Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!apple!agate!ucbvax!hplabs!hpcc05!hpcuhb!hpihoah!mj
From: mj@hpihoah.cup.hp.com (Marlin Jones)
Newsgroups: sci.electronics
Subject: Re: Max. Junction Temp. for MRF492?
Message-ID: <5910005@hpihoah.cup.hp.com>
Date: 14 May 91 00:17:33 GMT
References: <1694@aupair.cs.athabascau.ca>
Organization: Hewlett Packard, Cupertino
Lines: 23

> / hpihoah:sci.electronics / lyndon@cs.athabascau.ca (Lyndon Nerenberg) /  2:44 pm  May 10, 1991 /
> Does anyone know the maximum (and recommended operating) junction
> temperature for the Motorola MRF492 RF transistor? I was a bit surprised
> to see that the data sheet does not list this.
>     Lyndon Nerenberg  VE6BBM / Computing Services / Athabasca University


My data book doesn't have this spec. either, but you can derive it.  If
you note Pd (at 25deg C) max = 250Watts, and combine that with the derating
of 1.43 W/deg C, you'll find that Pd (max) = zero at 175 deg. C.   Subtract
the nominal temp (25 deg C) and you get 150 deg. C.  Since its pretty hard 
to have a negative Pd, I'd say 150 degrees is about tops.  :-)
(all temps relate to the case temp.)

Hope this helps,

Marlin Jones

_______
Marlin Jones       hplabs!hpda!mj    mj@hpda.hp.com

"I practice safe motorcycling - I keep the rubber on the road."
I don't speak for Hewlett Packard, HP doesn't speak for me.