STW12NK90Z FET

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STW12NK90Z FET

Postby n4lta » Sat Aug 21, 2010 1:48 pm

Has anyone tried the STM 12NK90Z in the place of the 11N90?

It has a little more input capacitance but the on resisstance is .88 ohms

I have 5 that I may try but just looking for a little support before I burn my fingers and beat my head against the wall.

Pat
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Re: STW12NK90Z FET

Postby kf1z » Sun Aug 22, 2010 7:27 am

That FET should work ok...

the only real difference is the max device dissapation is 230 watts, compared with the 11n90 300watts.

the input C is the same and the Rds is the same. ( the MAX Rds for 11n90 is .96, typical is .75)
The MAX Ciss for 11n90 is 3500pf.


I would assume one would need to operate the STW fet at slightly less power output. maybe 75% ?

But, worth a try if they are already on hand.
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Re: STW12NK90Z FET

Postby n4lta » Sun Aug 22, 2010 9:39 am

I may try them in a 100 watt class D amp.

I am waiting for some 11N90s from Steve for a 450 watt rig. I already have completed a PWM modulator.
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Re: STW12NK90Z FET

Postby steve_qix » Wed Sep 01, 2010 12:50 pm

n4lta wrote:I may try them in a 100 watt class D amp.

I am waiting for some 11N90s from Steve for a 450 watt rig. I already have completed a PWM modulator.


Right - I've got to get that order out. I've been spending copious amounts of time at Rattlesnake Island (check this: http://www.rattlesnakeisland.net) this summer - as we really GOT a good summer this year - not like last year, and Sherrie has the summers off from her job. I can do mine off site a lot of the time.

I'll get that stuff shipped ASAP. How much do those other FETs cost per unit? The FQA is, from what I can see, still the most cost effective!
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Re: STW12NK90Z FET

Postby kf1z » Wed Sep 01, 2010 2:35 pm

The STW part is $2.80 each in small quantities ( under 10 pcs )
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Re: STW12NK90Z FET

Postby steve_qix » Wed Sep 01, 2010 4:24 pm

kf1z wrote:The STW part is $2.80 each in small quantities ( under 10 pcs )


Where? Mouser has them for $4.37 each.
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Re: STW12NK90Z FET

Postby steve_qix » Wed Sep 01, 2010 4:33 pm

Looking closely at the device, it may work. The die is larger, as indicated by the higher gate capacitance and higher gate charge. The reverse transfer capacitance is higher also... all indicative of a larger die. Probably, the thermal resistance within the package may be higher. The device should have a similar dissipation to the FQA, but there may be other factors involved.

These will probably work on 75 meters and of course 160. 40 will be questionable.

The 11n90s still have somewhat better characteristics, but the STW is one of the closest I've seen in a long time.

If I can get some eval units, I'll run some experiments.

Regards,

Steve
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Re: STW12NK90Z FET

Postby kf1z » Wed Sep 01, 2010 5:19 pm

Future Electronics.....

http://www.futureelectronics.com/en/Sea ... e,Nea:True


Sorry... it's $2.89 each
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Re: STW12NK90Z FET

Postby n4lta » Thu Sep 09, 2010 1:14 pm

Steve,

I got the parts and thanks again.

I think the above mentioned parts that I have are samples. I should have my modulator ready to go in a week or so and I may try a few of them in a simple class D
push pull circuit to see what happens.

Pat
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