I made my own from T stock from ONLINEMETALS.COM In Wallingford, CT
.25" thick.
I drilled the holes using the circuit board as my template and used a countersink bit to chamfer the holes to make sure no burrs were around the holes. Pretty straight forward metal working.
You absolutely do not need to anodize the aluminum black. It is inside the chassis. The idea is to conduct the heat into the heatsink. You don't want it to radiate inside the chassis, it's hot enough inside. Black color radiates much more than the aluminum color does.
I also sanded all areas of contact with the heatsink and the transistors with a long straight flat sanding block.
Hope this helps.
Rush
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Rush, I'm only considering and mentioning originality. As that mis-used word and condition constantely comes up. How far does one take it. You can't say it is original unless made by the builder in period. If you or I build it, it's not original. Can you restore to original spec? Yes.
Since I could not get the Modushop brackets as the pair I bought was the last and needing 2 pair this VFET is not original and will be built considering that problem.
I'm not even using a T bracket to mount. 😱
They won't even be painted or anodized any color. 🙁
I've built chassis and bodies for vintage race cars. The owner then claims them to be original. I am at pains to be correct but unless you are an expert in many fields you won't know. I've even put in 'easter eggs' to be found out later it is not original.
For the Q1/Q2 pairs, I have matched Toshibas with Idss values of either 7.5 mA or 9 mA. Which one should I use?
The original NP Pt2 article specifies 8 mA.
The original NP Pt2 article specifies 8 mA.
Gentlemen,
Merry Christmas to everyone!
I need a confirmation that Q3 is ZTX450 and Q4 is ZTX550.
Thank you in advance,
Roumen Sotirov
Merry Christmas to everyone!
I need a confirmation that Q3 is ZTX450 and Q4 is ZTX550.
Thank you in advance,
Roumen Sotirov
No vfets yet. I was getting there. One channel..all voltages ok.
The other channel, T18 to G is at 28V..
What should I look for?
Need help...
Thank you
The other channel, T18 to G is at 28V..
What should I look for?
Need help...
Thank you
What voltages do you see across the R5/R6 (47.5R) and R34/R35 (221R) resistors?
Also what are the T19-G and T20-G voltages?
Also what are the T19-G and T20-G voltages?
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Hi Dennis,
At R5 -0.173v, R6 - 0.382, T19 -G is at 9.29v, T20 to G is 8.67v.
R34 at 0.19, R35 at 0.19v.
Thank you for your help.
At R5 -0.173v, R6 - 0.382, T19 -G is at 9.29v, T20 to G is 8.67v.
R34 at 0.19, R35 at 0.19v.
Thank you for your help.
Quick question, I bought the kit some years ago now, only boards and vfets. I would like to build it now. Do the power mosfets, the cascode transistors and the front end mosfets have to be matched? thanks
Those values seem very low; is that a typo? For example, 221R resistors and (say) 8mA current, you should see about 1.7V.
Only Q1 and Q2 need to be matched within one channel.
If I have more of them I will measure and choose close values for the other FETs. Otherwise they will go straight in and will proceed with the test and biasing of the front end.
They sound exactly the same to me (even with my ear pressed to them). Both have very, very low noise. 
Serious answer - I was lucky enough to get Toshibas for my VFET build, but I'd happily have used Fairchild parts. The basis for my opinion is swapping them out (I built two) in a BA-3 configuration for comparison. I don't recall there being that much of a difference, if any. The only time I've never compared them 'back-to-back' with the intention of trying to hear the difference was in the BA-3. So, as always, YMMV. Others may have different opinions, ears, brains, systems etc. They're all just as valid or possibly more so, my hearing is not fantastic.
Serious answer - I was lucky enough to get Toshibas for my VFET build, but I'd happily have used Fairchild parts. The basis for my opinion is swapping them out (I built two) in a BA-3 configuration for comparison. I don't recall there being that much of a difference, if any. The only time I've never compared them 'back-to-back' with the intention of trying to hear the difference was in the BA-3. So, as always, YMMV. Others may have different opinions, ears, brains, systems etc. They're all just as valid or possibly more so, my hearing is not fantastic.