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Re: [Amps] 'heat spreader' sizing ??

Subject: Re: [Amps] 'heat spreader' sizing ??
From: Steve Thompson <>
Date: Wed, 09 Feb 2011 22:36:11 +0000
List-post: <">>
>>> Both Freescale and NXP discuss mounting the latest high power
>>> devices in application notes. For example, see NXP #10800 para. 2.5.
>> Sorry, that should be AN10858.
> To me they look kinda impractical for linear techniques and particularly 
> at HF.
> A 1200 watt transistor to get an average of 200 out?
> 73
> Roger (K8RI)

Certainly wasted at hf, and I'd have worries about ruggedness at 
lower frequencies. Its a 1200W transistor for 1200W peak out with 
digital radio or TV signals, which have a lower average power - 
but you need some linearity and headroom to keep the IMD under 

There's lots of info. from N1DPM on a cw version for 144MHz on the 
VK4DD forum. That thread is currently public without needing to 
register (it's free) at

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