Vishay Dale mil spec metal film resistors

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Bruciep07
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Vishay Dale mil spec metal film resistors

Post by Bruciep07 »

I need some info on Dale RN60 resistors... I ordered 1/2 resistors and the supplier I got them from sent me RN60 resistors, which as far as I can tell from the data sheet, are rated at 1/4W. I contacted the supplier and was told that they are mil spec 1/4W which in commercial applications are considered 1/2W. I replied to this supplier that nowhere on the data sheet does it state that they are rated to 1/2W and they assured me that they tested them themselves to 1/2W and they barely got warm. I don't like the idea of using 1/4W resistors in a 1/2W application just because the guy that sold them to me said they were ok... Can anyone confirm any of the info above?
Bruce
rfgordon
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Re: Vishay Dale mil spec metal film resistors

Post by rfgordon »

The Vishay Dales used in Dumble builds (and are fine in other designs as plate resistors) are the RN65, not RN60.

I've used lots of RN65s, but couldn't comment on the RN60. Compare the data sheets for the two types, and that should tell you what you need to know.
Rich Gordon
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"The takers get the honey, the givers get the blues." --Robin Trower
Jana
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Re: Vishay Dale mil spec metal film resistors

Post by Jana »

I have used lots of RN60's in amps in places that take a 1/2 watt and they are fine. They are physically the size of a regular 1/2 watt. I know, size isn't the whole story, just saying.

Recently I have been using RN65's as my RN60 stock is depleted. No other reason than the 65's were easier to get at the time and the leads were a little longer.

So, bottom line, use the 60's and feel safe.
C Moore
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Re: Vishay Dale mil spec metal film resistors

Post by C Moore »

Is this factual? I mean what Bruciep07 was told by the supplier. Is a "military" watt worth more than a "commercial" watt???
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FYL
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Re: Vishay Dale mil spec metal film resistors

Post by FYL »

I contacted the supplier and was told that they are mil spec 1/4W which in commercial applications are considered 1/2W.
The commercial equivalent of the RN60 is the RMF60, rated at .5 watts.

From the RFM datasheet : "(Except for marking, the Industrial and Military versions are exactly the same. Depending upon stock, military marked parts may be supplied as industrial rated parts)".

http://www.vishay.com/docs/31018/cmfind.pdf
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ToneMerc
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Re: Vishay Dale mil spec metal film resistors

Post by ToneMerc »

hired hand wrote:Is this factual? I mean what Bruciep07 was told by the supplier. Is a "military" watt worth more than a "commercial" watt???
The supplier is correct.

An "RN" is a military resistor built to a combat specification. It is fit for vibration, humidity, temperature extremes, and operation at maximum rating for long periods of time. For this reason the military power rating is less than the commercial rating. The military specifiction (milspec) for the RN resistor is MIL-R-10509 (M10509 for short).

The RN60 military power rating at 70 degress C is 1/4 watt and 1/8 watt at 125 degrees C. The equivalent commercial power rating at 70 degrees C is 1/2 watt (except .4 watt for Electra).

TM
Bruciep07
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Re: Vishay Dale mil spec metal film resistors

Post by Bruciep07 »

Thanks for all the replies guys, the data sheet is confusing to me because it shows the equivalent as being the cmf60 and it shows 4 different power ratings in the same column, but being that the watage rating drops down to 1/4W at a specific temp, I just didn't understand how that could still be rated at 1/2W... I think mouser and Newark had them listed as 1/4W... Guess I'll just use them...
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FYL
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Re: Vishay Dale mil spec metal film resistors

Post by FYL »

Take a very conservative 40°C value for heat rise: 1/2w rating.
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Structo
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Re: Vishay Dale mil spec metal film resistors

Post by Structo »

Yeah I remember when I was researching the RN65D resistors.
The way Mouser has them listed I wasn't sure of their rating.

I was looking at the 150K RN65D, the description said it was a 1/2 watt but when I brought the resistor up, it called it a 1/4 watt resistor.

The RN series has a max voltage of 350v, but that is mil spec so more likely you could double that spec.

The power rating is spec'd at .5 watt on the datasheet.

As the voltage rating, you can safely say that this resistor is capable of handling power much above that rating.

The main thing about these resistors is there low noise floor and close tolerances, heat does not affect them like other resistors.
Tom

Don't let that smoke out!
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