[volt-nuts] HP3457

Wed Aug 22 07:23:01 UTC 2012

So this is normal, hmm, my shop can be over 30 degrees when it is a hot summer and 15 degrees in a Cold winter so keeping it powered will not help in my case ( i am just an amateur voltnut so climatize my room is no option.

But The service manual describes a test  were you run it at 15 degrees, then at 38 degrees and then adjust diodecurrent until you get the best tempco. That would imply the thing should not react much on a few degrees. 

Would it be an option to ad tempcontrol. The meter itself is a sort of uncontrolled oven. If I add a temp sensor and find a way to keep the temp steady the meter should stay more stable. In this case cooling would be the best option because it gets over 45 - 50 degrees inside the meter. So it can heats it self pretty well, The problem is temp follows the oudside temp, so if Measure inside temp at for instance 18 or 20 degrees room temp and cool it if the inside gets hotter then the inner temp at 20 degrees outside, than it must be more stable.

Maybe a piezo element from a coolerbox inside (the piezo is inside, a coolrib and fan on theoutside. I experimented with a coolrib on the cabinet straight above the transformer, that was allready an improvent. Or some aluminum tubes through the cabinet. Open on one side, a box on the other side with a fan in it sucking the air through the pipes and cooling the inside when needed, or copper tubing where i can solder ribs on. If not enough I can pomp water through it and keep the water in an isolated box at 30 degrees using an aquarium heater if needed. That would cover 95% of the year.

Stupid idea ?

Fred PA4TIM

Op 22 aug. 2012 om 03:32 heeft John Phillips <john.phillips0 at gmail.com> het volgende geschreven:

> To get better performance form you Solarton keep it a constant Hot
> temperature all the time. Do not turn it off! Do not let the room
> temperature fluctuate more than a few degrees. The more stale the better.
> Cooling in most cases will induce error. If you can keep it at 20C all the
> time go for it but if you are more stable at 28C then 28 is better.
> 
> The longer you run it the more stable it will get. We do not turn off any
> of our best meters unless we are moving them or the power gos off.
> 
> 
> On Tue, Aug 21, 2012 at 4:21 PM, Fred Schneider <pa4tim at gmail.com> wrote:
> 
>> I looked at the DC specs of the 3457 and thats the same as the solartron.
>> I am looking sub uV like the solartron. The 3457 does not have that. So I
>> think, regarding your reactions and the price, i'd better first take a look
>> at the solartron. Modify it a bit ( cooling-ribs on the outside, one on top
>> above the transformer and one on the back where the regulators should be (
>> i'm told, not looked yet) maybe a fan blowing over the ribs.) replace the
>> keylock with a switch ( i have not a good key, it works but not smooth)
>> then put banana busses instead of the back nr2 input connector on the front
>> and replace the mainsswitch to the front. ( instead of climbing on a hair
>> to reach the switch)
>> 
>> I printed the service manual of the 7061 and i think I first do the tests
>> ( psu, frequency, input current ect) i also noted my zero problem is
>> because I shorted both inputs but i need to short the reference and front
>> inputs. That could explain why zero often does not work ( error, zero to
>> large or something lile that)
>> 
>> I bought a Keithley 2000 last year, it was comparable to the Fluke 8046
>> but around 400 euro cheaper. I bought it straight from Keithley including
>> calibration. Besides that I have a keithley 196 that was just calibrated
>> when I bought it. ( and a 199)
>> 
>> I was aiming for the holy grale of meters and a 3457 turns out to be a
>> whole different beast. Someone I know bought a 3456 for 225 euro, fresh
>> calibrated, that is 6,5 digits too. So i wondered why is a 3457 so much
>> more expensive.
>> 
>> But I better wait and save more money in the hope to find one day an
>> affortable 3458.
>> One should always keep something to dream about :-)
>> 
>> Fred
>> 
>> 
>> 
>> 
>> Fred PA4TIM
>> 
>> Op 21 aug. 2012 om 22:06 heeft John Phillips <john.phillips0 at gmail.com>
>> het volgende geschreven:
>> 
>>> you can put your 3457A into statistics mode and pick up +/- 29,999,999
>>> counts from the display.
>>> +/- 2,999,999 counts  is all you can get form the normal /live mode.
>>> 
>>> On Tue, Aug 21, 2012 at 12:52 PM, J. L. Trantham <jltran at att.net> wrote:
>>> 
>>>> Fred,
>>>> 
>>>> 700 euro seems a bit high, at least by US standards, for a 3457A.  It
>> is a
>>>> good meter and I have one.  Though no longer supported, Agilent will
>> still
>>>> calibrate one for $200.22, according to their website.
>>>> 
>>>> You might want to consider a Fluke 8846A.  I  have seen them sell for
>> $900
>>>> new.  I don't have one but it was going to be my next addition until I
>> got
>>>> a
>>>> 3458A.
>>>> 
>>>> What is the issue with the 7061?
>>>> 
>>>> Joe
>>>> 
>>>> -----Original Message-----
>>>> From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
>>>> Behalf Of Fred Schneider
>>>> Sent: Tuesday, August 21, 2012 2:00 PM
>>>> To: volt-nuts at febo.com
>>>> Subject: [volt-nuts] HP3457
>>>> 
>>>> I have a solatron 7061 but i am not very impressed with it. Must I go
>>>> looking for an alternative or is this 7061 when i gave it a good
>> checkup /
>>>> overhaul a good meter ?
>>>> I am offered a 3457 for 700 euro and the owner, will calibrate it (he
>> has
>>>> several calibrtors, standards and a couple of 3458  meters. My intuition
>>>> tells me to trusts him ( and that had never let me down before))
>>>> 
>>>> But he also told it is only 7,5 digit over hpib, and has 6,5 digit
>> display.
>>>> 
>>>> My Keithly 2000 is 6,5 digits and over RS232 i get two digits extra. I
>> once
>>>> tried that, but that took me a lot of time to get it more ore less
>> working,
>>>> I am not so into computers and afraid I do not get it to work.
>>>> 
>>>> Is it really better as my ( one year old 2000 ?) and better as my
>> Solartron
>>>> can be ?
>>>> I am afraid a 3458 is outside my budget.
>>>> 
>>>> Fred
>>>> 
>>>> 
>>>> 
>>>> Fred PA4TIM
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>>>> 
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>>> 
>>> 
>>> 
>>> --
>>> John Phillips
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> 
> 
> 
> -- 
> John Phillips
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