scale.? I
have done the
test indicated in the 8552b manual to test the final
amp.? I
injected a
3mhz signal at pin 14 of card XA4 with that
card
pulled.? The test
indicated the amp was not
working.? Where do I go from
here??? The down
loaded Hp
manual is not that easy to use or read.
Another thing that I
don't
understand is why would all functions continue
to work with a failed
amp.? One thing that may help someone who understands
this
unit is when
I change the gain(db or mv) the entire trace
will
shift either up or
down on the screen, sometimes out of the
range of the
vertical position
control.? This problem would be
corrected by a balance
control
adjustment on an old tube type
scope.
Thanks for any help or comments
Dave Faria
WA5TEZ
?????
?????
__________________________________
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Dave I have a cap. checker built into a vom.?
Would I be able to test the cap.s in the circuit without doing damage to
surrounding componets?? The checker is a late model Wavetech
Meterman.? I know I will not get accurate readings but, will an obviously
bad cap. stand out?? I don't really want to pull loose one end of the cap
to test.? I don't have good de-soldering equipment.? Also can I use a
VOM and read DC resistance and get info that way?? Again would checking DC
resistance damage associated componets?? I don't want to cause any more
problems and I'm being very careful with every step.? Like I say I'm very
new to working on SS and I don't want to cause problems.
?
Thanks for ur help
Dave Faria/WA5TEZ
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, August 04, 2004 8:53
AM
Subject: [hp_agilent_equipment] Re: 8552B
problem
Dave,
Interesting that you have that problem.?
I have an
8552B that exhibits the same symptoms!? Or at least
I
think it does.? My display (in log mode - linear mode
is not
often useful in a spectrum analyzer) shows
about 20dB down from the
intended calibrated level.
You are to be congratulated on narrowing it
down to
the final amplifier - that's good troubleshooting.
Remember
that if an amplifier fails, it does not block
all signals.? Instead, a
single-stage amplifier may
change from a 15dB gain block (if that's what it
was
intended to be) to a 15dB LOSS block - in my case,
that would
explain the 30dB down symptom.
In a solid state amplifier, the first
suspect is the
amplifying device itself - the transistor.? If
the
amplifier is common-emitter, it may have a resistor
from emitter to
ground, bypassed by a capacitor.? If
that capacitor fails open
circuit, then the
amplifier's gain will be seriously degraded.
Particularly suspect would be any electrolytic
capacitors, at the age
of these instruments.
How were you able to operate the IF section
outside of
the mainframe?? Or did you plug the module into
a
mainframe without an RF section and able to
troubleshoot from the
little bit of topside access
that would get you?
As far as the
vertical positioning question, remember
that a spectrum analyzer is not
intended to be
zero-centered like a scope.? Instead, the bottom
line
or the top line of the graticule is the reference.? In
linear
mode, that means zero volts at the bottom of
the screen.? The analyzer
uses a diode detector in
linear mode, so there's never negative voltage -
just
RF envelope voltage.? In log mode, the top line is
the
reference.? If you set the gain controls so that zero
dBm (one
milliwatt into 50 ohms) is at the top of the
screen, then each division
down from that is 2dB or
10dB depending on the setting of the log/lin
switch.
With an oscilloscope, we move the vertical position
control
around to get the signal on screen, and take
note of where zero
landed.? The signal goes up and
down from zero.? On a spectrum
analyzer, the absolute
position of the signal on screen is a part of
the
measurement, so the zero volt line is at the bottom,
always, and the
dB reference line is at the top,
always.
Good
troubleshooting!
Dave
?
Date: Tue, 3 Aug 2004 15:06:34
-0700
From: "Dave Faria"
Subject: HP
8552b Problem
Good afternoon list.? I have an HP141T with the
Hp
8553b and Hp 8552b
plug ins.? I am new to solid state test
equipment and
need some help.? I
have down loaded all the manuals
from the BAMA list.
The situation of
my unit is it appears to work in
all aspects except it
does not have
sufficient vertical gain.? It
will show its
calibration signal in all
modes 2db log, 10db log, and
linear but, the display
will not show the
peaks at the levels that it
should(7.1mv, -30db).? The
signals are abt 2/3
of what they should
be on the .1uv and -60db scale.? I
have done the
test indicated in
the 8552b manual to test the final
amp.? I injected a
3mhz signal
at pin 14 of card XA4 with that card
pulled.? The test
indicated
the amp was not working.? Where do I go from
here??? The down
loaded Hp manual is not that easy to use or read.
Another thing that I
don't understand is why would all functions continue
to work with a
failed
amp.? One thing that may help someone who understands
this
unit is when
I change the gain(db or mv) the entire trace will
shift
either up or
down on the screen, sometimes out of the range of
the
vertical position
control.? This problem would be corrected by
a balance
control
adjustment on an old tube type scope.
Thanks
for any help or comments
Dave Faria
WA5TEZ
?????
?????
__________________________________
Do
you Yahoo!?
Yahoo! Mail - 50x more storage than other providers!
|
Hello?Dave ,
?
In my many years of experience?in
?service / fault finding it is my opinion that only two good ways exist for
cap checking ...
1) knowing how the circuit works and finding the
fault by measuring voltages and waveforms under normal operating conditions in
order to detect the faulty component .? Of course schematics wanted or at
least electronic experience is a must .
?
2) Replacing the cap with a known good one .?
If the part of ?the circuit where you could isolate the trouble is rather
small in component count ,? replace them all .? For older power
supplies , if you want to keep the instrument reliable in the future , best
replace all elcos .? Specially those located near to hot spots
(transformers /larger transistors ).
?
Measuring capacitors is troublesome?, this
because in many cases the trouble is related to applied voltage /waveform or
current or temperature or ...?? so it is very difficult to detect
faulty one's unless they died completely of course .
Moreover desoldering and resoldering is also a
factor that can cause new troubles.
?
Good luck ,
Erik
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, August 04, 2004 10:48
PM
Subject: Re: [hp_agilent_equipment] Re:
8552B problem
Dave I have a cap. checker built into a
vom.? Would I be able to test the cap.s in the circuit without doing
damage to surrounding componets?? The checker is a late model Wavetech
Meterman.? I know I will not get accurate readings but, will an obviously
bad cap. stand out?? I don't really want to pull loose one end of the cap
to test.? I don't have good de-soldering equipment.? Also can I use
a VOM and read DC resistance and get info that way?? Again would checking
DC resistance damage associated componets?? I don't want to cause any
more problems and I'm being very careful with every step.? Like I say I'm
very new to working on SS and I don't want to cause problems.
?
Thanks for ur help
Dave Faria/WA5TEZ
----- Original Message -----
Sent: Wednesday, August 04, 2004 8:53
AM
Subject: [hp_agilent_equipment] Re:
8552B problem
Dave,
Interesting that you have that
problem.? I have an
8552B that exhibits the same symptoms!? Or
at least I
think it does.? My display (in log mode - linear
mode
is not often useful in a spectrum analyzer) shows
about 20dB down
from the intended calibrated level.
You are to be congratulated on
narrowing it down to
the final amplifier - that's good troubleshooting.
Remember that if an amplifier fails, it does not block
all
signals.? Instead, a single-stage amplifier may
change from a 15dB
gain block (if that's what it was
intended to be) to a 15dB LOSS block -
in my case,
that would explain the 30dB down symptom.
In a solid
state amplifier, the first suspect is the
amplifying device itself - the
transistor.? If the
amplifier is common-emitter, it may have a
resistor
from emitter to ground, bypassed by a capacitor.?
If
that capacitor fails open circuit, then the
amplifier's gain will
be seriously degraded.
Particularly suspect would be any
electrolytic
capacitors, at the age of these instruments.
How were
you able to operate the IF section outside of
the mainframe?? Or did
you plug the module into a
mainframe without an RF section and able
to
troubleshoot from the little bit of topside access
that would get
you?
As far as the vertical positioning question, remember
that a
spectrum analyzer is not intended to be
zero-centered like a scope.?
Instead, the bottom line
or the top line of the graticule is the
reference.? In
linear mode, that means zero volts at the bottom
of
the screen.? The analyzer uses a diode detector in
linear
mode, so there's never negative voltage - just
RF envelope voltage.?
In log mode, the top line is the
reference.? If you set the gain
controls so that zero
dBm (one milliwatt into 50 ohms) is at the top of
the
screen, then each division down from that is 2dB or
10dB depending
on the setting of the log/lin switch.
With an oscilloscope, we move
the vertical position
control around to get the signal on screen, and
take
note of where zero landed.? The signal goes up and
down from
zero.? On a spectrum analyzer, the absolute
position of the signal
on screen is a part of the
measurement, so the zero volt line is at the
bottom,
always, and the dB reference line is at the
top,
always.
Good troubleshooting!
Dave
?
Date: Tue, 3 Aug 2004 15:06:34 -0700
From: "Dave Faria"
Subject: HP 8552b Problem
Good
afternoon list.? I have an HP141T with the Hp
8553b and Hp 8552b
plug ins.? I am new to solid state test equipment and
need some
help.? I
have down loaded all the manuals from the BAMA list.
The situation of
my unit is it appears to work in all aspects except
it
does not have
sufficient vertical gain.? It will show
its
calibration signal in all
modes 2db log, 10db log, and linear
but, the display
will not show the
peaks at the levels that it
should(7.1mv, -30db).? The
signals are abt 2/3
of what they
should be on the .1uv and -60db scale.? I
have done the
test
indicated in the 8552b manual to test the final
amp.? I injected a
3mhz signal at pin 14 of card XA4 with that card
pulled.? The
test
indicated the amp was not working.? Where do I go
from
here??? The down
loaded Hp manual is not that easy to use
or read.
Another thing that I
don't understand is why would all
functions continue
to work with a failed
amp.? One thing that
may help someone who understands
this unit is when
I change the
gain(db or mv) the entire trace will
shift either up or
down on the
screen, sometimes out of the range of the
vertical position
control.? This problem would be corrected by a balance
control
adjustment on an old tube type scope.
Thanks for any help or
comments
Dave Faria WA5TEZ
?????
?????
__________________________________
Do
you Yahoo!?
Yahoo! Mail - 50x more storage than other providers!
|
Re: HP 8657A HIGH STABILITY REFERENCE
Bruce: Check with George at the following
website:
If you talk with him, tell him that Harold from
Spartanburg recommended him.
Good luck!
Harold
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, August 04, 2004 1:41
PM
Subject: [hp_agilent_equipment] HP 8657A
HIGH STABILITY REFERENCE
I am still looking for a 10mhz reference oscillator for
this sig.
gen.? HP Part# 08656 - 16195 I believe.? Does anyone
know who sells
the options for older HP
equipment?
???????????????????????????????????
Bruce.
|
Hi Dave.? Thanks for ur comments.? The
way I tested the unit is I soldered a cable to the test points and removed the
side panels on the main frame.? Both the side panel and carriage frame are
held in with screws and once removed u can slide the rf head and IF unit in with
the test cable out the side.? Ur unit seems to have more gain than
mine.
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Wednesday, August 04, 2004 8:53
AM
Subject: [hp_agilent_equipment] Re: 8552B
problem
Dave,
Interesting that you have that problem.?
I have an
8552B that exhibits the same symptoms!? Or at least
I
think it does.? My display (in log mode - linear mode
is not
often useful in a spectrum analyzer) shows
about 20dB down from the
intended calibrated level.
You are to be congratulated on narrowing it
down to
the final amplifier - that's good troubleshooting.
Remember
that if an amplifier fails, it does not block
all signals.? Instead, a
single-stage amplifier may
change from a 15dB gain block (if that's what it
was
intended to be) to a 15dB LOSS block - in my case,
that would
explain the 30dB down symptom.
In a solid state amplifier, the first
suspect is the
amplifying device itself - the transistor.? If
the
amplifier is common-emitter, it may have a resistor
from emitter to
ground, bypassed by a capacitor.? If
that capacitor fails open
circuit, then the
amplifier's gain will be seriously degraded.
Particularly suspect would be any electrolytic
capacitors, at the age
of these instruments.
How were you able to operate the IF section
outside of
the mainframe?? Or did you plug the module into
a
mainframe without an RF section and able to
troubleshoot from the
little bit of topside access
that would get you?
As far as the
vertical positioning question, remember
that a spectrum analyzer is not
intended to be
zero-centered like a scope.? Instead, the bottom
line
or the top line of the graticule is the reference.? In
linear
mode, that means zero volts at the bottom of
the screen.? The analyzer
uses a diode detector in
linear mode, so there's never negative voltage -
just
RF envelope voltage.? In log mode, the top line is
the
reference.? If you set the gain controls so that zero
dBm (one
milliwatt into 50 ohms) is at the top of the
screen, then each division
down from that is 2dB or
10dB depending on the setting of the log/lin
switch.
With an oscilloscope, we move the vertical position
control
around to get the signal on screen, and take
note of where zero
landed.? The signal goes up and
down from zero.? On a spectrum
analyzer, the absolute
position of the signal on screen is a part of
the
measurement, so the zero volt line is at the bottom,
always, and the
dB reference line is at the top,
always.
Good
troubleshooting!
Dave
?
Date: Tue, 3 Aug 2004 15:06:34
-0700
From: "Dave Faria" Subject: HP
8552b Problem
Good afternoon list.? I have an HP141T with the
Hp
8553b and Hp 8552b
plug ins.? I am new to solid state test
equipment and
need some help.? I
have down loaded all the manuals
from the BAMA list.
The situation of
my unit is it appears to work in
all aspects except it
does not have
sufficient vertical gain.? It
will show its
calibration signal in all
modes 2db log, 10db log, and
linear but, the display
will not show the
peaks at the levels that it
should(7.1mv, -30db).? The
signals are abt 2/3
of what they should
be on the .1uv and -60db scale.? I
have done the
test indicated in
the 8552b manual to test the final
amp.? I injected a
3mhz signal
at pin 14 of card XA4 with that card
pulled.? The test
indicated
the amp was not working.? Where do I go from
here??? The down
loaded Hp manual is not that easy to use or read.
Another thing that I
don't understand is why would all functions continue
to work with a
failed
amp.? One thing that may help someone who understands
this
unit is when
I change the gain(db or mv) the entire trace will
shift
either up or
down on the screen, sometimes out of the range of
the
vertical position
control.? This problem would be corrected by
a balance
control
adjustment on an old tube type scope.
Thanks
for any help or comments
Dave Faria
WA5TEZ
?????
?????
__________________________________
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you Yahoo!?
Yahoo! Mail - 50x more storage than other providers!
|
