[Amps] KPA1500 Efficiency vs. RF-Kit B26

[Artek Manuals]

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 at telus.net <
> jim.thom at telus.net> wrote:
>
>> Date: Mon, 12 Jul 2021 01:40:49 -0700
>> From: Jim Brown <jim at audiosystemsgroup.com>
>> To: amps at 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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