Just need to know where to look I guess...
Pretty sure Hannes still has some about.
F5 Transistor kit
Pretty sure Hannes still has some about.
F5 Transistor kit
The only tough ones to get are the input JFETs and amongst other places mentioned above, you can get them from spencer at fetaudio.com - I believe many have bought from him. Not cheap but they are the originals.
If you need a full kit (all the transistors in one package, and his Jfets are genuine) I would happily suggest Hannes, his Forum name is " h_a " Search and send him a message.
I have bought from him before, he is great to work with.
Buzzforb has really nice output transistors.
The little ones in the limiter circuit are available by the bazillion at all the normal distributors.
I have bought from him before, he is great to work with.
Buzzforb has really nice output transistors.
The little ones in the limiter circuit are available by the bazillion at all the normal distributors.
The 2SJ74 may very well be perfectly within tolerance for IDSS.
NONE of the ones I got from ebay or from other asian sources are genuine, there is a thread here about fakes, look for it, there are examples of the JFET fakes. Also some USA suppliers are just passing along fakes from asia.
The problem is mostly going to be the 2SJ74. The 2SK170 being offered may or may not be a real 2SK170, but it is easier to make N ch JFETs and the ones being offered work and curve trace ok.
The J74s I have obtained DO NOT match at all when curve traced.
The gains are different, as is the linearity.
But it is a functioning JFet, just not a Toshiba that is anywhere near a compliment to the K170.
This is not a low noise circuit, or one where low noise is required, so that aspect does not matter.
The performance of the amp in terms of harmonic distortion will be altered by the difference between the P & Nch JFETs in the front end. The amp will function regardless.
Hannes probably has legit parts. Spencer I have no information about.
Beyond this, it is apparent that JFETs and through hole parts in general are becoming rare quickly, and may end up being more difficult to source than tubes! Ironic.
_-_-bear
NONE of the ones I got from ebay or from other asian sources are genuine, there is a thread here about fakes, look for it, there are examples of the JFET fakes. Also some USA suppliers are just passing along fakes from asia.
The problem is mostly going to be the 2SJ74. The 2SK170 being offered may or may not be a real 2SK170, but it is easier to make N ch JFETs and the ones being offered work and curve trace ok.
The J74s I have obtained DO NOT match at all when curve traced.
The gains are different, as is the linearity.
But it is a functioning JFet, just not a Toshiba that is anywhere near a compliment to the K170.
This is not a low noise circuit, or one where low noise is required, so that aspect does not matter.
The performance of the amp in terms of harmonic distortion will be altered by the difference between the P & Nch JFETs in the front end. The amp will function regardless.
Hannes probably has legit parts. Spencer I have no information about.
Beyond this, it is apparent that JFETs and through hole parts in general are becoming rare quickly, and may end up being more difficult to source than tubes! Ironic.
_-_-bear
I concur with Bear. The K170's and SJ74's I've purchased through eBay in the past couple years were revealed as fakes on a curve tracer, even if their Idss happened to be within spec. I can confirm that Spencer's product looks genuine when curve traced. Unfortunately, he has been raising prices as things become scarce (can't blame him, supply and demand). Maybe Linear systems will one day bring their sj74 to market, but don't hold your breath.
Papa our question is not if but when ? I ask that with all due respect to you. RegardsI have "reliable" information that this will occur.
This is also our finding.
A team member of XEN who has the best equipment in the Team (R&S UPV) did extensive measurements on LSK170 compared to 2SK170.
As a result of his measurements, we immediately bought a life time stock of Toshiba devices from Japan even at premium prices.
(This supplier is now also out of stock.)
While most of the LSK170s meet noise specs, their distortion in a typical circuit is higher than 2SK170.
And they also need to be operated at much higher Vds than the Toshiba's.
So even though we are fully aware of the possible (since 2005?) availability of the LSJ74s, we shall continue to want to use Toshiba's in our DIY lifetime.
You only need to compare the annual budget for process development at Toshiba, to say the total turnover of Linear, to understand why.
And look around in all Japanese (as well as elsewhere) semiconductor manufacturers.
Who else has ever managed to put out a low-noise, high-Yfs P-JFET ?
Only NEC, years and years ago (2SK163 / 2SJ44).
A few years from now, Toshiba FETs will just become like NOS tubes from Telefunken etc.
You can still get new equivalent tubes from Russia or China these days, but they are just not the same.
Patrick
A team member of XEN who has the best equipment in the Team (R&S UPV) did extensive measurements on LSK170 compared to 2SK170.
As a result of his measurements, we immediately bought a life time stock of Toshiba devices from Japan even at premium prices.
(This supplier is now also out of stock.)
While most of the LSK170s meet noise specs, their distortion in a typical circuit is higher than 2SK170.
And they also need to be operated at much higher Vds than the Toshiba's.
So even though we are fully aware of the possible (since 2005?) availability of the LSJ74s, we shall continue to want to use Toshiba's in our DIY lifetime.
You only need to compare the annual budget for process development at Toshiba, to say the total turnover of Linear, to understand why.
And look around in all Japanese (as well as elsewhere) semiconductor manufacturers.
Who else has ever managed to put out a low-noise, high-Yfs P-JFET ?
Only NEC, years and years ago (2SK163 / 2SJ44).
A few years from now, Toshiba FETs will just become like NOS tubes from Telefunken etc.
You can still get new equivalent tubes from Russia or China these days, but they are just not the same.
Patrick
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.