[volt-nuts] Precision resistors

[Joseph Gray]

Yes, I realize that I don't want to heat the resistors. I was asking if
anyone knew the ratings for these resistors, as they are incompletely
marked. I'm not looking to start a long discussion.

Joe Gray
W5JG



On Sun, Aug 18, 2013 at 12:57 AM, Laurence Motteram <
LMotteram at scientific-devices.com.au> wrote:

> "Wattage" and precision resistors could make for a very long thread.  For
> best stability, you do not want to heat up the resistor very much.  A power
> rating would normally be related to a permitted temperature rise, but you
> might not want your resistor to rise to that temperature.  This way leads
> to several interrelated compromises.
>
> Laurence Motteram
>
> ________________________________________
> From: volt-nuts-bounces at febo.com [volt-nuts-bounces at febo.com] on behalf
> of Joseph Gray [jgray at zianet.com]
> Sent: Sunday, 18 August 2013 2:47 PM
> To: Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] Precision resistors
>
> Raj and John,
>
> Thanks for the advice. I'll go with some mild dish detergent and water. The
> black, rectangular resistors are definitely marked "Daven", just like all
> the others.
>
> The bobbins are marked .02%, 1/2 W. The black rectangles are .1% (no
> wattage) and the micas are simply marked 85, which I assume is the
> resistance. Any idea what the wattage of the black ones are? Also, what
> percentage and wattage would the micas be? The micas are thumb-sized
> squares (just so I don't confuse the metric or imperial users :-) ).
>
> Joe Gray
> W5JG
>
>
>
> On Sat, Aug 17, 2013 at 7:18 AM, J. Forster <jfor at quikus.com> wrote:
>
> > The red 'sealant' is Glyptal laquer. Probably safe to water wash.
> >
> > I would not use any solvent on the bobbins.
> >
> > The black encapsulates are likely Vishay, if they look like CK-05/6
> > ceramic caps. Alcohol should be safe for a quick rinse.
> >
> > -John
> >
> > =============
> >
> >
> >
> > > Nothing abrasive should be used. Soap and water and old toothbrush is
> > what
> > > I would try. Very high values avoid water!
> > > I use a cheap ultrasonic clear for some things in the shack!
> > >
> > > Raj
> > > VU2ZAP
> > > (former resistor manufacturer)
> > >
> > > At 17-08-2013, you wrote:
> > >>What is the recommended method for cleaning dirt, oil, etc from
> precision
> > >>resistors? I'm talking about a combination of wirewound on plastic
> > >> bobbins,
> > >>wirewound on mica (and sealed with something) and an unknown type that
> is
> > >>encapsulated in black plastic rectangles. These are all 1950-1960
> vintage
> > >>and are marked "Daven".
> > >>
> > >>Joe Gray
> > >>W5JG
> > >>_______________________________________________
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> >
> >
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