[Amps] LDMOS HEAT SPREADERS

[Kevin]

On 8/31/2016 9:49 AM, Manfred Mornhinweg wrote:
>
> In the PC overclocking scene, a lot of snake oil is being sold. 
Not necessarily. My quad core AMD running at 3.5GHz per core, full tilt, 
will dissipate 135W. The Zallman cooler I have on mine will keep the CPU 
temp in a range of 32-35 C at full output. It's a very large, round, 
brazed up combination of heat pipes and copper radiator fins surrounding 
a 135mm diameter fan.
> I would first do a reality check on any CPU cooler rated for several 
> hundred watts, before using it for a real high power application. 
The newest AMD processors are eight core and will dissipate 225W when 
run full out. Want to stress a CPU and it's cooler...give it to a bunch 
of gamers. If it passes muster with them it's pretty good. This is how 
PC water cooling got started. Alienware was the first manufacturer to 
offer water cooled gaming rigs. I believe they were also one of the 
first companies to try liquid N2 cooling. They got a 125% overclock 
running stable with liquid N2. We used to dance in the street when we 
got 30% with air cooling. I got an Intel Celeron 300A up to 450MHz, 50% 
overclock, but it took some serious messing around with CPU and memory 
voltages, CAS/RAS memory latency, etc.... These days they hook up a 
water cooler and get that all day long.

Would I recommend trying to cheap out and use PC coolers for cooling an 
LDMOS amp. Of course not. anybody who does so needs a good public 
slapping. The stuff being sold in overclocking circles isn't snake oil. 
If you sell crap in the "PC Enthusiast" market you'll be out of business 
in a week, two tops. They can get vicious if they think they're getting 
screwed.

By the way, the 1dB compression point on a typical LDMOS package like 
the BLF188XR with 50V is about 1100W out.
I'd use a pair and keep each chip in the 750-800W range.


-- 
R. Kevin Stover
AC0H
ARRL
FISTS #11993
SKCC #215
NAQCC #3441


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus