How Good is this Transistor?

[Super_BQ]

Was at the scrap metal yard the other day. While salvaging 30kg of heatsinks I came across this IRF transistor.

HOW suitable is this transistor for say SoZ or the Zen v4 - anotherwords, how comparable is it to the IRF240? I recall IRF made some mosfets (ie IRF140?) that gave better performance than the 240.

from: http://www.microsemi.com/catalog/part.asp?id=46162

Breakdown Voltage Drain-to-Source BVDSS 200 V
Drain Current (Continuous) ID 25 A
Power Dissipation PD 150 W
Thermal Resistance, Junction to Case RqJC 0.83 ºC/Watt

BQ

[Mark A. Gulbrandsen]

I would think it would work unless there is too much capacitance involved with this device.....are there alot of them?
Mark

[Super_BQ]

Mark,

There wasn't many ; only 8 that were individually mounted on the heatsinks that I was after. Interestingly, they were on a single PCB so possibly all 8 of them may be matched.

Quite often I come across similar transistors and large can computer grade capacitors at this yard. As long as i'm buying those heavy heatsinks, they don't bother charging anything for the non-metal related items. Big can electrolytics do age but I havn't heard of transistors losing their potency with age?

Nevertheless, most transistors are cheap - it's just the exotic older ones that are no longer in production I wouldn't mind trying.

BQ

PS: may be a silly question but has anyone proven that TO-3 type transistors sound better than TO-247 ones of the same spec?

[Mark A. Gulbrandsen]

Don't know...you would have to ask the Man Himself about the sound difference between the two. The metal casings do not suffer nearly as badly from thermal fatigue over repeated thermal cyclings though. I know that plastics have gotten better in that department, but I doubt they can match metal case semi's.
Its too bad there were not more of them but you never know....more may turn up in the near future if more equipment like that is disposed of. Sounds like a handy yard to have around!
Mark

[halojoy]

Originally posted by Mark A. Gulbrandsen
I would think it would work unless there is too much capacitance involved with this device.....are there alot of them?
Mark

Found this NICE SITE
Perfect for Pass Amplifier DIY-selvers

MOSPEC SEMICONDUCTOR www.mospec.com

Put In Favourites !!!!!!!!!!!!

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http://www.mospec.com.tw/mosfet.htm

IRF240 200V 18A 0.18ohm 1600pF 125W TO-3
IRF252 200V 25A 0.12ohm 3000pF 150W TO-3
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You can use this transistor
But you might have to use MORE current in the Driverstage (double the current)
to compensate for the higher Capacitance 3000/1600

You have to consult Nelson. There might be enough current already.
Nelson likes to be on The Safe Side (regarding currents!!!)
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/halo - ask a question - halo can do the SEARCH

[halojoy]

I found this page with Technical Papers at - www.irf.com
this page have about MOSFETs including HEXFETs

http://www.irf.com/technical-info/papers.html#mosfet
--------------------------------------------------------

Interesting for All of You who PARALLELL mosfets
this will include a great number of you Pass-amp-Builders
This PDF is 30 pages and deals with

Paralleling of Power MOSFETs for Higher Power Output
James B. Forsythe, Member IEEE
International Rectifier, E1 Segundo, California

Abstract - Dynamic current and transition energy unbalance resulting from parameter mismatch between
parallel MOSFET branches are mapped over wide operating ranges. Unbalance generator magnitudes are given
for HEXFET Power MOSFET data sheet ant typical production batch extremes.
-----------------------
I (c) Potential Causes of Unbalance
There are several conceivable causes for current unbalance that may result in a particular device exceeding its peak current or
continuous thermal ratings. Unbalance may be generated by:
(i) device parameter mismatch
- ON resistance mismatch RDS (on)
- threshold voltage (VT)
- gain factor (GF, µ g fs )
- capacitance mismatch (CGD, gate-to-drain (Miller) or CGS, gate-to-source)
(ii) gate driver mismatch
- decoupling resistor (RG)
- gate loop inductance (LG)
(iii) power circuit mismatch
- branch inductance (LD, excluding LS)
- source inductance common to power and gate circuit (LS)

Paralleling of Power MOSFETs for Higher Power Output PDF

Nota bene: Even Nelson could learn a few small things by reading this PDF
Or maybe he has learned all there is?? If he thinks so, he is to pity .....
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halo - got no illusions about any person - and still is in lack of a GURU - besides his ALLMIGHTY GOD
- do as halojoy does: .... BE YOUR OWN GURU ....

[AudioFreak]

halojoy,

Nelson has stated on more than one occassion that Vgs matching has a large effect and is a very easy test to do. If you use devices from the same lot code, that is they are all from the same wafer, you usually find that the devices that were physically near each other on the wafer have the closest match for Vgs and also generally have a tight tolerance in all the other relevant specs.

As for the original question, it would help if we knew the transconductance of this device.

[Mark A. Gulbrandsen]

I found that to be very true. I ordered 100 IRFP240's from the same lot code and they are all pretty close to each other. Needless to say all 100 devices can find their way into amplifiers!!
Mark

[janneman]

Originally posted by Super_BQ
Mark,
[snip]PS: may be a silly question but has anyone proven that TO-3 type transistors sound better than TO-247 ones of the same spec?

BQ,

In my experience TO-3s can produce a mechanical sound when driven hard, the metal cap will be vibrating. Plastic TO-247s have more internal damping it seems, although they also can "sing" when too loose (correct Frank?) on the heatsink.

Jan Didden

[Nelson Pass]

I say use them and be happy.