开云体育

They are very likely Sealectro or MicroDot. If you email me a (small ) pic of
both M and F, off list, I'll see if I can ID them.

If they are gold plated with Teflon insulation between center and outer
conductors, Sealectro is the most likely choice.

-John




David C. Hallam wrote:

If you can email me photographs, I'll compare them to
what's in my 8443A.

But it doesn't really matter. The only important one
for your present purpose is A6W1, the one from the RF amp to
the counter's INT input. All you have to do is scope
it long enough to verify that there's RF there; this
can be accomplished without an adaptor.

Dave Wise

I did call them GOOFY because that is what they are. They are goofy because
I think the only place in the whole world they were used was the jacks and
plugs for the cables of the connections between modules of the 8443A. They
are not SMA, SMB, or SMC. I have looked at drawing of each of these types
are the are not same as what HP used. I have no idea what they are or
where to obtain them. I would certainly appreciate it if anyone could
identify them along with a source of supply. As far as I am concerned their
official description is "unobtainiun".

David
KC2JD/4

I didn't call them goofy, David Hallam (the OP) did.
You and I are referring to what's more commonly called
"Hybrid-D" connectors. (From context,
I judge that David Hallam is thinking of the SMB (SMC?)
plugs on the inter-assembly cables inside the instrument.
The hybrid-D of interest in this thread actually has no
standard D contacts at all, it's all coaxes. Which by the
way are called "Size 8". Not to inundate you with 8's,
but the connector pin layout is called "8W8", which
predictably means 8 contacts 8 of which are coax.

Regards,
Dave Wise

Sealectro is a brand. They made SMA, SMB, SMC, and a number of other miniature
coax connectors. They ALSO made a number of proprietary types in addition to the
standards.

As to 'goofy', do you mean the D connectors w/ the mix of coax and ordinary
pins?

-John



David Wise wrote:

I said that two sentences later:

"At narrow
RBW settings, you have to fine-tune the TG to be exactly
on frequency, that's the screwdriver adjustment on the front
panel. Since you don't know that it's spot-on, start with
a wide RBW then narrow it down."

Said screwdriver adjustment trims the 3MHz LO which mimics the
final I.F. of the 8552. Late versions of the 8443A have a
"Restore Signal" mode which uses the actual IF signal from
the 8552. In that mode, as long as it's within the SA's RBW,
the TG puts out exactly the frequency presented to the SA's RF input.
Note: This doesn't work with early 8552's, they don't bring
their final IF out to the bulkhead. While the mod is conceptually
simple, it's physically difficult due to the location of
the contacts, so I haven't done it to my 8552A.

And another note: When the 8553B is in FULL scan mode, it
puts out its own marker in addition to the one from the
8443A. Fortunately they are recognisably different:
the former is a dip in trace height while the latter
is a change in trace intensity. And a note about that.
How much brighter it gets depends on the Marker Intensity
control, which adjusts the time the scan is paused at
the marker position.

Regards,
Dave Wise

ONLY, if the TG is actually putting out the same frequency as the SA is
tuned to. I have an AIL 757 and TG. If the tracking control is not tuned
right, the YIG in the SA's front end will be tuned to a different frequency
than the TG and you see little to nothing on the SA.

-John




David Wise wrote:

Take a look at the Wiltrons. The advantage is that the marker accuracy is independent of the GHz/Volt calibrations. In fact, I have a little home brew unit in a Tek TM-500 PI that does just that... mixer, LPF, detector, comparator.

-John



lothar baier wrote:

FWIW, do it over a tray w/ turned up edges. I just spent over an hour chasing
small bits of an assembly because I ignored that precaution.

Best,
-John



g47g wrote:

They did call them by an obsolete name, "selectro" (or was it "sealectro"?).

usually HP used SMC and SMB on the inside of most instrument, i havent seen anything special in any of the HP Gear

Dan Rae <danrae@...> wrote: David C. Hallam wrote:

I
believe it might be more expeditious to find another 8443A I can purchase,
only after verification that it is working properly, than to attempt the
repair of mine.

David if you do look for another one, try to find a later one with LED
displays rather than nixie tubes, they are a little bit more reliable.

But they are pretty easy to work on, all in all, given a modicum of test
gear. I'd bet it is probably something very minor wrong with yours.
And it's probably ten years since I had the lid off mine, but I don't
remember anything odd about the coax connectors inside, SMC I think.

Good luck,
Dan






---------------------------------
Be a better pen pal. Text or chat with friends inside Yahoo! Mail. See how.

David C. Hallam wrote:

I
believe it might be more expeditious to find another 8443A I can purchase,
only after verification that it is working properly, than to attempt the
repair of mine.

David if you do look for another one, try to find a later one with LED displays rather than nixie tubes, they are a little bit more reliable.

But they are pretty easy to work on, all in all, given a modicum of test gear. I'd bet it is probably something very minor wrong with yours. And it's probably ten years since I had the lid off mine, but I don't remember anything odd about the coax connectors inside, SMC I think.

Good luck,
Dan

Thank you to all who replied to my request for help. I now understand more
about the operation of this piece of test gear and also believe the solution
to my problem is more complex than I originally thought.

Given the investment in time, money, and effort it will take to acquire
and/or fabricate things like circuit board extenders and jumper cables with
those goofy (Yes I still think HP used "goofy" connectors, they aren't SMA,
SMB, SMC, or SM* anything) connectors on one end and BNC on the other, I
believe it might be more expeditious to find another 8443A I can purchase,
only after verification that it is working properly, than to attempt the
repair of mine.

I will do what trouble shooting I can without those items before writing
this one off.

David
KC2JD/4

Thanks. I'll try to disassemble the unit, then I hope I'll see the
reason of the failure.

--- In hp_agilent_equipment@..., lothar baier
<microwaveengineer1968@...> wrote:

most likely the cam is worn out or the little ball that locks the

cam in place is missing

g47g <g47g@...> wrote: Hi Lothar,

I have a 8495A manual step attenuator, and though it has the correct
attenuations on every step(?), but it needs force to switch the
attenuator in different positions, and also the well known "click"
cannot be heard, when turning (with some force) the knob.

Could you help me with some idea and procedure, as you did with the
electronic controlled equivalent ?

Thanks
George Galambos

--- In hp_agilent_equipment@..., "microwaveengineer1968"
<microwaveengineer1968@> wrote:

Since Agilent continiously ups the spare part prices and discontinues
parts it has become more and more important to go past normal repair
practices.
Step Attenuators for example can be repaired without any special
tools or cleanroom enviroment !
Lets take a look at the failure modes first, there are a few:

1.) Blown pads
Usually common with spectrum analyzers if a level past the damage
level of the attenuator was applied

2.) Cracked pads, pad has developed a hairline crack due to
mechanical stress !

3.) Improper contact, the contact in between the attenuator and
contact fingers is disturbed.

4.) Stuck solenoid
Quite common if attenuator hasnt been used in awhile

After we remove the attenuator from the instrument the first step is
to obtain the pinout and build us a little test bench consisting of a
powermeter and a signal generator, the good old 8481D or 8484A will
do nicely, if you dont have a sig gen use the 50MHz calibrator output
of the 435 or 436 or similar model, connect the cal output to the
30dB pad connect the sensor and zero and calibrate meter, the meter
will read -30dBm.
Disconnect the sensor from the attenuator and insert the Step
Attenuator, set step attenuator to 0dB, note the level on the
powermeter, now switch in the attenuator sections one by one measure
and note the level, 70dB attenuators are comprised of a 10 20 and
40dB Pad while 110dB Attenuators normally comprise of a 10 20 and two
40dB pads !
check every section individually, you should hear a click as you
enable each section, if you find a bad section note the value it
should have if all sections appear to be good repeat the test at a
higher frequency using a sig gen, if everything appears to be ok at
low frequency then most likely you have attenuator that just needs
cleaning.
Now lets take the attenuator apart, looking at the top you will see a
nut on each SMA connector, remove this nut this will allow for you to
remove the nameplate, under the plate you will see a wealth of allen
screws, remove those but note that the screws close to the SMA
connector are shorter than the other ones.
Now look at the small sideplate, not the one with the ribbon cable
but the other side - there are 4 small allen screws, remove those and
then remove the sideplate, careful not to lose the little wire mesh
here ! now slide out the u shaped cover and remove the top side.
You now have two parts, one beein the bottom side containing the
solenoids and the other one beein the top part containing the
attenuator pads.
First lets inspect the pads, you can measure them with a ohm meter,
they should measure in the vicinity of 50ohms , except of the 10dB
pad which can measure up to 70ohms or more.
Inspect the pads visually, are there any burned or cracked pads ? if
all pads look ok and check out at DC take a surgical swab and
isopropilic alcohol and carefully clean the contacts pads on the
attenuators.
Next look at the contacts, enable all solenoids and observe the
position of the contact tongues, they should be slightly above the
surface of the block, carefully clean the contact tongues with
alcohol, be careful not to bend them.
next put the solenoids back into the 0 position and look at the top
of the solenoids, you will see two little white plastic rods where
those meet the solenoid you should see little rubber rings , there
are 4 of those on each segment, usually over the years they go
briddle and then disappear, with those rings gone the attenuator wont
make contact anymore, you can buy the rings from watchmakers supply
stores as they are beein used for sprocket gaskets !
Now if your gaskets are there put the attenuator back together after
you cleaned everything and it should work now.
If you have a broken or burned pad dont stress over it the pads are
used in all HP attenuators so just find a attenuator on ebay and take
the pad you need out of it, you can also buy pads from agilent
however be prepared to pay $100-150 per
piece

---------------------------------
Get easy, one-click access to your favorites. Make Yahoo! your

homepage.

You don't even have to select zero span. The function and
purpose of a TG is to output, at all times, whatever frequency
the SA is listening to. As the SA scans, so does the TG.
In all scan modes, the SA should show a horizontal line
at a height determined by the TG's output amplitude.
So just route the TG RF out to the SA RF in. If the trace
rises, you have RF, if it doesn't, you don't, and either
the TG is not outputting or it's off frequency. At narrow
RBW settings, you have to fine-tune the TG to be exactly
on frequency, that's the screwdriver adjustment on the front
panel. Since you don't know that it's spot-on, start with
a wide RBW then narrow it down.

You could also view the TG output on your scope, at low frequencies.
If the SA is on low band, the TG will be between 100kHz and 11MHz.
However, the counter is tapped off at a different point so it's
possible for the TG to output RF without counting, even if the
counter works in EXT mode. Check the condition of A6W1 (Service
Sheet 3) and scope it for RF.

You've received good advice when it comes to checking the
connections; with their inadequate brackets, those
bulkhead-mounted hybrid-D's are notorious
for "signalus interruptus".

A couple of minor corrections to earlier postings:

1. The 8552 47MHz LO is not fixed; it's tuned by the Fine Tuning
control, and swept on spans narrower than 50kHz. The 8443A's
predecessor, the 8601A Option <mumble>, used with the 8553L,
did not input the 47MHz LO. The 8601A generates its marker
with RF blanking.

2. The marker is not necessarily at the SA center frequency,
it can be moved side-to-side with the Marker Position control.

Regards,
Dave Wise

I cant be bothered to look at the manual as it it out of reach, but has it
occured that you are assuming that the marker and RF output are
connected......they may not be. Check you actually have a RF output on a
scope or an RF voltmeter. The marker could be generated from the scan and
the RF signal could get lost before the counter take-off and the output
terminal. Like all fault finding you need to go round the loop checking for
signals with an independent piece of gear. Dont just make assumptions about
how it works. Things that "must" be working usually arn't from my
experience, until proved otherwise !!

Alan

most likely the cam is worn out or the little ball that locks the cam in place is missing

g47g <g47g@...> wrote: Hi Lothar,

I have a 8495A manual step attenuator, and though it has the correct
attenuations on every step(?), but it needs force to switch the
attenuator in different positions, and also the well known "click"
cannot be heard, when turning (with some force) the knob.

Could you help me with some idea and procedure, as you did with the
electronic controlled equivalent ?

Thanks
George Galambos

--- In hp_agilent_equipment@..., "microwaveengineer1968"
<microwaveengineer1968@...> wrote:

Since Agilent continiously ups the spare part prices and discontinues
parts it has become more and more important to go past normal repair
practices.
Step Attenuators for example can be repaired without any special
tools or cleanroom enviroment !
Lets take a look at the failure modes first, there are a few:

1.) Blown pads
Usually common with spectrum analyzers if a level past the damage
level of the attenuator was applied

2.) Cracked pads, pad has developed a hairline crack due to
mechanical stress !

3.) Improper contact, the contact in between the attenuator and
contact fingers is disturbed.

4.) Stuck solenoid
Quite common if attenuator hasnt been used in awhile

After we remove the attenuator from the instrument the first step is
to obtain the pinout and build us a little test bench consisting of a
powermeter and a signal generator, the good old 8481D or 8484A will
do nicely, if you dont have a sig gen use the 50MHz calibrator output
of the 435 or 436 or similar model, connect the cal output to the
30dB pad connect the sensor and zero and calibrate meter, the meter
will read -30dBm.
Disconnect the sensor from the attenuator and insert the Step
Attenuator, set step attenuator to 0dB, note the level on the
powermeter, now switch in the attenuator sections one by one measure
and note the level, 70dB attenuators are comprised of a 10 20 and
40dB Pad while 110dB Attenuators normally comprise of a 10 20 and two
40dB pads !
check every section individually, you should hear a click as you
enable each section, if you find a bad section note the value it
should have if all sections appear to be good repeat the test at a
higher frequency using a sig gen, if everything appears to be ok at
low frequency then most likely you have attenuator that just needs
cleaning.
Now lets take the attenuator apart, looking at the top you will see a
nut on each SMA connector, remove this nut this will allow for you to
remove the nameplate, under the plate you will see a wealth of allen
screws, remove those but note that the screws close to the SMA
connector are shorter than the other ones.
Now look at the small sideplate, not the one with the ribbon cable
but the other side - there are 4 small allen screws, remove those and
then remove the sideplate, careful not to lose the little wire mesh
here ! now slide out the u shaped cover and remove the top side.
You now have two parts, one beein the bottom side containing the
solenoids and the other one beein the top part containing the
attenuator pads.
First lets inspect the pads, you can measure them with a ohm meter,
they should measure in the vicinity of 50ohms , except of the 10dB
pad which can measure up to 70ohms or more.
Inspect the pads visually, are there any burned or cracked pads ? if
all pads look ok and check out at DC take a surgical swab and
isopropilic alcohol and carefully clean the contacts pads on the
attenuators.
Next look at the contacts, enable all solenoids and observe the
position of the contact tongues, they should be slightly above the
surface of the block, carefully clean the contact tongues with
alcohol, be careful not to bend them.
next put the solenoids back into the 0 position and look at the top
of the solenoids, you will see two little white plastic rods where
those meet the solenoid you should see little rubber rings , there
are 4 of those on each segment, usually over the years they go
briddle and then disappear, with those rings gone the attenuator wont
make contact anymore, you can buy the rings from watchmakers supply
stores as they are beein used for sprocket gaskets !
Now if your gaskets are there put the attenuator back together after
you cleaned everything and it should work now.
If you have a broken or burned pad dont stress over it the pads are
used in all HP attenuators so just find a attenuator on ebay and take
the pad you need out of it, you can also buy pads from agilent
however be prepared to pay $100-150 per
piece

---------------------------------
Get easy, one-click access to your favorites. Make Yahoo! your homepage.

yes i think so

John Miles <jmiles@...> wrote: Isn't that what the 86222 sweeper plugin with the marker option does? Those
are pretty common.

-- john, KE5FX

this is another way but i havent seen anyone using this in
centuries, the last time i saw it was on a old jerrold sweeper,
everything i had ever since was using the approach i described,
problem with the RF method is that its quite expensive to
realize, a directional coupler, sampling mixer and the oscillator
and frequency counter costs money and space and also takes away
from the RF power, another factor is that whenever you use a comb
generator you run the risk of finding your peaks "everywhere"
even in places you dont want them :)
DC or LF stuff is cheap and doesnt take up much space so i
think thats why most companies opted for this approach

J Forster <jfor@...> wrote:
lothar baier wrote:

ok there are two basic ways to create a marker in a swept

system, one is called RF blanking the other one is called
intensity modulation, ok usually you have a control voltage thats
proportional to your RF frequency, if the analyzer sweeps its
basically a ramp, each point of the ramp corresponds to a certain
frequency, you feed this signal to a comparator and compare it to
a DC voltage thats adjustable (coming from your marker pot)
anytime the ramp "hits" this threshold you get a pulse on your
comparator output, you route this pulse back into your display
and use it to crank up the intensity just a bit at this point and
there you have a marker blip on your screen :)

There is another way. You sample the RF, mix it with a (frequency
settable) oscillator, run the output through a LPF, detector, and
comparator and use this output for intensity markers.

This system has the advantage that you can count the oscillator
and have accurate digital markers, and, if you replace the
oscillator w/ a comb generator, you get nice, calibrated pips.

---------------------------------
Be a better sports nut! Let your teams follow you with Yahoo Mobile. Try it now.

Hi Lothar,

I have a 8495A manual step attenuator, and though it has the correct
attenuations on every step(?), but it needs force to switch the
attenuator in different positions, and also the well known "click"
cannot be heard, when turning (with some force) the knob.

Could you help me with some idea and procedure, as you did with the
electronic controlled equivalent ?

Thanks
George Galambos

--- In hp_agilent_equipment@..., "microwaveengineer1968"
<microwaveengineer1968@...> wrote:

Since Agilent continiously ups the spare part prices and discontinues
parts it has become more and more important to go past normal repair
practices.
Step Attenuators for example can be repaired without any special
tools or cleanroom enviroment !
Lets take a look at the failure modes first, there are a few:

1.) Blown pads
Usually common with spectrum analyzers if a level past the damage
level of the attenuator was applied

2.) Cracked pads, pad has developed a hairline crack due to
mechanical stress !

3.) Improper contact, the contact in between the attenuator and
contact fingers is disturbed.

4.) Stuck solenoid
Quite common if attenuator hasnt been used in awhile

After we remove the attenuator from the instrument the first step is
to obtain the pinout and build us a little test bench consisting of a
powermeter and a signal generator, the good old 8481D or 8484A will
do nicely, if you dont have a sig gen use the 50MHz calibrator output
of the 435 or 436 or similar model, connect the cal output to the
30dB pad connect the sensor and zero and calibrate meter, the meter
will read -30dBm.
Disconnect the sensor from the attenuator and insert the Step
Attenuator, set step attenuator to 0dB, note the level on the
powermeter, now switch in the attenuator sections one by one measure
and note the level, 70dB attenuators are comprised of a 10 20 and
40dB Pad while 110dB Attenuators normally comprise of a 10 20 and two
40dB pads !
check every section individually, you should hear a click as you
enable each section, if you find a bad section note the value it
should have if all sections appear to be good repeat the test at a
higher frequency using a sig gen, if everything appears to be ok at
low frequency then most likely you have attenuator that just needs
cleaning.
Now lets take the attenuator apart, looking at the top you will see a
nut on each SMA connector, remove this nut this will allow for you to
remove the nameplate, under the plate you will see a wealth of allen
screws, remove those but note that the screws close to the SMA
connector are shorter than the other ones.
Now look at the small sideplate, not the one with the ribbon cable
but the other side - there are 4 small allen screws, remove those and
then remove the sideplate, careful not to lose the little wire mesh
here ! now slide out the u shaped cover and remove the top side.
You now have two parts, one beein the bottom side containing the
solenoids and the other one beein the top part containing the
attenuator pads.
First lets inspect the pads, you can measure them with a ohm meter,
they should measure in the vicinity of 50ohms , except of the 10dB
pad which can measure up to 70ohms or more.
Inspect the pads visually, are there any burned or cracked pads ? if
all pads look ok and check out at DC take a surgical swab and
isopropilic alcohol and carefully clean the contacts pads on the
attenuators.
Next look at the contacts, enable all solenoids and observe the
position of the contact tongues, they should be slightly above the
surface of the block, carefully clean the contact tongues with
alcohol, be careful not to bend them.
next put the solenoids back into the 0 position and look at the top
of the solenoids, you will see two little white plastic rods where
those meet the solenoid you should see little rubber rings , there
are 4 of those on each segment, usually over the years they go
briddle and then disappear, with those rings gone the attenuator wont
make contact anymore, you can buy the rings from watchmakers supply
stores as they are beein used for sprocket gaskets !
Now if your gaskets are there put the attenuator back together after
you cleaned everything and it should work now.
If you have a broken or burned pad dont stress over it the pads are
used in all HP attenuators so just find a attenuator on ebay and take
the pad you need out of it, you can also buy pads from agilent
however be prepared to pay $100-150 per
piece

David C. Hallam wrote:

Lothar,

I hate to be stubborn or dense, but where does the marker come from if the
"RF is dead on the tracking generator"?

I do have an operation and maintenance manual. I quote from the manual:

In Marker mode the scan ramp of the spectrum analyzer is stopped momentarily
at a point determined by the Model 844A Marker Position control. At the
point where the scan is stopped, a bright marker appears on the analyzer
display CRT. Simultaneously, the RF Output frequency from the tracking
generator is counted by the Model 8443A counter. If the Function switch is
set to Track Analyzer, the counter frequency indicates marker frequency,
independent of Spectrum Analyzer input signal frequency. If Function switch
is set to Restore Frequency, the counter indicates the Spectrum Analyzer
input signal frequency (as long as the marker is placed on the signal
response).

From the above statement it seems to me the generation of the marker on the

CRT display and the counting of the marker frequency are two independent
operations, i.e., you can generate a marker and still not be able to count
it.

Since I have demonstrated the counter portion of the 8443A is functional as
it will count an external signal from my signal generator and the RF output
the 8443A is functional since there is a marker on the CRT display, the
problem is in the counting of RF output frequency at the point where the
scan is stopped to generate the marker.

If I am still off base, HELP.

David

David,
You do seem to have been given a lot of advice on various topics, not all of which seem relevant to your problem. For example, the known 141 problem with bent D-sub connector brackets really only applies to the ones between the RF and IF sections. Usually due to the RF section being put on a flat surface, thus pushing on the connector. If the interconnect between the mainframe and TG is seated well at both ends, and locked in position, you should not have a problem there.

The marker is generated as you know by stopping the scan for a period depending on the resolution selected and simultaneously opening the counter gate. The marker will thus appear on the 141 display regardless of whether the TG is outputting anything. You can therefore have a marker and no output easily enough...

So your statemant:

the RF output (of)
the 8443A is functional since there is a marker on the CRT display

is not the case at all.


The easiest way to test for TG output is to select zero span on the SA and connect the TG output to the external counter input. With the TG output set above -20 dBm then you should now have a frequency reading identical to that you get normally. No output, no reading. You can also receive the TG output signal in a receiver tuned to the output frequency. Hard to avoid in fact with the full scan :^)