Bottlehead Forum

General Category => Technical topics => Topic started by: Jim R. on May 29, 2013, 05:45:26 AM

Title: Aluminum body power resistors?
Post by: Jim R. on May 29, 2013, 05:45:26 AM

Hi Folks,

I'm looking for those, what I remember as being gold anodized, finned aluminum power resistors with the offset mounting flanges (mounting ears on opposite sides at opposite ends of the body of the resistor.)  They used to be made by Dale and/or TRW, but suppose they must be vishay something or another nowadays.  Anybody got a clue or example part number for say a 1.5 k maybe 15/20 watt version?  I've looked at mouser and digikey but the list is daunting and without the pictures I cannot be sure of what I'm ordering.

From the holes on the paramount/paramour plate that are between driver andpower tube it appears that maybe a similar resistor to this was used, at least at some point.

Thanks,

Jim

Title: Re: Aluminum body power resistors?
Post by: galyons on May 29, 2013, 06:04:48 AM

Michael Percy sells 50W power resistors:

50W NI POWER RESISTORS: 1%, 50ppm, 50 watt, 890VDC, non-inductive wire
wound resistors with gold anodized aluminum finned case custom made
for us.

50 watt rating at 25

Title: Re: Aluminum body power resistors?
Post by: nullspace on May 29, 2013, 06:32:37 AM

Hi Jim,

At Mouser, if you search '71-NH' you'll get a list of all the Vishay, chassis-mount non-inductive wirewounds. They have a 71-NH50-1.5K for $10.04 per in stock.

Regards,
John

Title: Re: Aluminum body power resistors?
Post by: Jim R. on May 29, 2013, 07:03:48 AM

Thanks, Gents.  This should get me going and then some.

-- Jim

Title: Re: Aluminum body power resistors?
Post by: coca on May 29, 2013, 05:59:49 PM

The Parts Connexion has a selection of Mills non iductive as well.

Bernie.

Title: Re: Aluminum body power resistors?
Post by: 2wo on May 29, 2013, 06:22:23 PM

Hi Jim,

Consider the Mills MRA-5, or 12w, if rating permits. Axial leads, easier to implement.   

Title: Re: Aluminum body power resistors?
Post by: Jim R. on May 30, 2013, 03:14:26 AM

Hi John and Bernie,

I already have plenty of the Mills but wanted something that could handle more power and be easily heat sinkable.  Thanks for the suggestions anyway.

-- Jim

John, did you get the heatsinks?

Title: Re: Aluminum body power resistors?
Post by: Grainger49 on May 30, 2013, 12:11:04 PM

Jim,

Wouldn't heat shrinking the aluminum bodied resistors hurt the heat dissipation?  Or are you taking this into account?

Title: Re: Aluminum body power resistors?
Post by: 2wo on May 30, 2013, 01:05:32 PM

Jim, yes I did. thank you...John

Title: Re: Aluminum body power resistors?
Post by: Jim R. on May 30, 2013, 01:12:39 PM

Grainger,

That's heat *sinking* not *shrinking* :-).  No, I have no desire to build something that fills the room with toxic gases when it is powered on ;-).

John, hope they work out for you -- they seem to fit very nicely here.

-- Jim

Title: Re: Aluminum body power resistors?
Post by: Grainger49 on May 30, 2013, 03:35:37 PM

Jim,

After 6.5 hours in a car, my mother-in-law in the back reading to us (she can't turn up her hearing aids so doesn't  know when someone else is talking) I should not try to read with my eyes permanently crossed.  When I arrived I was ready to put a bullet in my ear.

I went back, it says heat sinking not shrinking.