Re: [Amps] KPA1500 Efficiency vs. RF-Kit B26

[Adrian <vk4tux@gmail.com>]

The problem also with that is the temperature at the LDMOS source 
material (mount flange) is usually much hotter than where the sensor
is located. In the SPE anyway, on which I have measured (infra red laser 
thermometer) a 69 deg C TD between the two.
So the indicated temp is usually the heat-sink average, and not the device.

That is why 50 deg C indicated is a safer limit, I would not take it 
past 70 in a pinch.
It would interesting to check the sensor and LDMOS (on both) TD in the 
KPA1500.

vk4tux


On 14/7/21 5:25 am, jim.thom 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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