[volt-nuts] Fluke 731B parts xref

[ed breya]

Current regulator diodes are typically JFETs with gate-source tied so 
that their Idss is more or less constant over a wide voltage range. 
Anything in the 1 mA to 50 mA range can be replicated by selecting 
common JFETs for the right Idss, up to 40 V or so, or by selecting 
one with slightly higher current, then adding series R in the source 
to degenerate it to the right amount. They are not very precise, but 
much better than resistive biasing over wide voltage ranges. If 
higher current is needed, they can be paralleled. If less than 5 V 
overhead, or more than 40 V compliance are needed, it's better to go 
with an active circuit with appropriate devices.

Ed

At 02:48 PM 11/21/2012, you wrote:

>Just picked up a 731B that turned out to be in a bit less than ideal shape.
>
>It has been broken, repaired and then broken again.
>
>
>I need to replace a number of bits, and am having trouble xrefing a few.
>
>
>
>The UV pot, listed as 3509S9-502, may be bournes 3509S-9-502 but cannot
>find the part or a data sheet.
>
>
>Switch,toggle MSTL206N (locking on/off switch)
>
>
>On the power and adjust board
>
>
>CR5-CR9, diode, Si,hi-speed switch TD8253
>
>CR10, diode,FET,current regulator E505
>
>CR11 diode, zener, 18v 1N967B seems to be discontinued.  Is fairchild
>1N5248B a suitable replacement.
>
>
>Anyway, if anyone can point me at suitable replacements or sources it
>would be a great help.
>
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