If they’re measuring the case temp I’ll buy 90C.
If it was on the spreader the amp would be dead by now. 40C is a
conservative limit for the spreader, 50C if you’re taking chances.
90C is a reasonable temp for the ceramic case over the junction… tricky to
keep the thermistor wires out of the way of the device tabs and decoupled,
though.
73,
Jim N7CXI
On Tue, Jul 13, 2021 at 12:25 PM jim.thom jim.thom@telus.net <
jim.thom@telus.net> wrote:
> Date: Mon, 12 Jul 2021 01:40:49 -0700
> From: Jim Brown <jim@audiosystemsgroup.com>
> To: amps@contesting.com
> Subject: Re: [Amps] KPA1500 Efficiency vs. RF-Kit B26
>
>
>
>
> <When I'm contesting on HF, always at 1.5kW, I've seen temps at 90 C, the
> <fans run faster, I'm happy, and the amp is happy.
> <73, Jim K9YC
>
> ## 90 deg C ? wtf?
> 90 deg C = 194 deg F !
>
> ## Are u sure abt this ? That's stupid hor for a LDMOS device. What is
> the ambient temp in the shack when this is going on ?
>
> Jim VE7RF
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