[volt-nuts] Fluke 335A versus HP 740B

J. L. Trantham jltran at att.net
Sat Dec 15 05:00:50 UTC 2012

I am not familiar with the HP 740B.  It looks like it needs a special
connector for the front panel to get an output or input.  If true, I would
score that as a negative.

I have a 335A that had some problems when I got it.  Turned out it was just
some dead electrolytic caps that were identifiable by sight, bulging, etc.
I replaced them and all was well.  The manual is readily available.  It uses
binding posts for connection.  It recently developed a new problem, the
'Overload' light is continuously illuminated though the output is still
there and accurate.  I suspect a transistor issue but have not had a chance
to explore yet.

You will need a 5 1/2 digit DMM, minimum, to be able to see the 1 uV change.
Measuring that is a bit of a challenge in that it is not stable, voltage
source, meter, temp changes, etc., all playing a role.  However, I seem to
recall you have a Solartron 7081 so you can watch the 1 uV all the way up to
10 V.

I have been looking for an affordable 335D but, so far, have not found one.
However, I found a Fluke 5440B/AF.  It just arrived recently, seems to work
on initial, superficial, check out, but I have not had a chance to
incorporate it into my rack yet or investigate it's stability.  

However, at the current price, why not get all three, 335A, 335D, and 740B?


-----Original Message-----
From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
Behalf Of David C. Partridge
Sent: Friday, December 14, 2012 8:16 PM
To: 'Discussion of precise voltage measurement'
Subject: [volt-nuts] Fluke 335A versus HP 740B

Both DC Voltage standards up to 1000V or so, and also null differential

Also both being sold by the same vendor as the other stuff

Do the assembled mavens have a view as to which is preferable?


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