[NJARC] Rn-60, RN-55 etc ???

[antqradio at juno.com]

Hi Bill
Yes, the resistor ratings are confusing.
Download the following from IRC:
http://www.irctt.com/PDF_FILES/IBT.PDF for carbon composition resistors.
http://www.irctt.com/pdf_files/RN.pdf for RN metal film resistors.
Now compare:
RN (metal film) resistor are rated for 2X power rating for 10,000 hours
for a resistance change of +- 0.5%.
Carbon composition resistors are rated for 2.5X power rating for 5
seconds for a resistance change of +- 2%.
RN derate to zero watts at 175 degrees C, carbon composition derate to
zero watts at 130 degrees C.
To level the playing field, you can safely operate RN at twice the power
rating when compared to carbon composition.
Regards,
Jim


On Sun, 4 Dec 2005 09:00:57 EST Billoradio at aol.com writes:
> Visit our web site - See http://www.njarc.org
> _______________________________________________
> I am sorting a bunch of light green/turquoise old stock Dale metal 
> film  
> resistors. These came in snap in black plastic 10 piece trays. I 
> dont know what  
> to believe about the RN codes. 
>  
> A web search gives inconsistant information.
> Some are listed as
> RN-55  1/4 Watt
> RN-60  1/2 W
> RN-65  3/4 W
> RN-70  1 W
>  
> Then I saw some listed as
> RN-65  1 W
> RN-70  2 W
>  
> I found a package of Dales on a cardboard holder marked RN-55  that  
> had MF 
> 1/8 handwriten on the package at the factory.
>  
> Please set me straight.  I have about 3 or 4 thousand of these and  
> would 
> like to use some and pass some along.
>  
> Thanks
> Bill Overbeck