While they last...

[Analogico]

As you are aware "Shop5626058 Store" from diyAudio member pras1170 has the real deal.

 

[grataku]

Bought mine from watanabe on ebay.

 

[Gyuri]

Maybe I'm worrying too mutch.

The big gap if I screw up two Tokins together, is about 0.5 mm at the screwholes. If I measure gap perpendicular to the SITs longer side, it is decreases in a short way below 0.05 mm.
It is quite interesting at the same time, if I try to measure at the shorter side, I almost able to put through 0.05mm gap meter.
So this side is concave a littlebit.
I think, Soundhappy is right, when he recommend Kerafoil.
Mica too hard in this case, while Kerafoil 0.25 will be able to fill the gap.

Yet, it would be nice, if we know the recommended torque settings.

This is what I was trying to talk about:

 

[Gyuri]

So, I revised my previous viewpoint. I will use mica and goop.
I will use sandpaper before to reach a smooth plane.
Anyway, Keratherm-Kerafoil quite pricey, on that money I will buy some lottery rather.

 

[pras1170]

only stock

 

[Soundhappy]

@ Gyuri

You have 4 thermal pads for big Tokins from this
Kerafol 86/82 Thermally conductive film 0.25 mm 6.5 W/mK (L x W) 100 mm x 100 mm | Conrad.com
Kerafol ( brand name ) Keratherm ( product name ) high quality, price is not extravagant

 

[pras1170]

I can give the heat conducting film, the trap for free
(freight to be paid by yourself)

 

[Soundhappy]

So, I revised my previous viewpoint. I will use mica and goop.
I will use sandpaper before to reach a smooth plane.
Anyway, Keratherm-Kerafoil quite pricey, on that money I will buy some lottery rather.

Mica and goop do the job as well 😀 Most important is get use of the large size heat sinks

 

[triode_al]

Here’s my setup. 24v 2A transformer connected to the variac. Exactly as per your schematic.

Wow. That is the Thomas Edison version you have!

 

[sp33ls]

Oh man. I guess I shouldn't miss out on this VFET train, huh.

 

[Ylab]

View attachment 938389
Wow. That is the Thomas Edison version you have!

The original from Michael Rothacher look a little bit like this too, except for all the guts exposed 😉

If you have not seen it here it is : Frankentracer Part One - YouTube

 

[nicoch58]

only stock

NOS means :new old stock ,cannot be used 😛

 

[marantzfan]

Just ordered a roughly matched pair. Excited to see what Papa is cooking up!

 

[sp33ls]

Just ordered a roughly matched pair. Excited to see what Papa is cooking up!

Which did you end up going with?

 

[AlexRivera]

More fakes....

They don’t seem to have the base curvature issue tho... 😉

 

[marantzfan]

Which did you end up going with?

These ones:

Roughly matched pair (with rough data)THF-51S (2SK77,2SK182) TOKIN SIT NOS | eBay

 

[Gyuri]

You can see the dip:

 

[Soundhappy]

Thanks Gyuri 🙂

I keep original anodized metal protection layer.
Make up imperfections with small thermal paste goop layer is easy,
thermal film thickness can compensate as well.
Naked copper does easily oxidize and become grey green after a longer period of time.
Oxidation I am worry about.

 

[Gyuri]

Good point, Soundhappy!
And there is an eternal question:
If we would like to make a plain and smooth surface, how smooth is we need?
If it will be like a glass surface, there will no remain goop between device and heatsink.
About oxidation, you are correct, I doesn't gave a tought to this viewpoint.
I hope so, on the fixed device with mica and goop it will be not an issue.

 

[nicoch58]

gyuri need just a micron of paste