Re: Oscilloscopes - analog but with digital capability?
On Mon, 31 Dec 2012 10:48:34 +0000 (GMT), you wrote: In article <p7o1e8tfknjh74fth8cdeic53dem20kga8@...>,
Harvey White <madyn@...> wrote:
Look at the Tek 468 scope. It had a digital backpack, capable of
about 10 Mhz bandwidth. The processor was (IIRC) and 8051 style, with
limited memory, etc. Yes, I have one of those, it works well. It's my favorite "go take it somewhere there's no wheels" scope. I have one which someone modified, has a new case, not painted, but the same TEK hammertone metal texture (impressed on the metal), it brings out a DB9 connector which allows remote access to the store command signals. No indication that it might have been Tek who did it, but someone did a nice job. Not working, though, needs that high voltage divider, so it may never get operational and remain a spares unit. Imagine that 8051 replaced with an XMEGA or the equivalent, and a very slightly modified (replace switch type only) front panel with perhaps a different display. Ought to be an interesting project. Anyone have the source of the 468's program? Harvey
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Re: Best DVM for general purpose work - 3478A or 34401A ?
Capabilities aside, I prefer VFD displays over LCD any day of the week. From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...] On Behalf Of m1k3k1 Sent: Monday, December 31, 2012 5:37 AM To: hp_agilent_equipment@... Subject: [hp_agilent_equipment] Re: Best DVM for general purpose work - 3478A or 34401A ? Well a quick google showed that the 34401A is a 6.5 digit, and the 3478A is a 5.5 digit, so the reference on the 34401A will be quieter, and should age slower, also being the older instrument its ageing will have improved. I would keep the 34401A M K --- In hp_agilent_equipment@...<mailto:hp_agilent_equipment%40yahoogroups.com>, "kt6uk" <tim.forrester@...<mailto:tim.forrester@...>> wrote:
Hi,
I have a few too many DVM's in the workshop and am thinking about disposing of at least one of them.
Specifically I have a 34401A and 3478A. They appear to have similar features and measure the same values to within a fraction of 1% when tested side by side- although the 3478A does show uncalibrated when first powered up.
So the questions are - what are they worth and which one to keep ?
I'm in the UK so would not want to ship overseas.
I'm tending toward keeping the 34401A as it's newer and doesn't show uncalibrated !
Both are in excellent cosmetic condition.
Regards Tim
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I have a couple of sets of 1/4" hex bits which include Pozidriv bits, but I've been unimpressed with them for the most part. They're fine for infrequent use, but I've found that the alloy is usually pretty soft and the bits don't hold their sharp edges very long. I do a lot of work on Tek scopes and they are almost completely put together with Pozidriv screws.
In addition, the problem with some of the interchangeable-bit drivers is the size of the receptacle on the end of the driver shank which holds the bit. Some of them are nearly 1/2" in diameter. I haven't seen any of them less than 3/8" in diameter.
After getting frustrated multiple times by my inability to get into narrow spaces with the interchangeable-bit driver approach, I went searching for one-piece Pozidriv screwdrivers. Most of them are made by known companies and their quality control and materials appear to be better than the Chinese-made interchangeable-bit sets.
If money is no object, you can buy a complete set of drivers (not bits) from Snap-On for around $100! For mere mortals such as myself, I would suggest you check out K-D Tools, GearWrench, Proto and/or Blackhawk. Google for a local supplier. I found my Blackhawk #1 and #2 Pozi drivers for $7 each at an industrial supply house (Grainger) here in the St. Louis area. Several auto parts houses can get Pozi drivers, but most of them don't carry them in stock.
I believe that Pozi drivers are made in sizes from #0 to #4, but the most common sizes used on electronic gear are #1 and #2. The larger sizes are used primarily on industrial equipment and European cars.
Hope this helps ...
Mike, WB0LDJ
mharmon at att dot net
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Re: DIY: Repair of HP 8568B Step Attenuators - mystery solved and yet another question...
I have about 25 (assorted value) of these repair attenuator glass
replacements in a box someplace if I can ever find them. That I plan on
getting rid of on the TEtrader group.
Pete
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On 12/31/2012 8:06 AM, adrian_microwave wrote:
Jim,
You can order it from Agilent (formerly known as Hewlett Packard).
5180-2720 is the 40 dB pad and costs $57.29
Adrian
--- In hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>, Jim Schatzman
<james.schatzman@...> wrote:
Vladan and the group -
Wow! That is one fancy piece of miniature mechanical manufacturing.
Like a Swiss watch. Beautiful. Crazy. Amazing.
Unfortunately, the 40 dB attenuator is indeed open at one end. And
it is nothing like a few simple resistors. It is a beautiful glass
contraption about 5 mm by 10 mm with gold and resistive elements
plated in a fancy pattern.
Any ideas how I can get a new one?
It is open on the input end. It would appear that someone set the SA
for 40dB attenuation and then attached it to some high power source.
Apparently, the perpetrator failed to read the manual where it
explains (multiple times) that the input limit is 30 dBm AT ALL
ATTENUATOR SETTINGS!
Actually, I am kind of surprised that this delicate device can even
take 30 dBm. Maybe it really can't....
Thanks!
Jim
At 09:16 PM 12/30/2012, you wrote:
Hi Jim,
Do not unscrew the solenoids on the top, at least not for now. To
see what's happening, you will have to open the lower part where the
RF action is.
The two SMA connectors have hex-nuts. Remove them. There is thin
name plate that you can now remove. It covers the whole area between
the SMA connectors. It probably has a few glue spots on its other
side, so carefully pry it off without bending the it. Now, you will
see a bunch of socket cap screws. When you remove them, you will be
able to carefully separate the parts and gain access to the attenuator
pads and plungers. The rubber O-rings are on the tiny nylon plungers
that are attached to the gold plated spring contacts. I think there
are two rings on each plunger, one on the RF side and one on the
solenoid side.
Vladan
--- In
<mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>, Jim Schatzman
<james.schatzman@> wrote:
Vladan-
I got the cover off without trouble. By testing I note that when
the middle (40 dB) switch is triggered, the output turns off
completely. As far as I can determine, the plunger is actuated
correctly. Moving it manually also results in the loss of output. The
other two switches (10 and 20 dB) work fine.
I suppose that either the switch contacts are failing or the 40
dB resistor is open. Apparently both switches and resistors are inside
the two-piece machined steel block. All the RF path seems to be
inside. It would appear that I need to get this apart, but I am not
sure how to. There are quite a few screws attaching the solenoids to
the steel block, but I am not seeing what is holding the steel block
together.
This attenuator has a PC board with several chips on it. I have
noticed before that HP seems to have adopted the philosophy that if 2
chips are good, then 20 must be better. It is a surprisingly
complicated device.
Any advice??
Thanks!
Jim
At 08:45 PM 12/30/2012, you wrote:
Jim,
You will have to pull out the front panel. There are a few
flat-head screws along the front frame (top and bottom, maybe even
sides - don't remember any more). Once you remove them, the front
panel pulls out of the front frame, though it still has a couple of
umbilicals attached. From there, you will see how to get the
attenuator out.
The most common failure has to do with the tiny rubber O-rings
on the plungers. This is all delicate magnifier work. Do not succumb
to the "magnetized housing" myth of repair. The attenuator depends on
magnets for latching. It's just that when the O-ring fails and either
splits or falls off, the mechanism shifts closer to the magnet and the
force of magnetic attraction increases. At that point, the solenoid
(which has nothing wrong with it) no longer can pull the parts away
from the magnet (which also has nothing wrong with it). This is when
some people decide that demagnetizing everything will fix things. If
you have the patience, study the design, it's interesting. The goal
was to use current only when switching a stage is required and then
interrupt all current to the coils as soon as the task is accomplished.
You open the attenuator by removing one of the end caps and
sliding the U-shaped steel cover off. It comes off relatively easily.
Don't try to remove it by prying with screwdrivers.
There are two versions of the attenuators. The older ones are
all electro-mechanical, the newer ones have a p.c. board with some ICs
on them.
Good luck, they can be fixed, but the work requires some
patience and you may have to order no O-rings from Agilent.
Vladan
--- In
<mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>, Jim Schatzman
<james.schatzman@> wrote:
All-
O.k., I have an 8568B with a bad attenuator (40dB and below
are dead).
My big question is - how do you get access to the attenuator
to take it apart and clean/repair? It seems to be really buried under
a maze of stuff...
Thanks!
Jim
At 01:44 PM 12/27/2012, you wrote:
Thanks a lot of this.
I just managed to get a 8568B that attenuator has some
problems with the 20dB step.
These instructions encourage me to open the attenuator and
clean the pads with isopropyl alcohol. Now it works fine.
I didn't made a testped for it i just cold moved carefully
the solenoids and checked with dg8saq vnwa the attenuator pads. I'm
not sure is the solenoid stuck or is it actually a contact failure.
The instructions how to disaasemble the attenuator was very
accurate and easy to follow.
BR, Jarmo
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So does anyone have any idea what the differences are between the 2703A prefix and the 3114A prefix. I know the "A" is US made from what I understand. I'm not finding anything in the docs, or just not looking in the right location.
Thanks,
Jeff
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On 12/30/2012 4:34 PM, J. L. Trantham wrote:
Steve,
Thanks for the data. Mine is also 2703A prefix with REV?:6,0 and
CALNUM?:98. Not a multiple of 34. Would be interesting to see what the
CALNUM increments by after an Agilent CAL.
I, too, need to look at the battery condition. I have not looked at the
manual regarding replacing the battery. Has anyone done that without losing
the CAL Constants?
Joe
-----Original Message-----
From: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of Steve
Sent: Sunday, December 30, 2012 4:14 PM
To: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: Re: [hp_agilent_equipment] 3457a on the way
It would be interesting to see if a newer rev is out there. My 3457A is s.n.
prefix 2703, with rev 6,0 and option 0, CALNUM=34. I wonder if that's a
default number for anything less than a full cal at Agilent? The last
calibration was at least 6 years ago and performed by what was then Boeing
Military Airplane Company's metrology lab. I need to open it up and check
the battery condition.
Steve
On Dec 29, 2012, at 8:08 PM, "J. L. Trantham" <jltran@... <mailto:jltran%40att.net>
<mailto:jltran%40att.net> > wrote:
If the 'SELF TEST OK' message appears, there is no need to make any
'adjustments'. Just do the 'front panel CAL' if needed.
As I said, I would check it out, assume it is the best instrument in your
collection, send it to Agilent for CAL and see what you get.
I would appreciate knowing what 'REV?' and 'OPT?' says when you get a
chance. 'CALNUM?' would be interesting as well.
In the 3458A, the firmware is in an EPROM (6 EPROM's for the older units)
and can be removed, a socket placed, and easily upgraded by purchasing the
latest pre-programmed EPROM (or EPROM's for the older units) from Agilent.
The only problem is they have a $50 minimum for this $18 part for the later
units.
My wife thinks I am going to appear on an episode of 'Hoarders'.
Joe
-----Original Message-----
From: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com> ] On Behalf Of Jeff Machesky
Sent: Saturday, December 29, 2012 8:01 PM
To: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: Re: [hp_agilent_equipment] 3457a on the way
Wow, lots of replies all of a sudden. I'm already prepping the wife for
the $200 + price tag of calibration. Funny how when I was single I would
have about $800 in cash in my wallet at all times and now I beg for 20
bucks, Hmm. Sad part is I make about 4 times the money. In any event
I've not received to much feedback on the "Self Test OK" message the
seller had posted. Any comments? I'm too much of a skeptic when it comes
to eBay purchases. It's just a convenient place to purchase such goods.
Any feedback would be appreciated as to possible pitfalls regarding this
device. I like to prep for issues rather then build myself up for
failure. What do they say...it's better to be pleasantly surprised then
let down.
Thanks,
Jeff
On 12/29/2012 5:40 PM, J. L. Trantham wrote:
According to the manual, there are only two 'adjustments' that can be
made
on a 3457A, Input Offset Amplifier adjustment and AC Converter
Frequency
Response, both needed only if there is a 'HARDWARE ERR' failure
message
after 'TEST' is selected and then only if it is a specific
'AUXERR' or
16 or
256 is seen. Otherwise, all the calibrations are done from the front
panel
with specific inputs from the front panel.
The CALNUM? is incremented by 'several digits' with a 'complete
calibration', one for each calibration point entered, per the manual.
Interestingly, when I sent my two 3458A's to Agilent for calibration,
the
CALNUM incremented by only 1. However, when I calibrated one of them
before
sending it to Agilent, (since I lost the data in the DALLAS CALRAM
chip that
I was removing) the CALNUM went from 1 to something like 34 or
something. I
don't recall. It seems that if you have the appropriate software to
run the
complete calibration protocol, it only increments by '1' instead of by
all
the data points entered. Such software exists for the 3457A but I have
never seen it available 'on theBay'. I suspect Agilent would have that
software and equipment to do that calibration and, thus, an Agilent
calibration may only increment the CALNUM? by 1.
When getting an Agilent calibration of the 3458A, you get 'As
Received' and
'As Completed' data. Very helpful to me in that the only two points my
'House CAL' of the one 3458A failed were the two 'midrange' AC Voltage
values. All else 'PASSED'.
I agree with Dave. If it's HP/Agilent, I prefer Agilent to do the CAL.
If
it's Solartron, I prefer AMETEK (Solartron), etc.
I believe that having some 'basic' professionally calibrated
instruments
(DMM's, Noise Sources, Power Sensors, Frequency Standards (unless you
have a
GPSDO, CS Standard, etc.) etc.), that you can then use as 'transfer
standards' to do your own 'in house' calibration of other instruments,
is
very important if you want to set up a reliable workshop.
Of course, you will also need a 'stable' source of the various
signals
that
you will use to be 'measured' by the various 'DUT's', such as
resistance,
voltage, current, frequency, etc. The 3458A is relatively easy to
calibrate, requiring only 10.000000 VDC, 10000.000 ohms, and some AC
voltage
at various frequencies, IIRC. I have never CAL'd a 3457A but the
3478A
is a
multi-step process.
This whole thing can become very 'addictive'. Be careful.
Joe
-----Original Message-----
From: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
[mailto:hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>] On Behalf Of David
Kirkby
Sent: Saturday, December 29, 2012 5:53 PM
To: hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
<mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: Re: [hp_agilent_equipment] 3457a on the way
On 29 December 2012 20:01, Jeff Machesky <jeff@...
<mailto:jeff%40codebest.com>
<mailto:jeff%40codebest.com>
<mailto:jeff%40codebest.com>
<mailto:jeff%40codebest.com> > wrote:
Thanks Dave, I actually have watched those videos. Bit drawn out
like
most of his videos..but still good. Too much detail is not always a
bad
thing. I thought the bit showing the noise on the DVM was a bit silly when it
was connected to a DC power supply.
As for the 3457A, if it works I plan on getting it calibrated by
Agilent
within the year. From what I understand it's about a $200 US
investment.
The meter was last calibrated in '98, so I'll be curious to see how
accurate it is when I get it. I think the calibration service you chose might dictate whether you
get data about the condition when sent.
When I send mine in for cal, I'd like to know what was out and by how
much. But I'm not going to pay extra for a calibration service that
provides that. As far as I'm concerned, if Agilent calibrate it, then
it is OK. For me personally, it makes no difference whatsoever if it
has ISO, NIST or whatever calibration. But I'd prefer Agilent to
someone else.
I have calibration certificate here for an Agilent VNA calibration
kit. It was done by a calibration house in the USA. But from what I
can gather from reading the documentation, the equipment to calibrate
them is not available commerically. So it makes me wonder how a lab
can calibrate a cal kit, when the equipment to do it can't be bought.
I suspect there is a fairly cosy realationship between some test
equipment dealers and calibration facilities.
I plan on purchasing some
voltage references from the well known site as a basic test of the
3457A. I may even calibrate it based on those references if it's way
out
and later getting it NIST traceable calibrated. I don't know if there are pots in there you can adjust with a trimmer,
or if it is all done electronically. You might find it is impossible
to calibrate yourself.
I never had any reason to look inside mine.
Dave
------------------------------------
Yahoo! Groups Links
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I don't know. It seems odd that they would have a minimum of $50 for the
cheapest way to order (web based, no 'live humans') but no minimum for the
more expensive way to order ('live humans').
I have placed orders by phone in the past for as little as $4 (thermal fuse
for a 10811) and there was not a minimum. It's been a while though.
Joe
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-----Original Message----- From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...] On Behalf Of jayw_comark Sent: Monday, December 31, 2012 5:11 AM To: hp_agilent_equipment@... Subject: [hp_agilent_equipment] Re: 3457a on the way --- In hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com> , "J. L. Trantham" <jltran@...> wrote: [...] In the 3458A, the firmware is in an EPROM (6 EPROM's for the older units)
and can be removed, a socket placed, and easily upgraded by purchasing the
latest pre-programmed EPROM (or EPROM's for the older units) from Agilent.
The only problem is they have a $50 minimum for this $18 part for the later units.
My wife thinks I am going to appear on an episode of 'Hoarders'.
Joe Hi Joe, I think Agilent will waive the $50 minimum order if you phone it in. The minimum only applies when ordering through their web site. Correct me if I'm wrong... Jay
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Re: Directional bridge in HP 85046A
If the bridge design is basically the same as others, there is coax on one side, and the other side is only wound for symmetry purposes, so it doesn't matter if there is the same coax or solid wire of the same outer diameter.
If the through line behaves like a high pass, there is probably an open circuit or hair crack that acts as a small capacitance.
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--- In hp_agilent_equipment@..., "Peter Bunge" <bunge@...> wrote:
The A3 Directional Bridge (Port 1) has a pair of toroids on each side. The pair with brown "wire" is wound with coax. Is the grey "wire" on the other pair also coax?
I have an 85046A S parameter test set with identical faults on both directional couplers (I did not believe it either) and looking at the inside of one seems suspicious as the "Bridge" does not appear balanced in construction. Each end of the grey "wire" out of the toroid pair ends in a solder blob. I cannot see if it is/was a coax.
I looked at the coupler on the VNA from input to output after doing a B/R thru calibration and it starts at -20dB and climbs exponentially to -2dB at 1GHz, stays there then drops off a bit at the 3GHz end. I used a Transmission/Reflection Test Set with "Test" feeding the Transfer Switch end and with the Port 1 end on "B" on the 8753B. Coupler port terminated but it does not change anything.
When connected to the 8753B S11 and S22 with the ports open have identical shapes with two humps starting at -70dB rising to -15dB,and separated by a notch going to -55dB around 2GHz. When terminated they both rise exponentially from -70dB to -20dB at around 2GHz then flatten out. (this has nothing to do with the other thread I started, this is a different 85046A)
I have eliminated the splitter, attenuator, and Transfer Switch because I thought it had to be something in common to both Directional Bridges. I am now looking at the A3 as a separate component.
I can send a full description .docx file with pictures if I have an email.
Main question: is the grey "wire" on the toroids a coax?
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Re: DIY: Repair of HP 8568B Step Attenuators - mystery solved and yet another question...
Jim,
You can order it from Agilent (formerly known as Hewlett Packard).
5180-2720 is the 40 dB pad and costs $57.29
Adrian
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Show quoted text
--- In hp_agilent_equipment@..., Jim Schatzman <james.schatzman@...> wrote:
Vladan and the group -
Wow! That is one fancy piece of miniature mechanical manufacturing. Like a Swiss watch. Beautiful. Crazy. Amazing.
Unfortunately, the 40 dB attenuator is indeed open at one end. And it is nothing like a few simple resistors. It is a beautiful glass contraption about 5 mm by 10 mm with gold and resistive elements plated in a fancy pattern.
Any ideas how I can get a new one?
It is open on the input end. It would appear that someone set the SA for 40dB attenuation and then attached it to some high power source. Apparently, the perpetrator failed to read the manual where it explains (multiple times) that the input limit is 30 dBm AT ALL ATTENUATOR SETTINGS!
Actually, I am kind of surprised that this delicate device can even take 30 dBm. Maybe it really can't....
Thanks!
Jim
At 09:16 PM 12/30/2012, you wrote:
Hi Jim,
Do not unscrew the solenoids on the top, at least not for now. To see what's happening, you will have to open the lower part where the RF action is.
The two SMA connectors have hex-nuts. Remove them. There is thin name plate that you can now remove. It covers the whole area between the SMA connectors. It probably has a few glue spots on its other side, so carefully pry it off without bending the it. Now, you will see a bunch of socket cap screws. When you remove them, you will be able to carefully separate the parts and gain access to the attenuator pads and plungers. The rubber O-rings are on the tiny nylon plungers that are attached to the gold plated spring contacts. I think there are two rings on each plunger, one on the RF side and one on the solenoid side.
Vladan
--- In <mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@..., Jim Schatzman <james.schatzman@> wrote:
Vladan-
I got the cover off without trouble. By testing I note that when the middle (40 dB) switch is triggered, the output turns off completely. As far as I can determine, the plunger is actuated correctly. Moving it manually also results in the loss of output. The other two switches (10 and 20 dB) work fine.
I suppose that either the switch contacts are failing or the 40 dB resistor is open. Apparently both switches and resistors are inside the two-piece machined steel block. All the RF path seems to be inside. It would appear that I need to get this apart, but I am not sure how to. There are quite a few screws attaching the solenoids to the steel block, but I am not seeing what is holding the steel block together.
This attenuator has a PC board with several chips on it. I have noticed before that HP seems to have adopted the philosophy that if 2 chips are good, then 20 must be better. It is a surprisingly complicated device.
Any advice??
Thanks!
Jim
At 08:45 PM 12/30/2012, you wrote:
Jim,
You will have to pull out the front panel. There are a few flat-head screws along the front frame (top and bottom, maybe even sides - don't remember any more). Once you remove them, the front panel pulls out of the front frame, though it still has a couple of umbilicals attached. From there, you will see how to get the attenuator out.
The most common failure has to do with the tiny rubber O-rings on the plungers. This is all delicate magnifier work. Do not succumb to the "magnetized housing" myth of repair. The attenuator depends on magnets for latching. It's just that when the O-ring fails and either splits or falls off, the mechanism shifts closer to the magnet and the force of magnetic attraction increases. At that point, the solenoid (which has nothing wrong with it) no longer can pull the parts away from the magnet (which also has nothing wrong with it). This is when some people decide that demagnetizing everything will fix things. If you have the patience, study the design, it's interesting. The goal was to use current only when switching a stage is required and then interrupt all current to the coils as soon as the task is accomplished.
You open the attenuator by removing one of the end caps and sliding the U-shaped steel cover off. It comes off relatively easily. Don't try to remove it by prying with screwdrivers.
There are two versions of the attenuators. The older ones are all electro-mechanical, the newer ones have a p.c. board with some ICs on them.
Good luck, they can be fixed, but the work requires some patience and you may have to order no O-rings from Agilent.
Vladan
--- In <mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@..., Jim Schatzman <james.schatzman@> wrote:
All-
O.k., I have an 8568B with a bad attenuator (40dB and below are dead).
My big question is - how do you get access to the attenuator to take it apart and clean/repair? It seems to be really buried under a maze of stuff...
Thanks!
Jim
At 01:44 PM 12/27/2012, you wrote:
Thanks a lot of this.
I just managed to get a 8568B that attenuator has some problems with the 20dB step.
These instructions encourage me to open the attenuator and clean the pads with isopropyl alcohol. Now it works fine.
I didn't made a testped for it i just cold moved carefully the solenoids and checked with dg8saq vnwa the attenuator pads. I'm not sure is the solenoid stuck or is it actually a contact failure.
The instructions how to disaasemble the attenuator was very accurate and easy to follow.
BR, Jarmo
[Non-text portions of this message have been removed]
[Non-text portions of this message have been removed]
[Non-text portions of this message have been removed]
|
--- In hp_agilent_equipment@..., "J. L. Trantham" <jltran@...> wrote: [...] In the 3458A, the firmware is in an EPROM (6 EPROM's for the older units)
and can be removed, a socket placed, and easily upgraded by purchasing the
latest pre-programmed EPROM (or EPROM's for the older units) from Agilent.
The only problem is they have a $50 minimum for this $18 part for the later
units.
My wife thinks I am going to appear on an episode of 'Hoarders'.
Joe Hi Joe, I think Agilent will waive the $50 minimum order if you phone it in. The minimum only applies when ordering through their web site. Correct me if I'm wrong... Jay
|
Re: Oscilloscopes - analog but with digital capability?
In article <p7o1e8tfknjh74fth8cdeic53dem20kga8@...>, Harvey White <madyn@...> wrote: Look at the Tek 468 scope. It had a digital backpack, capable of
about 10 Mhz bandwidth. The processor was (IIRC) and 8051 style, with
limited memory, etc. Yes, I have one of those, it works well. -- Stuart Winsor Only plain text for emails
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Re: Best DVM for general purpose work - 3478A or 34401A ?
Well a quick google showed that the 34401A is a 6.5 digit, and the 3478A is a 5.5 digit, so the reference on the 34401A will be quieter, and should age slower, also being the older instrument its ageing will have improved.
I would keep the 34401A
M K
toggle quoted message
Show quoted text
--- In hp_agilent_equipment@..., "kt6uk" <tim.forrester@...> wrote:
Hi,
I have a few too many DVM's in the workshop and am thinking about disposing of at least one of them.
Specifically I have a 34401A and 3478A. They appear to have similar features and measure the same values to within a fraction of 1% when tested side by side- although the 3478A does show uncalibrated when first powered up.
So the questions are - what are they worth and which one to keep ?
I'm in the UK so would not want to ship overseas.
I'm tending toward keeping the 34401A as it's newer and doesn't show uncalibrated !
Both are in excellent cosmetic condition.
Regards Tim
|
Best DVM for general purpose work - 3478A or 34401A ?
Hi,
I have a few too many DVM's in the workshop and am thinking about disposing of at least one of them.
Specifically I have a 34401A and 3478A. They appear to have similar features and measure the same values to within a fraction of 1% when tested side by side- although the 3478A does show uncalibrated when first powered up.
So the questions are - what are they worth and which one to keep ?
I'm in the UK so would not want to ship overseas.
I'm tending toward keeping the 34401A as it's newer and doesn't show uncalibrated !
Both are in excellent cosmetic condition.
Regards Tim
|
I was lucky and got a set of Pozi bits in the local Sears (#26493). Looks
like they are out of them now - they are quoting 13 to 15 days for store
pickup.
Orin.
toggle quoted message
Show quoted text
On Sun, Dec 30, 2012 at 9:31 PM, Richard Knoppow <dickburk@...>wrote: **
----- Original Message -----
From: "bownes" <bownes@...>
To: <hp_agilent_equipment@...>
Sent: Sunday, December 30, 2012 9:03 PM
Subject: [hp_agilent_equipment] Pozi-Drive bits
I know this has come up many times in the past so when I
stumbled upon PoziDrive driver bits today in the HomeDepot
I thought I would pass on the tip (Pardon the pun please).
There are two driver bit sets, a 29 piece, and a 30 piece,
both are three dollars apiece. Between the two there are
bits sized from PZ0 to PZ3, with some duplication. I
thought that $6 wasn't a bad price to have all these in
the tool box.
They are in private labeled assortments sold under the HD
brand.
Bob
Thank you very much Bob. When I searched around for
Pozidriv screwdrivers I discovered no one locally seemed to
have them and some places never heard of them. I wound up
buying them from Amazon. These are _much_ cheaper and one
hopes of decent quality.
--
Richard Knoppow
Los Angeles
WB6KBL
dickburk@...
|
Or roll your own... :) Happy New year, everyone! -- Anders Gustafsson Engineer, CNE6, ASE Pedago, The Aaland Islands (N60 E20) www.pedago.fi phone +358 18 12060 mobile +358 40506 7099 fax +358 18 14060 Peter Gottlieb <hpnpilot@...> 2012-12-31 00:13 >>>
Haha, I guess not as it sold really quickly!
|
Re: DIY: Repair of HP 8568B Step Attenuators - mystery solved and yet another question...
John- If the picture is to be believed, then it appears that 5180-2720 is exactly the right design but about 10% too small. 5180-2720: 3/8 by 5/16 My part: 7/16 by 3/8 I am wondering if HP's photographic technique might be imperfect. Interesting that they use an inch ruler in their picture. Looking up the whole attenuator on the parts website, this is what I find 5086-7815 exchange with 5086-6815 replaced by 85680-60228 5086-6815: obsolete/unavailable replaced by 85680-60228 85680-60228: obsolete/unavailable replaced by 5062-6643 --> there is actually one for sale on Ebay at $300 5062-6643: aka Replacement Kit 33321RC. obsolete/unavailable --> available on Ebay for $400 The website says that the equipment using 5180-2720 is 33321H, 8495B, 8405H, 8496B, 8672A, E2500B-508. It does not actually list the 8594A/E that you mention. Looking up the parts for the 33321H (attenuator assembly), it lists the 5180-2720 40 dB attenuator chip, but says that the 10 dB and 20 dB chips are "agilent trade restricted/ not orderable". Odd. Finding the specs for that attenuator assembly, it appears to be the same size as the 5086-7815. I think that I will order the 5180-2720 and keep my fingers crossed. Thanks! Jim At 11:22 PM 12/30/2012, you wrote:
Jim,
I think the same basic attenuator hybrids are used in the 8594(A-E) and similar frequency range spectrum analyzers. (Some higher bandwidth analyzers (22GHz) use a pair of 20dB pads to get the 40dB step.) The 40dB hybrid for the 8594E attenuator is Agilent part number 5180-2720, in stock at about $58.00. Go to parts.agilent.com to get a picture of the part (select the "view larger image" after looking up the part in find-by-part and clicking on the part number).
See if it looks like the same physical size.
--John Gord
--- In <mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@..., Jim Schatzman <james.schatzman@...> wrote:
Vladan and the group -
Wow! That is one fancy piece of miniature mechanical manufacturing. Like a Swiss watch. Beautiful. Crazy. Amazing.
Unfortunately, the 40 dB attenuator is indeed open at one end. And it is nothing like a few simple resistors. It is a beautiful glass contraption about 5 mm by 10 mm with gold and resistive elements plated in a fancy pattern.
Any ideas how I can get a new one?
It is open on the input end. It would appear that someone set the SA for 40dB attenuation and then attached it to some high power source. Apparently, the perpetrator failed to read the manual where it explains (multiple times) that the input limit is 30 dBm AT ALL ATTENUATOR SETTINGS!
Actually, I am kind of surprised that this delicate device can even take 30 dBm. Maybe it really can't....
Thanks!
Jim
At 09:16 PM 12/30/2012, you wrote:
Hi Jim,
Do not unscrew the solenoids on the top, at least not for now. To see what's happening, you will have to open the lower part where the RF action is.
The two SMA connectors have hex-nuts. Remove them. There is thin name plate that you can now remove. It covers the whole area between the SMA connectors. It probably has a few glue spots on its other side, so carefully pry it off without bending the it. Now, you will see a bunch of socket cap screws. When you remove them, you will be able to carefully separate the parts and gain access to the attenuator pads and plungers. The rubber O-rings are on the tiny nylon plungers that are attached to the gold plated spring contacts. I think there are two rings on each plunger, one on the RF side and one on the solenoid side.
Vladan
--- In <mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@..., Jim Schatzman <james.schatzman@> wrote:
Vladan-
I got the cover off without trouble. By testing I note that when the middle (40 dB) switch is triggered, the output turns off completely. As far as I can determine, the plunger is actuated correctly. Moving it manually also results in the loss of output. The other two switches (10 and 20 dB) work fine.
I suppose that either the switch contacts are failing or the 40 dB resistor is open. Apparently both switches and resistors are inside the two-piece machined steel block. All the RF path seems to be inside. It would appear that I need to get this apart, but I am not sure how to. There are quite a few screws attaching the solenoids to the steel block, but I am not seeing what is holding the steel block together.
This attenuator has a PC board with several chips on it. I have noticed before that HP seems to have adopted the philosophy that if 2 chips are good, then 20 must be better. It is a surprisingly complicated device.
Any advice??
Thanks!
Jim
At 08:45 PM 12/30/2012, you wrote:
Jim,
You will have to pull out the front panel. There are a few flat-head screws along the front frame (top and bottom, maybe even sides - don't remember any more). Once you remove them, the front panel pulls out of the front frame, though it still has a couple of umbilicals attached. From there, you will see how to get the attenuator out.
The most common failure has to do with the tiny rubber O-rings on the plungers. This is all delicate magnifier work. Do not succumb to the "magnetized housing" myth of repair. The attenuator depends on magnets for latching. It's just that when the O-ring fails and either splits or falls off, the mechanism shifts closer to the magnet and the force of magnetic attraction increases. At that point, the solenoid (which has nothing wrong with it) no longer can pull the parts away from the magnet (which also has nothing wrong with it). This is when some people decide that demagnetizing everything will fix things. If you have the patience, study the design, it's interesting. The goal was to use current only when switching a stage is required and then interrupt all current to the coils as soon as the task is accomplished.
You open the attenuator by removing one of the end caps and sliding the U-shaped steel cover off. It comes off relatively easily. Don't try to remove it by prying with screwdrivers.
There are two versions of the attenuators. The older ones are all electro-mechanical, the newer ones have a p.c. board with some ICs on them.
Good luck, they can be fixed, but the work requires some patience and you may have to order no O-rings from Agilent.
Vladan
--- In <mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@..., Jim Schatzman <james.schatzman@> wrote:
All-
O.k., I have an 8568B with a bad attenuator (40dB and below are dead).
My big question is - how do you get access to the attenuator to take it apart and clean/repair? It seems to be really buried under a maze of stuff...
Thanks!
Jim
At 01:44 PM 12/27/2012, you wrote:
Thanks a lot of this.
I just managed to get a 8568B that attenuator has some problems with the 20dB step.
These instructions encourage me to open the attenuator and clean the pads with isopropyl alcohol. Now it works fine.
I didn't made a testped for it i just cold moved carefully the solenoids and checked with dg8saq vnwa the attenuator pads. I'm not sure is the solenoid stuck or is it actually a contact failure.
The instructions how to disaasemble the attenuator was very accurate and easy to follow.
BR, Jarmo
[Non-text portions of this message have been removed]
[Non-text portions of this message have been removed]
[Non-text portions of this message have been removed]
|
Re: Oscilloscopes - analog but with digital capability?
On Sun, 30 Dec 2012 15:46:26 -0800 (PST), "J. Forster" <jfor@...> wrote: The 7854 does take some learning, especially if you want to use the
keyboard functions. That is sure the case. BTW, a 7B53A is not the correct PI as a sweep. It is a sweep for something
like a 7603 or other 100 MHz mainframes. The only problem with the 7B53A or other 100 MHz 7B5x timebases is that the 7854 vertical delay line at 65ns is too short to show the leading edge. The same restriction applies to the other 400 MHz and faster mainframes. I am not sure about the 200 MHz mainframes which have a 90ns delay line. One might want to use the 7B53A for its delayed sweep, mixed sweep, variable holdoff, or external amplifier in capability but in general like you say, the 7B92A is a better choice. The 7854 is a 400 MHz mainframe. The proper sweeps for the 7854 are the
7B80 & 7B85 or the 7B92A.
To use the digitizing functions properly, you need the 7B87. The 7854 only requires the 7B87 for pretrigger and single shot acquisitions. Full bandwidth equivalent time sampling acquisitions work fine with any of the other timebases.
|
Re: DIY: Repair of HP 8568B Step Attenuators - mystery solved and yet another question...
Jim,
I think the same basic attenuator hybrids are used in the 8594(A-E) and similar frequency range spectrum analyzers. (Some higher bandwidth analyzers (22GHz) use a pair of 20dB pads to get the 40dB step.) The 40dB hybrid for the 8594E attenuator is Agilent part number 5180-2720, in stock at about $58.00. Go to parts.agilent.com to get a picture of the part (select the "view larger image" after looking up the part in find-by-part and clicking on the part number).
See if it looks like the same physical size.
--John Gord
toggle quoted message
Show quoted text
--- In hp_agilent_equipment@..., Jim Schatzman <james.schatzman@...> wrote:
Vladan and the group -
Wow! That is one fancy piece of miniature mechanical manufacturing. Like a Swiss watch. Beautiful. Crazy. Amazing.
Unfortunately, the 40 dB attenuator is indeed open at one end. And it is nothing like a few simple resistors. It is a beautiful glass contraption about 5 mm by 10 mm with gold and resistive elements plated in a fancy pattern.
Any ideas how I can get a new one?
It is open on the input end. It would appear that someone set the SA for 40dB attenuation and then attached it to some high power source. Apparently, the perpetrator failed to read the manual where it explains (multiple times) that the input limit is 30 dBm AT ALL ATTENUATOR SETTINGS!
Actually, I am kind of surprised that this delicate device can even take 30 dBm. Maybe it really can't....
Thanks!
Jim
At 09:16 PM 12/30/2012, you wrote:
Hi Jim,
Do not unscrew the solenoids on the top, at least not for now. To see what's happening, you will have to open the lower part where the RF action is.
The two SMA connectors have hex-nuts. Remove them. There is thin name plate that you can now remove. It covers the whole area between the SMA connectors. It probably has a few glue spots on its other side, so carefully pry it off without bending the it. Now, you will see a bunch of socket cap screws. When you remove them, you will be able to carefully separate the parts and gain access to the attenuator pads and plungers. The rubber O-rings are on the tiny nylon plungers that are attached to the gold plated spring contacts. I think there are two rings on each plunger, one on the RF side and one on the solenoid side.
Vladan
--- In <mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@..., Jim Schatzman <james.schatzman@> wrote:
Vladan-
I got the cover off without trouble. By testing I note that when the middle (40 dB) switch is triggered, the output turns off completely. As far as I can determine, the plunger is actuated correctly. Moving it manually also results in the loss of output. The other two switches (10 and 20 dB) work fine.
I suppose that either the switch contacts are failing or the 40 dB resistor is open. Apparently both switches and resistors are inside the two-piece machined steel block. All the RF path seems to be inside. It would appear that I need to get this apart, but I am not sure how to. There are quite a few screws attaching the solenoids to the steel block, but I am not seeing what is holding the steel block together.
This attenuator has a PC board with several chips on it. I have noticed before that HP seems to have adopted the philosophy that if 2 chips are good, then 20 must be better. It is a surprisingly complicated device.
Any advice??
Thanks!
Jim
At 08:45 PM 12/30/2012, you wrote:
Jim,
You will have to pull out the front panel. There are a few flat-head screws along the front frame (top and bottom, maybe even sides - don't remember any more). Once you remove them, the front panel pulls out of the front frame, though it still has a couple of umbilicals attached. From there, you will see how to get the attenuator out.
The most common failure has to do with the tiny rubber O-rings on the plungers. This is all delicate magnifier work. Do not succumb to the "magnetized housing" myth of repair. The attenuator depends on magnets for latching. It's just that when the O-ring fails and either splits or falls off, the mechanism shifts closer to the magnet and the force of magnetic attraction increases. At that point, the solenoid (which has nothing wrong with it) no longer can pull the parts away from the magnet (which also has nothing wrong with it). This is when some people decide that demagnetizing everything will fix things. If you have the patience, study the design, it's interesting. The goal was to use current only when switching a stage is required and then interrupt all current to the coils as soon as the task is accomplished.
You open the attenuator by removing one of the end caps and sliding the U-shaped steel cover off. It comes off relatively easily. Don't try to remove it by prying with screwdrivers.
There are two versions of the attenuators. The older ones are all electro-mechanical, the newer ones have a p.c. board with some ICs on them.
Good luck, they can be fixed, but the work requires some patience and you may have to order no O-rings from Agilent.
Vladan
--- In <mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@..., Jim Schatzman <james.schatzman@> wrote:
All-
O.k., I have an 8568B with a bad attenuator (40dB and below are dead).
My big question is - how do you get access to the attenuator to take it apart and clean/repair? It seems to be really buried under a maze of stuff...
Thanks!
Jim
At 01:44 PM 12/27/2012, you wrote:
Thanks a lot of this.
I just managed to get a 8568B that attenuator has some problems with the 20dB step.
These instructions encourage me to open the attenuator and clean the pads with isopropyl alcohol. Now it works fine.
I didn't made a testped for it i just cold moved carefully the solenoids and checked with dg8saq vnwa the attenuator pads. I'm not sure is the solenoid stuck or is it actually a contact failure.
The instructions how to disaasemble the attenuator was very accurate and easy to follow.
BR, Jarmo
|
toggle quoted message
Show quoted text
----- Original Message ----- From: "bownes" <bownes@...> To: <hp_agilent_equipment@...> Sent: Sunday, December 30, 2012 9:03 PM Subject: [hp_agilent_equipment] Pozi-Drive bits
I know this has come up many times in the past so when I stumbled upon PoziDrive driver bits today in the HomeDepot I thought I would pass on the tip (Pardon the pun please).
There are two driver bit sets, a 29 piece, and a 30 piece, both are three dollars apiece. Between the two there are bits sized from PZ0 to PZ3, with some duplication. I thought that $6 wasn't a bad price to have all these in the tool box.
They are in private labeled assortments sold under the HD brand.
Bob
Thank you very much Bob. When I searched around for Pozidriv screwdrivers I discovered no one locally seemed to have them and some places never heard of them. I wound up buying them from Amazon. These are _much_ cheaper and one hopes of decent quality. -- Richard Knoppow Los Angeles WB6KBL dickburk@...
|
I know this has come up many times in the past so when I stumbled upon PoziDrive driver bits today in the HomeDepot I thought I would pass on the tip (Pardon the pun please).
There are two driver bit sets, a 29 piece, and a 30 piece, both are three dollars apiece. Between the two there are bits sized from PZ0 to PZ3, with some duplication. I thought that $6 wasn't a bad price to have all these in the tool box.
They are in private labeled assortments sold under the HD brand.
Bob
|
Re: DIY: Repair of HP 8568B Step Attenuators - mystery solved and yet another question...
Vladan and the group - Wow! That is one fancy piece of miniature mechanical manufacturing. Like a Swiss watch. Beautiful. Crazy. Amazing. Unfortunately, the 40 dB attenuator is indeed open at one end. And it is nothing like a few simple resistors. It is a beautiful glass contraption about 5 mm by 10 mm with gold and resistive elements plated in a fancy pattern. Any ideas how I can get a new one? It is open on the input end. It would appear that someone set the SA for 40dB attenuation and then attached it to some high power source. Apparently, the perpetrator failed to read the manual where it explains (multiple times) that the input limit is 30 dBm AT ALL ATTENUATOR SETTINGS! Actually, I am kind of surprised that this delicate device can even take 30 dBm. Maybe it really can't.... Thanks! Jim At 09:16 PM 12/30/2012, you wrote:
Hi Jim,
Do not unscrew the solenoids on the top, at least not for now. To see what's happening, you will have to open the lower part where the RF action is.
The two SMA connectors have hex-nuts. Remove them. There is thin name plate that you can now remove. It covers the whole area between the SMA connectors. It probably has a few glue spots on its other side, so carefully pry it off without bending the it. Now, you will see a bunch of socket cap screws. When you remove them, you will be able to carefully separate the parts and gain access to the attenuator pads and plungers. The rubber O-rings are on the tiny nylon plungers that are attached to the gold plated spring contacts. I think there are two rings on each plunger, one on the RF side and one on the solenoid side.
Vladan
--- In <mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@..., Jim Schatzman <james.schatzman@...> wrote:
Vladan-
I got the cover off without trouble. By testing I note that when the middle (40 dB) switch is triggered, the output turns off completely. As far as I can determine, the plunger is actuated correctly. Moving it manually also results in the loss of output. The other two switches (10 and 20 dB) work fine.
I suppose that either the switch contacts are failing or the 40 dB resistor is open. Apparently both switches and resistors are inside the two-piece machined steel block. All the RF path seems to be inside. It would appear that I need to get this apart, but I am not sure how to. There are quite a few screws attaching the solenoids to the steel block, but I am not seeing what is holding the steel block together.
This attenuator has a PC board with several chips on it. I have noticed before that HP seems to have adopted the philosophy that if 2 chips are good, then 20 must be better. It is a surprisingly complicated device.
Any advice??
Thanks!
Jim
At 08:45 PM 12/30/2012, you wrote:
Jim,
You will have to pull out the front panel. There are a few flat-head screws along the front frame (top and bottom, maybe even sides - don't remember any more). Once you remove them, the front panel pulls out of the front frame, though it still has a couple of umbilicals attached. From there, you will see how to get the attenuator out.
The most common failure has to do with the tiny rubber O-rings on the plungers. This is all delicate magnifier work. Do not succumb to the "magnetized housing" myth of repair. The attenuator depends on magnets for latching. It's just that when the O-ring fails and either splits or falls off, the mechanism shifts closer to the magnet and the force of magnetic attraction increases. At that point, the solenoid (which has nothing wrong with it) no longer can pull the parts away from the magnet (which also has nothing wrong with it). This is when some people decide that demagnetizing everything will fix things. If you have the patience, study the design, it's interesting. The goal was to use current only when switching a stage is required and then interrupt all current to the coils as soon as the task is accomplished.
You open the attenuator by removing one of the end caps and sliding the U-shaped steel cover off. It comes off relatively easily. Don't try to remove it by prying with screwdrivers.
There are two versions of the attenuators. The older ones are all electro-mechanical, the newer ones have a p.c. board with some ICs on them.
Good luck, they can be fixed, but the work requires some patience and you may have to order no O-rings from Agilent.
Vladan
--- In <mailto:hp_agilent_equipment%40yahoogroups.com>hp_agilent_equipment@..., Jim Schatzman <james.schatzman@> wrote:
All-
O.k., I have an 8568B with a bad attenuator (40dB and below are dead).
My big question is - how do you get access to the attenuator to take it apart and clean/repair? It seems to be really buried under a maze of stuff...
Thanks!
Jim
At 01:44 PM 12/27/2012, you wrote:
Thanks a lot of this.
I just managed to get a 8568B that attenuator has some problems with the 20dB step.
These instructions encourage me to open the attenuator and clean the pads with isopropyl alcohol. Now it works fine.
I didn't made a testped for it i just cold moved carefully the solenoids and checked with dg8saq vnwa the attenuator pads. I'm not sure is the solenoid stuck or is it actually a contact failure.
The instructions how to disaasemble the attenuator was very accurate and easy to follow.
BR, Jarmo
[Non-text portions of this message have been removed]
|
Anders
David Hess
bownes