[volt-nuts] Serious problems fluke 731A, 720 and solartron
Fred Schneider
pa4tim at gmail.com
Thu Sep 29 22:34:31 UTC 2011
The voltage collapses. I have to measure how much but not just a few uV. More like 200 mV if I remember it right. I know it is a resitive divider but the influence on each other is getting worse if it is on 24/7, another sign something is wrong. The 1V influences akso the 10 V so you keep it adjusting. If i set 10 V correct and then the 1 V's the 10 V is off again.
The 845 AB had its nicads removed and they placed a big zener instead. The most important thing, I made a regulated and good filtered powersupply. I placed the pcb for that in the space the nicds were mounted.
I also have a HP frequency standard that had a batterybox. But they were dead and i did not needed that so now i build a trimble thunderbolt into that space and used the 100 KHz output of the HP for the 10 MHz. That is the advantage of having gear with a battery option ;-)
I can think i can fix the solartron Problem if I can find a service manual. But now I can not even check the powersupply voltages because I do not know them. Filtercaps are good.
Fred
>>
>
> Fred,
>
> What happens to the 10 volt position of the Fluke 731 when you attach a 10 MegOhm input Voltmeter ?
>
> I am sure you know that the 1 volt positions are just resistive dividers and any loading of any kind will drop their value.
>
> Also, could you give details on what modifications you made to the 845AB ?
>
> thanks,
>
> Bill....WB6BNQ
>
>
>
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