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Re: 18 watt jtm / 18 watt Lite II
Posted: Sat 10/09/21 8:29 pm
by mehfuzhoss
these mosfets are 400V mouser part: 78-IRF740BPBF
Re: 18 watt jtm / 18 watt Lite II
Posted: Sat 10/09/21 8:30 pm
by geoff 1965
Try and post the mosfet spec sheet rather than the mouser part No.
I know they are a pain in the butt to source the correct type! i.e. the Toshiba ones I used are now obsolete and the NTE2377’s are over £15 each here in the UK.
Re: 18 watt jtm / 18 watt Lite II
Posted: Sat 10/09/21 9:11 pm
by mehfuzhoss
spec pdf attached
Re: 18 watt jtm / 18 watt Lite II
Posted: Sat 10/09/21 9:25 pm
by geoff 1965
The voltage and power dissipation look okay,you don’t want less than 600V especially if your going to use the 290paz with higher B+ and you have to take into account voltage surge when powering on which will be a lot higher than your stable B+ voltage.okay so get the spec sheet for the NTE2377 or NTE2973 and compare to see if it’s the same type.
Re: 18 watt jtm / 18 watt Lite II
Posted: Fri 10/15/21 4:57 pm
by mehfuzhoss
not same but very similar in specification comparison.
Drain source voltage is 600V and 297x upto 900v
Power dissipation is low at @180Watt whereas 297x has 250watt
input/output capacitance is 1350/70 pf whereas 297x input/output capacitance is: 2900/290 pf
so power dissipation and I/0 capacitance has a lots of gap.