[volt-nuts] Datron 4920M, AC Voltmeter, for sale on ebay - 1 day left

[Charles Black]

Hi Adrian,

I had some trouble testing my EL 1400's with my precsion attenuator 
(1.2Ghz B/W) not having a small enough minimum step for easy setting. It 
was fairly stable though. I checked everything with my scope and it was 
fairly flat to 20mhz with a gentle falloff to 30mhz if I remember 
correctly. The EL 1400's are "useable" to 300mhz with corrections that I 
don't have.

I will keep an eye out for a low priced 4920. It will have to be broken 
bad enough to be low priced though.

Charlie

On 9/1/2014 3:29 PM, acbern at gmx.de wrote:
> charlie,
>
> you can expand these tvcs by range resistors to work as higher voltage tvcs. if you do it right (rf-type setup) you can work up to a couple hundred khz with just minor additional error beyond its error in its orgininal voltage range. need to calibrate them however. using an attenuator is not a good idea, too unprecise. still tvcs are the most precise way to measure, if done right. pretty tme consuming though. but you need them e.g. to calibrate a 4920.
>
> adrian
>
>> Gesendet: Sonntag, 31. August 2014 um 21:41 Uhr
>> Von: "Charles Black" <cblack at centurytel.net>
>> An: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
>> Betreff: Re: [volt-nuts] Datron 4920M, AC Voltmeter, for sale on ebay - 1 day left
>>
>> Hi Stephen,
>>
>> Thanks for the info on the 4920M. It might be that I should pass on this
>> but it is nice to know that it is probably working. If I don't have the
>> necessary items needed for calibration it might still be a good source
>> uncalibrated.
>>
>> I was hoping that the 4920 had better minimum voltage out steps than my
>> present Rigol 4062 for 3458a AC calibration. I have two EL 1400 0.25V
>> voltage thermal converters that I was trying to use in a test setup but
>> they had such a low voltage range that I was forced to use my ATV-60
>> attenuator. It all kind of worked but a 0.1 db minimum step  is a little
>> course for easy use. The Rigol also suffers from this malady.
>>
>> Charlie
>>
>> On 8/31/2014 1:06 PM, Stephen Grady wrote:
>>> Charlie,
>>>
>>>
>>> The "Error Ur" is an under-range error; you have to apply an input above 10% of the range before it will display a reading. The 4920's are a very nice instrument. Their only problem is that they are all so old that they are reaching the stage where some components are drifting excessively or failing. I have come across 4920's that are drifting a little (more than there spec) between cals (and yes they need to be cal'd annually), another 4920 I came across had an intermittent failure in one of its power supplies.
>>>
>>> Kind Regards,
>>>
>>> Stephen Grady
>>> Sydney Australia
>>>
>>> -----Original Message-----
>>> From: volt-nuts [mailto:volt-nuts-bounces at febo.com] On Behalf Of Charles Black
>>> Sent: Monday, 1 September 2014 3:19 AM
>>> To: ben at veritechmeasurements.com.au; Discussion of precise voltage measurement
>>> Subject: Re: [volt-nuts] Datron 4920M, AC Voltmeter, for sale on ebay - 1 day left
>>>
>>> Hi Ben,
>>>
>>> I am going to check this out today to find if it might be helpfull around here for my AC calibration. It has an error message: "Error Ur"
>>> so some fixing is going to be needed. On the back it says it's got Option 80, whatever that is.
>>>
>>> Charlie
>>>
>>>
>>> On 8/31/2014 5:37 AM, ben wrote:
>>>> Hello all,
>>>> Just a heads up. I noted there is a lonely Datron / Wavetek 4920M AC
>>>> voltmeter for sale on ebay, starting at US$650 (ending in 1 day !). I
>>>> have little idea of its true working state or not (picture shows it powered on).
>>>> If fully working it would be a good buy for an AC voltmeter that is, I
>>>> reckon, better than an HP 3458A. Only drawback with these models is
>>>> the voltage input shell is always earthed, not floating. I have two of
>>>> these 4920M's already, not really tempted by a third. I have a paper
>>>> copies of operator, calibration, and service manual if anyone interested.
>>>>
>>>> regards,   ben.
>>>> _______________________________________________
>>>> volt-nuts mailing list -- volt-nuts at febo.com To unsubscribe, go to
>>>> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>>>> and follow the instructions there.
>>>>
>>>>
>>>>
>>> _______________________________________________
>>> volt-nuts mailing list -- volt-nuts at febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>>> and follow the instructions there.
>>>
>>>
>>> ---
>>> This email is free from viruses and malware because avast! Antivirus protection is active.
>>> http://www.avast.com
>>>
>>> _______________________________________________
>>> volt-nuts mailing list -- volt-nuts at febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>>> and follow the instructions there.
>>>
>>>
>>>
>>
>> _______________________________________________
>> volt-nuts mailing list -- volt-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
>> and follow the instructions there.
> _______________________________________________
> volt-nuts mailing list -- volt-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.
>
>
>