The toshiba and Fairchilds have very different bias voltages.
When I swapped from the toshiba's to the Fairchilds I had to increase the bias voltage a lot more to get the fairchilds to even register. When I swapped the toshiba's back I forgot to turn down the pot and almost blew the fets.
Trying to match the correct voltage with resistors I guess would be possible but doesn't seem like an easy task.
When I swapped from the toshiba's to the Fairchilds I had to increase the bias voltage a lot more to get the fairchilds to even register. When I swapped the toshiba's back I forgot to turn down the pot and almost blew the fets.
Trying to match the correct voltage with resistors I guess would be possible but doesn't seem like an easy task.
Tinitus,
A man of few words.
Looking at the datasheets (thank you BTW)
they conduct slightly more than 1/2 the potential current of the FQA. If one were to double them up, say run 4 pair rather than 2 pair (same bias), would that help with the "grunt" factor? ie:F5 vs F5T
I like the price!
Ron
A man of few words.
Looking at the datasheets (thank you BTW)
they conduct slightly more than 1/2 the potential current of the FQA. If one were to double them up, say run 4 pair rather than 2 pair (same bias), would that help with the "grunt" factor? ie:F5 vs F5T
I like the price!
Ron
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might be exstremely tough transistor
maybe the miller capacitance will be the limit to how many can be used
do you know how much we can handle ?
anyway, it might be possible to improve cooling/heat transfer further
the fact that 'base' metal is exposed on both sides means we could almost double the heat transfer with a special clamping device
maybe the miller capacitance will be the limit to how many can be used
do you know how much we can handle ?
anyway, it might be possible to improve cooling/heat transfer further
the fact that 'base' metal is exposed on both sides means we could almost double the heat transfer with a special clamping device
[QUOTE
The interesting thing about the Toshiba units is that you might be able to use other JFET's than the K170/J74, i.e. 2N5460/2N5457 in their smt versions. Same goes with the Renesas MOSFETs. It's the old "dog food" problem that you learned in linear programming.
QUOTE]
What do you mean with that? I would like to use the 2SJ201/1530's in my F5T, can I, or is it better to, use 2N5460/2N5457 at the input stage? What are the advantages?
The interesting thing about the Toshiba units is that you might be able to use other JFET's than the K170/J74, i.e. 2N5460/2N5457 in their smt versions. Same goes with the Renesas MOSFETs. It's the old "dog food" problem that you learned in linear programming.
QUOTE]
What do you mean with that? I would like to use the 2SJ201/1530's in my F5T, can I, or is it better to, use 2N5460/2N5457 at the input stage? What are the advantages?
Tinitus,
Your knowledge is Greatly appreciated and I especially thank you for "hand -holding".
The ouput Capacitance of the Vishay is less than the Fairchilds. The input capacitance is almost 10 times less. If the Miller effect is cumulative, then it would seem that having at least 4 pairs is possible.
Ron
Your knowledge is Greatly appreciated and I especially thank you for "hand -holding".
The ouput Capacitance of the Vishay is less than the Fairchilds. The input capacitance is almost 10 times less. If the Miller effect is cumulative, then it would seem that having at least 4 pairs is possible.
Ron
The two are the same; just extended characteristics (voltage/amperes). There is no mention of another type by Hitachi. All looks the same.
What made you think so? No reason for that kind of wrong presumptions.
I built an F5 variant with 2sk135/2sj successfully but I didn't write about it because I was displeased with the sound (a bit too soft, mellow). Someone else might like it. I suppose that two pairs per channel would make it more neutral (more gm, more OLG) but I wasn't ready to go that far (I found what I looked for with 2sk2013/2sj313).
F5 with laterals is an easy build - you don't need Source resistors for them and thermal comp. parts are not needed (NTCs). I leave out the over-current protection (ztx450/550) routinely. Laterals have lower Vgs (about 2V for Id of 1A) so they need less resistance in the drain circuit of input JFETs and that lowers the OLG further but there is a remedy for that - you can use GR grade of JFETs (Idss of 3-5mA) and they will work on lower current but the bandwidth won't be compromised since the laterals have lower parasitic capacitance than HEXFETs.
So, nothing stands in your way to build F5 with k135/j50 - it's simple enough to make a point-to-point test circuit and see if you like it...
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