On 8/21/2011 5:18 AM, Peter Frenning [OZ1PIF] wrote:
> Den 21-08-2011 10:54, Roger (sub1) skrev:
>> On 8/21/2011 3:56 AM, David Shapiro wrote:
>>> Someone requested the datasheet.
>>>
>>>
>> This causes me to reflect on that 1200 watt output rating a bit. They
>> emphasize that the 1200 watts is "pulsed" at 100 uSec width and 20% duty
>> cycle. Then they also list 1200 W out CW. I don't see how they can get
>> both.
>>
>> On the positive side they do operate with a case temp as high as 150C.
>> BUT they also say they higher the case temp the shorter meantime between
>> failures. It also appears to be operating class C.
>>
>> I've not taken the time to really look at the curves, but it appears at
>> a glance that to operate one in a linear fashion would only result in a
>> few hundred watts out per device. So, using them as most devices are
>> presently used in amateur service (4 in PP parallel) would give about a
>> KW out at a cost of about $1,000 in devices, not counting other components.
>>
>> Devices are improving and great strides have been made, but those I've
>> talked with who have reached the testing stages found their main
>> roadblocks were cooling. The small heat transfer area of the device
>> makes it difficult to get a decent transfer and keep the delta T down to
>> a point where the device does not self destruct.
>>
>> 73
>>
>> Roger (K8RI)
>>
> Some data points to ponder can be found here:
> http://www.frenning.dk/OZ1PIF_HOMEPAGE/LDMOS_SSPA.html describing my
> newly "almost completed" 144MHz amp using this device (singly). I run
> it fairly conservatively at ~900W out with good reports and so so
> measuments.
>
Very nice looking piece of work.
73
Roger (K8RI)
> --
> Vy 73 de OZ1PIF/5Q2M, Peter
>
> *****************************************
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> ** perspiration. **
> ** -- Thomas A. Edison **
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> Peter Frenning
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