J49/K135 Fets.............Anybody have these? - diyAudio
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Old 6th January 2006, 05:09 PM   #1
slizm is offline slizm  United States
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Default J49/K135 Fets.............Anybody have these?

I'm having trouble finding these parts and wondered if anyone can point me in the right direction. I need 2 of each(hitachi). Thanks in advance.
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Old 9th January 2006, 09:26 PM   #2
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The Hitachis in the early 80s were available in 3 voltage ranges.

2SK134/2SJ49 were in the same voltage range
2SK135/2SJ50 were in the same voltage range

The two devices you seek are not from the same voltage range. Tell us why you need these two and how they will be used.

I can help you with matched pairs of 2SK134/2SJ49.
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Old 9th January 2006, 11:08 PM   #3
slizm is offline slizm  United States
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I have an old EV powered mixing board I want to fix. It has 2 separate heat sinks with audio board attached with J49/k134 Fets(1 pair each). Just trying to replace these so I can get my audio going again.
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Old 10th January 2006, 02:08 PM   #4
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OK, thanks for the info. First, your specified K135, now you state K134.

I can help you with matched pairs of 2SK134/2SJ49. Are these what you want? If so, send me an email using the DIYaudio email messaging system.

I use a bona fide original Hafler MOSFET checker that can grade these MOSFETs into one of 7 categories (1-7). Do your MOSFETs in question have an add-on number either stenciled or hand written on them, a number 1-7? If either device is used in parallel pairs they must be matched on Vgs which my MOSFET checker can do.

Now, how do you know you need to replace the ones you have? These are very robust devices. In an amp other parts, such as on the PCB usually fail first, not the MOSFETs on the heat sinks.

Regardless, I will help if possible.
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Old 16th February 2006, 01:42 AM   #5
slizm is offline slizm  United States
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I took this amp to a shop and basically, they couldn't fix this since they couldn't get the necessary parts to fix,(j49/k134 fets).
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Old 17th February 2006, 10:24 AM   #6
poynton is offline poynton  United Kingdom
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Hi.

The '49/134 pairs were used in a 150w mosfet amp I had. When I wanted to build another, the following were supplied, as the originals were obsolete.

ECF10P16 / ECF10N16 125w 160v 8A
ECF10P20 / ECF10P20 125w 200v 8A

http://pdf1.alldatasheet.com/datashe.../ECF10N25.html



Hope this helps.

Andy
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Old 17th February 2006, 03:52 PM   #7
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But, you have to realized that the original pairs were matched. Profusion in the UK will sell replacement devices but they are ungraded. In other words you might have to purchase10-20 each of them, measure their Vgs, and then put them into pairs based on ±VGS. This is why graded pairs are more expensive than single items and matched pairs are mostly unavailable.

You can replace Hitachis with Exicon (Profusion) devices if the MOSFETs are used in singles, such as in the Hafler DH-120 amp, but if they are used in pairs or triplets they must be matched.

Some amateurs claim that getting devices from the same date/batch number means they will match on Vgs but this apparently has shown not to be true. Or, you could insert a series resistor between the source and load -- to force each device to share current equally. But, I suppose that if this were done both channels would have to be wired in a similar fashion to keep the output the same at each channel.

Sorry to be so long-winded but users need to realize that just replacing a device is only part of what is needed. I use a bona fide original Hafler MOSFET checking meter to match pairs or triplets.
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Old 27th September 2006, 05:42 PM   #8
bobelmo is offline bobelmo  United States
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Default j49 k134

I just found 8 (4 each) from a clone kit I never built. They all have 3D1 on them. Are these matched? If not, what would it cost to have them matched? Bob Eiser
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Old 27th September 2006, 06:21 PM   #9
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Dick, can you still get those testers?
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Old 27th September 2006, 08:07 PM   #10
mobyd is offline mobyd  New Zealand
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You can emulate the function of the Hafler tester with a couple of power supplies. It simply maps Vgs to Ids. One thing I have noticed is that it is difficult to mix'n'match original (Hitachi) parts with the replacement Exicon parts. It helps to have grab bag of assorted parts when trying to match a replacement with an incumbent in a parallel bank.
M
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