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 >_______________________________________________ >volt-nuts mailing list -- volt-nuts@febo.com >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >and follow the instructions there.

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 >>_______________________________________________ >>volt-nuts mailing list -- volt-nuts@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@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > >

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@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 > >>_______________________________________________ > >>volt-nuts mailing list -- volt-nuts@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@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@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > >

"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@febo.com [volt-nuts-bounces@febo.com] on behalf of Joseph Gray [jgray@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@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 > >>_______________________________________________ > >>volt-nuts mailing list -- volt-nuts@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@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@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@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. -- Message protected by MailGuard: e-mail anti-virus, anti-spam and content filtering. http://www.mailguard.com.au

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@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@febo.com [volt-nuts-bounces@febo.com] on behalf > of Joseph Gray [jgray@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@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 > > >>_______________________________________________ > > >>volt-nuts mailing list -- volt-nuts@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@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@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@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > -- > Message protected by MailGuard: e-mail anti-virus, anti-spam and content > filtering. > http://www.mailguard.com.au > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > >