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

Todd Micallef tmicallef at gmail.com
Tue Sep 2 12:19:18 EDT 2014 

I uploaded the user manual for the 4920 model some time ago. Of note, the 4920 was offered with option 10. This added four additional millivolt ranges. I have this meter with the option 10. I think it may be a better alternative to the 4920m if you don't need the wideband option. Some of the 4920 had an external wideband input jack, but I have not seen this adapter for sale.  It appears these were designed to compete with the Fluke 540B due to its AC/DC transfer feature. 

My meter has a limited calibration due to a couple ranges not meeting spec. Unfortunately, only the 4920M service manual is available. If anyone has the service manual for this, it would be appreciated.


Todd
Sent from my iPad

> On Sep 2, 2014, at 10:17, "ben" <ben at veritechmeasurements.com.au> wrote:
> 
> 
> 
> ----------------------------------------
> From: "ben" <ben at veritechmeasurements.com.au>
> Sent: Tuesday, September 02, 2014 11:25 PM
> To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
> Subject: Re: [volt-nuts] Datron 4920M, AC Voltmeter, for sale on ebay - 1 
> day left 
> 
> Hello all,  
> 
> I agree that the M version was made for military customers only, being a US 
> Navy contract in about 1990. Aside from the thermal converter Wideband V 
> input, key differences I am aware of between 4920 and 4920M are that the M 
> version does not have mV ranges below 0.3V, and the M version has Filter 
> options of only 100Hz and 10Hz (not additional 40Hz). Programming of Filter 
> uses different syntax too. 
> 
> After a question from another member I have scanned my paper copy of the D 
> 4920M Users manual, but its a bit of a mess. I will take it to work 
> tomorrow and re-do it again properly, then upload it to KO4BB and BAMA.  
> Hopefully the Calibration and Service manual will follow in short order. 
> 
> I can confirm that calibration of values 0.3V to 1000V use a thermal 
> converter. As well, calibration of 100mV (0.3V range) will require a 
> micropot and DC voltmeter.
> 
> --- I have an alternative version of this email sitting in the Moderators 
> in-tray which has attached a PDF of a paper presented at MSC 1990 
> conference (202kB file size). If returned to me I will find another site to 
> post the paper - it makes good reading.  If interested please email me and 
> I can send it out individually. Otherwise, the whole MSC 1990 conference 
> proceedings, including the Datron 4920M paper, can be found here -> 
> msc-conf.com/wp-content/uploads/proceedings/MSC1990.pdf
> 
> More to follow,
> regards,
> ben
> 
> 
> 
> ----------------------------------------
> From: "Stephen Grady" <grady.steve at gmail.com>
> Sent: Tuesday, September 02, 2014 7:54 PM
> To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
> Subject: Re: [volt-nuts] Datron 4920M, AC Voltmeter, for sale on ebay - 1 
> day left 
> 
> The Datron 4920M was a special version of the 4920 made for the military, 
> the major difference is the M version has a 50 Ohm (N-female) wideband 
> input and only the N-female input for the low frequency input. Whereas the 
> 4920 has a Binding Post Input as well as the N-female input. I am not aware 
> of the specs for the wideband input but the low frequency input will be the 
> same for both models.
> 
> I intend to reply in some detail soon on the calibration of these 
> instruments (and this will also apply to the Fluke 5790) and the principals 
> of AC calibration below 100mV as Charles has raised the issue of using 
> attenuators to do lower voltage measurements.
> 
> Kind Regards,
> 
> Stephen Grady
> Sydney, Australia
> 
> -----Original Message-----
> From: volt-nuts [mailto:volt-nuts-bounces at febo.com] On Behalf Of 
> acbern at gmx.de
> Sent: Tuesday, 2 September 2014 5:54 PM
> To: Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] Datron 4920M, AC Voltmeter, for sale on ebay - 1 
> day left
> 
> folks,
> 
> does anybody know the difference in specs between a 4920M and the standard 
> 4920. No data on the web.
> 
> thanks
> 
> 
> 
>> Gesendet: Sonntag, 31. August 2014 um 23:41 Uhr
>> Von: "Charles Black" 
>> An: "Discussion of precise voltage measurement" 
>> 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 
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>>> 
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