开云体育

A DC measurement across the output connector should show
53 ohms. I know this is not a standard value but that is what the diagram
says. My 608 shows infinity. That's not a good sign.

Regards.

Max. K 4 O DS.

It's really very simple. The center conductor of the connector goes through
a 53 ohm resistor to one side of the pickup coil, the other side of the
pickup coil goes to the sleeve. The center conductor also goes through the
series combination of a 53 ohm resistor and a variable capacitor to the
sleeve. The capacitor is designated as c37. The two resistors are
designated as R58 and R59. I can't find these listed in the parts list I
suspect that HP probably sold the entire attenuator assembly as a single
replacement part. A DC measurement across the output connector should show
53 ohms. I know this is not a standard value but that is what the diagram
says. My 608 shows infinity. That's not a good sign.

Regards.

Max. K 4 O DS.

The 3456a was the most accurate in the HP fleet when introduced in 1981. The model line was 345x, so in its heritage was the 3455, 3457, and finally the ersatz standard DMM today, introduced in ~1989, the 3458. HP introduced a high accuracy ADC method, multislope II, with 3456a, you'll see marked change in posted accuracy versus the 3455a. The 3458a further improves that technique. In summary, if you're looking for accuracy these series of DMMs are one to shoot for.

There are pros and cons to the discontinued models, 56a and 57a. For example, The 56a is as good as the 57a in DCV at 1 year ppm, while the 57a is 10x more stable in 1yr as a ohmmeter. The 57a uses all close case calibration and has more unobtanium in its parts list, versus the 56a, which was the last to use all pots based calibration. The basic 57a reads only to 300Vrms maximum, but also has a current mode.

As for prices, the low end is similar on both, about $50 without shipping, but on the high end with calibration, the 56a runs to $300 while 57a about $700.

The 3478a was a general purpose working meter, ~10x less accurate in DCV than the 3456a.

As mentioned earlier you can use a resistor network; dekaviders or KV bridges in DC, to generate other DC voltages needed to check ranges, but maintaining stability in the reference enough to check the meter's accuracy, is the challenge. Its enough a whole new forum discusses this issue alone, volt-nuts@... <mailto:volt-nuts%40febo.com>. A similar problem exists for AC.

To calibrate a meter to realize its best accuracy requires grasping key concepts in metrology. A simplest approach is to take your DMM and compare its readings against a known good DMM. The reference DMM should ideally be 4x to 10x more accurate than the DUT. This is the concept of TUR, test uncertainty ratio. When making comparisons, say voltages, the test volt must be stable and precise enough during the transfer, for example if you are checking the 1V range between DMMs, you need to generate a 1V voltage stable to 1uV resolution or less, 1.000 000 VDC. Without a high level of thoroughness and stability, your 6.5 digit DMM will have increasing uncertainty as you get to its LSD.

On the low end of the range, special conditions apply that are fully covered in Keithley's low level measurement handbook, and these need to be controlled once dealing with uV, mohms, and uA adjustments.

Lastly, one has to decide if the effort described in volt nuts is worth it, or should one just take your DUT to the calibrator periodically for $100-$150 to insure your 6.5 digit DMM is as good as you expect it to be.

--- In hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky <jeff@...> wrote:

So it's about the time of year where I'm allowed to buy one piece of
test gear and I'm thinking I want a bench meter with higher
resolution. The best I've got so far is the Tek 2465BDM which has a
20,000 count 0.03% accuracy DMM. It's however a little out of cal and
I just don't want to spend the cash to get it back in perfect spec.
It's also a bit crazy to have a scope running just to use the DMM.
This brings me to the 3478A. While I could technically afford to buy a
new 120,000 count DMM I just can't justify the cost for the hobby type
work that I do. Plus I love working with the older gear and saving

money.

Couple quick questions about the 3478A:

Can one range be calibrated at a time? This is not highly clear in the
service manual. Can I calibrate just the 3V range for example?
Are they reliable, or will I have to fix up most of what I would buy
on say ebay?

The problem I have with the meter on my Tek is that you have to run the
entire cal for each measurement type, If you start with DC you have to
go all the way up the range from millivolts up to several hundred
volts. As we all know it's easy to get a precision calibrated low
voltage references such as a DMM check board, it's another thing to get
500 volts or higher reference at the spec of the meter.

So is this really a meter to buy if your willing to send it off to be
calibrated or have a calibration transfer standard meter that's above
the specs of the 3478A? In other words if all you have is just a few
standards are you wasting your time?

Has anyone had any luck using a precision reference, some precision
resistors and an op-amp to generate other reference voltages with any
degree of accuracy? Also has anyone found a good source of say 500
volts 60 Hz AC? The right audio amp and a sig gen can get you some of
the other odd cal standards. High voltage DC is just so much easier to
obtain then a nice high voltage sine wave.

Sorry for the random questions, and thanks for any replies. The
54111D is still running great. My thanks again for everyone who helped
me fix the ROM's.

Jeff

On 12/22/2012 12:09 AM, Merchison Burke wrote:

If I recall correctly, I believe that the sliding portion of the
attenuator can be removed from the fixed portion to effect repairs on
the resistors and capacitor but it is ringed with spring fingers (to
provide grounding) and they must be carefully squeezed together in order
to insert the sliding portion back into the fixed portion. You may have
to use a piece of paper wrapped around the finger to squeeze them
together. I would not suggest using anything sticky, like tape to
squeeze and hold the fingers together. That would cause another problem.

Merchison in Toronto

On 2012-12-21 1:22 PM, Max Robinson wrote:

The sliding part of the attenuator has a couple of 53 ohm resistors

and a

variable capacitor in it. It may or may not be possible to get the thing
apart to replace them. In any case it would be a lot of work.

Regards.

Max. K 4 O DS.

Email: max@... <mailto:max%40maxsmusicplace.com>

Wonder if anyone here can post a schematic of the attenuator on some
accessible site. (I wonder, for instance, about "53" ohm resistors, since
that is not a standard value, and about the value of the capacitor and
what it is
used for, unless it's just a coupling cap to the output.) I might just
take a look
and see how complicated it might be to fix the thing.
The spring-finger stock doesn't surprise me, and it might very well take
more
than paper to squeeze the fingers back down to go into the tube--I'm
thinking
maybe .010" brass strip or similar--maybe a strip of aluminum cut from a
beer can might work.

Whoever named it a boat-anchor was right on--the whole line of HP generators
from that era fit the description--particularly the upper
microwave-range ones.
Was it the 620 that weighed about 100 pounds?

--doug





------------------------------------

Yahoo! Groups Links

Hi,

I have 2 HP3456A and I really like them.

The HP3456A is a shallow chassis. The HP54111 is about 4 inches longer (part
of that is the rear feet).

I have stacked alot of weight ontop of mine with no trouble. The HP54111
does weigh 59 lbs though...

Ross

-----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 Jeff Machesky
Sent: Saturday, December 22, 2012 6:03 PM
To: hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>
Subject: Re: [hp_agilent_equipment] HP 3456a was Re: HP 3478A general
questions

Wow, thanks for all the info. This will help me make up my mind as to the
direction I go. The boss lady has said no purchases until after x-mas. So
I'm doing my research while I wait. Think I can put the 54111D on top of one
of these without crushing it :)

Thanks,

Jeff

On 12/22/2012 10:17 AM, marvgozum wrote:

The 3456a was the most accurate in the HP fleet when introduced in
1981. The model line was 345x, so in its heritage was the 3455, 3457,
and finally the ersatz standard DMM today, introduced in ~1989, the
3458. HP introduced a high accuracy ADC method, multislope II, with
3456a, you'll see marked change in posted accuracy versus the 3455a.
The 3458a further improves that technique. In summary, if you're
looking for accuracy these series of DMMs are one to shoot for.

There are pros and cons to the discontinued models, 56a and 57a. For
example, The 56a is as good as the 57a in DCV at 1 year ppm, while the
57a is 10x more stable in 1yr as a ohmmeter. The 57a uses all close
case calibration and has more unobtanium in its parts list, versus the
56a, which was the last to use all pots based calibration. The basic
57a reads only to 300Vrms maximum, but also has a current mode.

As for prices, the low end is similar on both, about $50 without
shipping, but on the high end with calibration, the 56a runs to $300
while 57a about $700.

The 3478a was a general purpose working meter, ~10x less accurate in
DCV than the 3456a.

As mentioned earlier you can use a resistor network; dekaviders or KV
bridges in DC, to generate other DC voltages needed to check ranges,
but maintaining stability in the reference enough to check the meter's
accuracy, is the challenge. Its enough a whole new forum discusses
this issue alone, volt-nuts@... <mailto:volt-nuts%40febo.com>

<mailto:volt-nuts%40febo.com>. A

similar problem exists for AC.

To calibrate a meter to realize its best accuracy requires grasping
key concepts in metrology. A simplest approach is to take your DMM and
compare its readings against a known good DMM. The reference DMM
should ideally be 4x to 10x more accurate than the DUT. This is the
concept of TUR, test uncertainty ratio. When making comparisons, say
voltages, the test volt must be stable and precise enough during the
transfer, for example if you are checking the 1V range between DMMs,
you need to generate a 1V voltage stable to 1uV resolution or less,
1.000 000 VDC. Without a high level of thoroughness and stability,
your 6.5 digit DMM will have increasing uncertainty as you get to

its LSD.

On the low end of the range, special conditions apply that are fully
covered in Keithley's low level measurement handbook, and these need
to be controlled once dealing with uV, mohms, and uA adjustments.

Lastly, one has to decide if the effort described in volt nuts is
worth it, or should one just take your DUT to the calibrator
periodically for $100-$150 to insure your 6.5 digit DMM is as good as
you expect it to be.

--- In hp_agilent_equipment@...

<mailto:hp_agilent_equipment%40yahoogroups.com>

<mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky
<jeff@...> wrote:

So it's about the time of year where I'm allowed to buy one piece of
test gear and I'm thinking I want a bench meter with higher
resolution. The best I've got so far is the Tek 2465BDM which has a
20,000 count 0.03% accuracy DMM. It's however a little out of cal
and I just don't want to spend the cash to get it back in perfect

spec.

It's also a bit crazy to have a scope running just to use the DMM.
This brings me to the 3478A. While I could technically afford to buy
a new 120,000 count DMM I just can't justify the cost for the hobby
type work that I do. Plus I love working with the older gear and
saving

money.

Couple quick questions about the 3478A:

Can one range be calibrated at a time? This is not highly clear in
the service manual. Can I calibrate just the 3V range for example?
Are they reliable, or will I have to fix up most of what I would buy
on say ebay?

The problem I have with the meter on my Tek is that you have to run
the entire cal for each measurement type, If you start with DC you
have to go all the way up the range from millivolts up to several
hundred volts. As we all know it's easy to get a precision
calibrated low voltage references such as a DMM check board, it's
another thing to get 500 volts or higher reference at the spec of the

meter.

So is this really a meter to buy if your willing to send it off to
be calibrated or have a calibration transfer standard meter that's
above the specs of the 3478A? In other words if all you have is just
a few standards are you wasting your time?

Has anyone had any luck using a precision reference, some precision
resistors and an op-amp to generate other reference voltages with
any degree of accuracy? Also has anyone found a good source of say
500 volts 60 Hz AC? The right audio amp and a sig gen can get you
some of the other odd cal standards. High voltage DC is just so much
easier to obtain then a nice high voltage sine wave.

Sorry for the random questions, and thanks for any replies. The
54111D is still running great. My thanks again for everyone who
helped me fix the ROM's.

Jeff

------------------------------------

Yahoo! Groups Links

The 3456a was the most accurate in the HP fleet when introduced in
1981. The model line was 345x, so in its heritage was the 3455, 3457,
and finally the ersatz standard DMM today, introduced in ~1989, the
3458. HP introduced a high accuracy ADC method, multislope II, with
3456a, you'll see marked change in posted accuracy versus the 3455a.
The 3458a further improves that technique. In summary, if you're
looking for accuracy these series of DMMs are one to shoot for.

There are pros and cons to the discontinued models, 56a and 57a. For
example, The 56a is as good as the 57a in DCV at 1 year ppm, while the
57a is 10x more stable in 1yr as a ohmmeter. The 57a uses all close
case calibration and has more unobtanium in its parts list, versus the
56a, which was the last to use all pots based calibration. The basic
57a reads only to 300Vrms maximum, but also has a current mode.

As for prices, the low end is similar on both, about $50 without
shipping, but on the high end with calibration, the 56a runs to $300
while 57a about $700.

The 3478a was a general purpose working meter, ~10x less accurate in
DCV than the 3456a.

As mentioned earlier you can use a resistor network; dekaviders or KV
bridges in DC, to generate other DC voltages needed to check ranges,
but maintaining stability in the reference enough to check the meter's
accuracy, is the challenge. Its enough a whole new forum discusses
this issue alone, volt-nuts@... <mailto:volt-nuts%40febo.com>. A
similar problem exists for AC.

To calibrate a meter to realize its best accuracy requires grasping
key concepts in metrology. A simplest approach is to take your DMM and
compare its readings against a known good DMM. The reference DMM
should ideally be 4x to 10x more accurate than the DUT. This is the
concept of TUR, test uncertainty ratio. When making comparisons, say
voltages, the test volt must be stable and precise enough during the
transfer, for example if you are checking the 1V range between DMMs,
you need to generate a 1V voltage stable to 1uV resolution or less,
1.000 000 VDC. Without a high level of thoroughness and stability,
your 6.5 digit DMM will have increasing uncertainty as you get to its LSD.

On the low end of the range, special conditions apply that are fully
covered in Keithley's low level measurement handbook, and these need
to be controlled once dealing with uV, mohms, and uA adjustments.

Lastly, one has to decide if the effort described in volt nuts is
worth it, or should one just take your DUT to the calibrator
periodically for $100-$150 to insure your 6.5 digit DMM is as good as
you expect it to be.

--- In hp_agilent_equipment@...
<mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky
<jeff@...> wrote:

So it's about the time of year where I'm allowed to buy one piece of
test gear and I'm thinking I want a bench meter with higher
resolution. The best I've got so far is the Tek 2465BDM which has a
20,000 count 0.03% accuracy DMM. It's however a little out of cal
and I just don't want to spend the cash to get it back in perfect spec.
It's also a bit crazy to have a scope running just to use the DMM.
This brings me to the 3478A. While I could technically afford to buy
a new 120,000 count DMM I just can't justify the cost for the hobby
type work that I do. Plus I love working with the older gear and
saving

money.

Couple quick questions about the 3478A:

Can one range be calibrated at a time? This is not highly clear in
the service manual. Can I calibrate just the 3V range for example?
Are they reliable, or will I have to fix up most of what I would buy
on say ebay?

The problem I have with the meter on my Tek is that you have to run
the entire cal for each measurement type, If you start with DC you
have to go all the way up the range from millivolts up to several
hundred volts. As we all know it's easy to get a precision
calibrated low voltage references such as a DMM check board, it's
another thing to get 500 volts or higher reference at the spec of the

So is this really a meter to buy if your willing to send it off to
be calibrated or have a calibration transfer standard meter that's
above the specs of the 3478A? In other words if all you have is just
a few standards are you wasting your time?

Has anyone had any luck using a precision reference, some precision
resistors and an op-amp to generate other reference voltages with
any degree of accuracy? Also has anyone found a good source of say
500 volts 60 Hz AC? The right audio amp and a sig gen can get you
some of the other odd cal standards. High voltage DC is just so much
easier to obtain then a nice high voltage sine wave.

Sorry for the random questions, and thanks for any replies. The
54111D is still running great. My thanks again for everyone who
helped me fix the ROM's.

Jeff

The 3456a was the most accurate in the HP fleet when introduced in 1981. The model line was 345x, so in its heritage was the 3455, 3457, and finally the ersatz standard DMM today, introduced in ~1989, the 3458. HP introduced a high accuracy ADC method, multislope II, with 3456a, you'll see marked change in posted accuracy versus the 3455a. The 3458a further improves that technique. In summary, if you're looking for accuracy these series of DMMs are one to shoot for.

There are pros and cons to the discontinued models, 56a and 57a. For example, The 56a is as good as the 57a in DCV at 1 year ppm, while the 57a is 10x more stable in 1yr as a ohmmeter. The 57a uses all close case calibration and has more unobtanium in its parts list, versus the 56a, which was the last to use all pots based calibration. The basic 57a reads only to 300Vrms maximum, but also has a current mode.

As for prices, the low end is similar on both, about $50 without shipping, but on the high end with calibration, the 56a runs to $300 while 57a about $700.

The 3478a was a general purpose working meter, ~10x less accurate in DCV than the 3456a.

As mentioned earlier you can use a resistor network; dekaviders or KV bridges in DC, to generate other DC voltages needed to check ranges, but maintaining stability in the reference enough to check the meter's accuracy, is the challenge. Its enough a whole new forum discusses this issue alone, volt-nuts@... <mailto:volt-nuts%40febo.com>. A similar problem exists for AC.

To calibrate a meter to realize its best accuracy requires grasping key concepts in metrology. A simplest approach is to take your DMM and compare its readings against a known good DMM. The reference DMM should ideally be 4x to 10x more accurate than the DUT. This is the concept of TUR, test uncertainty ratio. When making comparisons, say voltages, the test volt must be stable and precise enough during the transfer, for example if you are checking the 1V range between DMMs, you need to generate a 1V voltage stable to 1uV resolution or less, 1.000 000 VDC. Without a high level of thoroughness and stability, your 6.5 digit DMM will have increasing uncertainty as you get to its LSD.

On the low end of the range, special conditions apply that are fully covered in Keithley's low level measurement handbook, and these need to be controlled once dealing with uV, mohms, and uA adjustments.

Lastly, one has to decide if the effort described in volt nuts is worth it, or should one just take your DUT to the calibrator periodically for $100-$150 to insure your 6.5 digit DMM is as good as you expect it to be.

--- In hp_agilent_equipment@... <mailto:hp_agilent_equipment%40yahoogroups.com>, Jeff Machesky <jeff@...> wrote:

So it's about the time of year where I'm allowed to buy one piece of
test gear and I'm thinking I want a bench meter with higher
resolution. The best I've got so far is the Tek 2465BDM which has a
20,000 count 0.03% accuracy DMM. It's however a little out of cal and
I just don't want to spend the cash to get it back in perfect spec.
It's also a bit crazy to have a scope running just to use the DMM.
This brings me to the 3478A. While I could technically afford to buy a
new 120,000 count DMM I just can't justify the cost for the hobby type
work that I do. Plus I love working with the older gear and saving

money.

Couple quick questions about the 3478A:

Can one range be calibrated at a time? This is not highly clear in the
service manual. Can I calibrate just the 3V range for example?
Are they reliable, or will I have to fix up most of what I would buy
on say ebay?

The problem I have with the meter on my Tek is that you have to run the
entire cal for each measurement type, If you start with DC you have to
go all the way up the range from millivolts up to several hundred
volts. As we all know it's easy to get a precision calibrated low
voltage references such as a DMM check board, it's another thing to get
500 volts or higher reference at the spec of the meter.

So is this really a meter to buy if your willing to send it off to be
calibrated or have a calibration transfer standard meter that's above
the specs of the 3478A? In other words if all you have is just a few
standards are you wasting your time?

Has anyone had any luck using a precision reference, some precision
resistors and an op-amp to generate other reference voltages with any
degree of accuracy? Also has anyone found a good source of say 500
volts 60 Hz AC? The right audio amp and a sig gen can get you some of
the other odd cal standards. High voltage DC is just so much easier to
obtain then a nice high voltage sine wave.

Sorry for the random questions, and thanks for any replies. The
54111D is still running great. My thanks again for everyone who helped
me fix the ROM's.

Jeff

Hi All

I think I can help answer this:

At a hamfest last year, I picked up a complete collection of the Boonton Radio Corp publication " The Notebook". This was a periodic publication by Boonton covering products and applications of their various products-- ( A great read BTW..Some day I will scan and post them somewhere --BAMA ???)

On the last page of Issue 33, the editor admitted to being HP.

" Editors Note:

BRC assumes Divisional Status:

Boonton Radio Corporation, a subsidiary of the Hewlett-Packard
company since 1959, assumed divisional status November 1, 1962.
At that time, BRC's name was changed to Boonton Radio Company.

The conversion of BRC to a division of the Hewlett-Packard Co. is a
part of the over-all program to achieve greater flexibility of the entire HP organization ......... "

It goes on to say that William Myers from HP - Palo Alto was named General Manager of the new division.


Hope this helps....

Ray Johnson WB0EBG / KE3QY
HP Components group 1993-1996

++++++++++++++++++++============================




--- In hp_agilent_equipment@..., Dave Daniel <kc0wjn@...> wrote:

Really? I thought I've seen Boonton instruments younger than that. Did
HP keep the Boonton name for a while after the acquisition?

Dave


On 12/21/2012 2:12 PM, w0eom@... wrote:

1959. the instruments are shown in the HP 1963 catalog.


In a message dated 12/21/2012 12:22:30 P.M. Pacific Standard Time,
kc0wjn@... <mailto:kc0wjn%40gmail.com> writes:

Wow. I didn't know HP bought Boonton. I always liked Boonton
instruments, probably because I was born in Boonton. When did

HP buy them?

------------------------------------

Yahoo! Groups Links

Hello to the group,

I picked up an ebay special, does not power up but fan comes on.

Ok, that one almost came with an easy button.

The 5 volt regulator transistor was lose in its socket (TO-3). Fixed that, got back the +5 and panel came up.

I could not get any input to count. So I opened it back up and there is a problem, the two ribbon cables from the amp to the front panel are missing. That's amazing as the calibration stickers were untouched.

Long story short, does anyone have those two cables for sale? It's a 2 1/2 inch long ribbon cable with a 18 pin dip plug on each end. It plugs into a 18 pin x .3 IC socket on each end. There are two cables needed.


Thanks for reading,
Tom


PS. Diego, thanks for putting the 1.1 version up on KO4BB. That will be my next project after I find some cables.




----- Original Message -----
From: diego.moimas
To: hp_agilent_equipment@...
Sent: Monday, December 17, 2012 6:00 AM
Subject: [hp_agilent_equipment] Re: HP 5335A - All Leds Light but Never Go Off - No Error Messages



P.S.: my FW1.1 is actually @ , I'll send Didier's an email asap

--- In hp_agilent_equipment@..., "diego.moimas" <diego.moimas@> wrote:
>

Really? I thought I've seen Boonton instruments younger than that. Did
HP keep the Boonton name for a while after the acquisition?

Dave


On 12/21/2012 2:12 PM, w0eom@... wrote:

1959. the instruments are shown in the HP 1963 catalog.


In a message dated 12/21/2012 12:22:30 P.M. Pacific Standard Time,
kc0wjn@... <mailto:kc0wjn%40gmail.com> writes:

Wow. I didn't know HP bought Boonton. I always liked Boonton
instruments, probably because I was born in Boonton. When did HP buy them?

If you open the castings of the 70902A, the filter shape of the 3 or 4??narrowest ist lost. Aligning the filters can only be done by the dedicated software.



________________________________
From: Ed Breya <edbreya@...>
To: hp_agilent_equipment@...
Sent: Saturday, December 22, 2012 12:21 AM
Subject: [hp_agilent_equipment] Re: 70902A spectrum analyzer IF module RESOLUTION BANDWIDTH problems

??
I think the IF filter architecture of the 70902A may be roughly the same as in the 8566. If so, those crystal filters are all 3.0 MHz center frequency, with the bandwidth set by controlling the load impedance, hence Q, by virtue of the RF resistance of PIN diodes. It should be a cascade of similar stages, all with varying PIN currents according to the selected IFBW. So, all of the sections should be active, but the BW is controlled by logical steps supplying PIN currents set by precision series resistors. The higher the PIN currents, the narrower the BW. There should be other PINs to route the IF around the crystal section at the wider bandwidths, and also some to provide gain compensation to match the gain for all the BW settings.

In the 8566, the 21.4 MHz IF is mixed down to 3 MHz, processed through the filters, then converted back up and sent on its way. I don't recall if the LC filters also process at 3 MHz, or at 21.4 MHz - either way is possible.

Those indicator lights may be the key to solving the problem, but not for the reason you suggested. It's possible that those are overload or other status indicators - not necessarily logical on/off. Maybe some of the logic states or levels are wrong, causing some filter BW settings to do the wrong thing. You would have to find the individual BW selection logic lines and see what they're doing. They may be high voltage logic - directly driving the PIN current setting resistors with up to +/- 20 V or so. Just remember, when the crystal section is needed, all the stages should be on, while the logically-controlled PIN currents set the BW.

Since these PIN signal routing and "tuning" lines actually can be considered to be analog control, a loose line out of control can allow for various wrong currents to flow between stages, causing interesting results - that is what I think may have happened. A wrongly tuned or stuck filter stage, or a partially turned on switch that should be on or off, could make quite a mess.

You may want to look at the down/up conversion process too, to make sure it's actually on the right frequency - there should be a crystal oscillator nearby running at 18.4 or 24.4 MHz. The filter crystals should say 3 MHz, or whatever they run at. If they are 21.4 MHz, then no down/up conversion is needed. If you can ID these you'll have a pretty good idea of what's going on.

It sounds like you don't have a schematic or manual, but maybe similar systems like the 8566 would at least provide some info you can use, presuming it's actually similar. I don't recall there being indicators on the filters, but I've never needed to look closely at the IF/display section yet.

The breakpoints around 10 kHz or 3 kHz make sense - the crystal filters are only used at the narrowest bandwidths, while the LC ones do the upper, and may also be in-line when the crystal section is used. I believe the LC filters are fixed BW, set only by the L and C adjustments - not by PIN loading - although there would be associated PIN switches for signal routing.

Ed

--- In mailto:hp_agilent_equipment%40yahoogroups.com, "roberto.barrios" <rbarrioss@> wrote:

Hello,

I am trying to fix a 71100A spectrum analyzer and I'm stuck. It passes the "analyzer test" built into the firmware but does not pass calibration of the resolution bandwidth for some of the bandwidth filters (in the 70902A IF module).

The problen is easily seen in the shape of the curve from the calibrator, which for three of the filters does not look like it should. If you take a look at



you will see that:

* 10 Hz: Looks like if it was composed of two filters in series not aligned to the same center frequency. Peak amplitude 8 dB down.

* 30 Hz: Almost right but again not 100% symmetric. Peak amplitude OK.

* 100 Hz: Seems nice to me.

* 300 Hz: Just A bit asymmetric

* 1.00 kHz: Ugly, centered but no simmetry. Peak amplitude OK.

* 3.00 kHz: Ugliest, a complete mess. Peak amplitude 13dB up.

* 30.0 kHz: Looks nice.

* 100 kHz: Strange shape, convex skirts instead of concave (??)

* 300 kHz: Strange shape, convex skirts instead of concave (??)


The first error ( 2023 , Illegal Cal Signal ) appears when the 3.0 kHz test is done. The last one ( 6011 , RBW hardware error ) appears after the last one, which is the 10Hz test.

I have the Component Level Information Package (from ARTEKMANUALS) for the module, and it shows there are (among other), 9 filter stages:

LC1 > LC2 > XTAL1 > XTAL2 > XTAL3 > XTAL4 > XTAL5 > LC3 > LC4

Most of the stages have a bandwidth and center control pot/cap, some also a symmetry control. I tweaked them and could not see any significant difference in the ones that don't look nice so I carefully left them all where they were.

There are also "SHORT" LEDs on each filter stage, I believe to signal which stages are being bypassed. What I do not understand is why the LC1, LC2, LC3 and LC4 LEDs are never ON and the XTAL1, XTAL2, XTAL3, XTAL4 and XTAL5 are either ON

of OFF, all at the same time. From 10K up they are all ON and from 3K and down they are all OFF. I was expecting some kind of weighted switching to get the desired filter bandwidth, so I could find and repair the stage that was failing, but it does not seem to be that easy. Since it is possible to have continuos bandwidth control, some of the stages are probably not as simple as I thought.

Appart from some of the trim caps being stuck, there was no physical damage that I could find.

Does anyone know how the filter stages work? Suggestions to try?

Thank you and Merry xmas to you all.

Roberto EB4EQA

I think the IF filter architecture of the 70902A may be roughly the same as in the 8566. If so, those crystal filters are all 3.0 MHz center frequency, with the bandwidth set by controlling the load impedance, hence Q, by virtue of the RF resistance of PIN diodes. It should be a cascade of similar stages, all with varying PIN currents according to the selected IFBW. So, all of the sections should be active, but the BW is controlled by logical steps supplying PIN currents set by precision series resistors. The higher the PIN currents, the narrower the BW. There should be other PINs to route the IF around the crystal section at the wider bandwidths, and also some to provide gain compensation to match the gain for all the BW settings.

In the 8566, the 21.4 MHz IF is mixed down to 3 MHz, processed through the filters, then converted back up and sent on its way. I don't recall if the LC filters also process at 3 MHz, or at 21.4 MHz - either way is possible.

Those indicator lights may be the key to solving the problem, but not for the reason you suggested. It's possible that those are overload or other status indicators - not necessarily logical on/off. Maybe some of the logic states or levels are wrong, causing some filter BW settings to do the wrong thing. You would have to find the individual BW selection logic lines and see what they're doing. They may be high voltage logic - directly driving the PIN current setting resistors with up to +/- 20 V or so. Just remember, when the crystal section is needed, all the stages should be on, while the logically-controlled PIN currents set the BW.

Since these PIN signal routing and "tuning" lines actually can be considered to be analog control, a loose line out of control can allow for various wrong currents to flow between stages, causing interesting results - that is what I think may have happened. A wrongly tuned or stuck filter stage, or a partially turned on switch that should be on or off, could make quite a mess.

You may want to look at the down/up conversion process too, to make sure it's actually on the right frequency - there should be a crystal oscillator nearby running at 18.4 or 24.4 MHz. The filter crystals should say 3 MHz, or whatever they run at. If they are 21.4 MHz, then no down/up conversion is needed. If you can ID these you'll have a pretty good idea of what's going on.

It sounds like you don't have a schematic or manual, but maybe similar systems like the 8566 would at least provide some info you can use, presuming it's actually similar. I don't recall there being indicators on the filters, but I've never needed to look closely at the IF/display section yet.

The breakpoints around 10 kHz or 3 kHz make sense - the crystal filters are only used at the narrowest bandwidths, while the LC ones do the upper, and may also be in-line when the crystal section is used. I believe the LC filters are fixed BW, set only by the L and C adjustments - not by PIN loading - although there would be associated PIN switches for signal routing.

Ed

--- In hp_agilent_equipment@..., "roberto.barrios" <rbarrioss@> wrote:

Hello,

I am trying to fix a 71100A spectrum analyzer and I'm stuck. It passes the "analyzer test" built into the firmware but does not pass calibration of the resolution bandwidth for some of the bandwidth filters (in the 70902A IF module).

The problen is easily seen in the shape of the curve from the calibrator, which for three of the filters does not look like it should. If you take a look at



you will see that:

* 10 Hz: Looks like if it was composed of two filters in series not aligned to the same center frequency. Peak amplitude 8 dB down.

* 30 Hz: Almost right but again not 100% symmetric. Peak amplitude OK.

* 100 Hz: Seems nice to me.

* 300 Hz: Just A bit asymmetric

* 1.00 kHz: Ugly, centered but no simmetry. Peak amplitude OK.

* 3.00 kHz: Ugliest, a complete mess. Peak amplitude 13dB up.

* 30.0 kHz: Looks nice.

* 100 kHz: Strange shape, convex skirts instead of concave (??)

* 300 kHz: Strange shape, convex skirts instead of concave (??)


The first error ( 2023 , Illegal Cal Signal ) appears when the 3.0 kHz test is done. The last one ( 6011 , RBW hardware error ) appears after the last one, which is the 10Hz test.

I have the Component Level Information Package (from ARTEKMANUALS) for the module, and it shows there are (among other), 9 filter stages:

LC1 > LC2 > XTAL1 > XTAL2 > XTAL3 > XTAL4 > XTAL5 > LC3 > LC4

Most of the stages have a bandwidth and center control pot/cap, some also a symmetry control. I tweaked them and could not see any significant difference in the ones that don't look nice so I carefully left them all where they were.

There are also "SHORT" LEDs on each filter stage, I believe to signal which stages are being bypassed. What I do not understand is why the LC1, LC2, LC3 and LC4 LEDs are never ON and the XTAL1, XTAL2, XTAL3, XTAL4 and XTAL5 are either ON

of OFF, all at the same time. From 10K up they are all ON and from 3K and down they are all OFF. I was expecting some kind of weighted switching to get the desired filter bandwidth, so I could find and repair the stage that was failing, but it does not seem to be that easy. Since it is possible to have continuos bandwidth control, some of the stages are probably not as simple as I thought.

Appart from some of the trim caps being stuck, there was no physical damage that I could find.

Does anyone know how the filter stages work? Suggestions to try?

Thank you and Merry xmas to you all.

Roberto EB4EQA

So it's about the time of year where I'm allowed to buy one piece of
test gear and I'm thinking I want a bench meter with higher
resolution. The best I've got so far is the Tek 2465BDM which has a
20,000 count 0.03% accuracy DMM. It's however a little out of cal and
I just don't want to spend the cash to get it back in perfect spec.
It's also a bit crazy to have a scope running just to use the DMM.
This brings me to the 3478A. While I could technically afford to buy a
new 120,000 count DMM I just can't justify the cost for the hobby type
work that I do. Plus I love working with the older gear and saving money.

Couple quick questions about the 3478A:

Can one range be calibrated at a time? This is not highly clear in the
service manual. Can I calibrate just the 3V range for example?
Are they reliable, or will I have to fix up most of what I would buy
on say ebay?

The problem I have with the meter on my Tek is that you have to run the
entire cal for each measurement type, If you start with DC you have to
go all the way up the range from millivolts up to several hundred
volts. As we all know it's easy to get a precision calibrated low
voltage references such as a DMM check board, it's another thing to get
500 volts or higher reference at the spec of the meter.

So is this really a meter to buy if your willing to send it off to be
calibrated or have a calibration transfer standard meter that's above
the specs of the 3478A? In other words if all you have is just a few
standards are you wasting your time?

Has anyone had any luck using a precision reference, some precision
resistors and an op-amp to generate other reference voltages with any
degree of accuracy? Also has anyone found a good source of say 500
volts 60 Hz AC? The right audio amp and a sig gen can get you some of
the other odd cal standards. High voltage DC is just so much easier to
obtain then a nice high voltage sine wave.

Sorry for the random questions, and thanks for any replies. The
54111D is still running great. My thanks again for everyone who helped
me fix the ROM's.

Jeff

Normal behaviour. They have VERY high input impedance on the low voltage ranges, so any stray charge can cause a reading.


Dave
-----Original Message-----
From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...] On Behalf Of Michael Hong
Sent: 20 December 2012 23:23
To: hp_agilent_equipment@...
Subject: [hp_agilent_equipment] 3456A Voltmeter

Hi everyone,
I just bought two 3456As from the same dealer off eBay.
Both of them have the same problem. When they are turned on, the number drift from low mV number and goes up to -8.nnnnn for one meter and the other meter to -6.nnnn. And then float around there. When I short the leads at Ohm or Volt setting, they show the near zero and when disconnected, go to their the number again.

I expect they stay at very low mV or zero without any input. What seems be the problem?
Thank you.






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