A friend in town (W7TOM) just bought an HP 3478A, and we were both very
favorably impressed by it.

The 3478A is certainly a nice meter, but I have a hard time getting my
bench lighting right so LCDs are readable without too much light falling
on the scopes. Too bad it doesn't have a backlit display.

My personal favorite DMM is a Solartron 7060, but it's a lot larger than a
3478A.

A friend in town (W7TOM) just bought an HP 3478A, and we were both very
favorably impressed by it. I have a HP 34401A on my bench which I bought
brand-new for $1K, and the 3478A is almost as good at 20% of the price. It
has one less digit of resolution than the 34401A (5.5 instead of 6.5, either
are more than sufficient for nearly any practical purpose and much more than
any handheld can offer), and a couple fewer bells and whistles (dB,
frequency...) that I don't use anyway. Calibration is simple, with no need
to open the cabinet, and the manuals are excellent. Bob's 3478A showed an
invalid calibration checksum on one DC voltage range, so we set it up
against my 34401A and he was good to go. The other ranges were so close to
the 34401A that no adjustment was warranted.

Dealers sell the 3478A for around $300; the going eBay rate is $200 or less.
These things are the T&M bargain of the century, IMHO. I wish I'd gone the
3478A route -- I could have gotten essentially the same meter for a lot less
money. Didn't know they were that cheap, or that good.

-- john KE5FX

Hi all,

I'm looking at getting an HP meter along the lines of the 3455, 3456
or 3457. Its to be used in a small lab. I don't require any remote
capabilities. I'm after a meter to carry on from where the handhelds
cease to be useful.
Are there any particular models that are best avoided and any that
are more highly prized than others?

Cheers
Ian Du Rieu

--- In hp_agilent_equipment@..., "vk2kyp" <gbeech@m...> wrote:

Hi All,
Happy Easter, some time ago I brought a secondhand HP3406A wideband
voltmeter. I would like to download the manuals for it.
Can anyone please help with a website to do this

Thank you Gary Beech VK2KYP

Hello Gary,

read the thread about the HP 8405A Probe repair,
the sampling head of the 3406 is quite the same
as the 8405's are.
And they usually die the same way.

73's

Jorgen
dj0ud

--- In hp_agilent_equipment@..., Arthur Shulman
<dentist@n...> wrote:

Thank you Jorgen. Your reply made me rethink my troubleshooting
strategy. I had failed to consider that the diodes are at greater risk
of failure, more so than the FET. The bad voltages measured around the
bridge do suggest this. You are right - I should subject them to some
reverse bias and see if they are leaky, at say, perhaps -20vdc.

Hello Arthur,

20 Volts is a bit high, do the measurement at 5 to 10 Volts.
The reverse voltage rating of this fast switching shottkys is quite low.


Jorgen

I don't have a curve tracer but I can make a test jig to do this. I will
forward the FET part# if I can find it - The board was sold by HP as a
unit replacement, so I'm not sure the FET carries a #.
Thank you once again for some fresh insight and the benefit of your
experience.
Arthur

Jorgen Lund-Nielsen wrote:

Hmm, surely, the fet could die, too, but "normaly" the probes fail
with shooted diodes! And they could measure nearly OK but some
parameters may have changed and so the bridge is roughly out of
balance...
the forward voltage differences have to be <20mV as far as i knew
and sometimes some diode leaks badly reverse and bring the bridge out
of balance. And sometimes a shooted diode measures fine at low
voltages as a Multimeter apply in the diode test mode but at higher
voltages (as the (reverse)bias from the bridge) the diodes act as a
soft zener and voila the bridge is out of balance and nothing goes.
Have you a chance to check them with a curve tracer?

You can substitute them with HP 5082-2815 Matched Quad.
Obsolete now but sometimes findable at some stores.
Did you have the hp-number for the fet? Maybe i gould give some data.
i have my 8405 manual no longer so i couldn't have a look.

73's

Jorgen
dj0ud


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Service.

Thank you Jorgen. Your reply made me rethink my troubleshooting strategy. I had failed to consider that the diodes are at greater risk of failure, more so than the FET. The bad voltages measured around the bridge do suggest this. You are right - I should subject them to some reverse bias and see if they are leaky, at say, perhaps -20vdc.
I don't have a curve tracer but I can make a test jig to do this. I will forward the FET part# if I can find it - The board was sold by HP as a unit replacement, so I'm not sure the FET carries a #.
Thank you once again for some fresh insight and the benefit of your experience.
Arthur

Jorgen Lund-Nielsen wrote:

--- In hp_agilent_equipment@..., Arthur Shulman
<dentist@n...> wrote:

I am saddled with a perfect 8405A with one defective probe. Swapping the
sampling board between probe tips shows that the fault follows the
board. The measured voltages are correct for the good board, but not for
the failing board. The diodes check out OK for F/B ratio, leaving not
much else to change except the FET.

Can anyone on the list suggest a suitable replacement part or
troubleshooting strategy?

Arthur Shulman VE3ZV

Hmm, surely, the fet could die, too, but "normaly" the probes fail
with shooted diodes! And they could measure nearly OK but some
parameters may have changed and so the bridge is roughly out of
balance...
the forward voltage differences have to be <20mV as far as i knew
and sometimes some diode leaks badly reverse and bring the bridge out
of balance. And sometimes a shooted diode measures fine at low
voltages as a Multimeter apply in the diode test mode but at higher
voltages (as the (reverse)bias from the bridge) the diodes act as a
soft zener and voila the bridge is out of balance and nothing goes.
Have you a chance to check them with a curve tracer?

You can substitute them with HP 5082-2815 Matched Quad.
Obsolete now but sometimes findable at some stores.
Did you have the hp-number for the fet? Maybe i gould give some data.
i have my 8405 manual no longer so i couldn't have a look.

73's

Jorgen
dj0ud

Hi Guys

This is my first posting to this group.
I am wondering if anybody knows about the "10032A"
scope probe? Its a 100:1 probe has 3Mohm 3pF input
loading and a max of 300V input. Its a really nice
compact size, I am looking for the upper frequency
limit.

Mervyn





____________________________________________________________
Yahoo! Messenger - Communicate instantly..."Ping"
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I own the manual of servicing the 54111D model .There is only a
block diagram for the 3 supplies:
One is general and the 2 others are for "digital" and for "analogic"
I will receive a second 54111D scope .
I suspect HP to have done economy on electrochimical capacitors .
Mine has a large ripple superposed and the trace oscillate .
Try to change these large capacitors .I can send the diagram ,but
there is no schematic .I am in France and if you are in the States
it is difficult to meet !But if you go to France I will glad to meet
you.I live in the French Riviera .
I know that HP editated a second service manual for this device ,
perhaps more complete .Mine is numbered 90902.
Best regards.Guy Royet,88 bd de Bazeilles,83480 Puget sur Argens ,
France .Email : guy.royet@...

--- In hp_agilent_equipment@..., "nn2027299"
<silvermoon.group@n...> wrote:

Dear All,

I have a 54110D scope which exhibits power supply problems. I've
followed the troubleshooting guide in the 54111D service manual
which leads me to believe that the analog board is faulty.

Has anyone got any schematics for these scopes, or a spare board
kicking around they'd like to sell?

Thanks in advance,

Ed.

Hi all, I hope you all enjoyed the Easter break.

I am looking for a site to download a manual for the HP5245L
frequency counter.

Thank you Gary Beech VK2KYP

Looking to purchase a copy or original manual for the subject equipment.

Arthur Shulman VE3ZV

I am saddled with a perfect 8405A with one defective probe. Swapping the
sampling board between probe tips shows that the fault follows the
board. The measured voltages are correct for the good board, but not for
the failing board. The diodes check out OK for F/B ratio, leaving not
much else to change except the FET.

Can anyone on the list suggest a suitable replacement part or
troubleshooting strategy?

Arthur Shulman VE3ZV

开云体育

Test

Dear All,

I have a 54110D scope which exhibits power supply problems. I've
followed the troubleshooting guide in the 54111D service manual
which leads me to believe that the analog board is faulty.

Has anyone got any schematics for these scopes, or a spare board
kicking around they'd like to sell?

Thanks in advance,

Ed.

test

Anyone using a 8558B Spectrum Analyzer in a 853A Digital Mainframe...
used with a HP 8444A Tracking Generator. I would like to communicate
with you...

Hi All,
Happy Easter, some time ago I brought a secondhand HP3406A wideband
voltmeter. I would like to download the manuals for it.
Can anyone please help with a website to do this

Thank you Gary Beech VK2KYP

Hi There, I have just brought a HP5385a, unfortunately it did not
come with any documentation. I would appreciate any help. The unit
appears to work well
thank you
73's Gary VK2KYP

Many thanks for your assistance. I now have an excellent copy.

Best regards

David