Jim N7CXI (too many Jim's)
Now that is a valid point. I have been into the amp and there no
thermocouples or sensors attached to the LDMOS ceramic or tabs for that
matter
One possible explanation is that it is a calculated number for the case
temperature based on the substrate temperature?
IF WE HAD SCHEMATICS ELECRAFT IT WOULD HELP ...(anybody listening?) 8^(
Dave
NR1DX
On 7/13/2021 3:42 PM, Jim Barber wrote:
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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