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The great FET hunt...

post #1 of 37
11/30/10 at 10:11am
Thread Starter 

I'm looking at building a Gilmore Lite/ Dynalo  but am having a devilish

time tying to find the FETs used in the front end.

2SJ109 and 2SK389 are the original spec and 2SJ74 and 2SK170 

have been listed as subs. All of these are pretty scarce.

Are there any modern/commonly available substitute?

Is there a re-design for a more commonly available part?

 

Maybe we could design a tube substitute for the FETs and

call it a Dynaglo...

 

EDIT: Changed part number...bad typing


Edited by Avro_Arrow - 12/3/10 at 4:24am
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post #2 of 37
11/30/10 at 10:18am

AMB has the 2SJ74 and 2SK107 available in his store. 

 

He will even match them as quads if you want.

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post #3 of 37
11/30/10 at 11:12am

depends on how long you are willing to wait. if you are a member of DIYA 'Zhoufang' has a sales thread there with 2sk170GR/BL for 35 per 100 can mix IDSS if you like, he has J74, but has not got around to putting them in bins yet for IDSS rating, has thousands of them, so will probably be a little while on that part. i'm waiting myself. the parts are legit, he has been selling them for some time now with no complaints. he also has semisouth power jfets too if thats of interest. the P channel linear systems LSJ74 is actually supposed to be really ready shortly and some were given away as samples at RMAF, so this problem may well be over, although of course they have a different pattern/pinout that must be dealt with.

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post #4 of 37
11/30/10 at 4:54pm
Thread Starter 

Thanks guys for the replies.

I guess I may be taking to AMB soon then.

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post #5 of 37
11/30/10 at 5:17pm

Not only does AMB carry the parts and pcbs, but also offers matching services for the jfets you require.

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post #6 of 37
11/30/10 at 9:45pm
Somehow I suspect that Avro_Arrow is not going to need a store-bought pcb for his dynalo. :-)
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post #7 of 37
11/30/10 at 10:01pm



 

Quote:
Originally Posted by jdkJake View Post

Somehow I suspect that Avro_Arrow is not going to need a store-bought pcb for his dynalo. :-)



I'd love to see a hand etched single sided Dynalo PCB using mostly SMD parts.

Toshiba 2sc2712 and 2sa1162 are near perfect SMD replacements for the

2sa1815 and 2sc1015. and they are available at Mouser for cheap.

 

You could increase the number of output transistors from 4 pairs to say 6 pairs and drop

the class A bias a bit to make up for the small SMD package heat dissipation.

A SMD dynalo should fit in a altoids tin pretty easily.

 

and when you're all done, you could publish the board artwork so clods like me

could make an attempt at etching. evil_smiley.gif


Edited by bada bing - 11/30/10 at 10:06pm
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post #8 of 37
12/1/10 at 5:00am
Thread Starter 

HaHaHa...Dynalo in a mint tin...Dynamint?

 

I might almost be tempted to try it.

Heat would be the biggest problem I think.

I'm going to do a full sized board first though.

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post #9 of 37
12/1/10 at 5:02am

I would build one in a second..not literally of course. that sounds like a way cool idea, love SMD!!

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post #10 of 37
12/1/10 at 6:51am

Sijosae was the best.

 

Gilmore in a mint tin

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post #11 of 37
12/1/10 at 7:05am
Thread Starter 

Yes, I love looking through his pictures and schematics...he was a master.
 

Quote:
Originally Posted by cobaltmute View Post

Sijosae was the best.

 

Gilmore in a mint tin

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post #12 of 37
12/2/10 at 8:34pm

It's 2SK170, not 107 BTW. B&D has both in stock, and I'm sure Amb does as well.

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post #13 of 37
12/3/10 at 4:25am
Thread Starter 

Your right....either my bad typing or bad reading...thanks for the catch!
 

 

Quote:
Originally Posted by Pars View Post

It's 2SK170, not 107 BTW. B&D has both in stock, and I'm sure Amb does as well.

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post #14 of 37
12/3/10 at 6:20am

I've seen lots of offers on ebay, don't know if that sources are reliable though

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post #15 of 37
12/3/10 at 6:35am

I've got a some 30 j74 coming in from ebay. Will test them out to see if they are genuine.

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