Questions regarding matching of 2SK170

[Ruach]

Hi guys, I am quite new to JFETs and I hope that you can entertain my basic questions on JFETs.

Does a well matched pair of 2SK170 in terms of Idss = a 2SK389?

Are there any other parameters that I must watch out for during the matching process like temperature?

Is there a simple and quick way to match the 2SK170?


The world is running out of 2SK389. If any of you have a few pieces to spare, I will be glad to buy them off you. I need them for a balanced outout stage

Thanks for your help in advance.

[hacknet]

nope, the a pair of matched 2sk170s are not really equal to a 2sk389 because the magic about the 389 is the fact that they are on the same silicon die so temperature variations between the two fets are minimized. you will unlikely be able to get such temperature tracking with 2 170s tied together.

i've been matching jfets by measuring their Idss. you will need a power supply and an ammeter for this. i dont know if there is a better way but i already cant find good matches with this method.

[ashok]

I think it is Linear Systems that makes LSK170 and LSK389. They are in production and are exact replacements for the original.
Do a google search.
Cheers.

[Christer]

Why do people always talk about replacements for 2SK170? Is there any evidence that Toshiba has quit making them? There are several indications that they are still in production there, although I have no hard evidence.

[ashok]

Christer is right. I gave the information as an alternative source.
I bought 2SK170's a couple of months ago. It appears to be fresh production.

[Ruach]

Thanks guys.

I spoke with the sales reps from Toshiba and I was told that 2SK389 and 2SJ109 are discontinued.

2SK170 and 2SJ74 are not discontinued items but there is no inventory in all of Toshiba's offices throughout the world. Toshiba is not replenishing these parts. The indication is that they will be discontinued soon as with the case for the 2SK389 and 2SJ109.

I have also checked with a local Toshiba components supplier and he confirmed what Toshiba told me.

Toshiba is checking for me if there will be a replacement or an equivalent.

ashok - better hang on to your 2SK170

[Christer]

I wonder how we are to interpret that statement? Do they mean that yes, we have stopped manufacturing them, but we are still selling the few we have left in stock, so they are not disconinued yet. Or do they mean that they have cut down on the production, causing supply problems, and will probably cut down even more?

Anyway, this is finally som credible, although somewhat cryptical, info.

[Ruach]

That was what Toshiba Asia said,

Maybe you would like to check with Toshiba Europe and get a clear update on the status of this JFET.