Vishay Dale mil spec metal film resistors

General discussion area for tube amps.

Moderators: pompeiisneaks, Structo, mhuss, HeeBGB

Post Reply
Bruciep07
Posts: 250
Joined: Sat Feb 07, 2009 6:56 am
Location: Central NJ

Vishay Dale mil spec metal film resistors

Post by Bruciep07 » Sat Feb 06, 2010 9:49 pm

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
Posts: 679
Joined: Tue May 02, 2006 12:59 am
Location: Virginia
Contact:

Re: Vishay Dale mil spec metal film resistors

Post by rfgordon » Sat Feb 06, 2010 10:05 pm

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
www.myspace.com/bigboyamplifiers

"The takers get the honey, the givers get the blues." --Robin Trower

Jana
Posts: 1314
Joined: Sun Sep 07, 2008 10:40 pm
Location: Minnesota

Re: Vishay Dale mil spec metal film resistors

Post by Jana » Sat Feb 06, 2010 10:20 pm

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
Posts: 1263
Joined: Mon Oct 22, 2007 9:28 am
Location: USA, California, 94585

Re: Vishay Dale mil spec metal film resistors

Post by C Moore » Sat Feb 06, 2010 10:44 pm

Is this factual? I mean what Bruciep07 was told by the supplier. Is a "military" watt worth more than a "commercial" watt???

User avatar
FYL
Posts: 654
Joined: Fri Feb 17, 2006 1:05 am

Re: Vishay Dale mil spec metal film resistors

Post by FYL » Sun Feb 07, 2010 12:07 am

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

User avatar
ToneMerc
Posts: 3466
Joined: Sun Apr 26, 2009 3:55 pm
Location: East Coast

Re: Vishay Dale mil spec metal film resistors

Post by ToneMerc » Sun Feb 07, 2010 12:17 am

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
Posts: 250
Joined: Sat Feb 07, 2009 6:56 am
Location: Central NJ

Re: Vishay Dale mil spec metal film resistors

Post by Bruciep07 » Sun Feb 07, 2010 4:17 am

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...

User avatar
FYL
Posts: 654
Joined: Fri Feb 17, 2006 1:05 am

Re: Vishay Dale mil spec metal film resistors

Post by FYL » Sun Feb 07, 2010 12:44 pm

Take a very conservative 40°C value for heat rise: 1/2w rating.

User avatar
Structo
Posts: 15451
Joined: Wed Oct 17, 2007 1:01 am
Location: Oregon

Re: Vishay Dale mil spec metal film resistors

Post by Structo » Sun Feb 07, 2010 5:15 pm

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!

Post Reply

Who is online

Users browsing this forum: No registered users and 10 guests