Let's pool our resources to find some used SITs, power JFETs etc

[Nelson Pass]

It's a junction device, might easily test as npn.

 

[adason]

I have bought parts that test as NPN (comupterized tester) but sold as SIT (THF51). (Or they are thyroids )

I was only talking about lu1014. Please see two posts earlier.

On the other hand I have few transistor testers and occasionally jfet is tested as bipolar. Nothing is perfect.

 

[mbrennwa]

Ha, just stumbled over this thread. Better late than never.
I believe the SIT hype is levelling off a bit. For those who are still looking for parts:

• Some Sony VFETs (both sexes) are available here.
• LD1014/LU1014 are available here.

 

[triode_al]

Adason. Sorry for misinterpreting (Yes I have some Lu1014, I know the part, would like to get copper strata placement boards).
As for the so-called THF51 that I got from the ALIpages, they are an NPN as my tester says, with a considerable gate current drive - the tester said µ=2, I measured Hfe 200* - 350*(warm). It is an NPN, fancy 'new device THF51' is just a scam.

- Test jig - an 8Ω resistor on the source (=emitter), a 5K pot for the gate (=base) and an ammeter in the gate lead. I just set it up such that if it is a SIT, that would show this way; output current would be self limiting; my "lab source" limits at around 1,4A.)
To double test my setting, I tested the 2N3055 same way.
(Invalid test. I did not have a constant Vce, please understand. Just comparative.)

 

[Zen Mod]

its simple as this - SIT is Normally On, while bjt is Normally Off

enough for differentiation

 

[mbrennwa]

As for the so-called THF51 that I got from the ALIpages

Link? Name of shop/seller?

 

[triode_al]

can't be giving the name (shrouded in history) but I had the choice of old and new and was so stupid to believe new was well sort of new old stock.
Anyway, nowadays I saw 2SK182 pucks advertised as thyristor, and be sure that is what it will test like - a rather hefty one. it is confusing for the layman.

 

[Demonkleaner]

I just bought a quad of "very closely matched" THF51's from Japan. Even have the curves for each device.
Curves would make a 300B jealous. Not cheap but I believe them to be authentic. Test as J-Fets on my not
so fancy tester. If I can finish my F5T mono blocks I want to try a MZM creation next. Have a 3U and 5U deluxe
case standing by 🙂

 

[pinholer]

Cheaper than a NOS 300B, though. And lasts a lot longer.

 

[Demonkleaner]

I have 2 sets of NOS 2A3's that I wanted to try in an amp but the cost
of good output transformers are insane. May just sell them to finance
future amps or maybe a pre-amp from these pages.

 

[mbrennwa]

300B or 2A3 are much more linear than the SITs.

 

[Svjatoslav]

There is still a question of who is more linear.
SITs can operate in an intermediate range between triode and pentode characteristics.
Similar to UL switching on tubes.
Where distortion is less than in a triode.

 

[mbrennwa]

Take a look at the curve data in the attachment. The 300B curves are nearly perfect copies of each other, at equal spacing. That's not the case for the SITs. The 300B is much more linear.

 

[Zen Mod]

if anyone is willing to send me a quantity of either .......... even better - both 300B and Tokin SIT (any), I'll be happy camper

though, 300B is linear as 300B + OPT combo is linear

btw. comparing to proper KT90 in UL, 300B is Miss Piggy

 

[Svjatoslav]

300V in the picture looks very linear.
Until the real load line is laid.
For SIT, you can choose it better.
In addition, let's not forget that there is no 300V without an output transformer. They must always be considered together

 

[pinholer]

And a 300B is only good for about 8 to 10 watts output. SIT, you can get 10 times that.

 

[Zen Mod]

again, send me some for free, either (better both) sand or glass, and I'll yeepyeepie tnx

 

[mbrennwa]

And 300B break if they fall off the work bench. And SITs are smaller. And 300Bs are available from new manufacture. And they are meant to do different things anyway. And, and, and. All I was trying to say is that SIT curves do not make a 300B jealous.

 

[Svjatoslav]

In other words, the 300V curves are very good to place on a picture. and hang it in the bedroom on the wall.
What I discovered for myself at SIT is work in the intermediate region between the pentode and the triode

 

[Demonkleaner]

And 300B break if they fall off the work bench. And SITs are smaller. And 300Bs are available from new manufacture. And they are meant to do different things anyway. And, and, and. All I was trying to say is that SIT curves do not make a 300B jealous.

Didn't say they were better than a 300B but for a SS device they are damn nice 😉